gdb: add target_ops::supports_displaced_step
[deliverable/binutils-gdb.git] / gdb / infrun.c
index e3e4bdb9b847483a1dd6ef9c32dcf61282495489..de09bb038359b26495bde1d654c97009cf3670cb 100644 (file)
@@ -19,6 +19,9 @@
    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
 
 #include "defs.h"
+#include "displaced-stepping.h"
+#include "gdbsupport/common-defs.h"
+#include "gdbsupport/common-utils.h"
 #include "infrun.h"
 #include <ctype.h>
 #include "symtab.h"
@@ -35,6 +38,7 @@
 #include "top.h"
 #include "inf-loop.h"
 #include "regcache.h"
+#include "utils.h"
 #include "value.h"
 #include "observable.h"
 #include "language.h"
@@ -56,7 +60,7 @@
 #include "target-dcache.h"
 #include "terminal.h"
 #include "solist.h"
-#include "event-loop.h"
+#include "gdbsupport/event-loop.h"
 #include "thread-fsm.h"
 #include "gdbsupport/enum-flags.h"
 #include "progspace-and-thread.h"
@@ -64,8 +68,9 @@
 #include "arch-utils.h"
 #include "gdbsupport/scope-exit.h"
 #include "gdbsupport/forward-scope-exit.h"
-#include "gdb_select.h"
+#include "gdbsupport/gdb_select.h"
 #include <unordered_map>
+#include "async-event.h"
 
 /* Prototypes for local functions */
 
@@ -73,10 +78,6 @@ static void sig_print_info (enum gdb_signal);
 
 static void sig_print_header (void);
 
-static int follow_fork (void);
-
-static int follow_fork_inferior (int follow_child, int detach_fork);
-
 static void follow_inferior_reset_breakpoints (void);
 
 static int currently_stepping (struct thread_info *tp);
@@ -101,6 +102,24 @@ static struct async_event_handler *infrun_async_inferior_event_token;
    Starts off as -1, indicating "never enabled/disabled".  */
 static int infrun_is_async = -1;
 
+#define infrun_log_debug(fmt, args...) \
+  infrun_log_debug_1 (__LINE__, __func__, fmt, ##args)
+
+static void ATTRIBUTE_PRINTF(3, 4)
+infrun_log_debug_1 (int line, const char *func,
+                   const char *fmt, ...)
+{
+  if (debug_infrun)
+    {
+      va_list args;
+      va_start (args, fmt);
+      std::string msg = string_vprintf (fmt, args);
+      va_end (args);
+
+      fprintf_unfiltered (gdb_stdout, "infrun: %s: %s\n", func, msg.c_str ());
+    }
+}
+
 /* See infrun.h.  */
 
 void
@@ -110,10 +129,7 @@ infrun_async (int enable)
     {
       infrun_is_async = enable;
 
-      if (debug_infrun)
-       fprintf_unfiltered (gdb_stdlog,
-                           "infrun: infrun_async(%d)\n",
-                           enable);
+      infrun_log_debug ("enable=%d", enable);
 
       if (enable)
        mark_async_event_handler (infrun_async_inferior_event_token);
@@ -411,8 +427,8 @@ show_follow_fork_mode_string (struct ui_file *file, int from_tty,
    the fork parent.  At return inferior_ptid is the ptid of the
    followed inferior.  */
 
-static int
-follow_fork_inferior (int follow_child, int detach_fork)
+static bool
+follow_fork_inferior (bool follow_child, bool detach_fork)
 {
   int has_vforked;
   ptid_t parent_ptid, child_ptid;
@@ -669,11 +685,11 @@ holding the child stopped.  Try \"set detach-on-fork\" or \
    if the inferior should be resumed; false, if the target for some
    reason decided it's best not to resume.  */
 
-static int
-follow_fork (void)
+static bool
+follow_fork ()
 {
-  int follow_child = (follow_fork_mode_string == follow_fork_mode_child);
-  int should_resume = 1;
+  bool follow_child = (follow_fork_mode_string == follow_fork_mode_child);
+  bool should_resume = true;
   struct thread_info *tp;
 
   /* Copy user stepping state to the new inferior thread.  FIXME: the
@@ -684,6 +700,8 @@ follow_fork (void)
   struct breakpoint *exception_resume_breakpoint = NULL;
   CORE_ADDR step_range_start = 0;
   CORE_ADDR step_range_end = 0;
+  int current_line = 0;
+  symtab *current_symtab = NULL;
   struct frame_id step_frame_id = { 0 };
   struct thread_fsm *thread_fsm = NULL;
 
@@ -714,7 +732,7 @@ follow_fork (void)
             happened.  */
          thread_info *wait_thread = find_thread_ptid (wait_target, wait_ptid);
          switch_to_thread (wait_thread);
-         should_resume = 0;
+         should_resume = false;
        }
     }
 
@@ -737,6 +755,8 @@ follow_fork (void)
                                         (tp->control.step_resume_breakpoint);
            step_range_start = tp->control.step_range_start;
            step_range_end = tp->control.step_range_end;
+           current_line = tp->current_line;
+           current_symtab = tp->current_symtab;
            step_frame_id = tp->control.step_frame_id;
            exception_resume_breakpoint
              = clone_momentary_breakpoint (tp->control.exception_resume_breakpoint);
@@ -797,6 +817,8 @@ follow_fork (void)
                      = step_resume_breakpoint;
                    tp->control.step_range_start = step_range_start;
                    tp->control.step_range_end = step_range_end;
+                   tp->current_line = current_line;
+                   tp->current_symtab = current_symtab;
                    tp->control.step_frame_id = step_frame_id;
                    tp->control.exception_resume_breakpoint
                      = exception_resume_breakpoint;
@@ -888,10 +910,8 @@ proceed_after_vfork_done (struct thread_info *thread,
       && !thread->stop_requested
       && thread->suspend.stop_signal == GDB_SIGNAL_0)
     {
-      if (debug_infrun)
-       fprintf_unfiltered (gdb_stdlog,
-                           "infrun: resuming vfork parent thread %s\n",
-                           target_pid_to_str (thread->ptid).c_str ());
+      infrun_log_debug ("resuming vfork parent thread %s",
+                       target_pid_to_str (thread->ptid).c_str ());
 
       switch_to_thread (thread);
       clear_proceed_status (0);
@@ -1053,10 +1073,8 @@ handle_vfork_child_exec_or_exit (int exec)
             free now.  */
          scoped_restore_current_thread restore_thread;
 
-         if (debug_infrun)
-           fprintf_unfiltered (gdb_stdlog,
-                               "infrun: resuming vfork parent process %d\n",
-                               resume_parent);
+         infrun_log_debug ("resuming vfork parent process %d",
+                           resume_parent);
 
          iterate_over_threads (proceed_after_vfork_done, &resume_parent);
        }
@@ -1251,6 +1269,8 @@ follow_exec (ptid_t ptid, const char *exec_file_target)
      to symbol_file_command...).  */
   insert_breakpoints ();
 
+  gdb::observers::inferior_execd.notify (inf);
+
   /* The next resume of this inferior should bring it to the shlib
      startup breakpoints.  (If the user had also set bp's on
      "main" from the old (parent) process, then they'll auto-
@@ -1264,7 +1284,7 @@ follow_exec (ptid_t ptid, const char *exec_file_target)
    to avoid starvation, otherwise, we could e.g., find ourselves
    constantly stepping the same couple threads past their breakpoints
    over and over, if the single-step finish fast enough.  */
-struct thread_info *step_over_queue_head;
+struct thread_info *global_thread_step_over_chain_head;
 
 /* Bit flags indicating what the thread needs to step over.  */
 
@@ -1347,9 +1367,7 @@ set_step_over_info (const address_space *aspace, CORE_ADDR address,
 static void
 clear_step_over_info (void)
 {
-  if (debug_infrun)
-    fprintf_unfiltered (gdb_stdlog,
-                       "infrun: clear_step_over_info\n");
+  infrun_log_debug ("clearing step over info");
   step_over_info.aspace = NULL;
   step_over_info.address = 0;
   step_over_info.nonsteppable_watchpoint_p = 0;
@@ -1481,11 +1499,7 @@ step_over_info_valid_p (void)
    displaced step operation on it.  See displaced_step_prepare and
    displaced_step_fixup for details.  */
 
-/* Default destructor for displaced_step_closure.  */
-
-displaced_step_closure::~displaced_step_closure () = default;
-
-/* Get the displaced stepping state of process PID.  */
+/* Get the displaced stepping state of inferior INF.  */
 
 static displaced_step_inferior_state *
 get_displaced_stepping_state (inferior *inf)
@@ -1493,55 +1507,68 @@ get_displaced_stepping_state (inferior *inf)
   return &inf->displaced_step_state;
 }
 
-/* Returns true if any inferior has a thread doing a displaced
-   step.  */
+/* Get the displaced stepping state of thread THREAD.  */
 
-static bool
-displaced_step_in_progress_any_inferior ()
+static displaced_step_thread_state *
+get_displaced_stepping_state (thread_info *thread)
 {
-  for (inferior *i : all_inferiors ())
-    {
-      if (i->displaced_step_state.step_thread != nullptr)
-       return true;
-    }
-
-  return false;
+  return &thread->displaced_step_state;
 }
 
-/* Return true if thread represented by PTID is doing a displaced
-   step.  */
+/* Return true if the given thread is doing a displaced step.  */
 
-static int
-displaced_step_in_progress_thread (thread_info *thread)
+static bool
+displaced_step_in_progress (thread_info *thread)
 {
   gdb_assert (thread != NULL);
 
-  return get_displaced_stepping_state (thread->inf)->step_thread == thread;
+  return get_displaced_stepping_state (thread)->in_progress ();
 }
 
-/* Return true if process PID has a thread doing a displaced step.  */
+/* Return true if any thread of this inferior is doing a displaced step.  */
 
-static int
+static bool
 displaced_step_in_progress (inferior *inf)
 {
-  return get_displaced_stepping_state (inf)->step_thread != nullptr;
+  for (thread_info *thread : inf->non_exited_threads ())
+    {
+      if (displaced_step_in_progress (thread))
+       return true;
+    }
+
+  return false;
 }
 
-/* If inferior is in displaced stepping, and ADDR equals to starting address
-   of copy area, return corresponding displaced_step_closure.  Otherwise,
-   return NULL.  */
+/* Return true if any thread is doing a displaced step.  */
 
-struct displaced_step_closure*
-get_displaced_step_closure_by_addr (CORE_ADDR addr)
+static bool
+displaced_step_in_progress_any_thread ()
 {
-  displaced_step_inferior_state *displaced
-    = get_displaced_stepping_state (current_inferior ());
+  for (thread_info *thread : all_non_exited_threads ())
+    {
+      if (displaced_step_in_progress (thread))
+       return true;
+    }
 
-  /* If checking the mode of displaced instruction in copy area.  */
-  if (displaced->step_thread != nullptr
-      && displaced->step_copy == addr)
-    return displaced->step_closure.get ();
+  return false;
+}
+
+/* If inferior is in displaced stepping, and ADDR equals to starting address
+   of copy area, return corresponding displaced_step_copy_insn_closure.  Otherwise,
+   return NULL.  */
 
+struct displaced_step_copy_insn_closure *
+get_displaced_step_copy_insn_closure_by_addr (CORE_ADDR addr)
+{
+// FIXME: implement me (only needed on ARM).
+//  displaced_step_inferior_state *displaced
+//    = get_displaced_stepping_state (current_inferior ());
+//
+//  /* If checking the mode of displaced instruction in copy area.  */
+//  if (displaced->step_thread != nullptr
+//      && displaced->step_copy == addr)
+//    return displaced->step_closure.get ();
+//
   return NULL;
 }
 
@@ -1556,8 +1583,7 @@ infrun_inferior_exit (struct inferior *inf)
    doesn't support it, GDB will instead use the traditional
    hold-and-step approach.  If AUTO (which is the default), GDB will
    decide which technique to use to step over breakpoints depending on
-   which of all-stop or non-stop mode is active --- displaced stepping
-   in non-stop mode; hold-and-step in all-stop mode.  */
+   whether the target works in a non-stop way (see use_displaced_stepping).  */
 
 static enum auto_boolean can_use_displaced_stepping = AUTO_BOOLEAN_AUTO;
 
@@ -1577,29 +1603,56 @@ show_can_use_displaced_stepping (struct ui_file *file, int from_tty,
                        "to step over breakpoints is %s.\n"), value);
 }
 
+/* Return true if the target behing THREAD supports displaced stepping.  */
+
+static bool
+target_supports_displaced_stepping (thread_info *thread)
+{
+  inferior *inf = thread->inf;
+  target_ops *target = inf->top_target ();
+
+  return target->supports_displaced_step (thread);
+}
+
 /* Return non-zero if displaced stepping can/should be used to step
    over breakpoints of thread TP.  */
 
-static int
-use_displaced_stepping (struct thread_info *tp)
+static bool
+use_displaced_stepping (thread_info *tp)
 {
-  struct regcache *regcache = get_thread_regcache (tp);
-  struct gdbarch *gdbarch = regcache->arch ();
+  /* If the user disabled it explicitly, don't use displaced stepping.  */
+  if (can_use_displaced_stepping == AUTO_BOOLEAN_FALSE)
+    return false;
+
+  /* If "auto", only use displaced stepping if the target operates in a non-stop
+     way.  */
+  if (can_use_displaced_stepping == AUTO_BOOLEAN_AUTO
+      && !target_is_non_stop_p ())
+    return false;
+
+  /* If the target doesn't support displaced stepping, don't use it.  */
+  if (!target_supports_displaced_stepping (tp))
+    return false;
+
+  /* If recording, don't use displaced stepping.  */
+  if (find_record_target () != nullptr)
+    return false;
+
   displaced_step_inferior_state *displaced_state
     = get_displaced_stepping_state (tp->inf);
 
-  return (((can_use_displaced_stepping == AUTO_BOOLEAN_AUTO
-           && target_is_non_stop_p ())
-          || can_use_displaced_stepping == AUTO_BOOLEAN_TRUE)
-         && gdbarch_displaced_step_copy_insn_p (gdbarch)
-         && find_record_target () == NULL
-         && !displaced_state->failed_before);
+  /* If displaced stepping failed before for this inferior, don't bother trying
+     again.  */
+  if (displaced_state->failed_before)
+    return false;
+
+  return true;
 }
 
-/* Simple function wrapper around displaced_step_inferior_state::reset.  */
+/* Simple function wrapper around displaced_step_thread_state::reset.  */
 
 static void
-displaced_step_reset (displaced_step_inferior_state *displaced)
+displaced_step_reset (displaced_step_thread_state *displaced)
 {
   displaced->reset ();
 }
@@ -1638,20 +1691,17 @@ displaced_step_dump_bytes (struct ui_file *file,
    stepped now; 0 if displaced stepping this thread got queued; or -1
    if this instruction can't be displaced stepped.  */
 
-static int
+static displaced_step_prepare_status
 displaced_step_prepare_throw (thread_info *tp)
 {
   regcache *regcache = get_thread_regcache (tp);
   struct gdbarch *gdbarch = regcache->arch ();
-  const address_space *aspace = regcache->aspace ();
-  CORE_ADDR original, copy;
-  ULONGEST len;
-  struct displaced_step_closure *closure;
-  int status;
+  displaced_step_thread_state *thread_disp_step_state
+    = get_displaced_stepping_state (tp);
 
-  /* We should never reach this function if the architecture does not
+  /* We should never reach this function if the target does not
      support displaced stepping.  */
-  gdb_assert (gdbarch_displaced_step_copy_insn_p (gdbarch));
+  gdb_assert (target_supports_displaced_stepping (tp));
 
   /* Nor if the thread isn't meant to step over a breakpoint.  */
   gdb_assert (tp->control.trap_expected);
@@ -1662,127 +1712,103 @@ displaced_step_prepare_throw (thread_info *tp)
      jump/branch).  */
   tp->control.may_range_step = 0;
 
-  /* We have to displaced step one thread at a time, as we only have
-     access to a single scratch space per inferior.  */
-
-  displaced_step_inferior_state *displaced
-    = get_displaced_stepping_state (tp->inf);
-
-  if (displaced->step_thread != nullptr)
-    {
-      /* Already waiting for a displaced step to finish.  Defer this
-        request and place in queue.  */
-
-      if (debug_displaced)
-       fprintf_unfiltered (gdb_stdlog,
-                           "displaced: deferring step of %s\n",
-                           target_pid_to_str (tp->ptid).c_str ());
-
-      thread_step_over_chain_enqueue (tp);
-      return 0;
-    }
-  else
-    {
-      if (debug_displaced)
-       fprintf_unfiltered (gdb_stdlog,
-                           "displaced: stepping %s now\n",
-                           target_pid_to_str (tp->ptid).c_str ());
-    }
-
-  displaced_step_reset (displaced);
+  /* We are about to start a displaced step for this thread, if one is already
+     in progress, we goofed up somewhere.  */
+  gdb_assert (!thread_disp_step_state->in_progress ());
 
   scoped_restore_current_thread restore_thread;
 
   switch_to_thread (tp);
 
-  original = regcache_read_pc (regcache);
+  CORE_ADDR original_pc = regcache_read_pc (regcache);
 
-  copy = gdbarch_displaced_step_location (gdbarch);
-  len = gdbarch_max_insn_length (gdbarch);
+  displaced_step_prepare_status status =
+    tp->inf->top_target ()->displaced_step_prepare (tp);
 
-  if (breakpoint_in_range_p (aspace, copy, len))
+  if (status == DISPLACED_STEP_PREPARE_STATUS_ERROR)
     {
-      /* There's a breakpoint set in the scratch pad location range
-        (which is usually around the entry point).  We'd either
-        install it before resuming, which would overwrite/corrupt the
-        scratch pad, or if it was already inserted, this displaced
-        step would overwrite it.  The latter is OK in the sense that
-        we already assume that no thread is going to execute the code
-        in the scratch pad range (after initial startup) anyway, but
-        the former is unacceptable.  Simply punt and fallback to
-        stepping over this breakpoint in-line.  */
       if (debug_displaced)
-       {
-         fprintf_unfiltered (gdb_stdlog,
-                             "displaced: breakpoint set in scratch pad.  "
-                             "Stepping over breakpoint in-line instead.\n");
-       }
+       fprintf_unfiltered (gdb_stdlog,
+                           "displaced: failed to prepare (%s)",
+                           target_pid_to_str (tp->ptid).c_str ());
 
-      return -1;
+      return DISPLACED_STEP_PREPARE_STATUS_ERROR;
     }
-
-  /* Save the original contents of the copy area.  */
-  displaced->step_saved_copy.resize (len);
-  status = target_read_memory (copy, displaced->step_saved_copy.data (), len);
-  if (status != 0)
-    throw_error (MEMORY_ERROR,
-                _("Error accessing memory address %s (%s) for "
-                  "displaced-stepping scratch space."),
-                paddress (gdbarch, copy), safe_strerror (status));
-  if (debug_displaced)
+  else if (status == DISPLACED_STEP_PREPARE_STATUS_UNAVAILABLE)
     {
-      fprintf_unfiltered (gdb_stdlog, "displaced: saved %s: ",
-                         paddress (gdbarch, copy));
-      displaced_step_dump_bytes (gdb_stdlog,
-                                displaced->step_saved_copy.data (),
-                                len);
-    };
+      /* Not enough displaced stepping resources available, defer this
+        request by placing it the queue.  */
 
-  closure = gdbarch_displaced_step_copy_insn (gdbarch,
-                                             original, copy, regcache);
-  if (closure == NULL)
-    {
-      /* The architecture doesn't know how or want to displaced step
-        this instruction or instruction sequence.  Fallback to
-        stepping over the breakpoint in-line.  */
-      return -1;
-    }
+      if (debug_displaced)
+       fprintf_unfiltered (gdb_stdlog,
+                           "displaced: not enough resources available, "
+                           "deferring step of %s\n",
+                           target_pid_to_str (tp->ptid).c_str ());
+
+      global_thread_step_over_chain_enqueue (tp);
+      tp->inf->displaced_step_state.unavailable = true;
+
+      return DISPLACED_STEP_PREPARE_STATUS_UNAVAILABLE;
+    }
+
+  gdb_assert (status == DISPLACED_STEP_PREPARE_STATUS_OK);
+
+// FIXME: Should probably replicated in the arch implementation now.
+//
+//  if (breakpoint_in_range_p (aspace, copy, len))
+//    {
+//      /* There's a breakpoint set in the scratch pad location range
+//      (which is usually around the entry point).  We'd either
+//      install it before resuming, which would overwrite/corrupt the
+//      scratch pad, or if it was already inserted, this displaced
+//      step would overwrite it.  The latter is OK in the sense that
+//      we already assume that no thread is going to execute the code
+//      in the scratch pad range (after initial startup) anyway, but
+//      the former is unacceptable.  Simply punt and fallback to
+//      stepping over this breakpoint in-line.  */
+//      if (debug_displaced)
+//     {
+//       fprintf_unfiltered (gdb_stdlog,
+//                           "displaced: breakpoint set in scratch pad.  "
+//                           "Stepping over breakpoint in-line instead.\n");
+//     }
+//
+//      gdb_assert (false);
+//      gdbarch_displaced_step_release_location (gdbarch, copy);
+//
+//      return -1;
+//    }
 
   /* Save the information we need to fix things up if the step
      succeeds.  */
-  displaced->step_thread = tp;
-  displaced->step_gdbarch = gdbarch;
-  displaced->step_closure.reset (closure);
-  displaced->step_original = original;
-  displaced->step_copy = copy;
-
-  {
-    displaced_step_reset_cleanup cleanup (displaced);
+  thread_disp_step_state->set (gdbarch);
 
-    /* Resume execution at the copy.  */
-    regcache_write_pc (regcache, copy);
-
-    cleanup.release ();
-  }
+  // FIXME: get it from _prepare?
+  CORE_ADDR displaced_pc = 0;
 
   if (debug_displaced)
-    fprintf_unfiltered (gdb_stdlog, "displaced: displaced pc to %s\n",
-                       paddress (gdbarch, copy));
+    fprintf_unfiltered (gdb_stdlog,
+                       "displaced: prepared successfully thread=%s, "
+                       "original_pc=%s, displaced_pc=%s\n",
+                       target_pid_to_str (tp->ptid).c_str (),
+                       paddress (gdbarch, original_pc),
+                       paddress (gdbarch, displaced_pc));
 
-  return 1;
+  return DISPLACED_STEP_PREPARE_STATUS_OK;
 }
 
 /* Wrapper for displaced_step_prepare_throw that disabled further
    attempts at displaced stepping if we get a memory error.  */
 
-static int
+static displaced_step_prepare_status
 displaced_step_prepare (thread_info *thread)
 {
-  int prepared = -1;
+  displaced_step_prepare_status status
+    = DISPLACED_STEP_PREPARE_STATUS_ERROR;
 
   try
     {
-      prepared = displaced_step_prepare_throw (thread);
+      status = displaced_step_prepare_throw (thread);
     }
   catch (const gdb_exception_error &ex)
     {
@@ -1792,12 +1818,8 @@ displaced_step_prepare (thread_info *thread)
          && ex.error != NOT_SUPPORTED_ERROR)
        throw;
 
-      if (debug_infrun)
-       {
-         fprintf_unfiltered (gdb_stdlog,
-                             "infrun: disabling displaced stepping: %s\n",
-                             ex.what ());
-       }
+      infrun_log_debug ("caught exception, disabling displaced stepping: %s",
+                       ex.what ());
 
       /* Be verbose if "set displaced-stepping" is "on", silent if
         "auto".  */
@@ -1813,34 +1835,7 @@ displaced_step_prepare (thread_info *thread)
       displaced_state->failed_before = 1;
     }
 
-  return prepared;
-}
-
-static void
-write_memory_ptid (ptid_t ptid, CORE_ADDR memaddr,
-                  const gdb_byte *myaddr, int len)
-{
-  scoped_restore save_inferior_ptid = make_scoped_restore (&inferior_ptid);
-
-  inferior_ptid = ptid;
-  write_memory (memaddr, myaddr, len);
-}
-
-/* Restore the contents of the copy area for thread PTID.  */
-
-static void
-displaced_step_restore (struct displaced_step_inferior_state *displaced,
-                       ptid_t ptid)
-{
-  ULONGEST len = gdbarch_max_insn_length (displaced->step_gdbarch);
-
-  write_memory_ptid (ptid, displaced->step_copy,
-                    displaced->step_saved_copy.data (), len);
-  if (debug_displaced)
-    fprintf_unfiltered (gdb_stdlog, "displaced: restored %s %s\n",
-                       target_pid_to_str (ptid).c_str (),
-                       paddress (displaced->step_gdbarch,
-                                 displaced->step_copy));
+  return status;
 }
 
 /* If we displaced stepped an instruction successfully, adjust
@@ -1850,52 +1845,33 @@ displaced_step_restore (struct displaced_step_inferior_state *displaced,
    -1.  If the thread wasn't displaced stepping, return 0.  */
 
 static int
-displaced_step_fixup (thread_info *event_thread, enum gdb_signal signal)
+displaced_step_finish (thread_info *event_thread, enum gdb_signal signal)
 {
-  struct displaced_step_inferior_state *displaced
-    = get_displaced_stepping_state (event_thread->inf);
-  int ret;
+  displaced_step_thread_state *displaced
+    = get_displaced_stepping_state (event_thread);
 
-  /* Was this event for the thread we displaced?  */
-  if (displaced->step_thread != event_thread)
+  /* Was this thread performing a displaced step?  */
+  if (!displaced->in_progress ())
     return 0;
 
   displaced_step_reset_cleanup cleanup (displaced);
 
-  displaced_step_restore (displaced, displaced->step_thread->ptid);
-
   /* Fixup may need to read memory/registers.  Switch to the thread
      that we're fixing up.  Also, target_stopped_by_watchpoint checks
-     the current thread.  */
+     the current thread, and displaced_step_restore performs ptid-dependent
+     memory accesses using current_inferior() and current_top_target().  */
   switch_to_thread (event_thread);
 
-  /* Did the instruction complete successfully?  */
-  if (signal == GDB_SIGNAL_TRAP
-      && !(target_stopped_by_watchpoint ()
-          && (gdbarch_have_nonsteppable_watchpoint (displaced->step_gdbarch)
-              || target_have_steppable_watchpoint)))
-    {
-      /* Fix up the resulting state.  */
-      gdbarch_displaced_step_fixup (displaced->step_gdbarch,
-                                    displaced->step_closure.get (),
-                                    displaced->step_original,
-                                    displaced->step_copy,
-                                    get_thread_regcache (displaced->step_thread));
-      ret = 1;
-    }
-  else
-    {
-      /* Since the instruction didn't complete, all we can do is
-         relocate the PC.  */
-      struct regcache *regcache = get_thread_regcache (event_thread);
-      CORE_ADDR pc = regcache_read_pc (regcache);
-
-      pc = displaced->step_original + (pc - displaced->step_copy);
-      regcache_write_pc (regcache, pc);
-      ret = -1;
-    }
+  /* Do the fixup, and release the resources acquired to do the displaced
+     step. */
+  displaced_step_finish_status finish_status =
+    event_thread->inf->top_target ()->displaced_step_finish (event_thread,
+                                                            signal);
 
-  return ret;
+  if (finish_status == DISPLACED_STEP_FINISH_STATUS_OK)
+    return 1;
+  else
+    return -1;
 }
 
 /* Data to be passed around while handling an event.  This data is
@@ -1944,13 +1920,26 @@ static int
 start_step_over (void)
 {
   struct thread_info *tp, *next;
+  int started = 0;
 
   /* Don't start a new step-over if we already have an in-line
      step-over operation ongoing.  */
   if (step_over_info_valid_p ())
-    return 0;
+    return started;
 
-  for (tp = step_over_queue_head; tp != NULL; tp = next)
+  /* Steal the global thread step over chain.  */
+  thread_info *threads_to_step = global_thread_step_over_chain_head;
+  global_thread_step_over_chain_head = NULL;
+
+  if (debug_infrun)
+    fprintf_unfiltered (gdb_stdlog,
+                       "infrun: stealing list of %d threads to step from global queue\n",
+                       thread_step_over_chain_length (threads_to_step));
+
+  for (inferior *inf : all_inferiors ())
+    inf->displaced_step_state.unavailable = false;
+
+  for (tp = threads_to_step; tp != NULL; tp = next)
     {
       struct execution_control_state ecss;
       struct execution_control_state *ecs = &ecss;
@@ -1959,12 +1948,7 @@ start_step_over (void)
 
       gdb_assert (!tp->stop_requested);
 
-      next = thread_step_over_chain_next (tp);
-
-      /* If this inferior already has a displaced step in process,
-        don't start a new one.  */
-      if (displaced_step_in_progress (tp->inf))
-       continue;
+      next = thread_step_over_chain_next (threads_to_step, tp);
 
       step_what = thread_still_needs_step_over (tp);
       must_be_in_line = ((step_what & STEP_OVER_WATCHPOINT)
@@ -1974,17 +1958,10 @@ start_step_over (void)
       /* We currently stop all threads of all processes to step-over
         in-line.  If we need to start a new in-line step-over, let
         any pending displaced steps finish first.  */
-      if (must_be_in_line && displaced_step_in_progress_any_inferior ())
-       return 0;
-
-      thread_step_over_chain_remove (tp);
+      if (must_be_in_line && displaced_step_in_progress_any_thread ())
+       continue;
 
-      if (step_over_queue_head == NULL)
-       {
-         if (debug_infrun)
-           fprintf_unfiltered (gdb_stdlog,
-                               "infrun: step-over queue now empty\n");
-       }
+      thread_step_over_chain_remove (&threads_to_step, tp);
 
       if (tp->control.trap_expected
          || tp->resumed
@@ -1999,10 +1976,8 @@ start_step_over (void)
                          tp->executing);
        }
 
-      if (debug_infrun)
-       fprintf_unfiltered (gdb_stdlog,
-                           "infrun: resuming [%s] for step-over\n",
-                           target_pid_to_str (tp->ptid).c_str ());
+      infrun_log_debug ("resuming [%s] for step-over",
+                       target_pid_to_str (tp->ptid).c_str ());
 
       /* keep_going_pass_signal skips the step-over if the breakpoint
         is no longer inserted.  In all-stop, we want to keep looking
@@ -2013,6 +1988,12 @@ start_step_over (void)
       if (!target_is_non_stop_p () && !step_what)
        continue;
 
+      if (tp->inf->displaced_step_state.unavailable)
+       {
+         global_thread_step_over_chain_enqueue (tp);
+         continue;
+       }
+
       switch_to_thread (tp);
       reset_ecs (ecs, tp);
       keep_going_pass_signal (ecs);
@@ -2020,13 +2001,28 @@ start_step_over (void)
       if (!ecs->wait_some_more)
        error (_("Command aborted."));
 
-      gdb_assert (tp->resumed);
+      /* If the thread's step over could not be initiated, it was re-added
+         to the global step over chain.  */
+      if (tp->resumed)
+       {
+         infrun_log_debug ("start_step_over: [%s] was resumed.\n",
+                           target_pid_to_str (tp->ptid).c_str ());
+         gdb_assert (!thread_is_in_step_over_chain (tp));
+       }
+      else
+       {
+         infrun_log_debug ("infrun: start_step_over: [%s] was NOT resumed.\n",
+                           target_pid_to_str (tp->ptid).c_str ());
+         gdb_assert (thread_is_in_step_over_chain (tp));
+
+       }
 
       /* If we started a new in-line step-over, we're done.  */
       if (step_over_info_valid_p ())
        {
          gdb_assert (tp->control.trap_expected);
-         return 1;
+         started = 1;
+         break;
        }
 
       if (!target_is_non_stop_p ())
@@ -2039,7 +2035,8 @@ start_step_over (void)
          /* With remote targets (at least), in all-stop, we can't
             issue any further remote commands until the program stops
             again.  */
-         return 1;
+         started = 1;
+         break;
        }
 
       /* Either the thread no longer needed a step-over, or a new
@@ -2048,7 +2045,35 @@ start_step_over (void)
         displaced step on a thread of other process. */
     }
 
-  return 0;
+    /* If there are threads left in the THREADS_TO_STEP list, but we have
+       detected that we can't start anything more, put back these threads
+       in the global list.  */
+    if (threads_to_step == NULL)
+      {
+       if (debug_infrun)
+         fprintf_unfiltered (gdb_stdlog,
+                             "infrun: step-over queue now empty\n");
+      }
+    else
+      {
+       if (debug_infrun)
+         fprintf_unfiltered (gdb_stdlog,
+                             "infrun: putting back %d threads to step in global queue\n",
+                             thread_step_over_chain_length (threads_to_step));
+       while (threads_to_step != nullptr)
+         {
+           thread_info *thread = threads_to_step;
+
+           /* Remove from that list.  */
+           thread_step_over_chain_remove (&threads_to_step, thread);
+
+           /* Add to global list.  */
+           global_thread_step_over_chain_enqueue (thread);
+
+         }
+      }
+
+  return started;
 }
 
 /* Update global variables holding ptids to hold NEW_PTID if they were
@@ -2248,7 +2273,6 @@ resume_1 (enum gdb_signal sig)
   struct regcache *regcache = get_current_regcache ();
   struct gdbarch *gdbarch = regcache->arch ();
   struct thread_info *tp = inferior_thread ();
-  CORE_ADDR pc = regcache_read_pc (regcache);
   const address_space *aspace = regcache->aspace ();
   ptid_t resume_ptid;
   /* This represents the user's step vs continue request.  When
@@ -2266,18 +2290,12 @@ resume_1 (enum gdb_signal sig)
 
   if (tp->suspend.waitstatus_pending_p)
     {
-      if (debug_infrun)
-       {
-         std::string statstr
-           = target_waitstatus_to_string (&tp->suspend.waitstatus);
-
-         fprintf_unfiltered (gdb_stdlog,
-                             "infrun: resume: thread %s has pending wait "
-                             "status %s (currently_stepping=%d).\n",
-                             target_pid_to_str (tp->ptid).c_str (),
-                             statstr.c_str (),
-                             currently_stepping (tp));
-       }
+      infrun_log_debug
+       ("thread %s has pending wait "
+        "status %s (currently_stepping=%d).",
+        target_pid_to_str (tp->ptid).c_str (),
+        target_waitstatus_to_string (&tp->suspend.waitstatus).c_str (),
+        currently_stepping (tp));
 
       tp->inf->process_target ()->threads_executing = true;
       tp->resumed = true;
@@ -2321,20 +2339,18 @@ resume_1 (enum gdb_signal sig)
         Eventually, we'll see a TARGET_WAITKIND_VFORK_DONE event for
         the parent, and tell it to `keep_going', which automatically
         re-sets it stepping.  */
-      if (debug_infrun)
-       fprintf_unfiltered (gdb_stdlog,
-                           "infrun: resume : clear step\n");
+      infrun_log_debug ("resume : clear step");
       step = 0;
     }
 
-  if (debug_infrun)
-    fprintf_unfiltered (gdb_stdlog,
-                       "infrun: resume (step=%d, signal=%s), "
-                       "trap_expected=%d, current thread [%s] at %s\n",
-                       step, gdb_signal_to_symbol_string (sig),
-                       tp->control.trap_expected,
-                       target_pid_to_str (inferior_ptid).c_str (),
-                       paddress (gdbarch, pc));
+  CORE_ADDR pc = regcache_read_pc (regcache);
+
+  infrun_log_debug ("step=%d, signal=%s, trap_expected=%d, "
+                   "current thread [%s] at %s",
+                   step, gdb_signal_to_symbol_string (sig),
+                   tp->control.trap_expected,
+                   target_pid_to_str (inferior_ptid).c_str (),
+                   paddress (gdbarch, pc));
 
   /* Normally, by the time we reach `resume', the breakpoints are either
      removed or inserted, as appropriate.  The exception is if we're sitting
@@ -2358,10 +2374,8 @@ resume_1 (enum gdb_signal sig)
             signal handler (or hit some other event).  We'll delete
             the step-resume breakpoint then.  */
 
-         if (debug_infrun)
-           fprintf_unfiltered (gdb_stdlog,
-                               "infrun: resume: skipping permanent breakpoint, "
-                               "deliver signal first\n");
+         infrun_log_debug ("resume: skipping permanent breakpoint, "
+                           "deliver signal first");
 
          clear_step_over_info ();
          tp->control.trap_expected = 0;
@@ -2383,9 +2397,7 @@ resume_1 (enum gdb_signal sig)
        {
          /* There's no signal to pass, we can go ahead and skip the
             permanent breakpoint manually.  */
-         if (debug_infrun)
-           fprintf_unfiltered (gdb_stdlog,
-                               "infrun: resume: skipping permanent breakpoint\n");
+         infrun_log_debug ("skipping permanent breakpoint");
          gdbarch_skip_permanent_breakpoint (gdbarch, regcache);
          /* Update pc to reflect the new address from which we will
             execute instructions.  */
@@ -2436,18 +2448,17 @@ resume_1 (enum gdb_signal sig)
       && sig == GDB_SIGNAL_0
       && !current_inferior ()->waiting_for_vfork_done)
     {
-      int prepared = displaced_step_prepare (tp);
+      displaced_step_prepare_status prepare_status
+       = displaced_step_prepare (tp);
 
-      if (prepared == 0)
+      if (prepare_status == DISPLACED_STEP_PREPARE_STATUS_UNAVAILABLE)
        {
-         if (debug_infrun)
-           fprintf_unfiltered (gdb_stdlog,
-                               "Got placed in step-over queue\n");
+         infrun_log_debug ("Got placed in step-over queue");
 
          tp->control.trap_expected = 0;
          return;
        }
-      else if (prepared < 0)
+      else if (prepare_status == DISPLACED_STEP_PREPARE_STATUS_ERROR)
        {
          /* Fallback to stepping over the breakpoint in-line.  */
 
@@ -2461,18 +2472,12 @@ resume_1 (enum gdb_signal sig)
 
          insert_breakpoints ();
        }
-      else if (prepared > 0)
+      else if (prepare_status == DISPLACED_STEP_PREPARE_STATUS_OK)
        {
-         struct displaced_step_inferior_state *displaced;
-
-         /* Update pc to reflect the new address from which we will
-            execute instructions due to displaced stepping.  */
-         pc = regcache_read_pc (get_thread_regcache (tp));
-
-         displaced = get_displaced_stepping_state (tp->inf);
-         step = gdbarch_displaced_step_hw_singlestep
-           (gdbarch, displaced->step_closure.get ());
+         step = gdbarch_displaced_step_hw_singlestep (gdbarch, NULL);
        }
+      else
+       gdb_assert_not_reached ("invalid displaced_step_prepare_status value");
     }
 
   /* Do we need to do it the hard way, w/temp breakpoints?  */
@@ -2579,10 +2584,8 @@ resume_1 (enum gdb_signal sig)
         gdb.threads/non-stop-fair-events.exp, on targets that don't
         do displaced stepping.  */
 
-      if (debug_infrun)
-       fprintf_unfiltered (gdb_stdlog,
-                           "infrun: resume: [%s] stepped breakpoint\n",
-                           target_pid_to_str (tp->ptid).c_str ());
+      infrun_log_debug ("resume: [%s] stepped breakpoint",
+                       target_pid_to_str (tp->ptid).c_str ());
 
       tp->stepped_breakpoint = 1;
 
@@ -2683,10 +2686,7 @@ new_stop_id (void)
 static void
 clear_proceed_status_thread (struct thread_info *tp)
 {
-  if (debug_infrun)
-    fprintf_unfiltered (gdb_stdlog,
-                       "infrun: clear_proceed_status_thread (%s)\n",
-                       target_pid_to_str (tp->ptid).c_str ());
+  infrun_log_debug ("%s", target_pid_to_str (tp->ptid).c_str ());
 
   /* If we're starting a new sequence, then the previous finished
      single-step is no longer relevant.  */
@@ -2694,28 +2694,20 @@ clear_proceed_status_thread (struct thread_info *tp)
     {
       if (tp->suspend.stop_reason == TARGET_STOPPED_BY_SINGLE_STEP)
        {
-         if (debug_infrun)
-           fprintf_unfiltered (gdb_stdlog,
-                               "infrun: clear_proceed_status: pending "
-                               "event of %s was a finished step. "
-                               "Discarding.\n",
-                               target_pid_to_str (tp->ptid).c_str ());
+         infrun_log_debug ("pending event of %s was a finished step. "
+                           "Discarding.",
+                           target_pid_to_str (tp->ptid).c_str ());
 
          tp->suspend.waitstatus_pending_p = 0;
          tp->suspend.stop_reason = TARGET_STOPPED_BY_NO_REASON;
        }
-      else if (debug_infrun)
+      else
        {
-         std::string statstr
-           = target_waitstatus_to_string (&tp->suspend.waitstatus);
-
-         fprintf_unfiltered (gdb_stdlog,
-                             "infrun: clear_proceed_status_thread: thread %s "
-                             "has pending wait status %s "
-                             "(currently_stepping=%d).\n",
-                             target_pid_to_str (tp->ptid).c_str (),
-                             statstr.c_str (),
-                             currently_stepping (tp));
+         infrun_log_debug
+           ("thread %s has pending wait status %s (currently_stepping=%d).",
+            target_pid_to_str (tp->ptid).c_str (),
+            target_waitstatus_to_string (&tp->suspend.waitstatus).c_str (),
+            currently_stepping (tp));
        }
     }
 
@@ -2964,7 +2956,8 @@ proceed (CORE_ADDR addr, enum gdb_signal siggnal)
   gdbarch = regcache->arch ();
   const address_space *aspace = regcache->aspace ();
 
-  pc = regcache_read_pc (regcache);
+  pc = regcache_read_pc_protected (regcache);
+
   thread_info *cur_thr = inferior_thread ();
 
   /* Fill in with reasonable starting values.  */
@@ -3022,11 +3015,8 @@ proceed (CORE_ADDR addr, enum gdb_signal siggnal)
   if (!cur_thr->control.in_infcall)
     set_running (resume_target, resume_ptid, true);
 
-  if (debug_infrun)
-    fprintf_unfiltered (gdb_stdlog,
-                       "infrun: proceed (addr=%s, signal=%s)\n",
-                       paddress (gdbarch, addr),
-                       gdb_signal_to_symbol_string (siggnal));
+  infrun_log_debug ("addr=%s, signal=%s", paddress (gdbarch, addr),
+                   gdb_signal_to_symbol_string (siggnal));
 
   annotate_starting ();
 
@@ -3070,12 +3060,10 @@ proceed (CORE_ADDR addr, enum gdb_signal siggnal)
 
          gdb_assert (!thread_is_in_step_over_chain (tp));
 
-         if (debug_infrun)
-           fprintf_unfiltered (gdb_stdlog,
-                               "infrun: need to step-over [%s] first\n",
-                               target_pid_to_str (tp->ptid).c_str ());
+         infrun_log_debug ("need to step-over [%s] first",
+                           target_pid_to_str (tp->ptid).c_str ());
 
-         thread_step_over_chain_enqueue (tp);
+         global_thread_step_over_chain_enqueue (tp);
        }
 
       switch_to_thread (cur_thr);
@@ -3084,14 +3072,14 @@ proceed (CORE_ADDR addr, enum gdb_signal siggnal)
   /* Enqueue the current thread last, so that we move all other
      threads over their breakpoints first.  */
   if (cur_thr->stepping_over_breakpoint)
-    thread_step_over_chain_enqueue (cur_thr);
+    global_thread_step_over_chain_enqueue (cur_thr);
 
   /* If the thread isn't started, we'll still need to set its prev_pc,
      so that switch_back_to_stepped_thread knows the thread hasn't
      advanced.  Must do this before resuming any thread, as in
      all-stop/remote, once we resume we can't send any other packet
      until the target stops again.  */
-  cur_thr->prev_pc = regcache_read_pc (regcache);
+  cur_thr->prev_pc = regcache_read_pc_protected (regcache);
 
   {
     scoped_restore save_defer_tc = make_scoped_defer_target_commit_resume ();
@@ -3120,37 +3108,28 @@ proceed (CORE_ADDR addr, enum gdb_signal siggnal)
 
            if (!tp->inf->has_execution ())
              {
-               if (debug_infrun)
-                 fprintf_unfiltered (gdb_stdlog,
-                                     "infrun: proceed: [%s] target has "
-                                     "no execution\n",
-                                     target_pid_to_str (tp->ptid).c_str ());
+               infrun_log_debug ("[%s] target has no execution",
+                                 target_pid_to_str (tp->ptid).c_str ());
                continue;
              }
 
            if (tp->resumed)
              {
-               if (debug_infrun)
-                 fprintf_unfiltered (gdb_stdlog,
-                                     "infrun: proceed: [%s] resumed\n",
-                                     target_pid_to_str (tp->ptid).c_str ());
+               infrun_log_debug ("[%s] resumed",
+                                 target_pid_to_str (tp->ptid).c_str ());
                gdb_assert (tp->executing || tp->suspend.waitstatus_pending_p);
                continue;
              }
 
            if (thread_is_in_step_over_chain (tp))
              {
-               if (debug_infrun)
-                 fprintf_unfiltered (gdb_stdlog,
-                                     "infrun: proceed: [%s] needs step-over\n",
-                                     target_pid_to_str (tp->ptid).c_str ());
+               infrun_log_debug ("[%s] needs step-over",
+                                 target_pid_to_str (tp->ptid).c_str ());
                continue;
              }
 
-           if (debug_infrun)
-             fprintf_unfiltered (gdb_stdlog,
-                                 "infrun: proceed: resuming %s\n",
-                                 target_pid_to_str (tp->ptid).c_str ());
+           infrun_log_debug ("resuming %s",
+                             target_pid_to_str (tp->ptid).c_str ());
 
            reset_ecs (ecs, tp);
            switch_to_thread (tp);
@@ -3277,7 +3256,7 @@ infrun_thread_stop_requested (ptid_t ptid)
         start_step_over doesn't try to resume them
         automatically.  */
       if (thread_is_in_step_over_chain (tp))
-       thread_step_over_chain_remove (tp);
+       global_thread_step_over_chain_remove (tp);
 
       /* If the thread is stopped, but the user/frontend doesn't
         know about that yet, queue a pending event, as if the
@@ -3432,10 +3411,9 @@ random_pending_event_thread (inferior *inf, ptid_t waiton_ptid)
   int random_selector = (int) ((num_events * (double) rand ())
                               / (RAND_MAX + 1.0));
 
-  if (debug_infrun && num_events > 1)
-    fprintf_unfiltered (gdb_stdlog,
-                       "infrun: Found %d events, selecting #%d\n",
-                       num_events, random_selector);
+  if (num_events > 1)
+    infrun_log_debug ("Found %d events, selecting #%d",
+                     num_events, random_selector);
 
   /* Select the Nth thread that has had an event.  */
   for (thread_info *tp : inf->non_exited_threads ())
@@ -3458,6 +3436,12 @@ do_target_wait_1 (inferior *inf, ptid_t ptid,
   ptid_t event_ptid;
   struct thread_info *tp;
 
+  /* We know that we are looking for an event in the target of inferior
+     INF, but we don't know which thread the event might come from.  As
+     such we want to make sure that INFERIOR_PTID is reset so that none of
+     the wait code relies on it - doing so is always a mistake.  */
+  switch_to_inferior_no_thread (inf);
+
   /* First check if there is a resumed thread with a wait status
      pending.  */
   if (ptid == minus_one_ptid || ptid.is_pid ())
@@ -3466,10 +3450,8 @@ do_target_wait_1 (inferior *inf, ptid_t ptid,
     }
   else
     {
-      if (debug_infrun)
-       fprintf_unfiltered (gdb_stdlog,
-                           "infrun: Waiting for specific thread %s.\n",
-                           target_pid_to_str (ptid).c_str ());
+      infrun_log_debug ("Waiting for specific thread %s.",
+                       target_pid_to_str (ptid).c_str ());
 
       /* We have a specific thread to check.  */
       tp = find_thread_ptid (inf, ptid);
@@ -3491,31 +3473,25 @@ do_target_wait_1 (inferior *inf, ptid_t ptid,
 
       if (pc != tp->suspend.stop_pc)
        {
-         if (debug_infrun)
-           fprintf_unfiltered (gdb_stdlog,
-                               "infrun: PC of %s changed.  was=%s, now=%s\n",
-                               target_pid_to_str (tp->ptid).c_str (),
-                               paddress (gdbarch, tp->suspend.stop_pc),
-                               paddress (gdbarch, pc));
+         infrun_log_debug ("PC of %s changed.  was=%s, now=%s",
+                           target_pid_to_str (tp->ptid).c_str (),
+                           paddress (gdbarch, tp->suspend.stop_pc),
+                           paddress (gdbarch, pc));
          discard = 1;
        }
       else if (!breakpoint_inserted_here_p (regcache->aspace (), pc))
        {
-         if (debug_infrun)
-           fprintf_unfiltered (gdb_stdlog,
-                               "infrun: previous breakpoint of %s, at %s gone\n",
-                               target_pid_to_str (tp->ptid).c_str (),
-                               paddress (gdbarch, pc));
+         infrun_log_debug ("previous breakpoint of %s, at %s gone",
+                           target_pid_to_str (tp->ptid).c_str (),
+                           paddress (gdbarch, pc));
 
          discard = 1;
        }
 
       if (discard)
        {
-         if (debug_infrun)
-           fprintf_unfiltered (gdb_stdlog,
-                               "infrun: pending event of %s cancelled.\n",
-                               target_pid_to_str (tp->ptid).c_str ());
+         infrun_log_debug ("pending event of %s cancelled.",
+                           target_pid_to_str (tp->ptid).c_str ());
 
          tp->suspend.waitstatus.kind = TARGET_WAITKIND_SPURIOUS;
          tp->suspend.stop_reason = TARGET_STOPPED_BY_NO_REASON;
@@ -3524,16 +3500,10 @@ do_target_wait_1 (inferior *inf, ptid_t ptid,
 
   if (tp != NULL)
     {
-      if (debug_infrun)
-       {
-         std::string statstr
-           = target_waitstatus_to_string (&tp->suspend.waitstatus);
-
-         fprintf_unfiltered (gdb_stdlog,
-                             "infrun: Using pending wait status %s for %s.\n",
-                             statstr.c_str (),
-                             target_pid_to_str (tp->ptid).c_str ());
-       }
+      infrun_log_debug ("Using pending wait status %s for %s.",
+                       target_waitstatus_to_string
+                         (&tp->suspend.waitstatus).c_str (),
+                       target_pid_to_str (tp->ptid).c_str ());
 
       /* Now that we've selected our final event LWP, un-adjust its PC
         if it was a software breakpoint (and the target doesn't
@@ -3631,10 +3601,9 @@ do_target_wait (ptid_t wait_ptid, execution_control_state *ecs, int options)
   random_selector = (int)
     ((num_inferiors * (double) rand ()) / (RAND_MAX + 1.0));
 
-  if (debug_infrun && num_inferiors > 1)
-    fprintf_unfiltered (gdb_stdlog,
-                       "infrun: Found %d inferiors, starting at #%d\n",
-                       num_inferiors, random_selector);
+  if (num_inferiors > 1)
+    infrun_log_debug ("Found %d inferiors, starting at #%d",
+                     num_inferiors, random_selector);
 
   /* Select the Nth inferior that was resumed.  */
 
@@ -3653,8 +3622,6 @@ do_target_wait (ptid_t wait_ptid, execution_control_state *ecs, int options)
 
   auto do_wait = [&] (inferior *inf)
   {
-    switch_to_inferior_no_thread (inf);
-
     ecs->ptid = do_target_wait_1 (inf, wait_ptid, &ecs->ws, options);
     ecs->target = inf->process_target ();
     return (ecs->ws.kind != TARGET_WAITKIND_IGNORE);
@@ -3693,20 +3660,19 @@ prepare_for_detach (void)
   struct inferior *inf = current_inferior ();
   ptid_t pid_ptid = ptid_t (inf->pid);
 
-  displaced_step_inferior_state *displaced = get_displaced_stepping_state (inf);
+  // displaced_step_inferior_state *displaced = get_displaced_stepping_state (inf);
 
   /* Is any thread of this process displaced stepping?  If not,
      there's nothing else to do.  */
-  if (displaced->step_thread == nullptr)
+  if (displaced_step_in_progress (inf))
     return;
 
-  if (debug_infrun)
-    fprintf_unfiltered (gdb_stdlog,
-                       "displaced-stepping in-process while detaching");
+  infrun_log_debug ("displaced-stepping in-process while detaching");
 
   scoped_restore restore_detaching = make_scoped_restore (&inf->detaching, true);
 
-  while (displaced->step_thread != nullptr)
+  // FIXME
+  while (false)
     {
       struct execution_control_state ecss;
       struct execution_control_state *ecs;
@@ -3761,9 +3727,7 @@ prepare_for_detach (void)
 static void
 wait_for_inferior (inferior *inf)
 {
-  if (debug_infrun)
-    fprintf_unfiltered
-      (gdb_stdlog, "infrun: wait_for_inferior ()\n");
+  infrun_log_debug ("wait_for_inferior ()");
 
   SCOPE_EXIT { delete_just_stopped_threads_infrun_breakpoints (); };
 
@@ -4071,11 +4035,15 @@ fetch_inferior_event (void *client_data)
     printf_unfiltered (_("completed.\n"));
 }
 
-/* Record the frame and location we're currently stepping through.  */
+/* See infrun.h.  */
+
 void
-set_step_info (struct frame_info *frame, struct symtab_and_line sal)
+set_step_info (thread_info *tp, struct frame_info *frame,
+              struct symtab_and_line sal)
 {
-  struct thread_info *tp = inferior_thread ();
+  /* This can be removed once this function no longer implicitly relies on the
+     inferior_ptid value.  */
+  gdb_assert (inferior_ptid == tp->ptid);
 
   tp->control.step_frame_id = get_frame_id (frame);
   tp->control.step_stack_frame_id = get_stack_frame_id (frame);
@@ -4135,15 +4103,13 @@ nullify_last_target_wait_ptid (void)
 static void
 context_switch (execution_control_state *ecs)
 {
-  if (debug_infrun
-      && ecs->ptid != inferior_ptid
+  if (ecs->ptid != inferior_ptid
       && (inferior_ptid == null_ptid
          || ecs->event_thread != inferior_thread ()))
     {
-      fprintf_unfiltered (gdb_stdlog, "infrun: Switching context from %s ",
-                         target_pid_to_str (inferior_ptid).c_str ());
-      fprintf_unfiltered (gdb_stdlog, "to %s\n",
-                         target_pid_to_str (ecs->ptid).c_str ());
+      infrun_log_debug ("Switching context from %s to %s",
+                       target_pid_to_str (inferior_ptid).c_str (),
+                       target_pid_to_str (ecs->ptid).c_str ());
     }
 
   switch_to_thread (ecs->event_thread);
@@ -4388,9 +4354,7 @@ handle_syscall_event (struct execution_control_state *ecs)
   if (catch_syscall_enabled () > 0
       && catching_syscall_number (syscall_number) > 0)
     {
-      if (debug_infrun)
-        fprintf_unfiltered (gdb_stdlog, "infrun: syscall number = '%d'\n",
-                            syscall_number);
+      infrun_log_debug ("syscall number=%d", syscall_number);
 
       ecs->event_thread->control.stop_bpstat
        = bpstat_stop_status (regcache->aspace (),
@@ -4605,17 +4569,11 @@ THREAD_STOPPED_BY (hw_breakpoint)
 static void
 save_waitstatus (struct thread_info *tp, const target_waitstatus *ws)
 {
-  if (debug_infrun)
-    {
-      std::string statstr = target_waitstatus_to_string (ws);
-
-      fprintf_unfiltered (gdb_stdlog,
-                         "infrun: saving status %s for %d.%ld.%ld\n",
-                         statstr.c_str (),
-                         tp->ptid.pid (),
-                         tp->ptid.lwp (),
-                         tp->ptid.tid ());
-    }
+  infrun_log_debug ("saving status %s for %d.%ld.%ld",
+                   target_waitstatus_to_string (ws).c_str (),
+                   tp->ptid.pid (),
+                   tp->ptid.lwp (),
+                   tp->ptid.tid ());
 
   /* Record for later.  */
   tp->suspend.waitstatus = *ws;
@@ -4671,6 +4629,47 @@ save_waitstatus (struct thread_info *tp, const target_waitstatus *ws)
     }
 }
 
+/* Mark the non-executing threads accordingly.  In all-stop, all
+   threads of all processes are stopped when we get any event
+   reported.  In non-stop mode, only the event thread stops.  */
+
+static void
+mark_non_executing_threads (process_stratum_target *target,
+                           ptid_t event_ptid,
+                           struct target_waitstatus ws)
+{
+  ptid_t mark_ptid;
+
+  if (!target_is_non_stop_p ())
+    mark_ptid = minus_one_ptid;
+  else if (ws.kind == TARGET_WAITKIND_SIGNALLED
+          || ws.kind == TARGET_WAITKIND_EXITED)
+    {
+      /* If we're handling a process exit in non-stop mode, even
+        though threads haven't been deleted yet, one would think
+        that there is nothing to do, as threads of the dead process
+        will be soon deleted, and threads of any other process were
+        left running.  However, on some targets, threads survive a
+        process exit event.  E.g., for the "checkpoint" command,
+        when the current checkpoint/fork exits, linux-fork.c
+        automatically switches to another fork from within
+        target_mourn_inferior, by associating the same
+        inferior/thread to another fork.  We haven't mourned yet at
+        this point, but we must mark any threads left in the
+        process as not-executing so that finish_thread_state marks
+        them stopped (in the user's perspective) if/when we present
+        the stop to the user.  */
+      mark_ptid = ptid_t (event_ptid.pid ());
+    }
+  else
+    mark_ptid = event_ptid;
+
+  set_executing (target, mark_ptid, false);
+
+  /* Likewise the resumed flag.  */
+  set_resumed (target, mark_ptid, false);
+}
+
 /* See infrun.h.  */
 
 void
@@ -4680,15 +4679,31 @@ stop_all_threads (void)
   int pass;
   int iterations = 0;
 
-  gdb_assert (target_is_non_stop_p ());
+  gdb_assert (exists_non_stop_target ());
 
-  if (debug_infrun)
-    fprintf_unfiltered (gdb_stdlog, "infrun: stop_all_threads\n");
+  infrun_log_debug ("stop_all_threads");
 
   scoped_restore_current_thread restore_thread;
 
-  target_thread_events (1);
-  SCOPE_EXIT { target_thread_events (0); };
+  /* Enable thread events of all targets.  */
+  for (auto *target : all_non_exited_process_targets ())
+    {
+      switch_to_target_no_thread (target);
+      target_thread_events (true);
+    }
+
+  SCOPE_EXIT
+    {
+      /* Disable thread events of all targets.  */
+      for (auto *target : all_non_exited_process_targets ())
+       {
+         switch_to_target_no_thread (target);
+         target_thread_events (false);
+       }
+
+
+      infrun_log_debug ("stop_all_threads done");
+    };
 
   /* Request threads to stop, and then wait for the stops.  Because
      threads we already know about can spawn more threads while we're
@@ -4697,53 +4712,57 @@ stop_all_threads (void)
      until two passes find no threads that need to be stopped.  */
   for (pass = 0; pass < 2; pass++, iterations++)
     {
-      if (debug_infrun)
-       fprintf_unfiltered (gdb_stdlog,
-                           "infrun: stop_all_threads, pass=%d, "
-                           "iterations=%d\n", pass, iterations);
+      infrun_log_debug ("stop_all_threads, pass=%d, iterations=%d",
+                       pass, iterations);
       while (1)
        {
-         int need_wait = 0;
+         int waits_needed = 0;
 
-         update_thread_list ();
+         for (auto *target : all_non_exited_process_targets ())
+           {
+             switch_to_target_no_thread (target);
+             update_thread_list ();
+           }
 
          /* Go through all threads looking for threads that we need
             to tell the target to stop.  */
          for (thread_info *t : all_non_exited_threads ())
            {
+             /* For a single-target setting with an all-stop target,
+                we would not even arrive here.  For a multi-target
+                setting, until GDB is able to handle a mixture of
+                all-stop and non-stop targets, simply skip all-stop
+                targets' threads.  This should be fine due to the
+                protection of 'check_multi_target_resumption'.  */
+
+             switch_to_thread_no_regs (t);
+             if (!target_is_non_stop_p ())
+               continue;
+
              if (t->executing)
                {
                  /* If already stopping, don't request a stop again.
                     We just haven't seen the notification yet.  */
                  if (!t->stop_requested)
                    {
-                     if (debug_infrun)
-                       fprintf_unfiltered (gdb_stdlog,
-                                           "infrun:   %s executing, "
-                                           "need stop\n",
-                                           target_pid_to_str (t->ptid).c_str ());
-                     switch_to_thread_no_regs (t);
+                     infrun_log_debug ("  %s executing, need stop",
+                                       target_pid_to_str (t->ptid).c_str ());
                      target_stop (t->ptid);
                      t->stop_requested = 1;
                    }
                  else
                    {
-                     if (debug_infrun)
-                       fprintf_unfiltered (gdb_stdlog,
-                                           "infrun:   %s executing, "
-                                           "already stopping\n",
-                                           target_pid_to_str (t->ptid).c_str ());
+                     infrun_log_debug ("  %s executing, already stopping",
+                                       target_pid_to_str (t->ptid).c_str ());
                    }
 
                  if (t->stop_requested)
-                   need_wait = 1;
+                   waits_needed++;
                }
              else
                {
-                 if (debug_infrun)
-                   fprintf_unfiltered (gdb_stdlog,
-                                       "infrun:   %s not executing\n",
-                                       target_pid_to_str (t->ptid).c_str ());
+                 infrun_log_debug ("  %s not executing",
+                                   target_pid_to_str (t->ptid).c_str ());
 
                  /* The thread may be not executing, but still be
                     resumed with a pending status to process.  */
@@ -4751,7 +4770,7 @@ stop_all_threads (void)
                }
            }
 
-         if (!need_wait)
+         if (waits_needed == 0)
            break;
 
          /* If we find new threads on the second iteration, restart
@@ -4760,118 +4779,155 @@ stop_all_threads (void)
          if (pass > 0)
            pass = -1;
 
-         wait_one_event event = wait_one ();
-
-         if (debug_infrun)
+         for (int i = 0; i < waits_needed; i++)
            {
-             fprintf_unfiltered (gdb_stdlog,
-                                 "infrun: stop_all_threads %s %s\n",
-                                 target_waitstatus_to_string (&event.ws).c_str (),
-                                 target_pid_to_str (event.ptid).c_str ());
-           }
+             wait_one_event event = wait_one ();
 
-         if (event.ws.kind == TARGET_WAITKIND_NO_RESUMED
-             || event.ws.kind == TARGET_WAITKIND_THREAD_EXITED
-             || event.ws.kind == TARGET_WAITKIND_EXITED
-             || event.ws.kind == TARGET_WAITKIND_SIGNALLED)
-           {
-             /* All resumed threads exited
-                or one thread/process exited/signalled.  */
-           }
-         else
-           {
-             thread_info *t = find_thread_ptid (event.target, event.ptid);
-             if (t == NULL)
-               t = add_thread (event.target, event.ptid);
-
-             t->stop_requested = 0;
-             t->executing = 0;
-             t->resumed = false;
-             t->control.may_range_step = 0;
-
-             /* This may be the first time we see the inferior report
-                a stop.  */
-             inferior *inf = find_inferior_ptid (event.target, event.ptid);
-             if (inf->needs_setup)
+             infrun_log_debug ("%s %s\n",
+                               target_waitstatus_to_string (&event.ws).c_str (),
+                               target_pid_to_str (event.ptid).c_str ());
+
+             if (event.ws.kind == TARGET_WAITKIND_NO_RESUMED)
                {
-                 switch_to_thread_no_regs (t);
-                 setup_inferior (0);
+                 /* All resumed threads exited.  */
+                 break;
                }
-
-             if (event.ws.kind == TARGET_WAITKIND_STOPPED
-                 && event.ws.value.sig == GDB_SIGNAL_0)
+             else if (event.ws.kind == TARGET_WAITKIND_THREAD_EXITED
+                      || event.ws.kind == TARGET_WAITKIND_EXITED
+                      || event.ws.kind == TARGET_WAITKIND_SIGNALLED)
                {
-                 /* We caught the event that we intended to catch, so
-                    there's no event pending.  */
-                 t->suspend.waitstatus.kind = TARGET_WAITKIND_IGNORE;
-                 t->suspend.waitstatus_pending_p = 0;
+                 /* One thread/process exited/signalled.  */
+
+                 thread_info *t = nullptr;
 
-                 if (displaced_step_fixup (t, GDB_SIGNAL_0) < 0)
+                 /* The target may have reported just a pid.  If so, try
+                    the first non-exited thread.  */
+                 if (event.ptid.is_pid ())
                    {
-                     /* Add it back to the step-over queue.  */
-                     if (debug_infrun)
+                     int pid  = event.ptid.pid ();
+                     inferior *inf = find_inferior_pid (event.target, pid);
+                     for (thread_info *tp : inf->non_exited_threads ())
                        {
-                         fprintf_unfiltered (gdb_stdlog,
-                                             "infrun: displaced-step of %s "
-                                             "canceled: adding back to the "
-                                             "step-over queue\n",
-                                             target_pid_to_str (t->ptid).c_str ());
+                         t = tp;
+                         break;
                        }
-                     t->control.trap_expected = 0;
-                     thread_step_over_chain_enqueue (t);
+
+                     /* If there is no available thread, the event would
+                        have to be appended to a per-inferior event list,
+                        which does not exist (and if it did, we'd have
+                        to adjust run control command to be able to
+                        resume such an inferior).  We assert here instead
+                        of going into an infinite loop.  */
+                     gdb_assert (t != nullptr);
+
+                     infrun_log_debug ("using %s\n",
+                                       target_pid_to_str (t->ptid).c_str ());
+                   }
+                 else
+                   {
+                     t = find_thread_ptid (event.target, event.ptid);
+                     /* Check if this is the first time we see this thread.
+                        Don't bother adding if it individually exited.  */
+                     if (t == nullptr
+                         && event.ws.kind != TARGET_WAITKIND_THREAD_EXITED)
+                       t = add_thread (event.target, event.ptid);
+                   }
+
+                 if (t != nullptr)
+                   {
+                     /* Set the threads as non-executing to avoid
+                        another stop attempt on them.  */
+                     switch_to_thread_no_regs (t);
+                     mark_non_executing_threads (event.target, event.ptid,
+                                                 event.ws);
+                     save_waitstatus (t, &event.ws);
+                     t->stop_requested = false;
                    }
                }
              else
                {
-                 enum gdb_signal sig;
-                 struct regcache *regcache;
+                 thread_info *t = find_thread_ptid (event.target, event.ptid);
+                 if (t == NULL)
+                   t = add_thread (event.target, event.ptid);
+
+                 t->stop_requested = 0;
+                 t->executing = 0;
+                 t->resumed = false;
+                 t->control.may_range_step = 0;
 
-                 if (debug_infrun)
+                 /* This may be the first time we see the inferior report
+                    a stop.  */
+                 inferior *inf = find_inferior_ptid (event.target, event.ptid);
+                 if (inf->needs_setup)
                    {
-                     std::string statstr = target_waitstatus_to_string (&event.ws);
-
-                     fprintf_unfiltered (gdb_stdlog,
-                                         "infrun: target_wait %s, saving "
-                                         "status for %d.%ld.%ld\n",
-                                         statstr.c_str (),
-                                         t->ptid.pid (),
-                                         t->ptid.lwp (),
-                                         t->ptid.tid ());
+                     switch_to_thread_no_regs (t);
+                     setup_inferior (0);
                    }
 
-                 /* Record for later.  */
-                 save_waitstatus (t, &event.ws);
+                 if (event.ws.kind == TARGET_WAITKIND_STOPPED
+                     && event.ws.value.sig == GDB_SIGNAL_0)
+                   {
+                     /* We caught the event that we intended to catch, so
+                        there's no event pending.  */
+                     t->suspend.waitstatus.kind = TARGET_WAITKIND_IGNORE;
+                     t->suspend.waitstatus_pending_p = 0;
 
-                 sig = (event.ws.kind == TARGET_WAITKIND_STOPPED
-                        ? event.ws.value.sig : GDB_SIGNAL_0);
+                     if (displaced_step_finish (t, GDB_SIGNAL_0) < 0)
+                       {
+                         /* Add it back to the step-over queue.  */
+                         infrun_log_debug ("displaced-step of %s "
+                                           "canceled: adding back to the "
+                                           "step-over queue\n",
+                                           target_pid_to_str (t->ptid).c_str ());
 
-                 if (displaced_step_fixup (t, sig) < 0)
-                   {
-                     /* Add it back to the step-over queue.  */
-                     t->control.trap_expected = 0;
-                     thread_step_over_chain_enqueue (t);
+                         t->control.trap_expected = 0;
+                         global_thread_step_over_chain_enqueue (t);
+                       }
                    }
+                 else
+                   {
+                     enum gdb_signal sig;
+                     struct regcache *regcache;
 
-                 regcache = get_thread_regcache (t);
-                 t->suspend.stop_pc = regcache_read_pc (regcache);
+                     if (debug_infrun)
+                       {
+                         std::string statstr = target_waitstatus_to_string (&event.ws);
+
+                         infrun_log_debug ("target_wait %s, saving "
+                                           "status for %d.%ld.%ld\n",
+                                           statstr.c_str (),
+                                           t->ptid.pid (),
+                                           t->ptid.lwp (),
+                                           t->ptid.tid ());
+                       }
 
-                 if (debug_infrun)
-                   {
-                     fprintf_unfiltered (gdb_stdlog,
-                                         "infrun: saved stop_pc=%s for %s "
-                                         "(currently_stepping=%d)\n",
-                                         paddress (target_gdbarch (),
-                                                   t->suspend.stop_pc),
-                                         target_pid_to_str (t->ptid).c_str (),
-                                         currently_stepping (t));
+                     /* Record for later.  */
+                     save_waitstatus (t, &event.ws);
+
+                     sig = (event.ws.kind == TARGET_WAITKIND_STOPPED
+                            ? event.ws.value.sig : GDB_SIGNAL_0);
+
+                     if (displaced_step_finish (t, sig) < 0)
+                       {
+                         /* Add it back to the step-over queue.  */
+                         t->control.trap_expected = 0;
+                         global_thread_step_over_chain_enqueue (t);
+                       }
+
+                     regcache = get_thread_regcache (t);
+                     t->suspend.stop_pc = regcache_read_pc (regcache);
+
+                     infrun_log_debug ("saved stop_pc=%s for %s "
+                                       "(currently_stepping=%d)\n",
+                                       paddress (target_gdbarch (),
+                                                 t->suspend.stop_pc),
+                                       target_pid_to_str (t->ptid).c_str (),
+                                       currently_stepping (t));
                    }
                }
            }
        }
     }
-
-  if (debug_infrun)
-    fprintf_unfiltered (gdb_stdlog, "infrun: stop_all_threads done\n");
 }
 
 /* Handle a TARGET_WAITKIND_NO_RESUMED event.  */
@@ -4881,10 +4937,9 @@ handle_no_resumed (struct execution_control_state *ecs)
 {
   if (target_can_async_p ())
     {
-      struct ui *ui;
       int any_sync = 0;
 
-      ALL_UIS (ui)
+      for (ui *ui : all_uis ())
        {
          if (ui->prompt_state == PROMPT_BLOCKED)
            {
@@ -4898,10 +4953,7 @@ handle_no_resumed (struct execution_control_state *ecs)
             we're not synchronously waiting for events either.  Just
             ignore.  */
 
-         if (debug_infrun)
-           fprintf_unfiltered (gdb_stdlog,
-                               "infrun: TARGET_WAITKIND_NO_RESUMED "
-                               "(ignoring: bg)\n");
+         infrun_log_debug ("TARGET_WAITKIND_NO_RESUMED (ignoring: bg)");
          prepare_to_wait (ecs);
          return 1;
        }
@@ -4948,28 +5000,8 @@ handle_no_resumed (struct execution_control_state *ecs)
        {
          /* There were no unwaited-for children left in the target at
             some point, but there are now.  Just ignore.  */
-         if (debug_infrun)
-           fprintf_unfiltered (gdb_stdlog,
-                               "infrun: TARGET_WAITKIND_NO_RESUMED "
-                               "(ignoring: found resumed)\n");
-         prepare_to_wait (ecs);
-         return 1;
-       }
-    }
-
-  /* Note however that we may find no resumed thread because the whole
-     process exited meanwhile (thus updating the thread list results
-     in an empty thread list).  In this case we know we'll be getting
-     a process exit event shortly.  */
-  for (inferior *inf : all_non_exited_inferiors (ecs->target))
-    {
-      thread_info *thread = any_live_thread_of_inferior (inf);
-      if (thread == NULL)
-       {
-         if (debug_infrun)
-           fprintf_unfiltered (gdb_stdlog,
-                               "infrun: TARGET_WAITKIND_NO_RESUMED "
-                               "(expect process exit)\n");
+         infrun_log_debug ("TARGET_WAITKIND_NO_RESUMED "
+                           "(ignoring: found resumed)");
          prepare_to_wait (ecs);
          return 1;
        }
@@ -5002,9 +5034,7 @@ handle_inferior_event (struct execution_control_state *ecs)
 
   enum stop_kind stop_soon;
 
-  if (debug_infrun)
-    fprintf_unfiltered (gdb_stdlog, "infrun: handle_inferior_event %s\n",
-                       target_waitstatus_to_string (&ecs->ws).c_str ());
+  infrun_log_debug ("%s", target_waitstatus_to_string (&ecs->ws).c_str ());
 
   if (ecs->ws.kind == TARGET_WAITKIND_IGNORE)
     {
@@ -5087,48 +5117,12 @@ handle_inferior_event (struct execution_control_state *ecs)
       if (breakpoint_inserted_here_p (regcache->aspace (),
                                      regcache_read_pc (regcache)))
        {
-         if (debug_infrun)
-           fprintf_unfiltered (gdb_stdlog,
-                               "infrun: Treating signal as SIGTRAP\n");
+         infrun_log_debug ("Treating signal as SIGTRAP");
          ecs->ws.value.sig = GDB_SIGNAL_TRAP;
        }
     }
 
-  /* Mark the non-executing threads accordingly.  In all-stop, all
-     threads of all processes are stopped when we get any event
-     reported.  In non-stop mode, only the event thread stops.  */
-  {
-    ptid_t mark_ptid;
-
-    if (!target_is_non_stop_p ())
-      mark_ptid = minus_one_ptid;
-    else if (ecs->ws.kind == TARGET_WAITKIND_SIGNALLED
-            || ecs->ws.kind == TARGET_WAITKIND_EXITED)
-      {
-       /* If we're handling a process exit in non-stop mode, even
-          though threads haven't been deleted yet, one would think
-          that there is nothing to do, as threads of the dead process
-          will be soon deleted, and threads of any other process were
-          left running.  However, on some targets, threads survive a
-          process exit event.  E.g., for the "checkpoint" command,
-          when the current checkpoint/fork exits, linux-fork.c
-          automatically switches to another fork from within
-          target_mourn_inferior, by associating the same
-          inferior/thread to another fork.  We haven't mourned yet at
-          this point, but we must mark any threads left in the
-          process as not-executing so that finish_thread_state marks
-          them stopped (in the user's perspective) if/when we present
-          the stop to the user.  */
-       mark_ptid = ptid_t (ecs->ptid.pid ());
-      }
-    else
-      mark_ptid = ecs->ptid;
-
-    set_executing (ecs->target, mark_ptid, false);
-
-    /* Likewise the resumed flag.  */
-    set_resumed (ecs->target, mark_ptid, false);
-  }
+  mark_non_executing_threads (ecs->target, ecs->ptid, ecs->ws);
 
   switch (ecs->ws.kind)
     {
@@ -5200,8 +5194,7 @@ handle_inferior_event (struct execution_control_state *ecs)
       if (stop_soon == STOP_QUIETLY_NO_SIGSTOP
          || stop_soon == STOP_QUIETLY_REMOTE)
        {
-         if (debug_infrun)
-           fprintf_unfiltered (gdb_stdlog, "infrun: quietly stopped\n");
+         infrun_log_debug ("quietly stopped");
          stop_waiting (ecs);
          return;
        }
@@ -5273,9 +5266,8 @@ handle_inferior_event (struct execution_control_state *ecs)
                 information to the user.  It's better to just warn
                 her about it (if infrun debugging is enabled), and
                 give up.  */
-             if (debug_infrun)
-               fprintf_filtered (gdb_stdlog, _("\
-Cannot fill $_exitsignal with the correct signal number.\n"));
+             infrun_log_debug ("Cannot fill $_exitsignal with the correct "
+                               "signal number.");
            }
 
          gdb::observers::signal_exited.notify (ecs->ws.value.sig);
@@ -5296,7 +5288,7 @@ Cannot fill $_exitsignal with the correct signal number.\n"));
 
        /* If checking displaced stepping is supported, and thread
           ecs->ptid is displaced stepping.  */
-       if (displaced_step_in_progress_thread (ecs->event_thread))
+       if (displaced_step_in_progress (ecs->event_thread))
          {
            struct inferior *parent_inf
              = find_inferior_ptid (ecs->target, ecs->ptid);
@@ -5305,11 +5297,12 @@ Cannot fill $_exitsignal with the correct signal number.\n"));
 
            if (ecs->ws.kind == TARGET_WAITKIND_FORKED)
              {
-               struct displaced_step_inferior_state *displaced
-                 = get_displaced_stepping_state (parent_inf);
+               // struct displaced_step_inferior_state *displaced
+               //  = get_displaced_stepping_state (parent_inf);
 
                /* Restore scratch pad for child process.  */
-               displaced_step_restore (displaced, ecs->ws.value.related_pid);
+               //displaced_step_restore (displaced, ecs->ws.value.related_pid);
+               // FIXME: we should restore all the buffers that were currently in use
              }
 
            /* GDB has got TARGET_WAITKIND_FORKED or TARGET_WAITKIND_VFORKED,
@@ -5317,7 +5310,7 @@ Cannot fill $_exitsignal with the correct signal number.\n"));
               has been done.  Perform cleanup for parent process here.  Note
               that this operation also cleans up the child process for vfork,
               because their pages are shared.  */
-           displaced_step_fixup (ecs->event_thread, GDB_SIGNAL_TRAP);
+           displaced_step_finish (ecs->event_thread, GDB_SIGNAL_TRAP);
            /* Start a new step-over in another thread if there's one
               that needs it.  */
            start_step_over ();
@@ -5393,8 +5386,7 @@ Cannot fill $_exitsignal with the correct signal number.\n"));
         watchpoints, for example, always appear in the bpstat.  */
       if (!bpstat_causes_stop (ecs->event_thread->control.stop_bpstat))
        {
-         int should_resume;
-         int follow_child
+         bool follow_child
            = (follow_fork_mode_string == follow_fork_mode_child);
 
          ecs->event_thread->suspend.stop_signal = GDB_SIGNAL_0;
@@ -5402,7 +5394,7 @@ Cannot fill $_exitsignal with the correct signal number.\n"));
          process_stratum_target *targ
            = ecs->event_thread->inf->process_target ();
 
-         should_resume = follow_fork ();
+         bool should_resume = follow_fork ();
 
          /* Note that one of these may be an invalid pointer,
             depending on detach_fork.  */
@@ -5542,8 +5534,7 @@ Cannot fill $_exitsignal with the correct signal number.\n"));
 
       /* Switch to the stopped thread.  */
       context_switch (ecs);
-      if (debug_infrun)
-       fprintf_unfiltered (gdb_stdlog, "infrun: stopped\n");
+      infrun_log_debug ("stopped");
 
       delete_just_stopped_threads_single_step_breakpoints ();
       ecs->event_thread->suspend.stop_pc
@@ -5574,41 +5565,30 @@ restart_threads (struct thread_info *event_thread)
 
       if (tp == event_thread)
        {
-         if (debug_infrun)
-           fprintf_unfiltered (gdb_stdlog,
-                               "infrun: restart threads: "
-                               "[%s] is event thread\n",
-                               target_pid_to_str (tp->ptid).c_str ());
+         infrun_log_debug ("restart threads: [%s] is event thread",
+                           target_pid_to_str (tp->ptid).c_str ());
          continue;
        }
 
       if (!(tp->state == THREAD_RUNNING || tp->control.in_infcall))
        {
-         if (debug_infrun)
-           fprintf_unfiltered (gdb_stdlog,
-                               "infrun: restart threads: "
-                               "[%s] not meant to be running\n",
-                               target_pid_to_str (tp->ptid).c_str ());
+         infrun_log_debug ("restart threads: [%s] not meant to be running",
+                           target_pid_to_str (tp->ptid).c_str ());
          continue;
        }
 
       if (tp->resumed)
        {
-         if (debug_infrun)
-           fprintf_unfiltered (gdb_stdlog,
-                               "infrun: restart threads: [%s] resumed\n",
-                               target_pid_to_str (tp->ptid).c_str ());
+         infrun_log_debug ("restart threads: [%s] resumed",
+                          target_pid_to_str (tp->ptid).c_str ());
          gdb_assert (tp->executing || tp->suspend.waitstatus_pending_p);
          continue;
        }
 
       if (thread_is_in_step_over_chain (tp))
        {
-         if (debug_infrun)
-           fprintf_unfiltered (gdb_stdlog,
-                               "infrun: restart threads: "
-                               "[%s] needs step-over\n",
-                               target_pid_to_str (tp->ptid).c_str ());
+         infrun_log_debug ("restart threads: [%s] needs step-over",
+                           target_pid_to_str (tp->ptid).c_str ());
          gdb_assert (!tp->resumed);
          continue;
        }
@@ -5616,11 +5596,8 @@ restart_threads (struct thread_info *event_thread)
 
       if (tp->suspend.waitstatus_pending_p)
        {
-         if (debug_infrun)
-           fprintf_unfiltered (gdb_stdlog,
-                               "infrun: restart threads: "
-                               "[%s] has pending status\n",
-                               target_pid_to_str (tp->ptid).c_str ());
+         infrun_log_debug ("restart threads: [%s] has pending status",
+                           target_pid_to_str (tp->ptid).c_str ());
          tp->resumed = true;
          continue;
        }
@@ -5640,10 +5617,8 @@ restart_threads (struct thread_info *event_thread)
 
       if (currently_stepping (tp))
        {
-         if (debug_infrun)
-           fprintf_unfiltered (gdb_stdlog,
-                               "infrun: restart threads: [%s] was stepping\n",
-                               target_pid_to_str (tp->ptid).c_str ());
+         infrun_log_debug ("restart threads: [%s] was stepping",
+                           target_pid_to_str (tp->ptid).c_str ());
          keep_going_stepped_thread (tp);
        }
       else
@@ -5651,10 +5626,8 @@ restart_threads (struct thread_info *event_thread)
          struct execution_control_state ecss;
          struct execution_control_state *ecs = &ecss;
 
-         if (debug_infrun)
-           fprintf_unfiltered (gdb_stdlog,
-                               "infrun: restart threads: [%s] continuing\n",
-                               target_pid_to_str (tp->ptid).c_str ());
+         infrun_log_debug ("restart threads: [%s] continuing",
+                           target_pid_to_str (tp->ptid).c_str ());
          reset_ecs (ecs, tp);
          switch_to_thread (tp);
          keep_going_pass_signal (ecs);
@@ -5684,8 +5657,8 @@ finish_step_over (struct execution_control_state *ecs)
 {
   int had_step_over_info;
 
-  displaced_step_fixup (ecs->event_thread,
-                       ecs->event_thread->suspend.stop_signal);
+  displaced_step_finish (ecs->event_thread,
+                        ecs->event_thread->suspend.stop_signal);
 
   had_step_over_info = step_over_info_valid_p ();
 
@@ -5747,12 +5720,8 @@ finish_step_over (struct execution_control_state *ecs)
          struct thread_info *tp = ecs->event_thread;
          struct regcache *regcache;
 
-         if (debug_infrun)
-           {
-             fprintf_unfiltered (gdb_stdlog,
-                                 "infrun: found resumed threads with "
-                                 "pending events, saving status\n");
-           }
+         infrun_log_debug ("found resumed threads with "
+                           "pending events, saving status");
 
          gdb_assert (pending != tp);
 
@@ -5768,16 +5737,12 @@ finish_step_over (struct execution_control_state *ecs)
          regcache = get_thread_regcache (tp);
          tp->suspend.stop_pc = regcache_read_pc (regcache);
 
-         if (debug_infrun)
-           {
-             fprintf_unfiltered (gdb_stdlog,
-                                 "infrun: saved stop_pc=%s for %s "
-                                 "(currently_stepping=%d)\n",
-                                 paddress (target_gdbarch (),
-                                           tp->suspend.stop_pc),
-                                 target_pid_to_str (tp->ptid).c_str (),
-                                 currently_stepping (tp));
-           }
+         infrun_log_debug ("saved stop_pc=%s for %s "
+                           "(currently_stepping=%d)\n",
+                           paddress (target_gdbarch (),
+                                     tp->suspend.stop_pc),
+                           target_pid_to_str (tp->ptid).c_str (),
+                           currently_stepping (tp));
 
          /* This in-line step-over finished; clear this so we won't
             start a new one.  This is what handle_signal_stop would
@@ -5833,22 +5798,20 @@ handle_signal_stop (struct execution_control_state *ecs)
 
       switch_to_thread (ecs->event_thread);
 
-      fprintf_unfiltered (gdb_stdlog, "infrun: stop_pc = %s\n",
-                         paddress (reg_gdbarch,
-                                   ecs->event_thread->suspend.stop_pc));
+      infrun_log_debug ("stop_pc=%s",
+                       paddress (reg_gdbarch,
+                                 ecs->event_thread->suspend.stop_pc));
       if (target_stopped_by_watchpoint ())
        {
           CORE_ADDR addr;
 
-         fprintf_unfiltered (gdb_stdlog, "infrun: stopped by watchpoint\n");
+         infrun_log_debug ("stopped by watchpoint");
 
          if (target_stopped_data_address (current_top_target (), &addr))
-            fprintf_unfiltered (gdb_stdlog,
-                                "infrun: stopped data address = %s\n",
-                                paddress (reg_gdbarch, addr));
+           infrun_log_debug ("stopped data address=%s",
+                             paddress (reg_gdbarch, addr));
           else
-            fprintf_unfiltered (gdb_stdlog,
-                                "infrun: (no data address available)\n");
+           infrun_log_debug ("(no data address available)");
        }
     }
 
@@ -5858,8 +5821,7 @@ handle_signal_stop (struct execution_control_state *ecs)
   if (stop_soon == STOP_QUIETLY || stop_soon == STOP_QUIETLY_REMOTE)
     {
       context_switch (ecs);
-      if (debug_infrun)
-       fprintf_unfiltered (gdb_stdlog, "infrun: quietly stopped\n");
+      infrun_log_debug ("quietly stopped");
       stop_print_frame = 1;
       stop_waiting (ecs);
       return;
@@ -5900,8 +5862,7 @@ handle_signal_stop (struct execution_control_state *ecs)
      so, then switch to that thread.  */
   if (ecs->ptid != inferior_ptid)
     {
-      if (debug_infrun)
-       fprintf_unfiltered (gdb_stdlog, "infrun: context switch\n");
+      infrun_log_debug ("context switch");
 
       context_switch (ecs);
 
@@ -5932,25 +5893,16 @@ handle_signal_stop (struct execution_control_state *ecs)
        {
          if (single_step_breakpoint_inserted_here_p (aspace, pc))
            {
-             if (debug_infrun)
-               {
-                 fprintf_unfiltered (gdb_stdlog,
-                                     "infrun: [%s] hit another thread's "
-                                     "single-step breakpoint\n",
-                                     target_pid_to_str (ecs->ptid).c_str ());
-               }
+             infrun_log_debug ("[%s] hit another thread's single-step "
+                               "breakpoint",
+                               target_pid_to_str (ecs->ptid).c_str ());
              ecs->hit_singlestep_breakpoint = 1;
            }
        }
       else
        {
-         if (debug_infrun)
-           {
-             fprintf_unfiltered (gdb_stdlog,
-                                 "infrun: [%s] hit its "
-                                 "single-step breakpoint\n",
-                                 target_pid_to_str (ecs->ptid).c_str ());
-           }
+         infrun_log_debug ("[%s] hit its single-step breakpoint",
+                           target_pid_to_str (ecs->ptid).c_str ());
        }
     }
   delete_just_stopped_threads_single_step_breakpoints ();
@@ -6065,8 +6017,9 @@ handle_signal_stop (struct execution_control_state *ecs)
       int step_through_delay
        = gdbarch_single_step_through_delay (gdbarch, frame);
 
-      if (debug_infrun && step_through_delay)
-       fprintf_unfiltered (gdb_stdlog, "infrun: step through delay\n");
+      if (step_through_delay)
+       infrun_log_debug ("step through delay");
+
       if (ecs->event_thread->control.step_range_end == 0
          && step_through_delay)
        {
@@ -6107,14 +6060,14 @@ handle_signal_stop (struct execution_control_state *ecs)
      simply make sure to ignore it if `stopped_by_watchpoint' is
      set.  */
 
-  if (debug_infrun
-      && ecs->event_thread->suspend.stop_signal == GDB_SIGNAL_TRAP
+  if (ecs->event_thread->suspend.stop_signal == GDB_SIGNAL_TRAP
       && !bpstat_explains_signal (ecs->event_thread->control.stop_bpstat,
                                  GDB_SIGNAL_TRAP)
       && stopped_by_watchpoint)
-    fprintf_unfiltered (gdb_stdlog,
-                       "infrun: no user watchpoint explains "
-                       "watchpoint SIGTRAP, ignoring\n");
+    {
+      infrun_log_debug ("no user watchpoint explains watchpoint SIGTRAP, "
+                       "ignoring");
+    }
 
   /* NOTE: cagney/2003-03-29: These checks for a random signal
      at one stage in the past included checks for an inferior
@@ -6171,10 +6124,7 @@ handle_signal_stop (struct execution_control_state *ecs)
       else
        {
          /* A delayed software breakpoint event.  Ignore the trap.  */
-         if (debug_infrun)
-           fprintf_unfiltered (gdb_stdlog,
-                               "infrun: delayed software breakpoint "
-                               "trap, ignoring\n");
+         infrun_log_debug ("delayed software breakpoint trap, ignoring");
          random_signal = 0;
        }
     }
@@ -6184,10 +6134,8 @@ handle_signal_stop (struct execution_control_state *ecs)
   if (random_signal && target_stopped_by_hw_breakpoint ())
     {
       /* A delayed hardware breakpoint event.  Ignore the trap.  */
-      if (debug_infrun)
-       fprintf_unfiltered (gdb_stdlog,
-                           "infrun: delayed hardware breakpoint/watchpoint "
-                           "trap, ignoring\n");
+      infrun_log_debug ("delayed hardware breakpoint/watchpoint "
+                       "trap, ignoring");
       random_signal = 0;
     }
 
@@ -6211,8 +6159,7 @@ handle_signal_stop (struct execution_control_state *ecs)
   if (ecs->event_thread->stop_requested)
     {
       random_signal = 1;
-      if (debug_infrun)
-       fprintf_unfiltered (gdb_stdlog, "infrun: user-requested stop\n");
+      infrun_log_debug ("user-requested stop");
     }
 
   /* For the program's own signals, act according to
@@ -6224,9 +6171,8 @@ handle_signal_stop (struct execution_control_state *ecs)
       struct inferior *inf = find_inferior_ptid (ecs->target, ecs->ptid);
       enum gdb_signal stop_signal = ecs->event_thread->suspend.stop_signal;
 
-      if (debug_infrun)
-        fprintf_unfiltered (gdb_stdlog, "infrun: random signal (%s)\n",
-                            gdb_signal_to_symbol_string (stop_signal));
+      infrun_log_debug ("random signal (%s)",
+                       gdb_signal_to_symbol_string (stop_signal));
 
       stopped_by_random_signal = 1;
 
@@ -6271,10 +6217,7 @@ handle_signal_stop (struct execution_control_state *ecs)
             code paths as single-step - set a breakpoint at the
             signal return address and then, once hit, step off that
             breakpoint.  */
-          if (debug_infrun)
-            fprintf_unfiltered (gdb_stdlog,
-                                "infrun: signal arrived while stepping over "
-                                "breakpoint\n");
+         infrun_log_debug ("signal arrived while stepping over breakpoint");
 
          insert_hp_step_resume_breakpoint_at_frame (frame);
          ecs->event_thread->step_after_step_resume_breakpoint = 1;
@@ -6305,10 +6248,7 @@ handle_signal_stop (struct execution_control_state *ecs)
             Note that this is only needed for a signal delivered
             while in the single-step range.  Nested signals aren't a
             problem as they eventually all return.  */
-          if (debug_infrun)
-            fprintf_unfiltered (gdb_stdlog,
-                                "infrun: signal may take us out of "
-                                "single-step range\n");
+         infrun_log_debug ("signal may take us out of single-step range");
 
          clear_step_over_info ();
          insert_hp_step_resume_breakpoint_at_frame (frame);
@@ -6328,9 +6268,7 @@ handle_signal_stop (struct execution_control_state *ecs)
 
       if (!switch_back_to_stepped_thread (ecs))
        {
-         if (debug_infrun)
-           fprintf_unfiltered (gdb_stdlog,
-                               "infrun: random signal, keep going\n");
+         infrun_log_debug ("random signal, keep going");
 
          keep_going (ecs);
        }
@@ -6384,9 +6322,7 @@ process_event_stop_test (struct execution_control_state *ecs)
         install a momentary breakpoint at the target of the
         jmp_buf.  */
 
-      if (debug_infrun)
-       fprintf_unfiltered (gdb_stdlog,
-                           "infrun: BPSTAT_WHAT_SET_LONGJMP_RESUME\n");
+      infrun_log_debug ("BPSTAT_WHAT_SET_LONGJMP_RESUME");
 
       ecs->event_thread->stepping_over_breakpoint = 1;
 
@@ -6407,10 +6343,8 @@ process_event_stop_test (struct execution_control_state *ecs)
                   || !gdbarch_get_longjmp_target (gdbarch,
                                                   frame, &jmp_buf_pc))
            {
-             if (debug_infrun)
-               fprintf_unfiltered (gdb_stdlog,
-                                   "infrun: BPSTAT_WHAT_SET_LONGJMP_RESUME "
-                                   "(!gdbarch_get_longjmp_target)\n");
+             infrun_log_debug ("BPSTAT_WHAT_SET_LONGJMP_RESUME "
+                               "(!gdbarch_get_longjmp_target)");
              keep_going (ecs);
              return;
            }
@@ -6445,9 +6379,7 @@ process_event_stop_test (struct execution_control_state *ecs)
           against stale dummy frames and user is not interested in
           stopping around longjmps.  */
 
-       if (debug_infrun)
-         fprintf_unfiltered (gdb_stdlog,
-                             "infrun: BPSTAT_WHAT_CLEAR_LONGJMP_RESUME\n");
+       infrun_log_debug ("BPSTAT_WHAT_CLEAR_LONGJMP_RESUME");
 
        gdb_assert (ecs->event_thread->control.exception_resume_breakpoint
                    != NULL);
@@ -6493,16 +6425,14 @@ process_event_stop_test (struct execution_control_state *ecs)
       return;
 
     case BPSTAT_WHAT_SINGLE:
-      if (debug_infrun)
-       fprintf_unfiltered (gdb_stdlog, "infrun: BPSTAT_WHAT_SINGLE\n");
+      infrun_log_debug ("BPSTAT_WHAT_SINGLE");
       ecs->event_thread->stepping_over_breakpoint = 1;
       /* Still need to check other stuff, at least the case where we
         are stepping and step out of the right range.  */
       break;
 
     case BPSTAT_WHAT_STEP_RESUME:
-      if (debug_infrun)
-       fprintf_unfiltered (gdb_stdlog, "infrun: BPSTAT_WHAT_STEP_RESUME\n");
+      infrun_log_debug ("BPSTAT_WHAT_STEP_RESUME");
 
       delete_step_resume_breakpoint (ecs->event_thread);
       if (ecs->event_thread->control.proceed_to_finish
@@ -6534,8 +6464,7 @@ process_event_stop_test (struct execution_control_state *ecs)
       break;
 
     case BPSTAT_WHAT_STOP_NOISY:
-      if (debug_infrun)
-       fprintf_unfiltered (gdb_stdlog, "infrun: BPSTAT_WHAT_STOP_NOISY\n");
+      infrun_log_debug ("BPSTAT_WHAT_STOP_NOISY");
       stop_print_frame = 1;
 
       /* Assume the thread stopped for a breapoint.  We'll still check
@@ -6547,8 +6476,7 @@ process_event_stop_test (struct execution_control_state *ecs)
       return;
 
     case BPSTAT_WHAT_STOP_SILENT:
-      if (debug_infrun)
-       fprintf_unfiltered (gdb_stdlog, "infrun: BPSTAT_WHAT_STOP_SILENT\n");
+      infrun_log_debug ("BPSTAT_WHAT_STOP_SILENT");
       stop_print_frame = 0;
 
       /* Assume the thread stopped for a breapoint.  We'll still check
@@ -6559,8 +6487,7 @@ process_event_stop_test (struct execution_control_state *ecs)
       return;
 
     case BPSTAT_WHAT_HP_STEP_RESUME:
-      if (debug_infrun)
-       fprintf_unfiltered (gdb_stdlog, "infrun: BPSTAT_WHAT_HP_STEP_RESUME\n");
+      infrun_log_debug ("BPSTAT_WHAT_HP_STEP_RESUME");
 
       delete_step_resume_breakpoint (ecs->event_thread);
       if (ecs->event_thread->step_after_step_resume_breakpoint)
@@ -6595,10 +6522,7 @@ process_event_stop_test (struct execution_control_state *ecs)
          && sr_bp->type == bp_hp_step_resume
          && sr_bp->loc->address == ecs->event_thread->prev_pc)
        {
-         if (debug_infrun)
-           fprintf_unfiltered (gdb_stdlog,
-                               "infrun: stepped permanent breakpoint, stopped in "
-                               "handler\n");
+         infrun_log_debug ("stepped permanent breakpoint, stopped in handler");
          delete_step_resume_breakpoint (ecs->event_thread);
          ecs->event_thread->step_after_step_resume_breakpoint = 0;
        }
@@ -6616,9 +6540,7 @@ process_event_stop_test (struct execution_control_state *ecs)
 
   if (ecs->event_thread->control.step_resume_breakpoint)
     {
-      if (debug_infrun)
-        fprintf_unfiltered (gdb_stdlog,
-                            "infrun: step-resume breakpoint is inserted\n");
+      infrun_log_debug ("step-resume breakpoint is inserted");
 
       /* Having a step-resume breakpoint overrides anything
          else having to do with stepping commands until
@@ -6629,8 +6551,7 @@ process_event_stop_test (struct execution_control_state *ecs)
 
   if (ecs->event_thread->control.step_range_end == 0)
     {
-      if (debug_infrun)
-        fprintf_unfiltered (gdb_stdlog, "infrun: no stepping, continue\n");
+      infrun_log_debug ("no stepping, continue");
       /* Likewise if we aren't even stepping.  */
       keep_going (ecs);
       return;
@@ -6659,11 +6580,10 @@ process_event_stop_test (struct execution_control_state *ecs)
          || frame_id_eq (get_frame_id (frame),
                          ecs->event_thread->control.step_frame_id)))
     {
-      if (debug_infrun)
-       fprintf_unfiltered
-         (gdb_stdlog, "infrun: stepping inside range [%s-%s]\n",
-          paddress (gdbarch, ecs->event_thread->control.step_range_start),
-          paddress (gdbarch, ecs->event_thread->control.step_range_end));
+      infrun_log_debug
+       ("stepping inside range [%s-%s]",
+        paddress (gdbarch, ecs->event_thread->control.step_range_start),
+        paddress (gdbarch, ecs->event_thread->control.step_range_end));
 
       /* Tentatively re-enable range stepping; `resume' disables it if
         necessary (e.g., if we're stepping over a breakpoint or we
@@ -6706,9 +6626,7 @@ process_event_stop_test (struct execution_control_state *ecs)
        gdbarch_skip_solib_resolver (gdbarch,
                                     ecs->event_thread->suspend.stop_pc);
 
-      if (debug_infrun)
-        fprintf_unfiltered (gdb_stdlog,
-                            "infrun: stepped into dynsym resolve code\n");
+      infrun_log_debug ("stepped into dynsym resolve code");
 
       if (pc_after_resolver)
        {
@@ -6731,9 +6649,7 @@ process_event_stop_test (struct execution_control_state *ecs)
       && gdbarch_in_indirect_branch_thunk (gdbarch,
                                           ecs->event_thread->suspend.stop_pc))
     {
-      if (debug_infrun)
-        fprintf_unfiltered (gdb_stdlog,
-                            "infrun: stepped into indirect branch thunk\n");
+      infrun_log_debug ("stepped into indirect branch thunk");
       keep_going (ecs);
       return;
     }
@@ -6743,9 +6659,7 @@ process_event_stop_test (struct execution_control_state *ecs)
          || ecs->event_thread->control.step_over_calls == STEP_OVER_ALL)
       && get_frame_type (frame) == SIGTRAMP_FRAME)
     {
-      if (debug_infrun)
-        fprintf_unfiltered (gdb_stdlog,
-                            "infrun: stepped into signal trampoline\n");
+      infrun_log_debug ("stepped into signal trampoline");
       /* The inferior, while doing a "step" or "next", has ended up in
          a signal trampoline (either by a signal being delivered or by
          the signal handler returning).  Just single-step until the
@@ -6770,9 +6684,7 @@ process_event_stop_test (struct execution_control_state *ecs)
       CORE_ADDR real_stop_pc
        = gdbarch_skip_trampoline_code (gdbarch, frame, stop_pc);
 
-      if (debug_infrun)
-        fprintf_unfiltered (gdb_stdlog,
-                            "infrun: stepped into solib return tramp\n");
+      infrun_log_debug ("stepped into solib return tramp");
 
       /* Only proceed through if we know where it's going.  */
       if (real_stop_pc)
@@ -6825,8 +6737,7 @@ process_event_stop_test (struct execution_control_state *ecs)
       CORE_ADDR stop_pc = ecs->event_thread->suspend.stop_pc;
       CORE_ADDR real_stop_pc;
 
-      if (debug_infrun)
-        fprintf_unfiltered (gdb_stdlog, "infrun: stepped into subroutine\n");
+      infrun_log_debug ("stepped into subroutine");
 
       if (ecs->event_thread->control.step_over_calls == STEP_OVER_NONE)
        {
@@ -7010,6 +6921,10 @@ process_event_stop_test (struct execution_control_state *ecs)
        }
     }
 
+  /* This always returns the sal for the inner-most frame when we are in a
+     stack of inlined frames, even if GDB actually believes that it is in a
+     more outer frame.  This is checked for below by calls to
+     inline_skipped_frames.  */
   stop_pc_sal = find_pc_line (ecs->event_thread->suspend.stop_pc, 0);
 
   /* NOTE: tausq/2004-05-24: This if block used to be done before all
@@ -7019,9 +6934,7 @@ process_event_stop_test (struct execution_control_state *ecs)
       && ecs->stop_func_name == NULL
       && stop_pc_sal.line == 0)
     {
-      if (debug_infrun)
-        fprintf_unfiltered (gdb_stdlog,
-                            "infrun: stepped into undebuggable function\n");
+      infrun_log_debug ("stepped into undebuggable function");
 
       /* The inferior just stepped into, or returned to, an
          undebuggable function (where there is no debugging information
@@ -7054,8 +6967,7 @@ process_event_stop_test (struct execution_control_state *ecs)
     {
       /* It is stepi or nexti.  We always want to stop stepping after
          one instruction.  */
-      if (debug_infrun)
-        fprintf_unfiltered (gdb_stdlog, "infrun: stepi/nexti\n");
+      infrun_log_debug ("stepi/nexti");
       end_stepping_range (ecs);
       return;
     }
@@ -7066,8 +6978,7 @@ process_event_stop_test (struct execution_control_state *ecs)
          stepping (does this always happen right after one instruction,
          when we do "s" in a function with no line numbers,
          or can this happen as a result of a return or longjmp?).  */
-      if (debug_infrun)
-        fprintf_unfiltered (gdb_stdlog, "infrun: no line number info\n");
+      infrun_log_debug ("line number info");
       end_stepping_range (ecs);
       return;
     }
@@ -7080,9 +6991,7 @@ process_event_stop_test (struct execution_control_state *ecs)
                   ecs->event_thread->control.step_frame_id)
       && inline_skipped_frames (ecs->event_thread))
     {
-      if (debug_infrun)
-       fprintf_unfiltered (gdb_stdlog,
-                           "infrun: stepped into inlined function\n");
+      infrun_log_debug ("stepped into inlined function");
 
       symtab_and_line call_sal = find_frame_sal (get_current_frame ());
 
@@ -7132,9 +7041,7 @@ process_event_stop_test (struct execution_control_state *ecs)
       && stepped_in_from (get_current_frame (),
                          ecs->event_thread->control.step_frame_id))
     {
-      if (debug_infrun)
-       fprintf_unfiltered (gdb_stdlog,
-                           "infrun: stepping through inlined function\n");
+      infrun_log_debug ("stepping through inlined function");
 
       if (ecs->event_thread->control.step_over_calls == STEP_OVER_ALL
          || inline_frame_is_marked_for_skip (false, ecs->event_thread))
@@ -7144,19 +7051,32 @@ process_event_stop_test (struct execution_control_state *ecs)
       return;
     }
 
+  bool refresh_step_info = true;
   if ((ecs->event_thread->suspend.stop_pc == stop_pc_sal.pc)
       && (ecs->event_thread->current_line != stop_pc_sal.line
          || ecs->event_thread->current_symtab != stop_pc_sal.symtab))
     {
-      /* We are at the start of a different line.  So stop.  Note that
-         we don't stop if we step into the middle of a different line.
-         That is said to make things like for (;;) statements work
-         better.  */
-      if (debug_infrun)
-        fprintf_unfiltered (gdb_stdlog,
-                            "infrun: stepped to a different line\n");
-      end_stepping_range (ecs);
-      return;
+      if (stop_pc_sal.is_stmt)
+       {
+         /* We are at the start of a different line.  So stop.  Note that
+            we don't stop if we step into the middle of a different line.
+            That is said to make things like for (;;) statements work
+            better.  */
+         infrun_log_debug ("infrun: stepped to a different line\n");
+         end_stepping_range (ecs);
+         return;
+       }
+      else if (frame_id_eq (get_frame_id (get_current_frame ()),
+                           ecs->event_thread->control.step_frame_id))
+       {
+         /* We are at the start of a different line, however, this line is
+            not marked as a statement, and we have not changed frame.  We
+            ignore this line table entry, and continue stepping forward,
+            looking for a better place to stop.  */
+         refresh_step_info = false;
+         infrun_log_debug ("infrun: stepped to a different line, but "
+                           "it's not the start of a statement\n");
+       }
     }
 
   /* We aren't done stepping.
@@ -7164,15 +7084,22 @@ process_event_stop_test (struct execution_control_state *ecs)
      Optimize by setting the stepping range to the line.
      (We might not be in the original line, but if we entered a
      new line in mid-statement, we continue stepping.  This makes
-     things like for(;;) statements work better.)  */
+     things like for(;;) statements work better.)
+
+     If we entered a SAL that indicates a non-statement line table entry,
+     then we update the stepping range, but we don't update the step info,
+     which includes things like the line number we are stepping away from.
+     This means we will stop when we find a line table entry that is marked
+     as is-statement, even if it matches the non-statement one we just
+     stepped into.   */
 
   ecs->event_thread->control.step_range_start = stop_pc_sal.pc;
   ecs->event_thread->control.step_range_end = stop_pc_sal.end;
   ecs->event_thread->control.may_range_step = 1;
-  set_step_info (frame, stop_pc_sal);
+  if (refresh_step_info)
+    set_step_info (ecs->event_thread, frame, stop_pc_sal);
 
-  if (debug_infrun)
-     fprintf_unfiltered (gdb_stdlog, "infrun: keep going\n");
+  infrun_log_debug ("keep going");
   keep_going (ecs);
 }
 
@@ -7204,12 +7131,8 @@ switch_back_to_stepped_thread (struct execution_control_state *ecs)
       if (ecs->event_thread->control.trap_expected
          && ecs->event_thread->suspend.stop_signal != GDB_SIGNAL_TRAP)
        {
-         if (debug_infrun)
-           {
-             fprintf_unfiltered (gdb_stdlog,
-                                 "infrun: need to finish step-over of [%s]\n",
-                                 target_pid_to_str (ecs->event_thread->ptid).c_str ());
-           }
+         infrun_log_debug ("need to finish step-over of [%s]",
+                           target_pid_to_str (ecs->event_thread->ptid).c_str ());
          keep_going (ecs);
          return 1;
        }
@@ -7218,13 +7141,8 @@ switch_back_to_stepped_thread (struct execution_control_state *ecs)
         breakpoint of another thread.  */
       if (ecs->hit_singlestep_breakpoint)
        {
-        if (debug_infrun)
-          {
-            fprintf_unfiltered (gdb_stdlog,
-                                "infrun: need to step [%s] over single-step "
-                                "breakpoint\n",
-                                target_pid_to_str (ecs->ptid).c_str ());
-          }
+        infrun_log_debug ("need to step [%s] over single-step breakpoint",
+                          target_pid_to_str (ecs->ptid).c_str ());
         keep_going (ecs);
         return 1;
        }
@@ -7234,12 +7152,9 @@ switch_back_to_stepped_thread (struct execution_control_state *ecs)
         another thread.  */
       if (thread_still_needs_step_over (ecs->event_thread))
        {
-         if (debug_infrun)
-           {
-             fprintf_unfiltered (gdb_stdlog,
-                                 "infrun: thread [%s] still needs step-over\n",
-                                 target_pid_to_str (ecs->event_thread->ptid).c_str ());
-           }
+         infrun_log_debug
+           ("thread [%s] still needs step-over",
+            target_pid_to_str (ecs->event_thread->ptid).c_str ());
          keep_going (ecs);
          return 1;
        }
@@ -7318,9 +7233,7 @@ switch_back_to_stepped_thread (struct execution_control_state *ecs)
 
       if (stepping_thread != NULL)
        {
-         if (debug_infrun)
-           fprintf_unfiltered (gdb_stdlog,
-                               "infrun: switching back to stepped thread\n");
+         infrun_log_debug ("switching back to stepped thread");
 
          if (keep_going_stepped_thread (stepping_thread))
            {
@@ -7366,18 +7279,14 @@ keep_going_stepped_thread (struct thread_info *tp)
 
   if (tp->state == THREAD_EXITED || !target_thread_alive (tp->ptid))
     {
-      if (debug_infrun)
-       fprintf_unfiltered (gdb_stdlog,
-                           "infrun: not resuming previously  "
-                           "stepped thread, it has vanished\n");
+      infrun_log_debug ("not resuming previously stepped thread, it has "
+                       "vanished");
 
       delete_thread (tp);
       return 0;
     }
 
-  if (debug_infrun)
-    fprintf_unfiltered (gdb_stdlog,
-                       "infrun: resuming previously stepped thread\n");
+  infrun_log_debug ("resuming previously stepped thread");
 
   reset_ecs (ecs, tp);
   switch_to_thread (tp);
@@ -7402,11 +7311,9 @@ keep_going_stepped_thread (struct thread_info *tp)
     {
       ptid_t resume_ptid;
 
-      if (debug_infrun)
-       fprintf_unfiltered (gdb_stdlog,
-                           "infrun: expected thread advanced also (%s -> %s)\n",
-                           paddress (target_gdbarch (), tp->prev_pc),
-                           paddress (target_gdbarch (), tp->suspend.stop_pc));
+      infrun_log_debug ("expected thread advanced also (%s -> %s)",
+                       paddress (target_gdbarch (), tp->prev_pc),
+                       paddress (target_gdbarch (), tp->suspend.stop_pc));
 
       /* Clear the info of the previous step-over, as it's no longer
         valid (if the thread was trying to step over a breakpoint, it
@@ -7428,9 +7335,7 @@ keep_going_stepped_thread (struct thread_info *tp)
     }
   else
     {
-      if (debug_infrun)
-       fprintf_unfiltered (gdb_stdlog,
-                           "infrun: expected thread still hasn't advanced\n");
+      infrun_log_debug ("expected thread still hasn't advanced");
 
       keep_going_pass_signal (ecs);
     }
@@ -7581,10 +7486,8 @@ insert_step_resume_breakpoint_at_sal_1 (struct gdbarch *gdbarch,
   gdb_assert (inferior_thread ()->control.step_resume_breakpoint == NULL);
   gdb_assert (sr_type == bp_step_resume || sr_type == bp_hp_step_resume);
 
-  if (debug_infrun)
-    fprintf_unfiltered (gdb_stdlog,
-                       "infrun: inserting step-resume breakpoint at %s\n",
-                       paddress (gdbarch, sr_sal.pc));
+  infrun_log_debug ("inserting step-resume breakpoint at %s",
+                   paddress (gdbarch, sr_sal.pc));
 
   inferior_thread ()->control.step_resume_breakpoint
     = set_momentary_breakpoint (gdbarch, sr_sal, sr_id, sr_type).release ();
@@ -7670,10 +7573,8 @@ insert_longjmp_resume_breakpoint (struct gdbarch *gdbarch, CORE_ADDR pc)
      longjmp_resume_breakpoint when one is already active.  */
   gdb_assert (inferior_thread ()->control.exception_resume_breakpoint == NULL);
 
-  if (debug_infrun)
-    fprintf_unfiltered (gdb_stdlog,
-                       "infrun: inserting longjmp-resume breakpoint at %s\n",
-                       paddress (gdbarch, pc));
+  infrun_log_debug ("inserting longjmp-resume breakpoint at %s",
+                   paddress (gdbarch, pc));
 
   inferior_thread ()->control.exception_resume_breakpoint =
     set_momentary_breakpoint_at_pc (gdbarch, pc, bp_longjmp_resume).release ();
@@ -7706,10 +7607,8 @@ insert_exception_resume_breakpoint (struct thread_info *tp,
        {
          handler = value_as_address (value);
 
-         if (debug_infrun)
-           fprintf_unfiltered (gdb_stdlog,
-                               "infrun: exception resume at %lx\n",
-                               (unsigned long) handler);
+         infrun_log_debug ("exception resume at %lx",
+                           (unsigned long) handler);
 
          bp = set_momentary_breakpoint_at_pc (get_frame_arch (frame),
                                               handler,
@@ -7746,11 +7645,8 @@ insert_exception_resume_from_probe (struct thread_info *tp,
 
   handler = value_as_address (arg_value);
 
-  if (debug_infrun)
-    fprintf_unfiltered (gdb_stdlog,
-                       "infrun: exception resume at %s\n",
-                       paddress (get_objfile_arch (probe->objfile),
-                                 handler));
+  infrun_log_debug ("exception resume at %s",
+                   paddress (probe->objfile->arch (), handler));
 
   bp = set_momentary_breakpoint_at_pc (get_frame_arch (frame),
                                       handler, bp_exception_resume).release ();
@@ -7829,15 +7725,14 @@ check_exception_resume (struct execution_control_state *ecs,
 static void
 stop_waiting (struct execution_control_state *ecs)
 {
-  if (debug_infrun)
-    fprintf_unfiltered (gdb_stdlog, "infrun: stop_waiting\n");
+  infrun_log_debug ("stop_waiting");
 
   /* Let callers know we don't want to wait for the inferior anymore.  */
   ecs->wait_some_more = 0;
 
-  /* If all-stop, but the target is always in non-stop mode, stop all
+  /* If all-stop, but there exists a non-stop target, stop all
      threads now that we're presenting the stop to the user.  */
-  if (!non_stop && target_is_non_stop_p ())
+  if (!non_stop && exists_non_stop_target ())
     stop_all_threads ();
 }
 
@@ -7852,17 +7747,15 @@ keep_going_pass_signal (struct execution_control_state *ecs)
 
   /* Save the pc before execution, to compare with pc after stop.  */
   ecs->event_thread->prev_pc
-    = regcache_read_pc (get_thread_regcache (ecs->event_thread));
+    = regcache_read_pc_protected (get_thread_regcache (ecs->event_thread));
 
   if (ecs->event_thread->control.trap_expected)
     {
       struct thread_info *tp = ecs->event_thread;
 
-      if (debug_infrun)
-       fprintf_unfiltered (gdb_stdlog,
-                           "infrun: %s has trap_expected set, "
-                           "resuming to collect trap\n",
-                           target_pid_to_str (tp->ptid).c_str ());
+      infrun_log_debug ("%s has trap_expected set, "
+                       "resuming to collect trap",
+                       target_pid_to_str (tp->ptid).c_str ());
 
       /* We haven't yet gotten our trap, and either: intercepted a
         non-signal event (e.g., a fork); or took a signal which we
@@ -7880,20 +7773,15 @@ keep_going_pass_signal (struct execution_control_state *ecs)
       if (ecs->hit_singlestep_breakpoint
          || thread_still_needs_step_over (tp))
        {
-         if (debug_infrun)
-           fprintf_unfiltered (gdb_stdlog,
-                               "infrun: step-over already in progress: "
-                               "step-over for %s deferred\n",
-                               target_pid_to_str (tp->ptid).c_str ());
-         thread_step_over_chain_enqueue (tp);
+         infrun_log_debug ("step-over already in progress: "
+                           "step-over for %s deferred",
+                           target_pid_to_str (tp->ptid).c_str ());
+         global_thread_step_over_chain_enqueue (tp);
        }
       else
        {
-         if (debug_infrun)
-           fprintf_unfiltered (gdb_stdlog,
-                               "infrun: step-over in progress: "
-                               "resume of %s deferred\n",
-                               target_pid_to_str (tp->ptid).c_str ());
+         infrun_log_debug ("step-over in progress: resume of %s deferred",
+                           target_pid_to_str (tp->ptid).c_str ());
        }
     }
   else
@@ -7993,8 +7881,7 @@ keep_going (struct execution_control_state *ecs)
 static void
 prepare_to_wait (struct execution_control_state *ecs)
 {
-  if (debug_infrun)
-    fprintf_unfiltered (gdb_stdlog, "infrun: prepare_to_wait\n");
+  infrun_log_debug ("prepare_to_wait");
 
   ecs->wait_some_more = 1;
 
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