/* Native-dependent code for the i386.
- Copyright (C) 2001, 2004, 2005, 2007, 2008, 2009, 2010, 2011
- Free Software Foundation, Inc.
+ Copyright (C) 2001-2013 Free Software Foundation, Inc.
This file is part of GDB.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>. */
-#include "i386-nat.h"
#include "defs.h"
+#include "i386-nat.h"
#include "breakpoint.h"
#include "command.h"
#include "gdbcmd.h"
#include "target.h"
#include "gdb_assert.h"
+#include "inferior.h"
/* Support for hardware watchpoints and breakpoints using the i386
debug registers.
/* Support for 8-byte wide hw watchpoints. */
#define TARGET_HAS_DR_LEN_8 (i386_dr_low.debug_register_length == 8)
-/* Debug registers' indices. */
-#define DR_NADDR 4 /* The number of debug address registers. */
-#define DR_STATUS 6 /* Index of debug status register (DR6). */
-#define DR_CONTROL 7 /* Index of debug control register (DR7). */
-
/* DR7 Debug Control register fields. */
/* How many bits to skip in DR7 to get to R/W and LEN fields. */
/* A macro to loop over all debug registers. */
#define ALL_DEBUG_REGISTERS(i) for (i = 0; i < DR_NADDR; i++)
+/* Per-process data. We don't bind this to a per-inferior registry
+ because of targets like x86 GNU/Linux that need to keep track of
+ processes that aren't bound to any inferior (e.g., fork children,
+ checkpoints). */
-/* Global state needed to track h/w watchpoints. */
-
-struct i386_debug_reg_state
+struct i386_process_info
{
- /* Mirror the inferior's DRi registers. We keep the status and
- control registers separated because they don't hold addresses.
- Note that since we can change these mirrors while threads are
- running, we never trust them to explain a cause of a trap.
- For that, we need to peek directly in the inferior registers. */
- CORE_ADDR dr_mirror[DR_NADDR];
- unsigned dr_status_mirror, dr_control_mirror;
-
- /* Reference counts for each debug register. */
- int dr_ref_count[DR_NADDR];
+ /* Linked list. */
+ struct i386_process_info *next;
+
+ /* The process identifier. */
+ pid_t pid;
+
+ /* Copy of i386 hardware debug registers. */
+ struct i386_debug_reg_state state;
};
-/* Clear the reference counts and forget everything we knew about the
- debug registers. */
+static struct i386_process_info *i386_process_list = NULL;
-static void
-i386_init_dregs (struct i386_debug_reg_state *state)
+/* Find process data for process PID. */
+
+static struct i386_process_info *
+i386_find_process_pid (pid_t pid)
{
- int i;
+ struct i386_process_info *proc;
- ALL_DEBUG_REGISTERS (i)
- {
- state->dr_mirror[i] = 0;
- state->dr_ref_count[i] = 0;
- }
- state->dr_control_mirror = 0;
- state->dr_status_mirror = 0;
+ for (proc = i386_process_list; proc; proc = proc->next)
+ if (proc->pid == pid)
+ return proc;
+
+ return NULL;
}
-static struct i386_debug_reg_state dr_mirror;
+/* Add process data for process PID. Returns newly allocated info
+ object. */
+
+static struct i386_process_info *
+i386_add_process (pid_t pid)
+{
+ struct i386_process_info *proc;
+
+ proc = xcalloc (1, sizeof (*proc));
+ proc->pid = pid;
+
+ proc->next = i386_process_list;
+ i386_process_list = proc;
+
+ return proc;
+}
+
+/* Get data specific info for process PID, creating it if necessary.
+ Never returns NULL. */
+
+static struct i386_process_info *
+i386_process_info_get (pid_t pid)
+{
+ struct i386_process_info *proc;
+
+ proc = i386_find_process_pid (pid);
+ if (proc == NULL)
+ proc = i386_add_process (pid);
+
+ return proc;
+}
+
+/* Get debug registers state for process PID. */
+
+struct i386_debug_reg_state *
+i386_debug_reg_state (pid_t pid)
+{
+ return &i386_process_info_get (pid)->state;
+}
+
+/* See declaration in i386-nat.h. */
+
+void
+i386_forget_process (pid_t pid)
+{
+ struct i386_process_info *proc, **proc_link;
+
+ proc = i386_process_list;
+ proc_link = &i386_process_list;
-/* Reference counts for each debug register. */
-static int dr_ref_count[DR_NADDR];
+ while (proc != NULL)
+ {
+ if (proc->pid == pid)
+ {
+ *proc_link = proc->next;
+
+ xfree (proc);
+ return;
+ }
+
+ proc_link = &proc->next;
+ proc = *proc_link;
+ }
+}
/* Whether or not to print the mirrored debug registers. */
static int maint_show_dr;
void
i386_cleanup_dregs (void)
{
- i386_init_dregs (&dr_mirror);
+ /* Starting from scratch has the same effect. */
+ i386_forget_process (ptid_get_pid (inferior_ptid));
}
/* Print the values of the mirrored debug registers. This is called
const char *func, CORE_ADDR addr,
int len, enum target_hw_bp_type type)
{
- int addr_size = gdbarch_addr_bit (target_gdbarch) / 8;
+ int addr_size = gdbarch_addr_bit (target_gdbarch ()) / 8;
int i;
puts_unfiltered (func);
static void
i386_update_inferior_debug_regs (struct i386_debug_reg_state *new_state)
{
+ struct i386_debug_reg_state *state
+ = i386_debug_reg_state (ptid_get_pid (inferior_ptid));
int i;
ALL_DEBUG_REGISTERS (i)
{
- if (I386_DR_VACANT (new_state, i) != I386_DR_VACANT (&dr_mirror, i))
- {
- if (!I386_DR_VACANT (new_state, i))
- {
- i386_dr_low.set_addr (i, new_state->dr_mirror[i]);
-
- /* Only a sanity check for leftover bits (set possibly only
- by inferior). */
- if (i386_dr_low.unset_status)
- i386_dr_low.unset_status (I386_DR_WATCH_MASK (i));
- }
- else
- {
- if (i386_dr_low.reset_addr)
- i386_dr_low.reset_addr (i);
- }
- }
+ if (I386_DR_VACANT (new_state, i) != I386_DR_VACANT (state, i))
+ i386_dr_low.set_addr (i, new_state->dr_mirror[i]);
else
- gdb_assert (new_state->dr_mirror[i] == dr_mirror.dr_mirror[i]);
+ gdb_assert (new_state->dr_mirror[i] == state->dr_mirror[i]);
}
- if (new_state->dr_control_mirror != dr_mirror.dr_control_mirror)
+ if (new_state->dr_control_mirror != state->dr_control_mirror)
i386_dr_low.set_control (new_state->dr_control_mirror);
- dr_mirror = *new_state;
+ *state = *new_state;
}
/* Insert a watchpoint to watch a memory region which starts at
i386_insert_watchpoint (CORE_ADDR addr, int len, int type,
struct expression *cond)
{
+ struct i386_debug_reg_state *state
+ = i386_debug_reg_state (ptid_get_pid (inferior_ptid));
int retval;
/* Work on a local copy of the debug registers, and on success,
commit the change back to the inferior. */
- struct i386_debug_reg_state local_state = dr_mirror;
+ struct i386_debug_reg_state local_state = *state;
if (type == hw_read)
return 1; /* unsupported */
i386_update_inferior_debug_regs (&local_state);
if (maint_show_dr)
- i386_show_dr (&dr_mirror, "insert_watchpoint", addr, len, type);
+ i386_show_dr (state, "insert_watchpoint", addr, len, type);
return retval;
}
i386_remove_watchpoint (CORE_ADDR addr, int len, int type,
struct expression *cond)
{
+ struct i386_debug_reg_state *state
+ = i386_debug_reg_state (ptid_get_pid (inferior_ptid));
int retval;
/* Work on a local copy of the debug registers, and on success,
commit the change back to the inferior. */
- struct i386_debug_reg_state local_state = dr_mirror;
+ struct i386_debug_reg_state local_state = *state;
if (((len != 1 && len !=2 && len !=4) && !(TARGET_HAS_DR_LEN_8 && len == 8))
|| addr % len != 0)
i386_update_inferior_debug_regs (&local_state);
if (maint_show_dr)
- i386_show_dr (&dr_mirror, "remove_watchpoint", addr, len, type);
+ i386_show_dr (state, "remove_watchpoint", addr, len, type);
return retval;
}
static int
i386_region_ok_for_watchpoint (CORE_ADDR addr, int len)
{
+ struct i386_debug_reg_state *state
+ = i386_debug_reg_state (ptid_get_pid (inferior_ptid));
int nregs;
/* Compute how many aligned watchpoints we would need to cover this
region. */
- nregs = i386_handle_nonaligned_watchpoint (&dr_mirror,
+ nregs = i386_handle_nonaligned_watchpoint (state,
WP_COUNT, addr, len, hw_write);
return nregs <= DR_NADDR ? 1 : 0;
}
static int
i386_stopped_data_address (struct target_ops *ops, CORE_ADDR *addr_p)
{
+ struct i386_debug_reg_state *state
+ = i386_debug_reg_state (ptid_get_pid (inferior_ptid));
CORE_ADDR addr = 0;
int i;
int rc = 0;
+ /* The current thread's DR_STATUS. We always need to read this to
+ check whether some watchpoint caused the trap. */
unsigned status;
- unsigned control;
- struct i386_debug_reg_state *state = &dr_mirror;
-
- dr_mirror.dr_status_mirror = i386_dr_low.get_status ();
- status = dr_mirror.dr_status_mirror;
- control = dr_mirror.dr_control_mirror;
+ /* We need DR_CONTROL as well, but only iff DR_STATUS indicates a
+ data breakpoint trap. Only fetch it when necessary, to avoid an
+ unnecessary extra syscall when no watchpoint triggered. */
+ int control_p = 0;
+ unsigned control = 0;
+
+ /* In non-stop/async, threads can be running while we change the
+ STATE (and friends). Say, we set a watchpoint, and let threads
+ resume. Now, say you delete the watchpoint, or add/remove
+ watchpoints such that STATE changes while threads are running.
+ On targets that support non-stop, inserting/deleting watchpoints
+ updates the STATE only. It does not update the real thread's
+ debug registers; that's only done prior to resume. Instead, if
+ threads are running when the mirror changes, a temporary and
+ transparent stop on all threads is forced so they can get their
+ copy of the debug registers updated on re-resume. Now, say,
+ a thread hit a watchpoint before having been updated with the new
+ STATE contents, and we haven't yet handled the corresponding
+ SIGTRAP. If we trusted STATE below, we'd mistake the real
+ trapped address (from the last time we had updated debug
+ registers in the thread) with whatever was currently in STATE.
+ So to fix this, STATE always represents intention, what we _want_
+ threads to have in debug registers. To get at the address and
+ cause of the trap, we need to read the state the thread still has
+ in its debug registers.
+
+ In sum, always get the current debug register values the current
+ thread has, instead of trusting the global mirror. If the thread
+ was running when we last changed watchpoints, the mirror no
+ longer represents what was set in this thread's debug
+ registers. */
+ status = i386_dr_low.get_status ();
ALL_DEBUG_REGISTERS(i)
{
- if (I386_DR_WATCH_HIT (status, i)
- /* This second condition makes sure DRi is set up for a data
- watchpoint, not a hardware breakpoint. The reason is
- that GDB doesn't call the target_stopped_data_address
- method except for data watchpoints. In other words, I'm
- being paranoiac. */
- && I386_DR_GET_RW_LEN (control, i) != 0
- /* This third condition makes sure DRi is not vacant, this
- avoids false positives in windows-nat.c. */
- && !I386_DR_VACANT (state, i))
+ if (!I386_DR_WATCH_HIT (status, i))
+ continue;
+
+ if (!control_p)
+ {
+ control = i386_dr_low.get_control ();
+ control_p = 1;
+ }
+
+ /* This second condition makes sure DRi is set up for a data
+ watchpoint, not a hardware breakpoint. The reason is that
+ GDB doesn't call the target_stopped_data_address method
+ except for data watchpoints. In other words, I'm being
+ paranoiac. */
+ if (I386_DR_GET_RW_LEN (control, i) != 0)
{
- addr = state->dr_mirror[i];
+ addr = i386_dr_low.get_addr (i);
rc = 1;
if (maint_show_dr)
- i386_show_dr (&dr_mirror, "watchpoint_hit", addr, -1, hw_write);
+ i386_show_dr (state, "watchpoint_hit", addr, -1, hw_write);
}
}
if (maint_show_dr && addr == 0)
- i386_show_dr (&dr_mirror, "stopped_data_addr", 0, 0, hw_write);
+ i386_show_dr (state, "stopped_data_addr", 0, 0, hw_write);
if (rc)
*addr_p = addr;
i386_insert_hw_breakpoint (struct gdbarch *gdbarch,
struct bp_target_info *bp_tgt)
{
+ struct i386_debug_reg_state *state
+ = i386_debug_reg_state (ptid_get_pid (inferior_ptid));
unsigned len_rw = i386_length_and_rw_bits (1, hw_execute);
CORE_ADDR addr = bp_tgt->placed_address;
- int retval = i386_insert_aligned_watchpoint (&dr_mirror,
+ /* Work on a local copy of the debug registers, and on success,
+ commit the change back to the inferior. */
+ struct i386_debug_reg_state local_state = *state;
+ int retval = i386_insert_aligned_watchpoint (&local_state,
addr, len_rw) ? EBUSY : 0;
+ if (retval == 0)
+ i386_update_inferior_debug_regs (&local_state);
+
if (maint_show_dr)
- i386_show_dr (&dr_mirror, "insert_hwbp", addr, 1, hw_execute);
+ i386_show_dr (state, "insert_hwbp", addr, 1, hw_execute);
return retval;
}
i386_remove_hw_breakpoint (struct gdbarch *gdbarch,
struct bp_target_info *bp_tgt)
{
+ struct i386_debug_reg_state *state
+ = i386_debug_reg_state (ptid_get_pid (inferior_ptid));
unsigned len_rw = i386_length_and_rw_bits (1, hw_execute);
CORE_ADDR addr = bp_tgt->placed_address;
- int retval = i386_remove_aligned_watchpoint (&dr_mirror,
+ /* Work on a local copy of the debug registers, and on success,
+ commit the change back to the inferior. */
+ struct i386_debug_reg_state local_state = *state;
+ int retval = i386_remove_aligned_watchpoint (&local_state,
addr, len_rw);
+ if (retval == 0)
+ i386_update_inferior_debug_regs (&local_state);
+
if (maint_show_dr)
- i386_show_dr (&dr_mirror, "remove_hwbp", addr, 1, hw_execute);
+ i386_show_dr (state, "remove_hwbp", addr, 1, hw_execute);
return retval;
}
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