-/* Target-dependent code for Linux running on i386's, for GDB.
- Copyright (C) 2000 Free Software Foundation, Inc.
+/* Target-dependent code for GNU/Linux running on i386's, for GDB.
+
+ Copyright 2000, 2001, 2002, 2003 Free Software Foundation, Inc.
This file is part of GDB.
#include "gdbcore.h"
#include "frame.h"
#include "value.h"
+#include "regcache.h"
+#include "inferior.h"
+#include "reggroups.h"
+
+/* For i386_linux_skip_solib_resolver. */
+#include "symtab.h"
+#include "symfile.h"
+#include "objfiles.h"
+
+#include "solib-svr4.h" /* For struct link_map_offsets. */
+
+#include "osabi.h"
+
+#include "i386-tdep.h"
+#include "i386-linux-tdep.h"
+
+/* Return the name of register REG. */
+
+static const char *
+i386_linux_register_name (int reg)
+{
+ /* Deal with the extra "orig_eax" pseudo register. */
+ if (reg == I386_LINUX_ORIG_EAX_REGNUM)
+ return "orig_eax";
+
+ return i386_register_name (reg);
+}
+
+/* Return non-zero, when the register is in the corresponding register
+ group. Put the LINUX_ORIG_EAX register in the system group. */
+static int
+i386_linux_register_reggroup_p (struct gdbarch *gdbarch, int regnum,
+ struct reggroup *group)
+{
+ if (regnum == I386_LINUX_ORIG_EAX_REGNUM)
+ return (group == system_reggroup
+ || group == save_reggroup
+ || group == restore_reggroup);
+ return i386_register_reggroup_p (gdbarch, regnum, group);
+}
\f
/* Recognizing signal handler frames. */
-/* Linux has two flavors of signals. Normal signal handlers, and
+/* GNU/Linux has two flavors of signals. Normal signal handlers, and
"realtime" (RT) signals. The RT signals can provide additional
information to the signal handler if the SA_SIGINFO flag is set
when establishing a signal handler using `sigaction'. It is not
- unlikely that future versions of Linux will support SA_SIGINFO for
- normal signals too. */
+ unlikely that future versions of GNU/Linux will support SA_SIGINFO
+ for normal signals too. */
/* When the i386 Linux kernel calls a signal handler and the
SA_RESTORER flag isn't set, the return address points to a bit of
It kind of sucks that we have to read memory from the process in
order to identify a signal trampoline, but there doesn't seem to be
- any other way. The IN_SIGTRAMP macro in tm-linux.h arranges to
+ any other way. The PC_IN_SIGTRAMP macro in tm-linux.h arranges to
only call us if no function name could be identified, which should
be the case since the code is on the stack.
return pc;
}
-/* Return whether PC is in a Linux sigtramp routine. */
+/* Return whether PC is in a GNU/Linux sigtramp routine. */
-int
-i386_linux_in_sigtramp (CORE_ADDR pc, char *name)
+static int
+i386_linux_pc_in_sigtramp (CORE_ADDR pc, char *name)
{
- if (name)
- return STREQ ("__restore", name) || STREQ ("__restore_rt", name);
-
- return (i386_linux_sigtramp_start (pc) != 0
- || i386_linux_rt_sigtramp_start (pc) != 0);
+ /* If we have NAME, we can optimize the search. The trampolines are
+ named __restore and __restore_rt. However, they aren't dynamically
+ exported from the shared C library, so the trampoline may appear to
+ be part of the preceding function. This should always be sigaction,
+ __sigaction, or __libc_sigaction (all aliases to the same function). */
+ if (name == NULL || strstr (name, "sigaction") != NULL)
+ return (i386_linux_sigtramp_start (pc) != 0
+ || i386_linux_rt_sigtramp_start (pc) != 0);
+
+ return (strcmp ("__restore", name) == 0
+ || strcmp ("__restore_rt", name) == 0);
}
-/* Assuming FRAME is for a Linux sigtramp routine, return the address
- of the associated sigcontext structure. */
+/* Assuming FRAME is for a GNU/Linux sigtramp routine, return the
+ address of the associated sigcontext structure. */
-CORE_ADDR
+static CORE_ADDR
i386_linux_sigcontext_addr (struct frame_info *frame)
{
CORE_ADDR pc;
- pc = i386_linux_sigtramp_start (frame->pc);
+ pc = i386_linux_sigtramp_start (get_frame_pc (frame));
if (pc)
{
CORE_ADDR sp;
- if (frame->next)
+ if (get_next_frame (frame))
/* If this isn't the top frame, the next frame must be for the
signal handler itself. The sigcontext structure lives on
the stack, right after the signum argument. */
- return frame->next->frame + 12;
+ return get_frame_base (get_next_frame (frame)) + 12;
/* This is the top frame. We'll have to find the address of the
sigcontext structure by looking at the stack pointer. Keep
"pop %eax". If the PC is at this instruction, adjust the
returned value accordingly. */
sp = read_register (SP_REGNUM);
- if (pc == frame->pc)
+ if (pc == get_frame_pc (frame))
return sp + 4;
return sp;
}
- pc = i386_linux_rt_sigtramp_start (frame->pc);
+ pc = i386_linux_rt_sigtramp_start (get_frame_pc (frame));
if (pc)
{
- if (frame->next)
+ if (get_next_frame (frame))
/* If this isn't the top frame, the next frame must be for the
signal handler itself. The sigcontext structure is part of
the user context. A pointer to the user context is passed
as the third argument to the signal handler. */
- return read_memory_integer (frame->next->frame + 16, 4) + 20;
+ return read_memory_integer (get_frame_base (get_next_frame (frame))
+ + 16, 4) + 20;
/* This is the top frame. Again, use the stack pointer to find
the address of the sigcontext structure. */
return 0;
}
-/* Offset to saved PC in sigcontext, from <asm/sigcontext.h>. */
-#define LINUX_SIGCONTEXT_PC_OFFSET (56)
+/* Set the program counter for process PTID to PC. */
+
+static void
+i386_linux_write_pc (CORE_ADDR pc, ptid_t ptid)
+{
+ write_register_pid (PC_REGNUM, pc, ptid);
+
+ /* We must be careful with modifying the program counter. If we
+ just interrupted a system call, the kernel might try to restart
+ it when we resume the inferior. On restarting the system call,
+ the kernel will try backing up the program counter even though it
+ no longer points at the system call. This typically results in a
+ SIGSEGV or SIGILL. We can prevent this by writing `-1' in the
+ "orig_eax" pseudo-register.
+
+ Note that "orig_eax" is saved when setting up a dummy call frame.
+ This means that it is properly restored when that frame is
+ popped, and that the interrupted system call will be restarted
+ when we resume the inferior on return from a function call from
+ within GDB. In all other cases the system call will not be
+ restarted. */
+ write_register_pid (I386_LINUX_ORIG_EAX_REGNUM, -1, ptid);
+}
+\f
+/* Calling functions in shared libraries. */
-/* Assuming FRAME is for a Linux sigtramp routine, return the saved
- program counter. */
+/* Find the minimal symbol named NAME, and return both the minsym
+ struct and its objfile. This probably ought to be in minsym.c, but
+ everything there is trying to deal with things like C++ and
+ SOFUN_ADDRESS_MAYBE_TURQUOISE, ... Since this is so simple, it may
+ be considered too special-purpose for general consumption. */
-CORE_ADDR
-i386_linux_sigtramp_saved_pc (struct frame_info *frame)
+static struct minimal_symbol *
+find_minsym_and_objfile (char *name, struct objfile **objfile_p)
{
- CORE_ADDR addr;
- addr = i386_linux_sigcontext_addr (frame);
- return read_memory_integer (addr + LINUX_SIGCONTEXT_PC_OFFSET, 4);
+ struct objfile *objfile;
+
+ ALL_OBJFILES (objfile)
+ {
+ struct minimal_symbol *msym;
+
+ ALL_OBJFILE_MSYMBOLS (objfile, msym)
+ {
+ if (SYMBOL_NAME (msym)
+ && STREQ (SYMBOL_NAME (msym), name))
+ {
+ *objfile_p = objfile;
+ return msym;
+ }
+ }
+ }
+
+ return 0;
}
-/* Offset to saved SP in sigcontext, from <asm/sigcontext.h>. */
-#define LINUX_SIGCONTEXT_SP_OFFSET (28)
+static CORE_ADDR
+skip_hurd_resolver (CORE_ADDR pc)
+{
+ /* The HURD dynamic linker is part of the GNU C library, so many
+ GNU/Linux distributions use it. (All ELF versions, as far as I
+ know.) An unresolved PLT entry points to "_dl_runtime_resolve",
+ which calls "fixup" to patch the PLT, and then passes control to
+ the function.
+
+ We look for the symbol `_dl_runtime_resolve', and find `fixup' in
+ the same objfile. If we are at the entry point of `fixup', then
+ we set a breakpoint at the return address (at the top of the
+ stack), and continue.
+
+ It's kind of gross to do all these checks every time we're
+ called, since they don't change once the executable has gotten
+ started. But this is only a temporary hack --- upcoming versions
+ of GNU/Linux will provide a portable, efficient interface for
+ debugging programs that use shared libraries. */
+
+ struct objfile *objfile;
+ struct minimal_symbol *resolver
+ = find_minsym_and_objfile ("_dl_runtime_resolve", &objfile);
+
+ if (resolver)
+ {
+ struct minimal_symbol *fixup
+ = lookup_minimal_symbol ("fixup", NULL, objfile);
+
+ if (fixup && SYMBOL_VALUE_ADDRESS (fixup) == pc)
+ return (SAVED_PC_AFTER_CALL (get_current_frame ()));
+ }
+
+ return 0;
+}
-/* Assuming FRAME is for a Linux sigtramp routine, return the saved
- stack pointer. */
+/* See the comments for SKIP_SOLIB_RESOLVER at the top of infrun.c.
+ This function:
+ 1) decides whether a PLT has sent us into the linker to resolve
+ a function reference, and
+ 2) if so, tells us where to set a temporary breakpoint that will
+ trigger when the dynamic linker is done. */
CORE_ADDR
-i386_linux_sigtramp_saved_sp (struct frame_info *frame)
+i386_linux_skip_solib_resolver (CORE_ADDR pc)
{
- CORE_ADDR addr;
- addr = i386_linux_sigcontext_addr (frame);
- return read_memory_integer (addr + LINUX_SIGCONTEXT_SP_OFFSET, 4);
+ CORE_ADDR result;
+
+ /* Plug in functions for other kinds of resolvers here. */
+ result = skip_hurd_resolver (pc);
+ if (result)
+ return result;
+
+ return 0;
}
-/* Immediately after a function call, return the saved pc. */
+/* Fetch (and possibly build) an appropriate link_map_offsets
+ structure for native GNU/Linux x86 targets using the struct offsets
+ defined in link.h (but without actual reference to that file).
-CORE_ADDR
-i386_linux_saved_pc_after_call (struct frame_info *frame)
+ This makes it possible to access GNU/Linux x86 shared libraries
+ from a GDB that was not built on an GNU/Linux x86 host (for cross
+ debugging). */
+
+static struct link_map_offsets *
+i386_linux_svr4_fetch_link_map_offsets (void)
+{
+ static struct link_map_offsets lmo;
+ static struct link_map_offsets *lmp = NULL;
+
+ if (lmp == NULL)
+ {
+ lmp = &lmo;
+
+ lmo.r_debug_size = 8; /* The actual size is 20 bytes, but
+ this is all we need. */
+ lmo.r_map_offset = 4;
+ lmo.r_map_size = 4;
+
+ lmo.link_map_size = 20; /* The actual size is 552 bytes, but
+ this is all we need. */
+ lmo.l_addr_offset = 0;
+ lmo.l_addr_size = 4;
+
+ lmo.l_name_offset = 4;
+ lmo.l_name_size = 4;
+
+ lmo.l_next_offset = 12;
+ lmo.l_next_size = 4;
+
+ lmo.l_prev_offset = 16;
+ lmo.l_prev_size = 4;
+ }
+
+ return lmp;
+}
+\f
+
+static void
+i386_linux_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
{
- if (frame->signal_handler_caller)
- return i386_linux_sigtramp_saved_pc (frame);
+ struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
+
+ /* GNU/Linux uses ELF. */
+ i386_elf_init_abi (info, gdbarch);
+
+ /* We support the SSE registers on GNU/Linux. */
+ tdep->num_xmm_regs = I386_NUM_XREGS - 1;
+ /* set_gdbarch_num_regs (gdbarch, I386_SSE_NUM_REGS); */
+
+ /* Since we have the extra "orig_eax" register on GNU/Linux, we have
+ to adjust a few things. */
- return read_memory_integer (read_register (SP_REGNUM), 4);
+ set_gdbarch_write_pc (gdbarch, i386_linux_write_pc);
+ set_gdbarch_num_regs (gdbarch, I386_SSE_NUM_REGS + 1);
+ set_gdbarch_register_name (gdbarch, i386_linux_register_name);
+ set_gdbarch_register_reggroup_p (gdbarch, i386_linux_register_reggroup_p);
+ set_gdbarch_register_bytes (gdbarch, I386_SSE_SIZEOF_REGS + 4);
+
+ tdep->jb_pc_offset = 20; /* From <bits/setjmp.h>. */
+
+ tdep->sigcontext_addr = i386_linux_sigcontext_addr;
+ tdep->sc_pc_offset = 14 * 4; /* From <asm/sigcontext.h>. */
+ tdep->sc_sp_offset = 7 * 4;
+
+ /* When the i386 Linux kernel calls a signal handler, the return
+ address points to a bit of code on the stack. This function is
+ used to identify this bit of code as a signal trampoline in order
+ to support backtracing through calls to signal handlers. */
+ set_gdbarch_pc_in_sigtramp (gdbarch, i386_linux_pc_in_sigtramp);
+
+ set_solib_svr4_fetch_link_map_offsets (gdbarch,
+ i386_linux_svr4_fetch_link_map_offsets);
+}
+
+/* Provide a prototype to silence -Wmissing-prototypes. */
+extern void _initialize_i386_linux_tdep (void);
+
+void
+_initialize_i386_linux_tdep (void)
+{
+ gdbarch_register_osabi (bfd_arch_i386, 0, GDB_OSABI_LINUX,
+ i386_linux_init_abi);
}
projects / deliverable / binutils-gdb.git / blobdiff