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2008-12-05 Tristan Gingold <gingold@adacore.com>

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* i386-darwin-nat.c (i386_darwin_sstep_at_sigreturn): New function.
	(amd64_darwin_sstep_at_sigreturn): New function.
	(darwin_set_sstep): The sigreturn is a special case: the trace flag
	must be set in the mcontext structure.
This commit is contained in:
Tristan Gingold 2008-12-05 11:08:58 +00:00
parent e71c9293b3
commit acdb24a9cf
2 changed files with 77 additions and 0 deletions
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7
gdb/ChangeLog
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@ -1,3 +1,10 @@
2008-12-05 Tristan Gingold <gingold@adacore.com>
* i386-darwin-nat.c (i386_darwin_sstep_at_sigreturn): New function.
(amd64_darwin_sstep_at_sigreturn): New function.
(darwin_set_sstep): The sigreturn is a special case: the trace flag
must be set in the mcontext structure.
2008-12-05 Pedro Alves <pedro@codesourcery.com>
* infcmd.c (step_once): Remove dead code.

70
gdb/i386-darwin-nat.c
View File

@ -34,6 +34,7 @@
#include "i387-tdep.h"
#include "gdbarch.h"
#include "arch-utils.h"
#include "gdbcore.h"
#include "darwin-nat.h"
#include "i386-darwin-tdep.h"
@ -433,6 +434,70 @@ darwin_check_osabi (darwin_inferior *inf, thread_t thread)
#define X86_EFLAGS_T 0x100UL
/* Returning from a signal trampoline is done by calling a
special system call (sigreturn). This system call
restores the registers that were saved when the signal was
raised, including %eflags/%rflags. That means that single-stepping
won't work. Instead, we'll have to modify the signal context
that's about to be restored, and set the trace flag there. */
static int
i386_darwin_sstep_at_sigreturn (x86_thread_state_t *regs)
{
static const gdb_byte darwin_syscall[] = { 0xcd, 0x80 }; /* int 0x80 */
gdb_byte buf[sizeof (darwin_syscall)];
/* Check if PC is at a sigreturn system call. */
if (target_read_memory (regs->uts.ts32.__eip, buf, sizeof (buf)) == 0
&& memcmp (buf, darwin_syscall, sizeof (darwin_syscall)) == 0
&& regs->uts.ts32.__eax == 0xb8 /* SYS_sigreturn */)
{
ULONGEST uctx_addr;
ULONGEST mctx_addr;
ULONGEST flags_addr;
unsigned int eflags;
uctx_addr = read_memory_unsigned_integer (regs->uts.ts32.__esp + 4, 4);
mctx_addr = read_memory_unsigned_integer (uctx_addr + 28, 4);
flags_addr = mctx_addr + 12 + 9 * 4;
read_memory (flags_addr, (gdb_byte *) &eflags, 4);
eflags |= X86_EFLAGS_T;
write_memory (flags_addr, (gdb_byte *) &eflags, 4);
return 1;
}
return 0;
}
static int
amd64_darwin_sstep_at_sigreturn (x86_thread_state_t *regs)
{
static const gdb_byte darwin_syscall[] = { 0x0f, 0x05 }; /* syscall */
gdb_byte buf[sizeof (darwin_syscall)];
/* Check if PC is at a sigreturn system call. */
if (target_read_memory (regs->uts.ts64.__rip, buf, sizeof (buf)) == 0
&& memcmp (buf, darwin_syscall, sizeof (darwin_syscall)) == 0
&& (regs->uts.ts64.__rax & 0xffffffff) == 0x20000b8 /* SYS_sigreturn */)
{
ULONGEST mctx_addr;
ULONGEST flags_addr;
unsigned int rflags;
mctx_addr = read_memory_unsigned_integer (regs->uts.ts64.__rdi + 48, 8);
flags_addr = mctx_addr + 16 + 17 * 8;
/* AMD64 is little endian. */
read_memory (flags_addr, (gdb_byte *) &rflags, 4);
rflags |= X86_EFLAGS_T;
write_memory (flags_addr, (gdb_byte *) &rflags, 4);
return 1;
}
return 0;
}
void
darwin_set_sstep (thread_t thread, int enable)
{
@ -448,12 +513,15 @@ darwin_set_sstep (thread_t thread, int enable)
kret, thread);
return;
}
switch (regs.tsh.flavor)
{
case x86_THREAD_STATE32:
{
__uint32_t bit = enable ? X86_EFLAGS_T : 0;
if (enable && i386_darwin_sstep_at_sigreturn (&regs))
return;
if ((regs.uts.ts32.__eflags & X86_EFLAGS_T) == bit)
return;
regs.uts.ts32.__eflags = (regs.uts.ts32.__eflags & ~X86_EFLAGS_T) | bit;
@ -466,6 +534,8 @@ darwin_set_sstep (thread_t thread, int enable)
{
__uint64_t bit = enable ? X86_EFLAGS_T : 0;
if (enable && amd64_darwin_sstep_at_sigreturn (&regs))
return;
if ((regs.uts.ts64.__rflags & X86_EFLAGS_T) == bit)
return;
regs.uts.ts64.__rflags = (regs.uts.ts64.__rflags & ~X86_EFLAGS_T) | bit;