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authorTristan Gingold <gingold@adacore.com>2008-12-05 11:08:58 +0000
committerTristan Gingold <gingold@adacore.com>2008-12-05 11:08:58 +0000
commitacdb24a9cf14f4ba854078d25e3eeb94a64bbb78 (patch)
treef77d3bfc115816db15c2fde73e6a6f7eaff1e63f
parente71c9293b34654e2e01e9b33201b5e6c09dcc10a (diff)
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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.
-rw-r--r--gdb/ChangeLog7
-rw-r--r--gdb/i386-darwin-nat.c70
2 files changed, 77 insertions, 0 deletions
diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 50254b570e7..102a03de6c9 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -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.
diff --git a/gdb/i386-darwin-nat.c b/gdb/i386-darwin-nat.c
index 03051738699..7f8a8d5e222 100644
--- a/gdb/i386-darwin-nat.c
+++ b/gdb/i386-darwin-nat.c
@@ -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;