diff options
Diffstat (limited to 'gdb/i386-darwin-nat.c')
| -rw-r--r-- | gdb/i386-darwin-nat.c | 70 |
1 files changed, 70 insertions, 0 deletions
diff --git a/gdb/i386-darwin-nat.c b/gdb/i386-darwin-nat.c index 0305173..7f8a8d5 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 (®s)) + 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 (®s)) + return; if ((regs.uts.ts64.__rflags & X86_EFLAGS_T) == bit) return; regs.uts.ts64.__rflags = (regs.uts.ts64.__rflags & ~X86_EFLAGS_T) | bit; |