diff options
Diffstat (limited to 'gdb/i386obsd-tdep.c')
| -rw-r--r-- | gdb/i386obsd-tdep.c | 88 |
1 files changed, 84 insertions, 4 deletions
diff --git a/gdb/i386obsd-tdep.c b/gdb/i386obsd-tdep.c index be9e735..d8556ea 100644 --- a/gdb/i386obsd-tdep.c +++ b/gdb/i386obsd-tdep.c @@ -27,6 +27,7 @@ #include "regcache.h" #include "regset.h" #include "osabi.h" +#include "target.h" #include "gdb_assert.h" #include "gdb_string.h" @@ -35,6 +36,81 @@ #include "i387-tdep.h" #include "solib-svr4.h" +/* Support for signal handlers. */ + +/* Since OpenBSD 3.2, the sigtramp routine is mapped at a random page + in virtual memory. The randomness makes it somewhat tricky to + detect it, but fortunately we can rely on the fact that the start + of the sigtramp routine is page-aligned. By the way, the mapping + is read-only, so you cannot place a breakpoint in the signal + trampoline. */ + +/* Default page size. */ +static const int i386obsd_page_size = 4096; + +/* Return whether PC is in an OpenBSD sigtramp routine. */ + +static int +i386obsd_pc_in_sigtramp (CORE_ADDR pc, char *name) +{ + CORE_ADDR start_pc = (pc & ~(i386obsd_page_size - 1)); + const char sigreturn[] = + { + 0xb8, + 0x67, 0x00, 0x00, 0x00, /* movl $SYS_sigreturn, %eax */ + 0xcd, 0x80 /* int $0x80 */ + }; + char *buf; + + /* Avoid reading memory from the target if possible. If we're in a + named function, we're certainly not in a sigtramp routine + provided by the kernel. Take synthetic function names into + account though. */ + if (name && name[0] != '<') + return 0; + + /* If we can't read the instructions at START_PC, return zero. */ + buf = alloca (sizeof sigreturn); + if (target_read_memory (start_pc + 0x14, buf, sizeof sigreturn)) + return 0; + + /* Check for sigreturn(2). */ + if (memcmp (buf, sigreturn, sizeof sigreturn) == 0) + return 1; + + /* Check for a traditional BSD sigtramp routine. */ + return i386bsd_pc_in_sigtramp (pc, name); +} + +/* Return the start address of the sigtramp routine. */ + +static CORE_ADDR +i386obsd_sigtramp_start (CORE_ADDR pc) +{ + CORE_ADDR start_pc = (pc & ~(i386obsd_page_size - 1)); + + if (i386bsd_pc_in_sigtramp (pc, NULL)) + return i386bsd_sigtramp_start (pc); + + return start_pc; +} + +/* Return the end address of the sigtramp routine. */ + +static CORE_ADDR +i386obsd_sigtramp_end (CORE_ADDR pc) +{ + CORE_ADDR start_pc = (pc & ~(i386obsd_page_size - 1)); + + if (i386bsd_pc_in_sigtramp (pc, NULL)) + return i386bsd_sigtramp_end (pc); + + return start_pc + 0x22; +} + +/* Mapping between the general-purpose registers in `struct reg' + format and GDB's register cache layout. */ + /* From <machine/reg.h>. */ static int i386obsd_r_reg_offset[] = { @@ -95,8 +171,9 @@ i386obsd_aout_regset_from_core_section (struct gdbarch *gdbarch, } -CORE_ADDR i386obsd_sigtramp_start = 0xbfbfdf20; -CORE_ADDR i386obsd_sigtramp_end = 0xbfbfdff0; +/* Sigtramp routine location for OpenBSD 3.1 and earlier releases. */ +CORE_ADDR i386obsd_sigtramp_start_addr = 0xbfbfdf20; +CORE_ADDR i386obsd_sigtramp_end_addr = 0xbfbfdff0; /* From <machine/signal.h>. */ int i386obsd_sc_reg_offset[I386_NUM_GREGS] = @@ -136,8 +213,11 @@ i386obsd_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch) tdep->struct_return = reg_struct_return; /* OpenBSD uses a different memory layout. */ - tdep->sigtramp_start = i386obsd_sigtramp_start; - tdep->sigtramp_end = i386obsd_sigtramp_end; + tdep->sigtramp_start = i386obsd_sigtramp_start_addr; + tdep->sigtramp_end = i386obsd_sigtramp_end_addr; + set_gdbarch_pc_in_sigtramp (gdbarch, i386obsd_pc_in_sigtramp); + set_gdbarch_sigtramp_start (gdbarch, i386obsd_sigtramp_start); + set_gdbarch_sigtramp_end (gdbarch, i386obsd_sigtramp_end); /* OpenBSD has a `struct sigcontext' that's different from the origional 4.3 BSD. */ |