diff options
Diffstat (limited to 'gdb/i386-tdep.c')
| -rw-r--r-- | gdb/i386-tdep.c | 89 |
1 files changed, 61 insertions, 28 deletions
diff --git a/gdb/i386-tdep.c b/gdb/i386-tdep.c index 496c4ff..b74270a 100644 --- a/gdb/i386-tdep.c +++ b/gdb/i386-tdep.c @@ -20,6 +20,7 @@ along with this program. If not, see <http://www.gnu.org/licenses/>. */ #include "defs.h" +#include "opcode/i386.h" #include "arch-utils.h" #include "command.h" #include "dummy-frame.h" @@ -278,9 +279,44 @@ i386_breakpoint_from_pc (struct gdbarch *gdbarch, CORE_ADDR *pc, int *len) /* Displaced instruction handling. */ +/* Skip the legacy instruction prefixes in INSN. + Not all prefixes are valid for any particular insn + but we needn't care, the insn will fault if it's invalid. + The result is a pointer to the first opcode byte, + or NULL if we run off the end of the buffer. */ + +static gdb_byte * +i386_skip_prefixes (gdb_byte *insn, size_t max_len) +{ + gdb_byte *end = insn + max_len; + + while (insn < end) + { + switch (*insn) + { + case DATA_PREFIX_OPCODE: + case ADDR_PREFIX_OPCODE: + case CS_PREFIX_OPCODE: + case DS_PREFIX_OPCODE: + case ES_PREFIX_OPCODE: + case FS_PREFIX_OPCODE: + case GS_PREFIX_OPCODE: + case SS_PREFIX_OPCODE: + case LOCK_PREFIX_OPCODE: + case REPE_PREFIX_OPCODE: + case REPNE_PREFIX_OPCODE: + ++insn; + continue; + default: + return insn; + } + } + + return NULL; +} static int -i386_absolute_jmp_p (gdb_byte *insn) +i386_absolute_jmp_p (const gdb_byte *insn) { /* jmp far (absolute address in operand) */ if (insn[0] == 0xea) @@ -301,7 +337,7 @@ i386_absolute_jmp_p (gdb_byte *insn) } static int -i386_absolute_call_p (gdb_byte *insn) +i386_absolute_call_p (const gdb_byte *insn) { /* call far, absolute */ if (insn[0] == 0x9a) @@ -322,7 +358,7 @@ i386_absolute_call_p (gdb_byte *insn) } static int -i386_ret_p (gdb_byte *insn) +i386_ret_p (const gdb_byte *insn) { switch (insn[0]) { @@ -339,7 +375,7 @@ i386_ret_p (gdb_byte *insn) } static int -i386_call_p (gdb_byte *insn) +i386_call_p (const gdb_byte *insn) { if (i386_absolute_call_p (insn)) return 1; @@ -351,16 +387,11 @@ i386_call_p (gdb_byte *insn) return 0; } -static int -i386_breakpoint_p (gdb_byte *insn) -{ - return insn[0] == 0xcc; /* int 3 */ -} - /* Return non-zero if INSN is a system call, and set *LENGTHP to its length in bytes. Otherwise, return zero. */ + static int -i386_syscall_p (gdb_byte *insn, ULONGEST *lengthp) +i386_syscall_p (const gdb_byte *insn, ULONGEST *lengthp) { if (insn[0] == 0xcd) { @@ -373,6 +404,7 @@ i386_syscall_p (gdb_byte *insn, ULONGEST *lengthp) /* Fix up the state of registers and memory after having single-stepped a displaced instruction. */ + void i386_displaced_step_fixup (struct gdbarch *gdbarch, struct displaced_step_closure *closure, @@ -388,6 +420,8 @@ i386_displaced_step_fixup (struct gdbarch *gdbarch, /* Since we use simple_displaced_step_copy_insn, our closure is a copy of the instruction. */ gdb_byte *insn = (gdb_byte *) closure; + /* The start of the insn, needed in case we see some prefixes. */ + gdb_byte *insn_start = insn; if (debug_displaced) fprintf_unfiltered (gdb_stdlog, @@ -401,6 +435,18 @@ i386_displaced_step_fixup (struct gdbarch *gdbarch, /* Relocate the %eip, if necessary. */ + /* The instruction recognizers we use assume any leading prefixes + have been skipped. */ + { + /* This is the size of the buffer in closure. */ + size_t max_insn_len = gdbarch_max_insn_length (gdbarch); + gdb_byte *opcode = i386_skip_prefixes (insn, max_insn_len); + /* If there are too many prefixes, just ignore the insn. + It will fault when run. */ + if (opcode != NULL) + insn = opcode; + } + /* Except in the case of absolute or indirect jump or call instructions, or a return instruction, the new eip is relative to the displaced instruction; make it relative. Well, signal @@ -430,7 +476,7 @@ i386_displaced_step_fixup (struct gdbarch *gdbarch, it unrelocated. Goodness help us if there are PC-relative system calls. */ if (i386_syscall_p (insn, &insn_len) - && orig_eip != to + insn_len) + && orig_eip != to + (insn - insn_start) + insn_len) { if (debug_displaced) fprintf_unfiltered (gdb_stdlog, @@ -441,20 +487,9 @@ i386_displaced_step_fixup (struct gdbarch *gdbarch, { ULONGEST eip = (orig_eip - insn_offset) & 0xffffffffUL; - /* If we have stepped over a breakpoint, set the %eip to - point at the breakpoint instruction itself. - - (gdbarch_decr_pc_after_break was never something the core - of GDB should have been concerned with; arch-specific - code should be making PC values consistent before - presenting them to GDB.) */ - if (i386_breakpoint_p (insn)) - { - if (debug_displaced) - fprintf_unfiltered (gdb_stdlog, - "displaced: stepped breakpoint\n"); - eip--; - } + /* If we just stepped over a breakpoint insn, we don't backup + the pc on purpose; this is to match behaviour without + stepping. */ regcache_cooked_write_unsigned (regs, I386_EIP_REGNUM, eip); @@ -493,8 +528,6 @@ i386_displaced_step_fixup (struct gdbarch *gdbarch, paddr_nz (retaddr)); } } - - #ifdef I386_REGNO_TO_SYMMETRY #error "The Sequent Symmetry is no longer supported." |