diff options
Diffstat (limited to 'target-i386/translate.c')
| -rw-r--r-- | target-i386/translate.c | 14 |
1 files changed, 10 insertions, 4 deletions
diff --git a/target-i386/translate.c b/target-i386/translate.c index c1ede1a75..c792e7ace 100644 --- a/target-i386/translate.c +++ b/target-i386/translate.c @@ -7409,8 +7409,11 @@ static target_ulong disas_insn(DisasContext *s, target_ulong pc_start) gen_exception(s, EXCP0D_GPF, pc_start - s->cs_base); } else { modrm = ldub_code(s->pc++); - if ((modrm & 0xc0) != 0xc0) - goto illegal_op; + /* Ignore the mod bits (assume (modrm&0xc0)==0xc0). + * AMD documentation (24594.pdf) and testing of + * intel 386 and 486 processors all show that the mod bits + * are assumed to be 1's, regardless of actual values. + */ rm = (modrm & 7) | REX_B(s); reg = ((modrm >> 3) & 7) | rex_r; if (CODE64(s)) @@ -7451,8 +7454,11 @@ static target_ulong disas_insn(DisasContext *s, target_ulong pc_start) gen_exception(s, EXCP0D_GPF, pc_start - s->cs_base); } else { modrm = ldub_code(s->pc++); - if ((modrm & 0xc0) != 0xc0) - goto illegal_op; + /* Ignore the mod bits (assume (modrm&0xc0)==0xc0). + * AMD documentation (24594.pdf) and testing of + * intel 386 and 486 processors all show that the mod bits + * are assumed to be 1's, regardless of actual values. + */ rm = (modrm & 7) | REX_B(s); reg = ((modrm >> 3) & 7) | rex_r; if (CODE64(s)) |