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ndisasm: handle \366 codes, prefer unprefixed instructions

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- Implement \366 codes in ndisasm
- Prefer instruction patterns without loose prefixes if possible
- Fix improper initialization of operands in ndisasm
This commit is contained in:
H. Peter Anvin 2007-09-11 22:13:17 +00:00
parent 4f090502fb
commit 2ba7ed7122
1 changed files with 34 additions and 12 deletions
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46
disasm.c
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@ -10,6 +10,7 @@
#include <stdio.h>
#include <string.h>
#include <limits.h>
#include <inttypes.h>
#include "nasm.h"
@ -62,7 +63,7 @@ static uint64_t getu64(uint8_t *data)
#define gets64(x) ((int64_t)getu64(x))
/* Important: regval must already have been adjusted for rex extensions */
static int whichreg(int32_t regflags, int regval, int rex)
static enum reg_enum whichreg(int32_t regflags, int regval, int rex)
{
if (!(REG_AL & ~regflags))
return R_AL;
@ -319,7 +320,14 @@ static int matches(const struct itemplate *t, uint8_t *data, int asize,
uint8_t *origdata = data;
int a_used = FALSE, o_used = FALSE;
int drep = 0;
ins->oprs[0].segment = ins->oprs[1].segment =
ins->oprs[2].segment =
ins->oprs[0].addr_size = ins->oprs[1].addr_size =
ins->oprs[2].addr_size = (segsize == 64 ? SEG_64BIT :
segsize == 32 ? SEG_32BIT : 0);
ins->condition = -1;
*rexout = rex;
if (t->flags & (segsize == 64 ? IF_NOLONG : IF_LONG))
@ -555,6 +563,11 @@ static int matches(const struct itemplate *t, uint8_t *data, int asize,
rex |= REX_R;
lock = 0;
}
} else if (c == 0366) {
/* Fix: should look specifically for the presence of the prefix */
if (osize != ((segsize == 16) ? 32 : 16))
return FALSE;
o_used = TRUE;
}
}
@ -583,7 +596,8 @@ int32_t disasm(uint8_t *data, char *output, int outbufsize, int segsize,
const struct itemplate * const *p, * const *best_p;
int length, best_length = 0;
char *segover;
int rep, lock, asize, osize, i, slen, colon, rex, rexout, best_rex;
int rep, lock, asize, osize, i, slen, colon, rex, rexout;
int best_rex, best_pref;
uint8_t *origdata;
int works;
insn tmp_ins, ins;
@ -633,15 +647,11 @@ int32_t disasm(uint8_t *data, char *output, int outbufsize, int segsize,
}
}
tmp_ins.oprs[0].segment = tmp_ins.oprs[1].segment =
tmp_ins.oprs[2].segment =
tmp_ins.oprs[0].addr_size = tmp_ins.oprs[1].addr_size =
tmp_ins.oprs[2].addr_size = (segsize == 64 ? SEG_64BIT :
segsize == 32 ? SEG_32BIT : 0);
tmp_ins.condition = -1;
best = -1; /* Worst possible */
best_p = NULL;
best_rex = 0;
best_pref = INT_MAX;
for (p = itable[*data]; *p; p++) {
if ((length = matches(*p, data, asize, osize, segsize, rep,
&tmp_ins, rex, &rexout, lock))) {
@ -669,12 +679,22 @@ int32_t disasm(uint8_t *data, char *output, int outbufsize, int segsize,
}
}
/*
* Note: we always prefer instructions which incorporate
* prefixes in the instructions themselves. This is to allow
* e.g. PAUSE to be preferred to REP NOP, and deal with
* MMX/SSE instructions where prefixes are used to select
* between MMX and SSE register sets or outright opcode
* selection.
*/
if (works) {
goodness = ((*p)->flags & IF_PFMASK) ^ prefer;
if (goodness < best) {
if (tmp_ins.nprefix < best_pref ||
(tmp_ins.nprefix == best_pref && goodness < best)) {
/* This is the best one found so far */
best = goodness;
best_p = p;
best_pref = tmp_ins.nprefix;
best_length = length;
ins = tmp_ins;
best_rex = rexout;
@ -728,16 +748,18 @@ int32_t disasm(uint8_t *data, char *output, int outbufsize, int segsize,
case P_O32:
slen += snprintf(output + slen, outbufsize - slen, "o32 ");
break;
default:
break;
}
for (i = 0; i < elements(ico); i++)
for (i = 0; i < (int)elements(ico); i++)
if ((*p)->opcode == ico[i]) {
slen +=
snprintf(output + slen, outbufsize - slen, "%s%s", icn[i],
whichcond(ins.condition));
break;
}
if (i >= elements(ico))
if (i >= (int)elements(ico))
slen +=
snprintf(output + slen, outbufsize - slen, "%s",
insn_names[(*p)->opcode]);