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6068 libdisasm: previnstr arch op should have a sane default
Reviewed by: Robert Mustacchi <rm@joyent.com>
*** 170,230 ****
dis_i386_min_instrlen(dis_handle_t *dhp)
{
return (1);
}
- /*
- * Return the previous instruction. On x86, we have no choice except to
- * disassemble everything from the start of the symbol, and stop when we have
- * reached our instruction address. If we're not in the middle of a known
- * symbol, then we return the same address to indicate failure.
- */
- static uint64_t
- dis_i386_previnstr(dis_handle_t *dhp, uint64_t pc, int n)
- {
- uint64_t *hist, addr, start;
- int cur, nseen;
- uint64_t res = pc;
-
- if (n <= 0)
- return (pc);
-
- if (dhp->dh_lookup(dhp->dh_data, pc, NULL, 0, &start, NULL) != 0 ||
- start == pc)
- return (res);
-
- hist = dis_zalloc(sizeof (uint64_t) * n);
-
- for (cur = 0, nseen = 0, addr = start; addr < pc; addr = dhp->dh_addr) {
- hist[cur] = addr;
- cur = (cur + 1) % n;
- nseen++;
-
- /* if we cannot make forward progress, give up */
- if (dis_disassemble(dhp, addr, NULL, 0) != 0)
- goto done;
- }
-
- if (addr != pc) {
- /*
- * We scanned past %pc, but didn't find an instruction that
- * started at %pc. This means that either the caller specified
- * an invalid address, or we ran into something other than code
- * during our scan. Virtually any combination of bytes can be
- * construed as a valid Intel instruction, so any non-code bytes
- * we encounter will have thrown off the scan.
- */
- goto done;
- }
-
- res = hist[(cur + n - MIN(n, nseen)) % n];
-
- done:
- dis_free(hist, sizeof (uint64_t) * n);
- return (res);
- }
-
static int
dis_i386_supports_flags(int flags)
{
int archflags = flags & DIS_ARCH_MASK;
--- 170,179 ----
*** 247,256 ****
dis_arch_t dis_arch_i386 = {
.da_supports_flags = dis_i386_supports_flags,
.da_handle_attach = dis_i386_handle_attach,
.da_handle_detach = dis_i386_handle_detach,
.da_disassemble = dis_i386_disassemble,
- .da_previnstr = dis_i386_previnstr,
.da_min_instrlen = dis_i386_min_instrlen,
.da_max_instrlen = dis_i386_max_instrlen,
.da_instrlen = dis_i386_instrlen,
};
--- 196,204 ----