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i#731 re-rel: Convert native rseq PC targets to instrs #4023

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merged 1 commit into from
Jan 17, 2020
Merged

i#731 re-rel: Convert native rseq PC targets to instrs #4023

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11 changes: 3 additions & 8 deletions core/arch/disassemble_shared.c
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Original file line number Diff line number Diff line change
@@ -1,5 +1,5 @@
/* **********************************************************
* Copyright (c) 2011-2019 Google, Inc. All rights reserved.
* Copyright (c) 2011-2020 Google, Inc. All rights reserved.
* Copyright (c) 2001-2009 VMware, Inc. All rights reserved.
* **********************************************************/

Expand Down Expand Up @@ -1509,13 +1509,8 @@ instrlist_disassemble(dcontext_t *dcontext, app_pc tag, instrlist_t *ilist,
* as much about raw bytes
*/
int extra_sz;
if (level == 3) {
print_file(outfile, " +%-4d %c%d " IF_X64_ELSE("%20s", "%12s"), offs,
instr_is_app(instr) ? 'L' : 'm', level, " ");
} else {
print_file(outfile, " +%-4d %c%d @" PFX " ", offs,
instr_is_app(instr) ? 'L' : 'm', level, instr);
}
print_file(outfile, " +%-4d %c%d @" PFX " ", offs,
instr_is_app(instr) ? 'L' : 'm', level, instr);
extra_sz = print_bytes_to_file(outfile, addr, addr + len, instr);
instr_disassemble(dcontext, instr, outfile);
print_file(outfile, "\n");
Expand Down
37 changes: 31 additions & 6 deletions core/arch/mangle_shared.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1086,6 +1086,10 @@ mangle_rseq_insert_native_sequence(dcontext_t *dcontext, instrlist_t *ilist,
* not stores, and restartable).
*/
app_pc pc = start;
/* Store the PC values for faster conversion of intra-region targets. */
generic_table_t *pc2instr =
generic_hash_create(dcontext, 6 /*expect few entries*/, 80 /* load factor */, 0,
NULL _IF_DEBUG("pc2instr"));
PRE(ilist, insert_at, label_start);
while (pc < end) {
instr_t *copy = instr_create(dcontext);
Expand All @@ -1096,17 +1100,13 @@ mangle_rseq_insert_native_sequence(dcontext_t *dcontext, instrlist_t *ilist,
"Invalid instruction inside rseq region");
ASSERT_NOT_REACHED();
}
generic_hash_add(dcontext, pc2instr, (ptr_uint_t)get_app_instr_xl8(copy), copy);
/* Make intra-region branches meta; all others are exit ctis. */
if ((instr_is_cbr(copy) || instr_is_ubr(copy)) &&
opnd_is_pc(instr_get_target(copy))) {
app_pc tgt = opnd_get_pc(instr_get_target(copy));
if (tgt >= start && tgt < end) {
/* We do not want to use the absolute PC and re-relativize: we want
* to use the same relative offset. (An alternative would be to
* convert the PC operand to an instr_t pointer but that would take
* extra passes.)
*/
IF_X86(instr_set_rip_rel_valid(copy, false));
/* We change the target from a PC to an instr_t* at the end. */
PRE(ilist, insert_at, copy);
continue;
}
Expand All @@ -1129,6 +1129,31 @@ mangle_rseq_insert_native_sequence(dcontext_t *dcontext, instrlist_t *ilist,
}
}
PRE(ilist, insert_at, label_end);
/* Update all intra-region targets to use instr_t* operands. We can't simply
* leave absolute PC's and re-relativize (that would point into the app code).
* Nor can we use the hardcoded relative offset by calling
* instr_set_rip_rel_valid(, false) because there can be subsequent mangling that
* changes the offsets.
*/
for (instr_t *walk = label_start; walk != label_end; walk = instr_get_next(walk)) {
if (!instr_is_app(walk) && (instr_is_cbr(walk) || instr_is_ubr(walk))) {
ASSERT(opnd_is_pc(instr_get_target(walk)));
app_pc tgt_pc = opnd_get_pc(instr_get_target(walk));
instr_t *tgt_inst =
(instr_t *)generic_hash_lookup(dcontext, pc2instr, (ptr_uint_t)tgt_pc);
if (tgt_inst == NULL) {
LOG(THREAD, LOG_INTERP, 1,
"%s: pc2instr failed for branch from " PFX " to " PFX "\n",
__FUNCTION__, get_app_instr_xl8(walk), tgt_pc);
REPORT_FATAL_ERROR_AND_EXIT(RSEQ_BEHAVIOR_UNSUPPORTED, 3,
get_application_name(), get_application_pid(),
"Rseq branch target is mid-instruction");
ASSERT_NOT_REACHED();
}
instr_set_target(walk, opnd_create_instr(tgt_inst));
}
}
generic_hash_destroy(dcontext, pc2instr);
/* Now mangle from this point. */
*next_instr = start_mangling;

Expand Down