static dr_emit_flags_t
bb_event(void *drcontext, void *tag, instrlist_t *bb, bool for_trace, bool translating)
{
instr_t *instr, *next_instr;
for (instr = instrlist_first(bb); instr != NULL; instr = next_instr) {
next_instr = instr_get_next(instr);
if (instr_is_cbr(instr)) {
/* Conditional branch. We can determine the target and
* fallthrough addresses here, but we want to note the
* edge if and when it actually executes at runtime.
* Instead of using dr_insert_cbr_instrumentation(), we'll
* insert separate instrumentation for the taken and not
* taken cases and remove the instrumentation for an edge
* after it executes.
*/
cbr_state_t state;
bool insert_taken, insert_not_taken;
app_pc src = instr_get_app_pc(instr);
/* First look up the state of this branch so we
* know what instrumentation to insert, if any.
*/
elem_t *elem = lookup(table, src);
if (elem == NULL) {
state = CBR_NEITHER;
insert(table, src, CBR_NEITHER);
}
else {
state = elem->state;
}
insert_taken = (state & CBR_TAKEN) == 0;
insert_not_taken = (state & CBR_NOT_TAKEN) == 0;
if (insert_taken || insert_not_taken) {
app_pc fall = (app_pc)decode_next_pc(drcontext, (byte *)src);
app_pc targ = instr_get_branch_target_pc(instr);
/* Redirect the existing cbr to jump to a callout for
* the 'taken' case. We'll insert a 'not-taken'
* callout at the fallthrough address.
*/
instr_t *label = INSTR_CREATE_label(drcontext);
/* should be meta, and meta-instrs shouldn't have translations */
instr_set_meta_no_translation(instr);
/* it may not reach (in particular for x64) w/ our added clean call */
if (instr_is_cti_short(instr)) {
/* if jecxz/loop we want to set the target of the long-taken
* so set instr to the return value
*/
instr = instr_convert_short_meta_jmp_to_long(drcontext, bb, instr);
}
instr_set_target(instr, opnd_create_instr(label));
if (insert_not_taken) {
/* Callout for the not-taken case. Insert after
* the cbr (i.e., 3rd argument is NULL).
*/
dr_insert_clean_call(drcontext, bb, NULL,
(void*)at_not_taken,
false /* don't save fp state */,
2 /* 2 args for at_not_taken */,
OPND_CREATE_INTPTR(src),
OPND_CREATE_INTPTR(fall));
}
/* After the callout, jump to the original fallthrough
* address. Note that this is an exit cti, and should
* not be a meta-instruction. Therefore, we use
* preinsert instead of meta_preinsert, and we must
* set the translation field. On Windows, this jump
* and the final jump below never execute since the
* at_taken and at_not_taken callouts redirect
* execution and never return. However, since the API
* expects clients to produced well-formed code, we
* insert explicit exits from the block for Windows as
* well as Linux.
*/
instrlist_preinsert(bb, NULL,
INSTR_XL8(INSTR_CREATE_jmp
(drcontext, opnd_create_pc(fall)), fall));
/* label goes before the 'taken' callout */
MINSERT(bb, NULL, label);
if (insert_taken) {
/* Callout for the taken case */
dr_insert_clean_call(drcontext, bb, NULL,
(void*)at_taken,
false /* don't save fp state */,
2 /* 2 args for at_taken */,
OPND_CREATE_INTPTR(src),
OPND_CREATE_INTPTR(targ));
}
/* After the callout, jump to the original target
* block (this should not be a meta-instruction).
*/
instrlist_preinsert(bb, NULL,
INSTR_XL8(INSTR_CREATE_jmp
(drcontext, opnd_create_pc(targ)), targ));
}
}
}
/* since our added instrumentation is not constant, we ask to store
* translations now
*/
return DR_EMIT_STORE_TRANSLATIONS;
}
dr_emit_flags_t
bb_event(void *drcontext, void *tag, instrlist_t *bb, bool for_trace, bool translating)
{
instr_t *instr, *next_instr;
app_pc bb_addr = dr_fragment_app_pc(tag);
if (bb_addr == start_pc) {
instrument = true;
} else if (bb_addr == stop_pc) {
instrument = false;
}
if (!instrument) {
return DR_EMIT_DEFAULT;
}
for (instr = instrlist_first(bb); instr != NULL; instr = next_instr) {
next_instr = instr_get_next(instr);
/*
* Conditional branch. We can determine the target and
* fallthrough addresses here, but we need to instrument if we
* want to record the edge only if it actually executes at
* runtime. Instead of using dr_insert_cbr_instrumentation,
* we'll insert separate instrumentation for the taken and not
* taken cases and remove it separately after we see each
* case.
*/
if (instr_is_cbr(instr)) {
app_pc src = instr_get_app_pc(instr);
cbr_state_t state;
bool insert_taken, insert_not_taken;
/* First look up the state of this branch so we
* know what instrumentation to insert, if any.
*/
elem_t *elem = lookup(table, src);
if (elem == NULL) {
state = CBR_NONE;
insert(table, src, CBR_NONE);
} else {
state = elem->state;
}
insert_taken = (state & CBR_TAKEN) == 0;
insert_not_taken = (state & CBR_NOT_TAKEN) == 0;
if (insert_taken || insert_not_taken) {
app_pc fall = (app_pc)decode_next_pc(drcontext, (byte *)src);
app_pc targ = instr_get_branch_target_pc(instr);
/*
* Redirect the cbr to jump to the 'taken' callout.
* We'll insert a 'not-taken' callout at fallthrough
* address.
*/
instr_t *label = INSTR_CREATE_label(drcontext);
instr_set_meta(instr);
instr_set_translation(instr, NULL);
/* If this is a short cti, make sure it can reach its new target */
if (instr_is_cti_short(instr)) {
/* if jecxz/loop we want to set the target of the long-taken
* so set instr to the return value
*/
instr = instr_convert_short_meta_jmp_to_long(drcontext, bb, instr);
}
instr_set_target(instr, opnd_create_instr(label));
if (insert_not_taken) {
/*
* Callout for the not-taken case
*/
dr_insert_clean_call(drcontext, bb, NULL, (void *)at_not_taken,
false /* don't save fp state */,
2 /* 2 args for at_not_taken */,
OPND_CREATE_INTPTR((ptr_uint_t)src),
OPND_CREATE_INTPTR((ptr_uint_t)fall));
}
/*
* Jump to the original fall-through address.
* (This should not be a meta-instruction).
*/
instrlist_preinsert(
bb, NULL,
INSTR_XL8(INSTR_CREATE_jmp(drcontext, opnd_create_pc(fall)), fall));
/* label goes before the 'taken' callout */
MINSERT(bb, NULL, label);
if (insert_taken) {
/*
* Callout for the taken case
*/
dr_insert_clean_call(drcontext, bb, NULL, (void *)at_taken,
false /* don't save fp state */,
2 /* 2 args for at_taken */,
OPND_CREATE_INTPTR((ptr_uint_t)src),
OPND_CREATE_INTPTR((ptr_uint_t)targ));
}
/*
* Jump to the original target block (this should
* not be a meta-instruction).
*/
instrlist_preinsert(
bb, NULL,
INSTR_XL8(INSTR_CREATE_jmp(drcontext, opnd_create_pc(targ)), targ));
}
}
}
/* since our added instrumentation is not constant, we ask to store
* translations now
*/
return DR_EMIT_STORE_TRANSLATIONS;
}
