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; }