C++ (Cpp) drreg_reserve_aflags Examples

Example #1

File: countcalls.c Project: DynamoRIO/dynamorio

static void
insert_counter_update(void *drcontext, instrlist_t *bb, instr_t *where, int offset)
{
    /* Since the inc instruction clobbers 5 of the arithmetic eflags,
     * we have to save them around the inc. We could be more efficient
     * by not bothering to save the overflow flag and constructing our
     * own sequence of instructions to save the other 5 flags (using
     * lahf).
     */
    if (drreg_reserve_aflags(drcontext, bb, where) != DRREG_SUCCESS) {
        DR_ASSERT(false); /* cannot recover */
        return;
    }

    /* Increment the global counter using the lock prefix to make it atomic
     * across threads. It would be cheaper to aggregate the thread counters
     * in the exit events, but this sample is intended to illustrate inserted
     * instrumentation.
     */
    instrlist_meta_preinsert(
        bb, where,
        LOCK(INSTR_CREATE_inc(
            drcontext, OPND_CREATE_ABSMEM(((byte *)&global_count) + offset, OPSZ_4))));

    /* Increment the thread private counter. */
    if (dr_using_all_private_caches()) {
        per_thread_t *data = (per_thread_t *)drmgr_get_tls_field(drcontext, tls_idx);
        /* private caches - we can use an absolute address */
        instrlist_meta_preinsert(
            bb, where,
            INSTR_CREATE_inc(drcontext,
                             OPND_CREATE_ABSMEM(((byte *)&data) + offset, OPSZ_4)));
    } else {
        /* shared caches - we must indirect via thread local storage */
        reg_id_t scratch;
        if (drreg_reserve_register(drcontext, bb, where, NULL, &scratch) != DRREG_SUCCESS)
            DR_ASSERT(false);
        drmgr_insert_read_tls_field(drcontext, tls_idx, bb, where, scratch);
        instrlist_meta_preinsert(
            bb, where, INSTR_CREATE_inc(drcontext, OPND_CREATE_MEM32(scratch, offset)));
        if (drreg_unreserve_register(drcontext, bb, where, scratch) != DRREG_SUCCESS)
            DR_ASSERT(false);
    }

    if (drreg_unreserve_aflags(drcontext, bb, where) != DRREG_SUCCESS)
        DR_ASSERT(false); /* cannot recover */
}

Example #2

File: bbcount.c Project: AVGirl/dynamorio

static dr_emit_flags_t
event_app_instruction(void *drcontext, void *tag, instrlist_t *bb, instr_t *inst,
                      bool for_trace, bool translating, void *user_data)
{
#ifdef SHOW_RESULTS
    bool aflags_dead;
#endif

    if (!drmgr_is_first_instr(drcontext, inst))
        return DR_EMIT_DEFAULT;

#ifdef VERBOSE
    dr_printf("in dynamorio_basic_block(tag="PFX")\n", tag);
# ifdef VERBOSE_VERBOSE
    instrlist_disassemble(drcontext, tag, bb, STDOUT);
# endif
#endif

#ifdef SHOW_RESULTS
    if (drreg_are_aflags_dead(drcontext, inst, &aflags_dead) == DRREG_SUCCESS &&
        !aflags_dead)
        bbs_eflags_saved++;
    else
        bbs_no_eflags_saved++;
#endif

    /* We demonstrate how to use drreg for aflags save/restore here.
     * We could use drx_insert_counter_update instead of drreg.
     * Xref sample opcodes.c as an example of using drx_insert_counter_update.
     */
    if (drreg_reserve_aflags(drcontext, bb, inst) != DRREG_SUCCESS)
        DR_ASSERT(false && "fail to reserve aflags!");
    /* racy update on the counter for better performance */
    instrlist_meta_preinsert
        (bb, inst,
         INSTR_CREATE_inc(drcontext, OPND_CREATE_ABSMEM
                          ((byte *)&global_count, OPSZ_4)));
    if (drreg_unreserve_aflags(drcontext, bb, inst) != DRREG_SUCCESS)
        DR_ASSERT(false && "fail to unreserve aflags!");

#if defined(VERBOSE) && defined(VERBOSE_VERBOSE)
    dr_printf("Finished instrumenting dynamorio_basic_block(tag="PFX")\n", tag);
    instrlist_disassemble(drcontext, tag, bb, STDOUT);
#endif
    return DR_EMIT_DEFAULT;
}