static int victim_child(union pipe read_pipe, union pipe write_pipe)
{
FAIL_IF(wait_for_parent(read_pipe));
/* Setup our EBB handler, before the EBB event is created */
ebb_enable_pmc_counting(1);
setup_ebb_handler(standard_ebb_callee);
ebb_global_enable();
FAIL_IF(notify_parent(write_pipe));
while (ebb_state.stats.ebb_count < 20) {
FAIL_IF(core_busy_loop());
}
ebb_global_disable();
ebb_freeze_pmcs();
count_pmc(1, sample_period);
dump_ebb_state();
FAIL_IF(ebb_state.stats.ebb_count == 0);
return 0;
}
static void ebb_callee(void)
{
uint64_t siar, val;
val = mfspr(SPRN_BESCR);
if (!(val & BESCR_PMEO)) {
ebb_state.stats.spurious++;
goto out;
}
ebb_state.stats.ebb_count++;
trace_log_counter(ebb_state.trace, ebb_state.stats.ebb_count);
/* Resets the PMC */
count_pmc(1, sample_period);
out:
if (ebb_state.stats.ebb_count == NUMBER_OF_EBBS)
/* Reset but leave counters frozen */
reset_ebb_with_clear_mask(MMCR0_PMAO);
else
/* Unfreezes */
reset_ebb();
/* Do some stuff to chew some cycles and pop the counter */
siar = mfspr(SPRN_SIAR);
trace_log_reg(ebb_state.trace, SPRN_SIAR, siar);
val = mfspr(SPRN_PMC1);
trace_log_reg(ebb_state.trace, SPRN_PMC1, val);
val = mfspr(SPRN_MMCR0);
trace_log_reg(ebb_state.trace, SPRN_MMCR0, val);
}
int back_to_back_ebbs(void)
{
struct event event;
event_init_named(&event, 0x1001e, "cycles");
event_leader_ebb_init(&event);
event.attr.exclude_kernel = 1;
event.attr.exclude_hv = 1;
event.attr.exclude_idle = 1;
FAIL_IF(event_open(&event));
setup_ebb_handler(ebb_callee);
FAIL_IF(ebb_event_enable(&event));
sample_period = 5;
ebb_freeze_pmcs();
mtspr(SPRN_PMC1, pmc_sample_period(sample_period));
ebb_global_enable();
ebb_unfreeze_pmcs();
while (ebb_state.stats.ebb_count < NUMBER_OF_EBBS)
FAIL_IF(core_busy_loop());
ebb_global_disable();
ebb_freeze_pmcs();
count_pmc(1, sample_period);
dump_ebb_state();
event_close(&event);
FAIL_IF(ebb_state.stats.ebb_count != NUMBER_OF_EBBS);
return 0;
}
static int test_body(void)
{
int i, orig_period, max_period;
struct event event;
/* We use PMC4 to make sure the kernel switches all counters correctly */
event_init_named(&event, 0x40002, "instructions");
event_leader_ebb_init(&event);
event.attr.exclude_kernel = 1;
event.attr.exclude_hv = 1;
event.attr.exclude_idle = 1;
FAIL_IF(event_open(&event));
ebb_enable_pmc_counting(4);
setup_ebb_handler(standard_ebb_callee);
ebb_global_enable();
FAIL_IF(ebb_event_enable(&event));
/*
* We want a low sample period, but we also want to get out of the EBB
* handler without tripping up again.
*
* This value picked after much experimentation.
*/
orig_period = max_period = sample_period = 400;
mtspr(SPRN_PMC4, pmc_sample_period(sample_period));
while (ebb_state.stats.ebb_count < 1000000) {
/*
* We are trying to get the EBB exception to race exactly with
* us entering the kernel to do the syscall. We then need the
* kernel to decide our timeslice is up and context switch to
* the other thread. When we come back our EBB will have been
* lost and we'll spin in this while loop forever.
*/
for (i = 0; i < 100000; i++)
sched_yield();
/* Change the sample period slightly to try and hit the race */
if (sample_period >= (orig_period + 200))
sample_period = orig_period;
else
sample_period++;
if (sample_period > max_period)
max_period = sample_period;
}
ebb_freeze_pmcs();
ebb_global_disable();
count_pmc(4, sample_period);
mtspr(SPRN_PMC4, 0xdead);
dump_summary_ebb_state();
dump_ebb_hw_state();
event_close(&event);
FAIL_IF(ebb_state.stats.ebb_count == 0);
/* We vary our sample period so we need extra fudge here */
FAIL_IF(!ebb_check_count(4, orig_period, 2 * (max_period - orig_period)));
return 0;
}