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/*
* Copyright 2014, Michael Ellerman, IBM Corp.
* Licensed under GPLv2.
*/
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include "ebb.h"
#define NUMBER_OF_EBBS 50
/*
* Test that if we overflow the counter while in the EBB handler, we take
* another EBB on exiting from the handler.
*
* We do this by counting with a stupidly low sample period, causing us to
* overflow the PMU while we're still in the EBB handler, leading to another
* EBB.
*
* We get out of what would otherwise be an infinite loop by leaving the
* counter frozen once we've taken enough EBBs.
*/
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;
SKIP_IF(!ebb_is_supported());
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;
}
int main(void)
{
return test_harness(back_to_back_ebbs, "back_to_back_ebbs");
}
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