// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright 2014, Michael Ellerman, IBM Corp.
 */

#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();

        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");
}