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

#include <sched.h>
#include <signal.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>

#include "ebb.h"


/*
 * Test that the kernel properly handles PMAE across context switches.
 *
 * We test this by calling into the kernel inside our EBB handler, where PMAE
 * is clear. A cpu eater companion thread is running on the same CPU as us to
 * encourage the scheduler to switch us.
 *
 * The kernel must make sure that when it context switches us back in, it
 * honours the fact that we had PMAE clear.
 *
 * Observed to hit the failing case on the first EBB with a broken kernel.
 */

static bool mmcr0_mismatch;
static uint64_t before, after;

static void syscall_ebb_callee(void)
{
        uint64_t val;

        val = mfspr(SPRN_BESCR);
        if (!(val & BESCR_PMEO)) {
                ebb_state.stats.spurious++;
                goto out;
        }

        ebb_state.stats.ebb_count++;
        count_pmc(1, sample_period);

        before = mfspr(SPRN_MMCR0);

        /* Try and get ourselves scheduled, to force a PMU context switch */
        sched_yield();

        after = mfspr(SPRN_MMCR0);
        if (before != after)
                mmcr0_mismatch = true;

out:
        reset_ebb();
}

static int test_body(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(syscall_ebb_callee);
        ebb_global_enable();

        FAIL_IF(ebb_event_enable(&event));

        mtspr(SPRN_PMC1, pmc_sample_period(sample_period));

        while (ebb_state.stats.ebb_count < 20 && !mmcr0_mismatch)
                FAIL_IF(core_busy_loop());

        ebb_global_disable();
        ebb_freeze_pmcs();

        dump_ebb_state();

        if (mmcr0_mismatch)
                printf("Saw MMCR0 before 0x%lx after 0x%lx\n", before, after);

        event_close(&event);

        FAIL_IF(ebb_state.stats.ebb_count == 0);
        FAIL_IF(mmcr0_mismatch);

        return 0;
}

int pmae_handling(void)
{
        return eat_cpu(test_body);
}

int main(void)
{
        return test_harness(pmae_handling, "pmae_handling");
}