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

#define _GNU_SOURCE

#include <stdio.h>
#include <stdbool.h>
#include <string.h>
#include <sys/prctl.h>

#include "ebb.h"


/*
 * Run a calibrated instruction loop and count instructions executed using
 * EBBs. Make sure the counts look right.
 */

extern void thirty_two_instruction_loop(uint64_t loops);

static bool counters_frozen = true;

static int do_count_loop(struct event *event, uint64_t instructions,
                         uint64_t overhead, bool report)
{
        int64_t difference, expected;
        double percentage;

        clear_ebb_stats();

        counters_frozen = false;
        mb();
        mtspr(SPRN_MMCR0, mfspr(SPRN_MMCR0) & ~MMCR0_FC);

        thirty_two_instruction_loop(instructions >> 5);

        counters_frozen = true;
        mb();
        mtspr(SPRN_MMCR0, mfspr(SPRN_MMCR0) | MMCR0_FC);

        count_pmc(4, sample_period);

        event->result.value = ebb_state.stats.pmc_count[4-1];
        expected = instructions + overhead;
        difference = event->result.value - expected;
        percentage = (double)difference / event->result.value * 100;

        if (report) {
                printf("Looped for %lu instructions, overhead %lu\n", instructions, overhead);
                printf("Expected %lu\n", expected);
                printf("Actual   %llu\n", event->result.value);
                printf("Delta    %ld, %f%%\n", difference, percentage);
                printf("Took %d EBBs\n", ebb_state.stats.ebb_count);
        }

        if (difference < 0)
                difference = -difference;

        /* Tolerate a difference of up to 0.0001 % */
        difference *= 10000 * 100;
        if (difference / event->result.value)
                return -1;

        return 0;
}

/* Count how many instructions it takes to do a null loop */
static uint64_t determine_overhead(struct event *event)
{
        uint64_t current, overhead;
        int i;

        do_count_loop(event, 0, 0, false);
        overhead = event->result.value;

        for (i = 0; i < 100; i++) {
                do_count_loop(event, 0, 0, false);
                current = event->result.value;
                if (current < overhead) {
                        printf("Replacing overhead %lu with %lu\n", overhead, current);
                        overhead = current;
                }
        }

        return overhead;
}

static void pmc4_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(4, sample_period);
out:
        if (counters_frozen)
                reset_ebb_with_clear_mask(MMCR0_PMAO);
        else
                reset_ebb();
}

int instruction_count(void)
{
        struct event event;
        uint64_t overhead;

        SKIP_IF(!ebb_is_supported());

        event_init_named(&event, 0x400FA, "PM_RUN_INST_CMPL");
        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));
        FAIL_IF(ebb_event_enable(&event));

        sample_period = COUNTER_OVERFLOW;

        setup_ebb_handler(pmc4_ebb_callee);
        mtspr(SPRN_MMCR0, mfspr(SPRN_MMCR0) & ~MMCR0_FC);
        ebb_global_enable();

        overhead = determine_overhead(&event);
        printf("Overhead of null loop: %lu instructions\n", overhead);

        /* Run for 1M instructions */
        FAIL_IF(do_count_loop(&event, 0x100000, overhead, true));

        /* Run for 10M instructions */
        FAIL_IF(do_count_loop(&event, 0xa00000, overhead, true));

        /* Run for 100M instructions */
        FAIL_IF(do_count_loop(&event, 0x6400000, overhead, true));

        /* Run for 1G instructions */
        FAIL_IF(do_count_loop(&event, 0x40000000, overhead, true));

        /* Run for 16G instructions */
        FAIL_IF(do_count_loop(&event, 0x400000000, overhead, true));

        /* Run for 64G instructions */
        FAIL_IF(do_count_loop(&event, 0x1000000000, overhead, true));

        /* Run for 128G instructions */
        FAIL_IF(do_count_loop(&event, 0x2000000000, overhead, true));

        ebb_global_disable();
        event_close(&event);

        printf("Finished OK\n");

        return 0;
}

int main(void)
{
        test_harness_set_timeout(300);
        return test_harness(instruction_count, "instruction_count");
}