LXR linux/tools/testing/selftests/powerpc/pmu/ebb/cycles_with_freeze

   1// SPDX-License-Identifier: GPL-2.0-only
   2/*
   3 * Copyright 2014, Michael Ellerman, IBM Corp.
   4 */
   5
   6#include <stdio.h>
   7#include <stdlib.h>
   8#include <stdbool.h>
   9
  10#include "ebb.h"
  11
  12
  13/*
  14 * Test of counting cycles while using MMCR0_FC (freeze counters) to only count
  15 * parts of the code. This is complicated by the fact that FC is set by the
  16 * hardware when the event overflows. We may take the EBB after we have set FC,
  17 * so we have to be careful about whether we clear FC at the end of the EBB
  18 * handler or not.
  19 */
  20
  21static bool counters_frozen = false;
  22static int ebbs_while_frozen = 0;
  23
  24static void ebb_callee(void)
  25{
  26        uint64_t mask, val;
  27
  28        mask = MMCR0_PMAO | MMCR0_FC;
  29
  30        val = mfspr(SPRN_BESCR);
  31        if (!(val & BESCR_PMEO)) {
  32                ebb_state.stats.spurious++;
  33                goto out;
  34        }
  35
  36        ebb_state.stats.ebb_count++;
  37        trace_log_counter(ebb_state.trace, ebb_state.stats.ebb_count);
  38
  39        val = mfspr(SPRN_MMCR0);
  40        trace_log_reg(ebb_state.trace, SPRN_MMCR0, val);
  41
  42        if (counters_frozen) {
  43                trace_log_string(ebb_state.trace, "frozen");
  44                ebbs_while_frozen++;
  45                mask &= ~MMCR0_FC;
  46        }
  47
  48        count_pmc(1, sample_period);
  49out:
  50        reset_ebb_with_clear_mask(mask);
  51}
  52
  53int cycles_with_freeze(void)
  54{
  55        struct event event;
  56        uint64_t val;
  57        bool fc_cleared;
  58
  59        SKIP_IF(!ebb_is_supported());
  60
  61        event_init_named(&event, 0x1001e, "cycles");
  62        event_leader_ebb_init(&event);
  63
  64        event.attr.exclude_kernel = 1;
  65        event.attr.exclude_hv = 1;
  66        event.attr.exclude_idle = 1;
  67
  68        FAIL_IF(event_open(&event));
  69
  70        setup_ebb_handler(ebb_callee);
  71        ebb_global_enable();
  72        FAIL_IF(ebb_event_enable(&event));
  73
  74        mtspr(SPRN_PMC1, pmc_sample_period(sample_period));
  75
  76        fc_cleared = false;
  77
  78        /* Make sure we loop until we take at least one EBB */
  79        while ((ebb_state.stats.ebb_count < 20 && !fc_cleared) ||
  80                ebb_state.stats.ebb_count < 1)
  81        {
  82                counters_frozen = false;
  83                mb();
  84                mtspr(SPRN_MMCR0, mfspr(SPRN_MMCR0) & ~MMCR0_FC);
  85
  86                FAIL_IF(core_busy_loop());
  87
  88                counters_frozen = true;
  89                mb();
  90                mtspr(SPRN_MMCR0, mfspr(SPRN_MMCR0) |  MMCR0_FC);
  91
  92                val = mfspr(SPRN_MMCR0);
  93                if (! (val & MMCR0_FC)) {
  94                        printf("Outside of loop, FC NOT set MMCR0 0x%lx\n", val);
  95                        fc_cleared = true;
  96                }
  97        }
  98
  99        ebb_global_disable();
 100        ebb_freeze_pmcs();
 101
 102        dump_ebb_state();
 103
 104        printf("EBBs while frozen %d\n", ebbs_while_frozen);
 105
 106        event_close(&event);
 107
 108        FAIL_IF(ebb_state.stats.ebb_count == 0);
 109        FAIL_IF(fc_cleared);
 110
 111        return 0;
 112}
 113
 114int main(void)
 115{
 116        return test_harness(cycles_with_freeze, "cycles_with_freeze");
 117}
 118