tools/testing/selftests/powerpc/pmu/ebb/cycles_with_freeze_test.c

   1 /*
   2  * Copyright 2014, Michael Ellerman, IBM Corp.
   3  * Licensed under GPLv2.
   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
  21 static bool counters_frozen = false;
  22 static int ebbs_while_frozen = 0;
  23
  24 static 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);
  49 out:
  50         reset_ebb_with_clear_mask(mask);
  51 }
  52
  53 int 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         count_pmc(1, sample_period);
 103
 104         dump_ebb_state();
 105
 106         printf("EBBs while frozen %d\n", ebbs_while_frozen);
 107
 108         event_close(&event);
 109
 110         FAIL_IF(ebb_state.stats.ebb_count == 0);
 111         FAIL_IF(fc_cleared);
 112
 113         return 0;
 114 }
 115
 116 int main(void)
 117 {
 118         return test_harness(cycles_with_freeze, "cycles_with_freeze");
 119 }