| // 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"); |
| } |