diff options
Diffstat (limited to 'powerpc/pmu/ebb/lost_exception_test.c')
-rw-r--r-- | powerpc/pmu/ebb/lost_exception_test.c | 100 |
1 files changed, 0 insertions, 100 deletions
diff --git a/powerpc/pmu/ebb/lost_exception_test.c b/powerpc/pmu/ebb/lost_exception_test.c deleted file mode 100644 index 0c9dd9b..0000000 --- a/powerpc/pmu/ebb/lost_exception_test.c +++ /dev/null @@ -1,100 +0,0 @@ -/* - * Copyright 2014, Michael Ellerman, IBM Corp. - * Licensed under GPLv2. - */ - -#include <sched.h> -#include <signal.h> -#include <stdio.h> -#include <stdlib.h> -#include <sys/mman.h> - -#include "ebb.h" - - -/* - * Test that tries to trigger CPU_FTR_PMAO_BUG. Which is a hardware defect - * where an exception triggers but we context switch before it is delivered and - * lose the exception. - */ - -static int test_body(void) -{ - int i, orig_period, max_period; - struct event event; - - /* We use PMC4 to make sure the kernel switches all counters correctly */ - event_init_named(&event, 0x40002, "instructions"); - 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)); - - ebb_enable_pmc_counting(4); - setup_ebb_handler(standard_ebb_callee); - ebb_global_enable(); - FAIL_IF(ebb_event_enable(&event)); - - /* - * We want a low sample period, but we also want to get out of the EBB - * handler without tripping up again. - * - * This value picked after much experimentation. - */ - orig_period = max_period = sample_period = 400; - - mtspr(SPRN_PMC4, pmc_sample_period(sample_period)); - - while (ebb_state.stats.ebb_count < 1000000) { - /* - * We are trying to get the EBB exception to race exactly with - * us entering the kernel to do the syscall. We then need the - * kernel to decide our timeslice is up and context switch to - * the other thread. When we come back our EBB will have been - * lost and we'll spin in this while loop forever. - */ - - for (i = 0; i < 100000; i++) - sched_yield(); - - /* Change the sample period slightly to try and hit the race */ - if (sample_period >= (orig_period + 200)) - sample_period = orig_period; - else - sample_period++; - - if (sample_period > max_period) - max_period = sample_period; - } - - ebb_freeze_pmcs(); - ebb_global_disable(); - - count_pmc(4, sample_period); - mtspr(SPRN_PMC4, 0xdead); - - dump_summary_ebb_state(); - dump_ebb_hw_state(); - - event_close(&event); - - FAIL_IF(ebb_state.stats.ebb_count == 0); - - /* We vary our sample period so we need extra fudge here */ - FAIL_IF(!ebb_check_count(4, orig_period, 2 * (max_period - orig_period))); - - return 0; -} - -static int lost_exception(void) -{ - return eat_cpu(test_body); -} - -int main(void) -{ - return test_harness(lost_exception, "lost_exception"); -} |