From fda8158870063b99b88a0904bbb95188973b4297 Mon Sep 17 00:00:00 2001 From: Benjamin Gray Date: Thu, 6 Apr 2023 14:33:17 +1000 Subject: [PATCH] selftests/powerpc/dscr: Add lockstep test cases to DSCR explicit tests Add new cases to the relevant tests that use explicitly synchronized threads to test the behaviour across context switches with less randomness. By locking the participants to the same CPU we guarantee a context switch occurs each time they make progress, which is a likely failure point if the kernel is not tracking the thread local DSCR correctly. The random case is left in to keep exercising potential edge cases. Signed-off-by: Benjamin Gray Signed-off-by: Michael Ellerman Link: https://msgid.link/20230406043320.125138-5-bgray@linux.ibm.com --- tools/testing/selftests/powerpc/dscr/Makefile | 1 + .../powerpc/dscr/dscr_default_test.c | 87 ++++++++++++++++--- .../powerpc/dscr/dscr_explicit_test.c | 85 +++++++++++++++++- 3 files changed, 159 insertions(+), 14 deletions(-) diff --git a/tools/testing/selftests/powerpc/dscr/Makefile b/tools/testing/selftests/powerpc/dscr/Makefile index 845db6273a1b1..b29a8863a7340 100644 --- a/tools/testing/selftests/powerpc/dscr/Makefile +++ b/tools/testing/selftests/powerpc/dscr/Makefile @@ -9,5 +9,6 @@ top_srcdir = ../../../../.. include ../../lib.mk $(OUTPUT)/dscr_default_test: LDLIBS += -lpthread +$(OUTPUT)/dscr_explicit_test: LDLIBS += -lpthread $(TEST_GEN_PROGS): ../harness.c ../utils.c diff --git a/tools/testing/selftests/powerpc/dscr/dscr_default_test.c b/tools/testing/selftests/powerpc/dscr/dscr_default_test.c index e76611e608afe..18e533d46c9a9 100644 --- a/tools/testing/selftests/powerpc/dscr/dscr_default_test.c +++ b/tools/testing/selftests/powerpc/dscr/dscr_default_test.c @@ -9,8 +9,66 @@ * Copyright 2012, Anton Blanchard, IBM Corporation. * Copyright 2015, Anshuman Khandual, IBM Corporation. */ + +#define _GNU_SOURCE + #include "dscr.h" +#include +#include +#include + +static void *dscr_default_lockstep_writer(void *arg) +{ + sem_t *reader_sem = (sem_t *)arg; + sem_t *writer_sem = (sem_t *)arg + 1; + unsigned long expected_dscr = 0; + + for (int i = 0; i < COUNT; i++) { + FAIL_IF_EXIT(sem_wait(writer_sem)); + + set_default_dscr(expected_dscr); + expected_dscr = (expected_dscr + 1) % DSCR_MAX; + + FAIL_IF_EXIT(sem_post(reader_sem)); + } + + return NULL; +} + +int dscr_default_lockstep_test(void) +{ + pthread_t writer; + sem_t rw_semaphores[2]; + sem_t *reader_sem = &rw_semaphores[0]; + sem_t *writer_sem = &rw_semaphores[1]; + unsigned long expected_dscr = 0; + + SKIP_IF(!have_hwcap2(PPC_FEATURE2_DSCR)); + + FAIL_IF(sem_init(reader_sem, 0, 0)); + FAIL_IF(sem_init(writer_sem, 0, 1)); /* writer starts first */ + FAIL_IF(bind_to_cpu(BIND_CPU_ANY) < 0); + FAIL_IF(pthread_create(&writer, NULL, dscr_default_lockstep_writer, (void *)rw_semaphores)); + + for (int i = 0; i < COUNT ; i++) { + FAIL_IF(sem_wait(reader_sem)); + + FAIL_IF(get_dscr() != expected_dscr); + FAIL_IF(get_dscr_usr() != expected_dscr); + + expected_dscr = (expected_dscr + 1) % DSCR_MAX; + + FAIL_IF(sem_post(writer_sem)); + } + + FAIL_IF(pthread_join(writer, NULL)); + FAIL_IF(sem_destroy(reader_sem)); + FAIL_IF(sem_destroy(writer_sem)); + + return 0; +} + static unsigned long dscr; /* System DSCR default */ static unsigned long sequence; static unsigned long result[THREADS]; @@ -57,16 +115,13 @@ static void *do_test(void *in) pthread_exit(&result[thread]); } -int dscr_default(void) +int dscr_default_random_test(void) { pthread_t threads[THREADS]; unsigned long i, *status[THREADS]; - unsigned long orig_dscr_default; SKIP_IF(!have_hwcap2(PPC_FEATURE2_DSCR)); - orig_dscr_default = get_default_dscr(); - /* Initial DSCR default */ dscr = 1; set_default_dscr(dscr); @@ -75,7 +130,7 @@ int dscr_default(void) for (i = 0; i < THREADS; i++) { if (pthread_create(&threads[i], NULL, do_test, (void *)i)) { perror("pthread_create() failed"); - goto fail; + return 1; } } @@ -104,23 +159,31 @@ int dscr_default(void) for (i = 0; i < THREADS; i++) { if (pthread_join(threads[i], (void **)&(status[i]))) { perror("pthread_join() failed"); - goto fail; + return 1; } if (*status[i]) { printf("%ldth thread failed to join with %ld status\n", i, *status[i]); - goto fail; + return 1; } } - set_default_dscr(orig_dscr_default); return 0; -fail: - set_default_dscr(orig_dscr_default); - return 1; } int main(int argc, char *argv[]) { - return test_harness(dscr_default, "dscr_default_test"); + unsigned long orig_dscr_default = 0; + int err = 0; + + if (have_hwcap2(PPC_FEATURE2_DSCR)) + orig_dscr_default = get_default_dscr(); + + err |= test_harness(dscr_default_lockstep_test, "dscr_default_lockstep_test"); + err |= test_harness(dscr_default_random_test, "dscr_default_random_test"); + + if (have_hwcap2(PPC_FEATURE2_DSCR)) + set_default_dscr(orig_dscr_default); + + return err; } diff --git a/tools/testing/selftests/powerpc/dscr/dscr_explicit_test.c b/tools/testing/selftests/powerpc/dscr/dscr_explicit_test.c index 5659d98cf3409..3b98b9a882075 100644 --- a/tools/testing/selftests/powerpc/dscr/dscr_explicit_test.c +++ b/tools/testing/selftests/powerpc/dscr/dscr_explicit_test.c @@ -15,9 +15,78 @@ * Copyright 2012, Anton Blanchard, IBM Corporation. * Copyright 2015, Anshuman Khandual, IBM Corporation. */ + +#define _GNU_SOURCE + #include "dscr.h" +#include "utils.h" + +#include +#include +#include + +void *dscr_explicit_lockstep_thread(void *args) +{ + sem_t *prev = (sem_t *)args; + sem_t *next = (sem_t *)args + 1; + unsigned long expected_dscr = 0; + + set_dscr(expected_dscr); + srand(gettid()); + + for (int i = 0; i < COUNT; i++) { + FAIL_IF_EXIT(sem_wait(prev)); + + FAIL_IF_EXIT(expected_dscr != get_dscr()); + FAIL_IF_EXIT(expected_dscr != get_dscr_usr()); + + expected_dscr = (expected_dscr + 1) % DSCR_MAX; + set_dscr(expected_dscr); + + FAIL_IF_EXIT(sem_post(next)); + } + + return NULL; +} + +int dscr_explicit_lockstep_test(void) +{ + pthread_t thread; + sem_t semaphores[2]; + sem_t *prev = &semaphores[1]; /* reversed prev/next than for the other thread */ + sem_t *next = &semaphores[0]; + unsigned long expected_dscr = 0; + + SKIP_IF(!have_hwcap2(PPC_FEATURE2_DSCR)); + + srand(gettid()); + set_dscr(expected_dscr); + + FAIL_IF(sem_init(prev, 0, 0)); + FAIL_IF(sem_init(next, 0, 1)); /* other thread starts first */ + FAIL_IF(bind_to_cpu(BIND_CPU_ANY) < 0); + FAIL_IF(pthread_create(&thread, NULL, dscr_explicit_lockstep_thread, (void *)semaphores)); + + for (int i = 0; i < COUNT; i++) { + FAIL_IF(sem_wait(prev)); + + FAIL_IF(expected_dscr != get_dscr()); + FAIL_IF(expected_dscr != get_dscr_usr()); + + expected_dscr = (expected_dscr - 1) % DSCR_MAX; + set_dscr(expected_dscr); + + FAIL_IF(sem_post(next)); + } -int dscr_explicit(void) + FAIL_IF(pthread_join(thread, NULL)); + FAIL_IF(sem_destroy(prev)); + FAIL_IF(sem_destroy(next)); + + return 0; +} + +int dscr_explicit_random_test(void) { unsigned long i, dscr = 0; @@ -66,5 +135,17 @@ int dscr_explicit(void) int main(int argc, char *argv[]) { - return test_harness(dscr_explicit, "dscr_explicit_test"); + unsigned long orig_dscr_default = 0; + int err = 0; + + if (have_hwcap2(PPC_FEATURE2_DSCR)) + orig_dscr_default = get_default_dscr(); + + err |= test_harness(dscr_explicit_lockstep_test, "dscr_explicit_lockstep_test"); + err |= test_harness(dscr_explicit_random_test, "dscr_explicit_random_test"); + + if (have_hwcap2(PPC_FEATURE2_DSCR)) + set_default_dscr(orig_dscr_default); + + return err; } -- 2.30.2