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1// SPDX-License-Identifier: GPL-2.0-only2/*3 * POWER Data Stream Control Register (DSCR) explicit test4 *5 * This test modifies the DSCR value using mtspr instruction and6 * verifies the change with mfspr instruction. It uses both the7 * privilege state SPR and the problem state SPR for this purpose.8 *9 * When using the privilege state SPR, the instructions such as10 * mfspr or mtspr are privileged and the kernel emulates them11 * for us. Instructions using problem state SPR can be executed12 * directly without any emulation if the HW supports them. Else13 * they also get emulated by the kernel.14 *15 * Copyright 2012, Anton Blanchard, IBM Corporation.16 * Copyright 2015, Anshuman Khandual, IBM Corporation.17 */18 19#define _GNU_SOURCE20 21#include "dscr.h"22#include "utils.h"23 24#include <pthread.h>25#include <sched.h>26#include <semaphore.h>27 28void *dscr_explicit_lockstep_thread(void *args)29{30 sem_t *prev = (sem_t *)args;31 sem_t *next = (sem_t *)args + 1;32 unsigned long expected_dscr = 0;33 34 set_dscr(expected_dscr);35 srand(gettid());36 37 for (int i = 0; i < COUNT; i++) {38 FAIL_IF_EXIT(sem_wait(prev));39 40 FAIL_IF_EXIT(expected_dscr != get_dscr());41 FAIL_IF_EXIT(expected_dscr != get_dscr_usr());42 43 expected_dscr = (expected_dscr + 1) % DSCR_MAX;44 set_dscr(expected_dscr);45 46 FAIL_IF_EXIT(sem_post(next));47 }48 49 return NULL;50}51 52int dscr_explicit_lockstep_test(void)53{54 pthread_t thread;55 sem_t semaphores[2];56 sem_t *prev = &semaphores[1]; /* reversed prev/next than for the other thread */57 sem_t *next = &semaphores[0];58 unsigned long expected_dscr = 0;59 60 SKIP_IF(!have_hwcap2(PPC_FEATURE2_DSCR));61 62 srand(gettid());63 set_dscr(expected_dscr);64 65 FAIL_IF(sem_init(prev, 0, 0));66 FAIL_IF(sem_init(next, 0, 1)); /* other thread starts first */67 FAIL_IF(bind_to_cpu(BIND_CPU_ANY) < 0);68 FAIL_IF(pthread_create(&thread, NULL, dscr_explicit_lockstep_thread, (void *)semaphores));69 70 for (int i = 0; i < COUNT; i++) {71 FAIL_IF(sem_wait(prev));72 73 FAIL_IF(expected_dscr != get_dscr());74 FAIL_IF(expected_dscr != get_dscr_usr());75 76 expected_dscr = (expected_dscr - 1) % DSCR_MAX;77 set_dscr(expected_dscr);78 79 FAIL_IF(sem_post(next));80 }81 82 FAIL_IF(pthread_join(thread, NULL));83 FAIL_IF(sem_destroy(prev));84 FAIL_IF(sem_destroy(next));85 86 return 0;87}88 89struct random_thread_args {90 pthread_t thread_id;91 bool do_yields;92 pthread_barrier_t *barrier;93};94 95void *dscr_explicit_random_thread(void *in)96{97 struct random_thread_args *args = (struct random_thread_args *)in;98 unsigned long expected_dscr = 0;99 int err;100 101 srand(gettid());102 103 err = pthread_barrier_wait(args->barrier);104 FAIL_IF_EXIT(err != 0 && err != PTHREAD_BARRIER_SERIAL_THREAD);105 106 for (int i = 0; i < COUNT; i++) {107 expected_dscr = rand() % DSCR_MAX;108 set_dscr(expected_dscr);109 110 for (int j = rand() % 5; j > 0; --j) {111 FAIL_IF_EXIT(get_dscr() != expected_dscr);112 FAIL_IF_EXIT(get_dscr_usr() != expected_dscr);113 114 if (args->do_yields && rand() % 2)115 sched_yield();116 }117 118 expected_dscr = rand() % DSCR_MAX;119 set_dscr_usr(expected_dscr);120 121 for (int j = rand() % 5; j > 0; --j) {122 FAIL_IF_EXIT(get_dscr() != expected_dscr);123 FAIL_IF_EXIT(get_dscr_usr() != expected_dscr);124 125 if (args->do_yields && rand() % 2)126 sched_yield();127 }128 }129 130 return NULL;131}132 133int dscr_explicit_random_test(void)134{135 struct random_thread_args threads[THREADS];136 pthread_barrier_t barrier;137 138 SKIP_IF(!have_hwcap2(PPC_FEATURE2_DSCR));139 140 FAIL_IF(pthread_barrier_init(&barrier, NULL, THREADS));141 142 for (int i = 0; i < THREADS; i++) {143 threads[i].do_yields = i % 2 == 0;144 threads[i].barrier = &barrier;145 146 FAIL_IF(pthread_create(&threads[i].thread_id, NULL,147 dscr_explicit_random_thread, (void *)&threads[i]));148 }149 150 for (int i = 0; i < THREADS; i++)151 FAIL_IF(pthread_join(threads[i].thread_id, NULL));152 153 FAIL_IF(pthread_barrier_destroy(&barrier));154 155 return 0;156}157 158int main(int argc, char *argv[])159{160 unsigned long orig_dscr_default = 0;161 int err = 0;162 163 if (have_hwcap2(PPC_FEATURE2_DSCR))164 orig_dscr_default = get_default_dscr();165 166 err |= test_harness(dscr_explicit_lockstep_test, "dscr_explicit_lockstep_test");167 err |= test_harness(dscr_explicit_random_test, "dscr_explicit_random_test");168 169 if (have_hwcap2(PPC_FEATURE2_DSCR))170 set_default_dscr(orig_dscr_default);171 172 return err;173}174