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// SPDX-License-Identifier: GPL-2.0-only
/*
* POWER Data Stream Control Register (DSCR) explicit test
*
* This test modifies the DSCR value using mtspr instruction and
* verifies the change with mfspr instruction. It uses both the
* privilege state SPR and the problem state SPR for this purpose.
*
* When using the privilege state SPR, the instructions such as
* mfspr or mtspr are privileged and the kernel emulates them
* for us. Instructions using problem state SPR can be executed
* directly without any emulation if the HW supports them. Else
* they also get emulated by the kernel.
*
* Copyright 2012, Anton Blanchard, IBM Corporation.
* Copyright 2015, Anshuman Khandual, IBM Corporation.
*/
#define _GNU_SOURCE
#include "dscr.h"
#include "utils.h"
#include <pthread.h>
#include <sched.h>
#include <semaphore.h>
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));
}
FAIL_IF(pthread_join(thread, NULL));
FAIL_IF(sem_destroy(prev));
FAIL_IF(sem_destroy(next));
return 0;
}
struct random_thread_args {
pthread_t thread_id;
bool do_yields;
pthread_barrier_t *barrier;
};
void *dscr_explicit_random_thread(void *in)
{
struct random_thread_args *args = (struct random_thread_args *)in;
unsigned long expected_dscr = 0;
int err;
srand(gettid());
err = pthread_barrier_wait(args->barrier);
FAIL_IF_EXIT(err != 0 && err != PTHREAD_BARRIER_SERIAL_THREAD);
for (int i = 0; i < COUNT; i++) {
expected_dscr = rand() % DSCR_MAX;
set_dscr(expected_dscr);
for (int j = rand() % 5; j > 0; --j) {
FAIL_IF_EXIT(get_dscr() != expected_dscr);
FAIL_IF_EXIT(get_dscr_usr() != expected_dscr);
if (args->do_yields && rand() % 2)
sched_yield();
}
expected_dscr = rand() % DSCR_MAX;
set_dscr_usr(expected_dscr);
for (int j = rand() % 5; j > 0; --j) {
FAIL_IF_EXIT(get_dscr() != expected_dscr);
FAIL_IF_EXIT(get_dscr_usr() != expected_dscr);
if (args->do_yields && rand() % 2)
sched_yield();
}
}
return NULL;
}
int dscr_explicit_random_test(void)
{
struct random_thread_args threads[THREADS];
pthread_barrier_t barrier;
SKIP_IF(!have_hwcap2(PPC_FEATURE2_DSCR));
FAIL_IF(pthread_barrier_init(&barrier, NULL, THREADS));
for (int i = 0; i < THREADS; i++) {
threads[i].do_yields = i % 2 == 0;
threads[i].barrier = &barrier;
FAIL_IF(pthread_create(&threads[i].thread_id, NULL,
dscr_explicit_random_thread, (void *)&threads[i]));
}
for (int i = 0; i < THREADS; i++)
FAIL_IF(pthread_join(threads[i].thread_id, NULL));
FAIL_IF(pthread_barrier_destroy(&barrier));
return 0;
}
int main(int argc, char *argv[])
{
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;
}
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