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/* $Id: avx_sig.c,v 1.12 2021/12/11 22:47:09 kostik Exp $ */
/*
* Naive test to check that context switches and signal delivery do
* not corrupt AVX registers file (%xmm). Run until some
* inconsistency detected, then aborts.
*
* FreeBSD:
* ${CC} -Wall -Wextra -O -g -o avx_sig avx_sig.c -lpthread
* Linux
* ${CC} -D_GNU_SOURCE -Wall -Wextra -O -g -o avx_sig avx_sig.c -lbsd -lpthread
*/
#include <sys/param.h>
#include <sys/time.h>
#include <sys/resource.h>
#include <sys/syscall.h>
#include <errno.h>
#include <pthread.h>
#ifdef __FreeBSD__
#include <pthread_np.h>
#endif
#ifdef __linux__
#ifdef __GLIBC__
#include <gnu/libc-version.h>
#endif
#if !defined(__GLIBC__) || (__GLIBC__ * 100 + __GLIBC_MINOR__) < 236
#include <bsd/stdlib.h>
#endif
#endif
#include <signal.h>
#include <stdatomic.h>
#include <stdbool.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
/* SIGALRM interval in seconds. */
#ifndef TIMO
#define TIMO 5
#endif
#ifndef __unused
#define __unused __attribute__((__unused__))
#endif
#ifndef nitems
#define nitems(x) (sizeof((x)) / sizeof((x)[0]))
#endif
#if defined(__amd64__)
#define XREGSRNAM "xmm"
#define NREGS 16
#elif defined(__aarch64__)
#define XREGSRNAM "q"
#define NREGS 32
#endif
struct xregsreg {
uint8_t xregs_bytes[16];
};
struct xregs {
struct xregsreg xregsreg[NREGS];
};
void cpu_to_xregs(struct xregs *xregs);
void xregs_to_cpu(struct xregs *xregs);
static atomic_uint sigs;
static void
sigusr1_handler(int sig __unused, siginfo_t *si __unused, void *m __unused)
{
atomic_fetch_add_explicit(&sigs, 1, memory_order_relaxed);
}
static void
sigalrm_handler(int sig __unused)
{
struct rusage r;
if (getrusage(RUSAGE_SELF, &r) == 0) {
printf("%lu vctx %lu nvctx %lu nsigs %u SIGUSR1\n",
r.ru_nvcsw, r.ru_nivcsw, r.ru_nsignals, sigs);
}
alarm(TIMO);
}
static struct xregs zero_xregs = {};
static void
fill_xregs(struct xregs *xregs)
{
arc4random_buf(xregs, sizeof(*xregs));
}
static void
dump_xregs(const struct xregsreg *r)
{
unsigned k;
for (k = 0; k < nitems(r->xregs_bytes); k++) {
if (k != 0)
printf(" ");
printf("%02x", r->xregs_bytes[k]);
}
printf("\n");
}
static pthread_mutex_t show_lock;
static void
show_diff(const struct xregs *xregs1, const struct xregs *xregs2)
{
const struct xregsreg *r1, *r2;
unsigned i, j;
#if defined(__FreeBSD__)
printf("thr %d\n", pthread_getthreadid_np());
#elif defined(__linux__)
printf("thr %ld\n", syscall(SYS_gettid));
#endif
for (i = 0; i < nitems(xregs1->xregsreg); i++) {
r1 = &xregs1->xregsreg[i];
r2 = &xregs2->xregsreg[i];
for (j = 0; j < nitems(r1->xregs_bytes); j++) {
if (r1->xregs_bytes[j] != r2->xregs_bytes[j]) {
printf("%%%s%u\n", XREGSRNAM, i);
dump_xregs(r1);
dump_xregs(r2);
break;
}
}
}
}
static void
my_pause(void)
{
usleep(0);
}
static void *
worker_thread(void *arg __unused)
{
struct xregs xregs, xregs_cpu;
fill_xregs(&xregs);
for (;;) {
xregs_to_cpu(&xregs);
my_pause();
cpu_to_xregs(&xregs_cpu);
if (memcmp(&xregs, &xregs_cpu, sizeof(struct xregs)) != 0) {
pthread_mutex_lock(&show_lock);
show_diff(&xregs, &xregs_cpu);
abort();
pthread_mutex_unlock(&show_lock);
}
xregs_to_cpu(&zero_xregs);
my_pause();
cpu_to_xregs(&xregs_cpu);
if (memcmp(&zero_xregs, &xregs_cpu, sizeof(struct xregs)) != 0) {
pthread_mutex_lock(&show_lock);
show_diff(&zero_xregs, &xregs_cpu);
abort();
pthread_mutex_unlock(&show_lock);
}
}
return (NULL);
}
int
main(void)
{
struct sigaction sa;
int error, i, ncpu;
bzero(&sa, sizeof(sa));
sa.sa_handler = sigalrm_handler;
if (sigaction(SIGALRM, &sa, NULL) == -1) {
fprintf(stderr, "sigaction SIGALRM %s\n", strerror(errno));
exit(1);
}
bzero(&sa, sizeof(sa));
sa.sa_sigaction = sigusr1_handler;
sa.sa_flags = SA_SIGINFO;
if (sigaction(SIGUSR1, &sa, NULL) == -1) {
fprintf(stderr, "sigaction SIGUSR1 %s\n", strerror(errno));
exit(1);
}
error = pthread_mutex_init(&show_lock, NULL);
if (error != 0) {
fprintf(stderr, "pthread_mutex_init %s\n", strerror(error));
exit(1);
}
ncpu = sysconf(_SC_NPROCESSORS_ONLN);
ncpu *= 2;
pthread_t wt[ncpu];
for (i = 0; i < ncpu; i++) {
error = pthread_create(&wt[i], NULL, worker_thread, NULL);
if (error != 0) {
fprintf(stderr, "pthread_create %s\n", strerror(error));
}
}
alarm(TIMO);
for (;;) {
for (i = 0; i < ncpu; i++) {
my_pause();
pthread_kill(wt[i], SIGUSR1);
}
}
}
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