--- /dev/null
+// SPDX-License-Identifier: LGPL-2.1
+#define _GNU_SOURCE
+#include <assert.h>
+#include <pthread.h>
+#include <sched.h>
+#include <signal.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <string.h>
+#include <syscall.h>
+#include <unistd.h>
+
+#include <linux/prctl.h>
+#include <sys/prctl.h>
+#include <sys/time.h>
+
+#include "rseq.h"
+
+#include "../kselftest_harness.h"
+
+#ifndef __NR_rseq_slice_yield
+# define __NR_rseq_slice_yield 471
+#endif
+
+#define BITS_PER_INT 32
+#define BITS_PER_BYTE 8
+
+#ifndef PR_RSEQ_SLICE_EXTENSION
+# define PR_RSEQ_SLICE_EXTENSION 79
+# define PR_RSEQ_SLICE_EXTENSION_GET 1
+# define PR_RSEQ_SLICE_EXTENSION_SET 2
+# define PR_RSEQ_SLICE_EXT_ENABLE 0x01
+#endif
+
+#ifndef RSEQ_SLICE_EXT_REQUEST_BIT
+# define RSEQ_SLICE_EXT_REQUEST_BIT 0
+# define RSEQ_SLICE_EXT_GRANTED_BIT 1
+#endif
+
+#ifndef asm_inline
+# define asm_inline asm __inline
+#endif
+
+#define NSEC_PER_SEC 1000000000L
+#define NSEC_PER_USEC 1000L
+
+struct noise_params {
+ int64_t noise_nsecs;
+ int64_t sleep_nsecs;
+ int64_t run;
+};
+
+FIXTURE(slice_ext)
+{
+ pthread_t noise_thread;
+ struct noise_params noise_params;
+};
+
+FIXTURE_VARIANT(slice_ext)
+{
+ int64_t total_nsecs;
+ int64_t slice_nsecs;
+ int64_t noise_nsecs;
+ int64_t sleep_nsecs;
+ bool no_yield;
+};
+
+FIXTURE_VARIANT_ADD(slice_ext, n2_2_50)
+{
+ .total_nsecs = 5LL * NSEC_PER_SEC,
+ .slice_nsecs = 2LL * NSEC_PER_USEC,
+ .noise_nsecs = 2LL * NSEC_PER_USEC,
+ .sleep_nsecs = 50LL * NSEC_PER_USEC,
+};
+
+FIXTURE_VARIANT_ADD(slice_ext, n50_2_50)
+{
+ .total_nsecs = 5LL * NSEC_PER_SEC,
+ .slice_nsecs = 50LL * NSEC_PER_USEC,
+ .noise_nsecs = 2LL * NSEC_PER_USEC,
+ .sleep_nsecs = 50LL * NSEC_PER_USEC,
+};
+
+FIXTURE_VARIANT_ADD(slice_ext, n2_2_50_no_yield)
+{
+ .total_nsecs = 5LL * NSEC_PER_SEC,
+ .slice_nsecs = 2LL * NSEC_PER_USEC,
+ .noise_nsecs = 2LL * NSEC_PER_USEC,
+ .sleep_nsecs = 50LL * NSEC_PER_USEC,
+ .no_yield = true,
+};
+
+
+static inline bool elapsed(struct timespec *start, struct timespec *now,
+ int64_t span)
+{
+ int64_t delta = now->tv_sec - start->tv_sec;
+
+ delta *= NSEC_PER_SEC;
+ delta += now->tv_nsec - start->tv_nsec;
+ return delta >= span;
+}
+
+static void *noise_thread(void *arg)
+{
+ struct noise_params *p = arg;
+
+ while (RSEQ_READ_ONCE(p->run)) {
+ struct timespec ts_start, ts_now;
+
+ clock_gettime(CLOCK_MONOTONIC, &ts_start);
+ do {
+ clock_gettime(CLOCK_MONOTONIC, &ts_now);
+ } while (!elapsed(&ts_start, &ts_now, p->noise_nsecs));
+
+ ts_start.tv_sec = 0;
+ ts_start.tv_nsec = p->sleep_nsecs;
+ clock_nanosleep(CLOCK_MONOTONIC, 0, &ts_start, NULL);
+ }
+ return NULL;
+}
+
+FIXTURE_SETUP(slice_ext)
+{
+ cpu_set_t affinity;
+
+ ASSERT_EQ(sched_getaffinity(0, sizeof(affinity), &affinity), 0);
+
+ /* Pin it on a single CPU. Avoid CPU 0 */
+ for (int i = 1; i < CPU_SETSIZE; i++) {
+ if (!CPU_ISSET(i, &affinity))
+ continue;
+
+ CPU_ZERO(&affinity);
+ CPU_SET(i, &affinity);
+ ASSERT_EQ(sched_setaffinity(0, sizeof(affinity), &affinity), 0);
+ break;
+ }
+
+ ASSERT_EQ(rseq_register_current_thread(), 0);
+
+ ASSERT_EQ(prctl(PR_RSEQ_SLICE_EXTENSION, PR_RSEQ_SLICE_EXTENSION_SET,
+ PR_RSEQ_SLICE_EXT_ENABLE, 0, 0), 0);
+
+ self->noise_params.noise_nsecs = variant->noise_nsecs;
+ self->noise_params.sleep_nsecs = variant->sleep_nsecs;
+ self->noise_params.run = 1;
+
+ ASSERT_EQ(pthread_create(&self->noise_thread, NULL, noise_thread, &self->noise_params), 0);
+}
+
+FIXTURE_TEARDOWN(slice_ext)
+{
+ self->noise_params.run = 0;
+ pthread_join(self->noise_thread, NULL);
+}
+
+TEST_F(slice_ext, slice_test)
+{
+ unsigned long success = 0, yielded = 0, scheduled = 0, raced = 0;
+ unsigned long total = 0, aborted = 0;
+ struct rseq_abi *rs = rseq_get_abi();
+ struct timespec ts_start, ts_now;
+
+ ASSERT_NE(rs, NULL);
+
+ clock_gettime(CLOCK_MONOTONIC, &ts_start);
+ do {
+ struct timespec ts_cs;
+ bool req = false;
+
+ clock_gettime(CLOCK_MONOTONIC, &ts_cs);
+
+ total++;
+ RSEQ_WRITE_ONCE(rs->slice_ctrl.request, 1);
+ do {
+ clock_gettime(CLOCK_MONOTONIC, &ts_now);
+ } while (!elapsed(&ts_cs, &ts_now, variant->slice_nsecs));
+
+ /*
+ * request can be cleared unconditionally, but for making
+ * the stats work this is actually checking it first
+ */
+ if (RSEQ_READ_ONCE(rs->slice_ctrl.request)) {
+ RSEQ_WRITE_ONCE(rs->slice_ctrl.request, 0);
+ /* Race between check and clear! */
+ req = true;
+ success++;
+ }
+
+ if (RSEQ_READ_ONCE(rs->slice_ctrl.granted)) {
+ /* The above raced against a late grant */
+ if (req)
+ success--;
+ if (variant->no_yield) {
+ syscall(__NR_getpid);
+ aborted++;
+ } else {
+ yielded++;
+ if (!syscall(__NR_rseq_slice_yield))
+ raced++;
+ }
+ } else {
+ if (!req)
+ scheduled++;
+ }
+
+ clock_gettime(CLOCK_MONOTONIC, &ts_now);
+ } while (!elapsed(&ts_start, &ts_now, variant->total_nsecs));
+
+ printf("# Total %12ld\n", total);
+ printf("# Success %12ld\n", success);
+ printf("# Yielded %12ld\n", yielded);
+ printf("# Aborted %12ld\n", aborted);
+ printf("# Scheduled %12ld\n", scheduled);
+ printf("# Raced %12ld\n", raced);
+}
+
+TEST_HARNESS_MAIN
projects / thirdparty / kernel / linux.git / commitdiff
