Restartable sequences: self-tests
[deliverable/linux.git] / tools / testing / selftests / rseq / param_test.c
diff --git a/tools/testing/selftests/rseq/param_test.c b/tools/testing/selftests/rseq/param_test.c
new file mode 100644 (file)
index 0000000..d145d85
--- /dev/null
@@ -0,0 +1,1116 @@
+#define _GNU_SOURCE
+#include <assert.h>
+#include <pthread.h>
+#include <sched.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <syscall.h>
+#include <unistd.h>
+#include <poll.h>
+#include <sys/types.h>
+#include <signal.h>
+#include <errno.h>
+
+static inline pid_t gettid(void)
+{
+       return syscall(__NR_gettid);
+}
+
+#define NR_INJECT      9
+static int loop_cnt[NR_INJECT + 1];
+
+static int opt_modulo;
+
+static int opt_yield, opt_signal, opt_sleep, opt_fallback_cnt = 3,
+               opt_disable_rseq, opt_threads = 200,
+               opt_reps = 5000, opt_disable_mod = 0, opt_test = 's';
+
+static __thread unsigned int signals_delivered;
+
+static struct rseq_lock rseq_lock;
+
+#ifndef BENCHMARK
+
+static __thread unsigned int yield_mod_cnt, nr_retry;
+
+#define printf_nobench(fmt, ...)       printf(fmt, ## __VA_ARGS__)
+
+#define RSEQ_INJECT_INPUT \
+       , [loop_cnt_1]"m"(loop_cnt[1]) \
+       , [loop_cnt_2]"m"(loop_cnt[2]) \
+       , [loop_cnt_3]"m"(loop_cnt[3]) \
+       , [loop_cnt_4]"m"(loop_cnt[4]) \
+       , [loop_cnt_5]"m"(loop_cnt[5])
+
+#if defined(__x86_64__) || defined(__i386__)
+
+#define INJECT_ASM_REG "eax"
+
+#define RSEQ_INJECT_CLOBBER \
+       , INJECT_ASM_REG
+
+#define RSEQ_INJECT_ASM(n) \
+       "mov %[loop_cnt_" #n "], %%" INJECT_ASM_REG "\n\t" \
+       "test %%" INJECT_ASM_REG ",%%" INJECT_ASM_REG "\n\t" \
+       "jz 333f\n\t" \
+       "222:\n\t" \
+       "dec %%" INJECT_ASM_REG "\n\t" \
+       "jnz 222b\n\t" \
+       "333:\n\t"
+
+#elif defined(__ARMEL__)
+
+#define INJECT_ASM_REG "r4"
+
+#define RSEQ_INJECT_CLOBBER \
+       , INJECT_ASM_REG
+
+#define RSEQ_INJECT_ASM(n) \
+       "ldr " INJECT_ASM_REG ", %[loop_cnt_" #n "]\n\t" \
+       "cmp " INJECT_ASM_REG ", #0\n\t" \
+       "beq 333f\n\t" \
+       "222:\n\t" \
+       "subs " INJECT_ASM_REG ", #1\n\t" \
+       "bne 222b\n\t" \
+       "333:\n\t"
+
+#elif __PPC__
+#define INJECT_ASM_REG "r18"
+
+#define RSEQ_INJECT_CLOBBER \
+       , INJECT_ASM_REG
+
+#define RSEQ_INJECT_ASM(n) \
+       "lwz %%" INJECT_ASM_REG ", %[loop_cnt_" #n "]\n\t" \
+       "cmpwi %%" INJECT_ASM_REG ", 0\n\t" \
+       "beq 333f\n\t" \
+       "222:\n\t" \
+       "subic. %%" INJECT_ASM_REG ", %%" INJECT_ASM_REG ", 1\n\t" \
+       "bne 222b\n\t" \
+       "333:\n\t"
+#else
+#error unsupported target
+#endif
+
+#define RSEQ_INJECT_FAILED \
+       nr_retry++;
+
+#define RSEQ_INJECT_C(n) \
+{ \
+       int loc_i, loc_nr_loops = loop_cnt[n]; \
+       \
+       for (loc_i = 0; loc_i < loc_nr_loops; loc_i++) { \
+               barrier(); \
+       } \
+       if (loc_nr_loops == -1 && opt_modulo) { \
+               if (yield_mod_cnt == opt_modulo - 1) { \
+                       if (opt_sleep > 0) \
+                               poll(NULL, 0, opt_sleep); \
+                       if (opt_yield) \
+                               sched_yield(); \
+                       if (opt_signal) \
+                               raise(SIGUSR1); \
+                       yield_mod_cnt = 0; \
+               } else { \
+                       yield_mod_cnt++; \
+               } \
+       } \
+}
+
+#define RSEQ_FALLBACK_CNT      \
+       opt_fallback_cnt
+
+#else
+
+#define printf_nobench(fmt, ...)
+
+#endif /* BENCHMARK */
+
+#include <rseq.h>
+
+struct percpu_lock_entry {
+       intptr_t v;
+} __attribute__((aligned(128)));
+
+struct percpu_lock {
+       struct percpu_lock_entry c[CPU_SETSIZE];
+};
+
+struct test_data_entry {
+       intptr_t count;
+} __attribute__((aligned(128)));
+
+struct spinlock_test_data {
+       struct percpu_lock lock;
+       struct test_data_entry c[CPU_SETSIZE];
+};
+
+struct spinlock_thread_test_data {
+       struct spinlock_test_data *data;
+       int reps;
+       int reg;
+};
+
+struct inc_test_data {
+       struct test_data_entry c[CPU_SETSIZE];
+};
+
+struct inc_thread_test_data {
+       struct inc_test_data *data;
+       int reps;
+       int reg;
+};
+
+struct percpu_list_node {
+       intptr_t data;
+       struct percpu_list_node *next;
+};
+
+struct percpu_list_entry {
+       struct percpu_list_node *head;
+} __attribute__((aligned(128)));
+
+struct percpu_list {
+       struct percpu_list_entry c[CPU_SETSIZE];
+};
+
+#define BUFFER_ITEM_PER_CPU    100
+
+struct percpu_buffer_node {
+       intptr_t data;
+};
+
+struct percpu_buffer_entry {
+       intptr_t offset;
+       intptr_t buflen;
+       struct percpu_buffer_node **array;
+} __attribute__((aligned(128)));
+
+struct percpu_buffer {
+       struct percpu_buffer_entry c[CPU_SETSIZE];
+};
+
+#define MEMCPY_BUFFER_ITEM_PER_CPU     100
+
+struct percpu_memcpy_buffer_node {
+       intptr_t data1;
+       uint64_t data2;
+};
+
+struct percpu_memcpy_buffer_entry {
+       intptr_t offset;
+       intptr_t buflen;
+       struct percpu_memcpy_buffer_node *array;
+} __attribute__((aligned(128)));
+
+struct percpu_memcpy_buffer {
+       struct percpu_memcpy_buffer_entry c[CPU_SETSIZE];
+};
+
+/* A simple percpu spinlock.  Returns the cpu lock was acquired on. */
+static int rseq_percpu_lock(struct percpu_lock *lock)
+{
+       struct rseq_state rseq_state;
+       intptr_t *targetptr, newval;
+       int cpu;
+       bool result;
+
+       for (;;) {
+               do_rseq(&rseq_lock, rseq_state, cpu, result, targetptr, newval,
+                       {
+                               if (unlikely(lock->c[cpu].v)) {
+                                       result = false;
+                               } else {
+                                       newval = 1;
+                                       targetptr = (intptr_t *)&lock->c[cpu].v;
+                               }
+                       });
+               if (likely(result))
+                       break;
+       }
+       /*
+        * Acquire semantic when taking lock after control dependency.
+        * Matches smp_store_release().
+        */
+       smp_acquire__after_ctrl_dep();
+       return cpu;
+}
+
+static void rseq_percpu_unlock(struct percpu_lock *lock, int cpu)
+{
+       assert(lock->c[cpu].v == 1);
+       /*
+        * Release lock, with release semantic. Matches
+        * smp_acquire__after_ctrl_dep().
+        */
+       smp_store_release(&lock->c[cpu].v, 0);
+}
+
+void *test_percpu_spinlock_thread(void *arg)
+{
+       struct spinlock_thread_test_data *thread_data = arg;
+       struct spinlock_test_data *data = thread_data->data;
+       int i, cpu;
+
+       if (!opt_disable_rseq && thread_data->reg
+                       && rseq_register_current_thread())
+               abort();
+       for (i = 0; i < thread_data->reps; i++) {
+               cpu = rseq_percpu_lock(&data->lock);
+               data->c[cpu].count++;
+               rseq_percpu_unlock(&data->lock, cpu);
+#ifndef BENCHMARK
+               if (i != 0 && !(i % (thread_data->reps / 10)))
+                       printf("tid %d: count %d\n", (int) gettid(), i);
+#endif
+       }
+       printf_nobench("tid %d: number of retry: %d, signals delivered: %u, nr_fallback %u, nr_fallback_wait %u\n",
+               (int) gettid(), nr_retry, signals_delivered,
+               rseq_get_fallback_cnt(),
+               rseq_get_fallback_wait_cnt());
+       if (rseq_unregister_current_thread())
+               abort();
+       return NULL;
+}
+
+/*
+ * A simple test which implements a sharded counter using a per-cpu
+ * lock.  Obviously real applications might prefer to simply use a
+ * per-cpu increment; however, this is reasonable for a test and the
+ * lock can be extended to synchronize more complicated operations.
+ */
+void test_percpu_spinlock(void)
+{
+       const int num_threads = opt_threads;
+       int i, ret;
+       uint64_t sum;
+       pthread_t test_threads[num_threads];
+       struct spinlock_test_data data;
+       struct spinlock_thread_test_data thread_data[num_threads];
+
+       memset(&data, 0, sizeof(data));
+       for (i = 0; i < num_threads; i++) {
+               thread_data[i].reps = opt_reps;
+               if (opt_disable_mod <= 0 || (i % opt_disable_mod))
+                       thread_data[i].reg = 1;
+               else
+                       thread_data[i].reg = 0;
+               thread_data[i].data = &data;
+               ret = pthread_create(&test_threads[i], NULL,
+                       test_percpu_spinlock_thread, &thread_data[i]);
+               if (ret) {
+                       errno = ret;
+                       perror("pthread_create");
+                       abort();
+               }
+       }
+
+       for (i = 0; i < num_threads; i++) {
+               pthread_join(test_threads[i], NULL);
+               if (ret) {
+                       errno = ret;
+                       perror("pthread_join");
+                       abort();
+               }
+       }
+
+       sum = 0;
+       for (i = 0; i < CPU_SETSIZE; i++)
+               sum += data.c[i].count;
+
+       assert(sum == (uint64_t)opt_reps * num_threads);
+}
+
+void *test_percpu_inc_thread(void *arg)
+{
+       struct inc_thread_test_data *thread_data = arg;
+       struct inc_test_data *data = thread_data->data;
+       int i;
+
+       if (!opt_disable_rseq && thread_data->reg
+                       && rseq_register_current_thread())
+               abort();
+       for (i = 0; i < thread_data->reps; i++) {
+               struct rseq_state rseq_state;
+               intptr_t *targetptr, newval;
+               int cpu;
+               bool result;
+
+               do_rseq(&rseq_lock, rseq_state, cpu, result, targetptr, newval,
+                       {
+                               newval = (intptr_t)data->c[cpu].count + 1;
+                               targetptr = (intptr_t *)&data->c[cpu].count;
+                       });
+
+#ifndef BENCHMARK
+               if (i != 0 && !(i % (thread_data->reps / 10)))
+                       printf("tid %d: count %d\n", (int) gettid(), i);
+#endif
+       }
+       printf_nobench("tid %d: number of retry: %d, signals delivered: %u, nr_fallback %u, nr_fallback_wait %u\n",
+               (int) gettid(), nr_retry, signals_delivered,
+               rseq_get_fallback_cnt(),
+               rseq_get_fallback_wait_cnt());
+       if (rseq_unregister_current_thread())
+               abort();
+       return NULL;
+}
+
+void test_percpu_inc(void)
+{
+       const int num_threads = opt_threads;
+       int i, ret;
+       uint64_t sum;
+       pthread_t test_threads[num_threads];
+       struct inc_test_data data;
+       struct inc_thread_test_data thread_data[num_threads];
+
+       memset(&data, 0, sizeof(data));
+       for (i = 0; i < num_threads; i++) {
+               thread_data[i].reps = opt_reps;
+               if (opt_disable_mod <= 0 || (i % opt_disable_mod))
+                       thread_data[i].reg = 1;
+               else
+                       thread_data[i].reg = 0;
+               thread_data[i].data = &data;
+               ret = pthread_create(&test_threads[i], NULL,
+                       test_percpu_inc_thread, &thread_data[i]);
+               if (ret) {
+                       errno = ret;
+                       perror("pthread_create");
+                       abort();
+               }
+       }
+
+       for (i = 0; i < num_threads; i++) {
+               pthread_join(test_threads[i], NULL);
+               if (ret) {
+                       errno = ret;
+                       perror("pthread_join");
+                       abort();
+               }
+       }
+
+       sum = 0;
+       for (i = 0; i < CPU_SETSIZE; i++)
+               sum += data.c[i].count;
+
+       assert(sum == (uint64_t)opt_reps * num_threads);
+}
+
+int percpu_list_push(struct percpu_list *list, struct percpu_list_node *node)
+{
+       struct rseq_state rseq_state;
+       intptr_t *targetptr, newval;
+       int cpu;
+       bool result;
+
+       do_rseq(&rseq_lock, rseq_state, cpu, result, targetptr, newval,
+               {
+                       newval = (intptr_t)node;
+                       targetptr = (intptr_t *)&list->c[cpu].head;
+                       node->next = list->c[cpu].head;
+               });
+
+       return cpu;
+}
+
+/*
+ * Unlike a traditional lock-less linked list; the availability of a
+ * rseq primitive allows us to implement pop without concerns over
+ * ABA-type races.
+ */
+struct percpu_list_node *percpu_list_pop(struct percpu_list *list)
+{
+       struct percpu_list_node *head, *next;
+       struct rseq_state rseq_state;
+       intptr_t *targetptr, newval;
+       int cpu;
+       bool result;
+
+       do_rseq(&rseq_lock, rseq_state, cpu, result, targetptr, newval,
+               {
+                       head = list->c[cpu].head;
+                       if (!head) {
+                               result = false;
+                       } else {
+                               next = head->next;
+                               newval = (intptr_t) next;
+                               targetptr = (intptr_t *) &list->c[cpu].head;
+                       }
+               });
+
+       return head;
+}
+
+void *test_percpu_list_thread(void *arg)
+{
+       int i;
+       struct percpu_list *list = (struct percpu_list *)arg;
+
+       if (rseq_register_current_thread())
+               abort();
+
+       for (i = 0; i < opt_reps; i++) {
+               struct percpu_list_node *node = percpu_list_pop(list);
+
+               if (opt_yield)
+                       sched_yield();  /* encourage shuffling */
+               if (node)
+                       percpu_list_push(list, node);
+       }
+
+       if (rseq_unregister_current_thread())
+               abort();
+
+       return NULL;
+}
+
+/* Simultaneous modification to a per-cpu linked list from many threads.  */
+void test_percpu_list(void)
+{
+       const int num_threads = opt_threads;
+       int i, j, ret;
+       uint64_t sum = 0, expected_sum = 0;
+       struct percpu_list list;
+       pthread_t test_threads[num_threads];
+       cpu_set_t allowed_cpus;
+
+       memset(&list, 0, sizeof(list));
+
+       /* Generate list entries for every usable cpu. */
+       sched_getaffinity(0, sizeof(allowed_cpus), &allowed_cpus);
+       for (i = 0; i < CPU_SETSIZE; i++) {
+               if (!CPU_ISSET(i, &allowed_cpus))
+                       continue;
+               for (j = 1; j <= 100; j++) {
+                       struct percpu_list_node *node;
+
+                       expected_sum += j;
+
+                       node = malloc(sizeof(*node));
+                       assert(node);
+                       node->data = j;
+                       node->next = list.c[i].head;
+                       list.c[i].head = node;
+               }
+       }
+
+       for (i = 0; i < num_threads; i++) {
+               ret = pthread_create(&test_threads[i], NULL,
+                       test_percpu_list_thread, &list);
+               if (ret) {
+                       errno = ret;
+                       perror("pthread_create");
+                       abort();
+               }
+       }
+
+       for (i = 0; i < num_threads; i++) {
+               pthread_join(test_threads[i], NULL);
+               if (ret) {
+                       errno = ret;
+                       perror("pthread_join");
+                       abort();
+               }
+       }
+
+       for (i = 0; i < CPU_SETSIZE; i++) {
+               cpu_set_t pin_mask;
+               struct percpu_list_node *node;
+
+               if (!CPU_ISSET(i, &allowed_cpus))
+                       continue;
+
+               CPU_ZERO(&pin_mask);
+               CPU_SET(i, &pin_mask);
+               sched_setaffinity(0, sizeof(pin_mask), &pin_mask);
+
+               while ((node = percpu_list_pop(&list))) {
+                       sum += node->data;
+                       free(node);
+               }
+       }
+
+       /*
+        * All entries should now be accounted for (unless some external
+        * actor is interfering with our allowed affinity while this
+        * test is running).
+        */
+       assert(sum == expected_sum);
+}
+
+bool percpu_buffer_push(struct percpu_buffer *buffer,
+               struct percpu_buffer_node *node)
+{
+       struct rseq_state rseq_state;
+       intptr_t *targetptr_spec, newval_spec;
+       intptr_t *targetptr_final, newval_final;
+       int cpu;
+       bool result;
+
+       do_rseq2(&rseq_lock, rseq_state, cpu, result,
+               targetptr_spec, newval_spec, targetptr_final, newval_final,
+               {
+                       intptr_t offset = buffer->c[cpu].offset;
+
+                       if (offset == buffer->c[cpu].buflen) {
+                               result = false;
+                       } else {
+                               newval_spec = (intptr_t)node;
+                               targetptr_spec = (intptr_t *)&buffer->c[cpu].array[offset];
+                               newval_final = offset + 1;
+                               targetptr_final = &buffer->c[cpu].offset;
+                       }
+               });
+
+       return result;
+}
+
+struct percpu_buffer_node *percpu_buffer_pop(struct percpu_buffer *buffer)
+{
+       struct percpu_buffer_node *head;
+       struct rseq_state rseq_state;
+       intptr_t *targetptr, newval;
+       int cpu;
+       bool result;
+
+       do_rseq(&rseq_lock, rseq_state, cpu, result, targetptr, newval,
+               {
+                       intptr_t offset = buffer->c[cpu].offset;
+
+                       if (offset == 0) {
+                               result = false;
+                       } else {
+                               head = buffer->c[cpu].array[offset - 1];
+                               newval = offset - 1;
+                               targetptr = (intptr_t *)&buffer->c[cpu].offset;
+                       }
+               });
+
+       if (result)
+               return head;
+       else
+               return NULL;
+}
+
+void *test_percpu_buffer_thread(void *arg)
+{
+       int i;
+       struct percpu_buffer *buffer = (struct percpu_buffer *)arg;
+
+       if (rseq_register_current_thread())
+               abort();
+
+       for (i = 0; i < opt_reps; i++) {
+               struct percpu_buffer_node *node = percpu_buffer_pop(buffer);
+
+               if (opt_yield)
+                       sched_yield();  /* encourage shuffling */
+               if (node) {
+                       if (!percpu_buffer_push(buffer, node)) {
+                               /* Should increase buffer size. */
+                               abort();
+                       }
+               }
+       }
+
+       if (rseq_unregister_current_thread())
+               abort();
+
+       return NULL;
+}
+
+/* Simultaneous modification to a per-cpu buffer from many threads.  */
+void test_percpu_buffer(void)
+{
+       const int num_threads = opt_threads;
+       int i, j, ret;
+       uint64_t sum = 0, expected_sum = 0;
+       struct percpu_buffer buffer;
+       pthread_t test_threads[num_threads];
+       cpu_set_t allowed_cpus;
+
+       memset(&buffer, 0, sizeof(buffer));
+
+       /* Generate list entries for every usable cpu. */
+       sched_getaffinity(0, sizeof(allowed_cpus), &allowed_cpus);
+       for (i = 0; i < CPU_SETSIZE; i++) {
+               if (!CPU_ISSET(i, &allowed_cpus))
+                       continue;
+               /* Worse-case is every item in same CPU. */
+               buffer.c[i].array =
+                       malloc(sizeof(*buffer.c[i].array) * CPU_SETSIZE
+                               * BUFFER_ITEM_PER_CPU);
+               assert(buffer.c[i].array);
+               buffer.c[i].buflen = CPU_SETSIZE * BUFFER_ITEM_PER_CPU;
+               for (j = 1; j <= BUFFER_ITEM_PER_CPU; j++) {
+                       struct percpu_buffer_node *node;
+
+                       expected_sum += j;
+
+                       /*
+                        * We could theoretically put the word-sized
+                        * "data" directly in the buffer. However, we
+                        * want to model objects that would not fit
+                        * within a single word, so allocate an object
+                        * for each node.
+                        */
+                       node = malloc(sizeof(*node));
+                       assert(node);
+                       node->data = j;
+                       buffer.c[i].array[j - 1] = node;
+                       buffer.c[i].offset++;
+               }
+       }
+
+       for (i = 0; i < num_threads; i++) {
+               ret = pthread_create(&test_threads[i], NULL,
+                       test_percpu_buffer_thread, &buffer);
+               if (ret) {
+                       errno = ret;
+                       perror("pthread_create");
+                       abort();
+               }
+       }
+
+       for (i = 0; i < num_threads; i++) {
+               pthread_join(test_threads[i], NULL);
+               if (ret) {
+                       errno = ret;
+                       perror("pthread_join");
+                       abort();
+               }
+       }
+
+       for (i = 0; i < CPU_SETSIZE; i++) {
+               cpu_set_t pin_mask;
+               struct percpu_buffer_node *node;
+
+               if (!CPU_ISSET(i, &allowed_cpus))
+                       continue;
+
+               CPU_ZERO(&pin_mask);
+               CPU_SET(i, &pin_mask);
+               sched_setaffinity(0, sizeof(pin_mask), &pin_mask);
+
+               while ((node = percpu_buffer_pop(&buffer))) {
+                       sum += node->data;
+                       free(node);
+               }
+               free(buffer.c[i].array);
+       }
+
+       /*
+        * All entries should now be accounted for (unless some external
+        * actor is interfering with our allowed affinity while this
+        * test is running).
+        */
+       assert(sum == expected_sum);
+}
+
+bool percpu_memcpy_buffer_push(struct percpu_memcpy_buffer *buffer,
+               struct percpu_memcpy_buffer_node item)
+{
+       struct rseq_state rseq_state;
+       char *destptr, *srcptr;
+       size_t copylen;
+       intptr_t *targetptr_final, newval_final;
+       int cpu;
+       bool result;
+
+       do_rseq_memcpy(&rseq_lock, rseq_state, cpu, result,
+               destptr, srcptr, copylen, targetptr_final, newval_final,
+               {
+                       intptr_t offset = buffer->c[cpu].offset;
+
+                       if (offset == buffer->c[cpu].buflen) {
+                               result = false;
+                       } else {
+                               destptr = (char *)&buffer->c[cpu].array[offset];
+                               srcptr = (char *)&item;
+                               copylen = sizeof(item);
+                               newval_final = offset + 1;
+                               targetptr_final = &buffer->c[cpu].offset;
+                       }
+               });
+
+       return result;
+}
+
+bool percpu_memcpy_buffer_pop(struct percpu_memcpy_buffer *buffer,
+               struct percpu_memcpy_buffer_node *item)
+{
+       struct rseq_state rseq_state;
+       char *destptr, *srcptr;
+       size_t copylen;
+       intptr_t *targetptr_final, newval_final;
+       int cpu;
+       bool result;
+
+       do_rseq_memcpy(&rseq_lock, rseq_state, cpu, result,
+               destptr, srcptr, copylen, targetptr_final, newval_final,
+               {
+                       intptr_t offset = buffer->c[cpu].offset;
+
+                       if (offset == 0) {
+                               result = false;
+                       } else {
+                               destptr = (char *)item;
+                               srcptr = (char *)&buffer->c[cpu].array[offset - 1];
+                               copylen = sizeof(*item);
+                               newval_final = offset - 1;
+                               targetptr_final = &buffer->c[cpu].offset;
+                       }
+               });
+
+       return result;
+}
+
+void *test_percpu_memcpy_buffer_thread(void *arg)
+{
+       int i;
+       struct percpu_memcpy_buffer *buffer = (struct percpu_memcpy_buffer *)arg;
+
+       if (rseq_register_current_thread())
+               abort();
+
+       for (i = 0; i < opt_reps; i++) {
+               struct percpu_memcpy_buffer_node item;
+               bool result;
+
+               result = percpu_memcpy_buffer_pop(buffer, &item);
+               if (opt_yield)
+                       sched_yield();  /* encourage shuffling */
+               if (result) {
+                       if (!percpu_memcpy_buffer_push(buffer, item)) {
+                               /* Should increase buffer size. */
+                               abort();
+                       }
+               }
+       }
+
+       if (rseq_unregister_current_thread())
+               abort();
+
+       return NULL;
+}
+
+/* Simultaneous modification to a per-cpu buffer from many threads.  */
+void test_percpu_memcpy_buffer(void)
+{
+       const int num_threads = opt_threads;
+       int i, j, ret;
+       uint64_t sum = 0, expected_sum = 0;
+       struct percpu_memcpy_buffer buffer;
+       pthread_t test_threads[num_threads];
+       cpu_set_t allowed_cpus;
+
+       memset(&buffer, 0, sizeof(buffer));
+
+       /* Generate list entries for every usable cpu. */
+       sched_getaffinity(0, sizeof(allowed_cpus), &allowed_cpus);
+       for (i = 0; i < CPU_SETSIZE; i++) {
+               if (!CPU_ISSET(i, &allowed_cpus))
+                       continue;
+               /* Worse-case is every item in same CPU. */
+               buffer.c[i].array =
+                       malloc(sizeof(*buffer.c[i].array) * CPU_SETSIZE
+                               * MEMCPY_BUFFER_ITEM_PER_CPU);
+               assert(buffer.c[i].array);
+               buffer.c[i].buflen = CPU_SETSIZE * MEMCPY_BUFFER_ITEM_PER_CPU;
+               for (j = 1; j <= MEMCPY_BUFFER_ITEM_PER_CPU; j++) {
+                       expected_sum += 2 * j + 1;
+
+                       /*
+                        * We could theoretically put the word-sized
+                        * "data" directly in the buffer. However, we
+                        * want to model objects that would not fit
+                        * within a single word, so allocate an object
+                        * for each node.
+                        */
+                       buffer.c[i].array[j - 1].data1 = j;
+                       buffer.c[i].array[j - 1].data2 = j + 1;
+                       buffer.c[i].offset++;
+               }
+       }
+
+       for (i = 0; i < num_threads; i++) {
+               ret = pthread_create(&test_threads[i], NULL,
+                       test_percpu_memcpy_buffer_thread, &buffer);
+               if (ret) {
+                       errno = ret;
+                       perror("pthread_create");
+                       abort();
+               }
+       }
+
+       for (i = 0; i < num_threads; i++) {
+               pthread_join(test_threads[i], NULL);
+               if (ret) {
+                       errno = ret;
+                       perror("pthread_join");
+                       abort();
+               }
+       }
+
+       for (i = 0; i < CPU_SETSIZE; i++) {
+               cpu_set_t pin_mask;
+               struct percpu_memcpy_buffer_node item;
+
+               if (!CPU_ISSET(i, &allowed_cpus))
+                       continue;
+
+               CPU_ZERO(&pin_mask);
+               CPU_SET(i, &pin_mask);
+               sched_setaffinity(0, sizeof(pin_mask), &pin_mask);
+
+               while (percpu_memcpy_buffer_pop(&buffer, &item)) {
+                       sum += item.data1;
+                       sum += item.data2;
+               }
+               free(buffer.c[i].array);
+       }
+
+       /*
+        * All entries should now be accounted for (unless some external
+        * actor is interfering with our allowed affinity while this
+        * test is running).
+        */
+       assert(sum == expected_sum);
+}
+
+static void test_signal_interrupt_handler(int signo)
+{
+       signals_delivered++;
+}
+
+static int set_signal_handler(void)
+{
+       int ret = 0;
+       struct sigaction sa;
+       sigset_t sigset;
+
+       ret = sigemptyset(&sigset);
+       if (ret < 0) {
+               perror("sigemptyset");
+               return ret;
+       }
+
+       sa.sa_handler = test_signal_interrupt_handler;
+       sa.sa_mask = sigset;
+       sa.sa_flags = 0;
+       ret = sigaction(SIGUSR1, &sa, NULL);
+       if (ret < 0) {
+               perror("sigaction");
+               return ret;
+       }
+
+       printf_nobench("Signal handler set for SIGUSR1\n");
+
+       return ret;
+}
+
+static void show_usage(int argc, char **argv)
+{
+       printf("Usage : %s <OPTIONS>\n",
+               argv[0]);
+       printf("OPTIONS:\n");
+       printf("        [-1 loops] Number of loops for delay injection 1\n");
+       printf("        [-2 loops] Number of loops for delay injection 2\n");
+       printf("        [-3 loops] Number of loops for delay injection 3\n");
+       printf("        [-4 loops] Number of loops for delay injection 4\n");
+       printf("        [-5 loops] Number of loops for delay injection 5\n");
+       printf("        [-6 loops] Number of loops for delay injection 6 (-1 to enable -m)\n");
+       printf("        [-7 loops] Number of loops for delay injection 7 (-1 to enable -m)\n");
+       printf("        [-8 loops] Number of loops for delay injection 8 (-1 to enable -m)\n");
+       printf("        [-9 loops] Number of loops for delay injection 9 (-1 to enable -m)\n");
+       printf("        [-m N] Yield/sleep/kill every modulo N (default 0: disabled) (>= 0)\n");
+       printf("        [-y] Yield\n");
+       printf("        [-k] Kill thread with signal\n");
+       printf("        [-s S] S: =0: disabled (default), >0: sleep time (ms)\n");
+       printf("        [-f N] Use fallback every N failure (>= 1)\n");
+       printf("        [-t N] Number of threads (default 200)\n");
+       printf("        [-r N] Number of repetitions per thread (default 5000)\n");
+       printf("        [-d] Disable rseq system call (no initialization)\n");
+       printf("        [-D M] Disable rseq for each M threads\n");
+       printf("        [-T test] Choose test: (s)pinlock, (l)ist, (b)uffer, (m)emcpy, (i)ncrement\n");
+       printf("        [-h] Show this help.\n");
+       printf("\n");
+}
+
+int main(int argc, char **argv)
+{
+       int i;
+
+       if (rseq_init_lock(&rseq_lock)) {
+               perror("rseq_init_lock");
+               return -1;
+       }
+       if (set_signal_handler())
+               goto error;
+       for (i = 1; i < argc; i++) {
+               if (argv[i][0] != '-')
+                       continue;
+               switch (argv[i][1]) {
+               case '1':
+               case '2':
+               case '3':
+               case '4':
+               case '5':
+               case '6':
+               case '7':
+               case '8':
+               case '9':
+                       if (argc < i + 2) {
+                               show_usage(argc, argv);
+                               goto error;
+                       }
+                       loop_cnt[argv[i][1] - '0'] = atol(argv[i + 1]);
+                       i++;
+                       break;
+               case 'm':
+                       if (argc < i + 2) {
+                               show_usage(argc, argv);
+                               goto error;
+                       }
+                       opt_modulo = atol(argv[i + 1]);
+                       if (opt_modulo < 0) {
+                               show_usage(argc, argv);
+                               goto error;
+                       }
+                       i++;
+                       break;
+               case 's':
+                       if (argc < i + 2) {
+                               show_usage(argc, argv);
+                               goto error;
+                       }
+                       opt_sleep = atol(argv[i + 1]);
+                       if (opt_sleep < 0) {
+                               show_usage(argc, argv);
+                               goto error;
+                       }
+                       i++;
+                       break;
+               case 'y':
+                       opt_yield = 1;
+                       break;
+               case 'k':
+                       opt_signal = 1;
+                       break;
+               case 'd':
+                       opt_disable_rseq = 1;
+                       break;
+               case 'D':
+                       if (argc < i + 2) {
+                               show_usage(argc, argv);
+                               goto error;
+                       }
+                       opt_disable_mod = atol(argv[i + 1]);
+                       if (opt_disable_mod < 0) {
+                               show_usage(argc, argv);
+                               goto error;
+                       }
+                       i++;
+                       break;
+               case 'f':
+                       if (argc < i + 2) {
+                               show_usage(argc, argv);
+                               goto error;
+                       }
+                       opt_fallback_cnt = atol(argv[i + 1]);
+                       if (opt_fallback_cnt < 1) {
+                               show_usage(argc, argv);
+                               goto error;
+                       }
+                       i++;
+                       break;
+               case 't':
+                       if (argc < i + 2) {
+                               show_usage(argc, argv);
+                               goto error;
+                       }
+                       opt_threads = atol(argv[i + 1]);
+                       if (opt_threads < 0) {
+                               show_usage(argc, argv);
+                               goto error;
+                       }
+                       i++;
+                       break;
+               case 'r':
+                       if (argc < i + 2) {
+                               show_usage(argc, argv);
+                               goto error;
+                       }
+                       opt_reps = atol(argv[i + 1]);
+                       if (opt_reps < 0) {
+                               show_usage(argc, argv);
+                               goto error;
+                       }
+                       i++;
+                       break;
+               case 'h':
+                       show_usage(argc, argv);
+                       goto end;
+               case 'T':
+                       if (argc < i + 2) {
+                               show_usage(argc, argv);
+                               goto error;
+                       }
+                       opt_test = *argv[i + 1];
+                       switch (opt_test) {
+                       case 's':
+                       case 'l':
+                       case 'i':
+                       case 'b':
+                       case 'm':
+                               break;
+                       default:
+                               show_usage(argc, argv);
+                               goto error;
+                       }
+                       i++;
+                       break;
+               default:
+                       show_usage(argc, argv);
+                       goto error;
+               }
+       }
+
+       if (!opt_disable_rseq && rseq_register_current_thread())
+               goto error;
+       switch (opt_test) {
+       case 's':
+               printf_nobench("spinlock\n");
+               test_percpu_spinlock();
+               break;
+       case 'l':
+               printf_nobench("linked list\n");
+               test_percpu_list();
+               break;
+       case 'b':
+               printf_nobench("buffer\n");
+               test_percpu_buffer();
+               break;
+       case 'm':
+               printf_nobench("memcpy buffer\n");
+               test_percpu_memcpy_buffer();
+               break;
+       case 'i':
+               printf_nobench("counter increment\n");
+               test_percpu_inc();
+               break;
+       }
+       if (rseq_unregister_current_thread())
+               abort();
+end:
+       return 0;
+
+error:
+       if (rseq_destroy_lock(&rseq_lock))
+               perror("rseq_destroy_lock");
+       return -1;
+}
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