![Numfor Mbiziwo-Tiapo](/assets/img/avatar_default.png)
Running the 'perf test' command after building perf with a memory sanitizer causes a warning that says: WARNING: MemorySanitizer: use-of-uninitialized-value... in mmap-thread-lookup.c Initializing the go variable to 0 silences this harmless warning. Committer warning: This was harmless, just a simple test writing whatever was at that sizeof(int) memory area just to signal another thread blocked reading that file created with pipe(). Initialize it tho so that we don't get this warning. Signed-off-by: Numfor Mbiziwo-Tiapo <nums@google.com> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Ian Rogers <irogers@google.com> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Mark Drayton <mbd@fb.com> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Song Liu <songliubraving@fb.com> Cc: Stephane Eranian <eranian@google.com> Link: http://lkml.kernel.org/r/20190702173716.181223-1-nums@google.com Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
237 lines
4.6 KiB
C
237 lines
4.6 KiB
C
// SPDX-License-Identifier: GPL-2.0
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#include <inttypes.h>
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#include <unistd.h>
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#include <sys/syscall.h>
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#include <sys/types.h>
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#include <sys/mman.h>
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#include <pthread.h>
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#include <stdlib.h>
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#include <stdio.h>
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#include "debug.h"
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#include "tests.h"
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#include "machine.h"
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#include "thread_map.h"
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#include "map.h"
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#include "symbol.h"
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#include "thread.h"
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#include "util.h"
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#define THREADS 4
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static int go_away;
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struct thread_data {
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pthread_t pt;
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pid_t tid;
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void *map;
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int ready[2];
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};
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static struct thread_data threads[THREADS];
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static int thread_init(struct thread_data *td)
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{
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void *map;
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map = mmap(NULL, page_size,
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PROT_READ|PROT_WRITE|PROT_EXEC,
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MAP_SHARED|MAP_ANONYMOUS, -1, 0);
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if (map == MAP_FAILED) {
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perror("mmap failed");
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return -1;
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}
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td->map = map;
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td->tid = syscall(SYS_gettid);
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pr_debug("tid = %d, map = %p\n", td->tid, map);
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return 0;
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}
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static void *thread_fn(void *arg)
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{
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struct thread_data *td = arg;
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ssize_t ret;
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int go = 0;
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if (thread_init(td))
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return NULL;
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/* Signal thread_create thread is initialized. */
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ret = write(td->ready[1], &go, sizeof(int));
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if (ret != sizeof(int)) {
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pr_err("failed to notify\n");
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return NULL;
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}
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while (!go_away) {
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/* Waiting for main thread to kill us. */
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usleep(100);
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}
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munmap(td->map, page_size);
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return NULL;
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}
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static int thread_create(int i)
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{
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struct thread_data *td = &threads[i];
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int err, go;
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if (pipe(td->ready))
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return -1;
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err = pthread_create(&td->pt, NULL, thread_fn, td);
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if (!err) {
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/* Wait for thread initialization. */
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ssize_t ret = read(td->ready[0], &go, sizeof(int));
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err = ret != sizeof(int);
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}
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close(td->ready[0]);
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close(td->ready[1]);
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return err;
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}
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static int threads_create(void)
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{
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struct thread_data *td0 = &threads[0];
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int i, err = 0;
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go_away = 0;
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/* 0 is main thread */
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if (thread_init(td0))
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return -1;
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for (i = 1; !err && i < THREADS; i++)
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err = thread_create(i);
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return err;
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}
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static int threads_destroy(void)
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{
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struct thread_data *td0 = &threads[0];
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int i, err = 0;
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/* cleanup the main thread */
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munmap(td0->map, page_size);
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go_away = 1;
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for (i = 1; !err && i < THREADS; i++)
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err = pthread_join(threads[i].pt, NULL);
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return err;
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}
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typedef int (*synth_cb)(struct machine *machine);
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static int synth_all(struct machine *machine)
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{
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return perf_event__synthesize_threads(NULL,
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perf_event__process,
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machine, 0, 1);
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}
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static int synth_process(struct machine *machine)
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{
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struct thread_map *map;
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int err;
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map = thread_map__new_by_pid(getpid());
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err = perf_event__synthesize_thread_map(NULL, map,
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perf_event__process,
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machine, 0);
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thread_map__put(map);
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return err;
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}
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static int mmap_events(synth_cb synth)
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{
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struct machine *machine;
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int err, i;
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/*
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* The threads_create will not return before all threads
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* are spawned and all created memory map.
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*
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* They will loop until threads_destroy is called, so we
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* can safely run synthesizing function.
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*/
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TEST_ASSERT_VAL("failed to create threads", !threads_create());
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machine = machine__new_host();
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dump_trace = verbose > 1 ? 1 : 0;
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err = synth(machine);
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dump_trace = 0;
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TEST_ASSERT_VAL("failed to destroy threads", !threads_destroy());
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TEST_ASSERT_VAL("failed to synthesize maps", !err);
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/*
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* All data is synthesized, try to find map for each
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* thread object.
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*/
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for (i = 0; i < THREADS; i++) {
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struct thread_data *td = &threads[i];
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struct addr_location al;
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struct thread *thread;
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thread = machine__findnew_thread(machine, getpid(), td->tid);
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pr_debug("looking for map %p\n", td->map);
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thread__find_map(thread, PERF_RECORD_MISC_USER,
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(unsigned long) (td->map + 1), &al);
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thread__put(thread);
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if (!al.map) {
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pr_debug("failed, couldn't find map\n");
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err = -1;
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break;
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}
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pr_debug("map %p, addr %" PRIx64 "\n", al.map, al.map->start);
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}
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machine__delete_threads(machine);
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machine__delete(machine);
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return err;
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}
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/*
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* This test creates 'THREADS' number of threads (including
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* main thread) and each thread creates memory map.
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*
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* When threads are created, we synthesize them with both
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* (separate tests):
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* perf_event__synthesize_thread_map (process based)
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* perf_event__synthesize_threads (global)
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*
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* We test we can find all memory maps via:
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* thread__find_map
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*
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* by using all thread objects.
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*/
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int test__mmap_thread_lookup(struct test *test __maybe_unused, int subtest __maybe_unused)
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{
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/* perf_event__synthesize_threads synthesize */
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TEST_ASSERT_VAL("failed with sythesizing all",
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!mmap_events(synth_all));
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/* perf_event__synthesize_thread_map synthesize */
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TEST_ASSERT_VAL("failed with sythesizing process",
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!mmap_events(synth_process));
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return 0;
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}
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