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Message-ID: <874nbd3mob.fsf@sejong.aot.lge.com>
Date: Mon, 29 Jul 2013 15:28:04 +0900
From: Namhyung Kim <namhyung@...nel.org>
To: Adrian Hunter <adrian.hunter@...el.com>
Cc: Arnaldo Carvalho de Melo <acme@...stprotocols.net>,
linux-kernel@...r.kernel.org, David Ahern <dsahern@...il.com>,
Frederic Weisbecker <fweisbec@...il.com>,
Jiri Olsa <jolsa@...hat.com>, Mike Galbraith <efault@....de>,
Paul Mackerras <paulus@...ba.org>,
Peter Zijlstra <peterz@...radead.org>,
Stephane Eranian <eranian@...gle.com>,
Ingo Molnar <mingo@...nel.org>
Subject: Re: [PATCH 1/9] perf tools: add test for reading object code
Hi Adrian,
Just a few nitpicks below..
On Thu, 25 Jul 2013 17:01:22 +0300, Adrian Hunter wrote:
> Using the information in mmap events, perf tools can read object
> code associated with sampled addresses. A test is added that
> compares bytes read by perf with the same bytes read using
> objdump.
>
[SNIP]
> +
> +static int read_objdump_line(char *line, size_t line_len, void **buf,
> + size_t *len)
> +{
> + size_t i;
> +
> + /* Skip to a colon */
> + for (i = 0; i < line_len; i++) {
> + if (line[i] == ':')
> + break;
> + }
> + if (line[i++] != ':')
> + return 0;
strchr() ?
> +
> + /* Read bytes */
> + while (*len) {
> + char c1, c2;
> +
> + /* Skip spaces */
> + for (; i < line_len; i++) {
> + if (!isspace(line[i]))
> + break;
> + }
> + /* Get 2 hex digits */
> + if (i >= line_len || !isxdigit(line[i]))
> + break;
> + c1 = line[i++];
> + if (i >= line_len || !isxdigit(line[i]))
> + break;
> + c2 = line[i++];
> + /* Followed by a space */
> + if (i < line_len && line[i] && !isspace(line[i]))
> + break;
> + /* Store byte */
> + *(unsigned char *)*buf = (hex(c1) << 4) | hex(c2);
> + *buf += 1;
> + *len -= 1;
> + }
> +
> + return 0;
It seems this function always returns 0..
> +}
> +
> +static int read_objdump_output(FILE *f, void **buf, size_t *len)
> +{
> + char *line = NULL;
> + size_t line_len;
> + ssize_t ret;
> + int err = 0;
> +
> + while (1) {
> + ret = getline(&line, &line_len, f);
> + if (feof(f))
> + break;
> + if (ret < 0 || read_objdump_line(line, ret, buf, len)) {
so no need to check the return value.
> + pr_debug("getline failed\n");
> + err = -1;
> + break;
> + }
> + }
> +
> + free(line);
> +
> + return err;
> +}
> +
[SNIP]
> +
> +static int do_test_code_reading(void)
> +{
> + struct machines machines;
> + struct machine *machine;
> + struct thread *thread;
> + struct perf_record_opts opts = {
> + .mmap_pages = UINT_MAX,
> + .user_freq = UINT_MAX,
> + .user_interval = ULLONG_MAX,
> + .freq = 40000,
Is it intended to use the freq of 40000 instead of 4000 (default)?
> + .target = {
> + .uses_mmap = true,
> + },
> + };
> + struct thread_map *threads = NULL;
> + struct cpu_map *cpus = NULL;
> + struct perf_evlist *evlist = NULL;
> + struct perf_evsel *evsel = NULL;
> + int err = -1, ret;
> + pid_t pid;
> + struct map *map;
> + bool have_vmlinux, excl_kernel = false;
> +
> + pid = getpid();
> +
> + machines__init(&machines);
> + machine = &machines.host;
> +
> + ret = machine__create_kernel_maps(machine);
> + if (ret < 0) {
> + pr_debug("machine__create_kernel_maps failed\n");
> + goto out_err;
> + }
> +
> + /* Load kernel map */
> + map = machine->vmlinux_maps[MAP__FUNCTION];
> + ret = map__load(map, NULL);
> + if (ret < 0) {
> + pr_debug("map__load failed\n");
> + goto out_err;
> + }
> + have_vmlinux = map->dso->symtab_type == DSO_BINARY_TYPE__VMLINUX;
> + /* No point getting kernel events if there is no vmlinux */
> + if (!have_vmlinux)
> + excl_kernel = true;
> +
> + threads = thread_map__new_by_tid(pid);
> + if (!threads) {
> + pr_debug("thread_map__new_by_tid failed\n");
> + goto out_err;
> + }
> +
> + ret = perf_event__synthesize_thread_map(NULL, threads,
> + perf_event__process, machine);
> + if (ret < 0) {
> + pr_debug("perf_event__synthesize_thread_map failed\n");
> + goto out_err;
> + }
> +
> + thread = machine__findnew_thread(machine, pid, pid);
> + if (!thread) {
> + pr_debug("machine__findnew_thread failed\n");
> + goto out_err;
> + }
> +
> + cpus = cpu_map__new(NULL);
> + if (!cpus) {
> + pr_debug("cpu_map__new failed\n");
> + goto out_err;
> + }
> +
> + while (1) {
> + const char *str;
> +
> + evlist = perf_evlist__new();
> + if (!evlist) {
> + pr_debug("perf_evlist__new failed\n");
> + goto out_err;
> + }
> +
> + perf_evlist__set_maps(evlist, cpus, threads);
> +
> + if (excl_kernel)
> + str = "cycles:u";
A double whitespace.
> + else
> + str = "cycles";
> + pr_debug("Parsing event '%s'\n", str);
> + ret = parse_events(evlist, str);
> + if (ret < 0) {
> + pr_debug("parse_events failed\n");
> + goto out_err;
> + }
> +
> + perf_evlist__config(evlist, &opts);
> +
> + evsel = perf_evlist__first(evlist);
> +
> + evsel->attr.comm = 1;
> + evsel->attr.disabled = 1;
> + evsel->attr.enable_on_exec = 0;
> +
> + ret = perf_evlist__open(evlist);
> + if (ret < 0) {
> + if (!excl_kernel) {
> + excl_kernel = true;
> + continue;
It seems the evlist is leaked. perf_evlist__delete(evlist) is needed.
Thanks,
Namhyung
> + }
> + pr_debug("perf_evlist__open failed\n");
> + goto out_err;
> + }
> + break;
> + }
> +
> + ret = perf_evlist__mmap(evlist, UINT_MAX, false);
> + if (ret < 0) {
> + pr_debug("perf_evlist__mmap failed\n");
> + goto out_err;
> + }
> +
> + perf_evlist__enable(evlist);
> +
> + do_something();
> +
> + perf_evlist__disable(evlist);
> +
> + ret = process_events(machine, evlist);
> + if (ret < 0)
> + goto out_err;
> +
> + if (!have_vmlinux)
> + err = TEST_CODE_READING_NO_VMLINUX;
> + else if (excl_kernel)
> + err = TEST_CODE_READING_NO_ACCESS;
> + else
> + err = TEST_CODE_READING_OK;
> +out_err:
> + if (evlist) {
> + perf_evlist__disable(evlist);
> + perf_evlist__munmap(evlist);
> + perf_evlist__close(evlist);
> + perf_evlist__delete(evlist);
> + }
> + if (cpus)
> + cpu_map__delete(cpus);
> + if (threads)
> + thread_map__delete(threads);
> + machines__destroy_kernel_maps(&machines);
> + machine__delete_threads(machine);
> + machines__exit(&machines);
> +
> + return err;
> +}
> +
> +int test__code_reading(void)
> +{
> + int ret;
> +
> + ret = do_test_code_reading();
> +
> + switch (ret) {
> + case TEST_CODE_READING_OK:
> + return 0;
> + case TEST_CODE_READING_NO_VMLINUX:
> + fprintf(stderr, " (no vmlinux)");
> + return 0;
> + case TEST_CODE_READING_NO_ACCESS:
> + fprintf(stderr, " (no access)");
> + return 0;
> + default:
> + return -1;
> + };
> +}
> diff --git a/tools/perf/tests/tests.h b/tools/perf/tests/tests.h
> index 90e3056..fda12266 100644
> --- a/tools/perf/tests/tests.h
> +++ b/tools/perf/tests/tests.h
> @@ -36,5 +36,6 @@ int test__bp_signal_overflow(void);
> int test__task_exit(void);
> int test__sw_clock_freq(void);
> int test__sample_parsing(void);
> +int test__code_reading(void);
>
> #endif /* TESTS_H */
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