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Date: Tue, 16 Nov 2021 09:51:21 -0300
From: Arnaldo Carvalho de Melo <acme@...nel.org>
To: Marco Elver <elver@...gle.com>
Cc: Peter Zijlstra <peterz@...radead.org>,
Ingo Molnar <mingo@...hat.com>,
Mark Rutland <mark.rutland@....com>,
Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
Jiri Olsa <jolsa@...hat.com>,
Namhyung Kim <namhyung@...nel.org>,
Adrian Hunter <adrian.hunter@...el.com>,
Fabian Hemmer <copy@...y.sh>, Ian Rogers <irogers@...gle.com>,
linux-kernel@...r.kernel.org, linux-perf-users@...r.kernel.org,
kasan-dev@...glegroups.com
Subject: Re: [PATCH] perf test: Add basic stress test for sigtrap handling
Em Mon, Nov 15, 2021 at 12:28:23PM +0100, Marco Elver escreveu:
> Add basic stress test for sigtrap handling as a perf tool built-in test.
> This allows sanity checking the basic sigtrap functionality from within
> the perf tool.
Works as root:
[root@...e ~]# perf test sigtrap
73: Sigtrap : Ok
[root@...e ~]
Not for !root:
⬢[acme@...lbox perf]$ perf test sigtrap
73: Sigtrap : FAILED!
⬢[acme@...lbox perf]$ perf test -v sigtrap
Couldn't bump rlimit(MEMLOCK), failures may take place when creating BPF maps, etc
73: Sigtrap :
--- start ---
test child forked, pid 3812428
FAILED sys_perf_event_open()
test child finished with -1
---- end ----
Sigtrap: FAILED!
⬢[acme@...lbox perf]$
I'll add the following patch on top of it, with it I get:
⬢[acme@...lbox perf]$ perf test sigtrap
73: Sigtrap : FAILED!
⬢[acme@...lbox perf]$ perf test -v sigtrap
Couldn't bump rlimit(MEMLOCK), failures may take place when creating BPF maps, etc
73: Sigtrap :
--- start ---
test child forked, pid 3816772
FAILED sys_perf_event_open(): Permission denied
test child finished with -1
---- end ----
Sigtrap: FAILED!
⬢[acme@...lbox perf]$
diff --git a/tools/perf/tests/sigtrap.c b/tools/perf/tests/sigtrap.c
index febfa1609356c4c5..6344704619cd8a49 100644
--- a/tools/perf/tests/sigtrap.c
+++ b/tools/perf/tests/sigtrap.c
@@ -5,9 +5,11 @@
* Copyright (C) 2021, Google LLC.
*/
+#include <errno.h>
#include <stdint.h>
#include <stdlib.h>
#include <linux/hw_breakpoint.h>
+#include <linux/string.h>
#include <pthread.h>
#include <signal.h>
#include <sys/ioctl.h>
@@ -115,6 +117,7 @@ static int test__sigtrap(struct test_suite *test __maybe_unused, int subtest __m
struct sigaction oldact;
pthread_t threads[NUM_THREADS];
pthread_barrier_t barrier;
+ char sbuf[STRERR_BUFSIZE];
int i, fd, ret = TEST_FAIL;
pthread_barrier_init(&barrier, NULL, NUM_THREADS + 1);
@@ -123,19 +126,19 @@ static int test__sigtrap(struct test_suite *test __maybe_unused, int subtest __m
action.sa_sigaction = sigtrap_handler;
sigemptyset(&action.sa_mask);
if (sigaction(SIGTRAP, &action, &oldact)) {
- pr_debug("FAILED sigaction()\n");
+ pr_debug("FAILED sigaction(): %s\n", str_error_r(errno, sbuf, sizeof(sbuf)));
goto out;
}
fd = sys_perf_event_open(&attr, 0, -1, -1, perf_event_open_cloexec_flag());
if (fd < 0) {
- pr_debug("FAILED sys_perf_event_open()\n");
+ pr_debug("FAILED sys_perf_event_open(): %s\n", str_error_r(errno, sbuf, sizeof(sbuf)));
goto out_restore_sigaction;
}
for (i = 0; i < NUM_THREADS; i++) {
if (pthread_create(&threads[i], NULL, test_thread, &barrier)) {
- pr_debug("FAILED pthread_create()");
+ pr_debug("FAILED pthread_create(): %s\n", str_error_r(errno, sbuf, sizeof(sbuf)));
goto out_close_perf_event;
}
}
> Signed-off-by: Marco Elver <elver@...gle.com>
> ---
> tools/perf/tests/Build | 1 +
> tools/perf/tests/builtin-test.c | 1 +
> tools/perf/tests/sigtrap.c | 154 ++++++++++++++++++++++++++++++++
> tools/perf/tests/tests.h | 1 +
> 4 files changed, 157 insertions(+)
> create mode 100644 tools/perf/tests/sigtrap.c
>
> diff --git a/tools/perf/tests/Build b/tools/perf/tests/Build
> index 803ca426f8e6..af2b37ef7c70 100644
> --- a/tools/perf/tests/Build
> +++ b/tools/perf/tests/Build
> @@ -65,6 +65,7 @@ perf-y += pe-file-parsing.o
> perf-y += expand-cgroup.o
> perf-y += perf-time-to-tsc.o
> perf-y += dlfilter-test.o
> +perf-y += sigtrap.o
>
> $(OUTPUT)tests/llvm-src-base.c: tests/bpf-script-example.c tests/Build
> $(call rule_mkdir)
> diff --git a/tools/perf/tests/builtin-test.c b/tools/perf/tests/builtin-test.c
> index 8cb5a1c3489e..f1e6d2a3a578 100644
> --- a/tools/perf/tests/builtin-test.c
> +++ b/tools/perf/tests/builtin-test.c
> @@ -107,6 +107,7 @@ static struct test_suite *generic_tests[] = {
> &suite__expand_cgroup_events,
> &suite__perf_time_to_tsc,
> &suite__dlfilter,
> + &suite__sigtrap,
> NULL,
> };
>
> diff --git a/tools/perf/tests/sigtrap.c b/tools/perf/tests/sigtrap.c
> new file mode 100644
> index 000000000000..febfa1609356
> --- /dev/null
> +++ b/tools/perf/tests/sigtrap.c
> @@ -0,0 +1,154 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Basic test for sigtrap support.
> + *
> + * Copyright (C) 2021, Google LLC.
> + */
> +
> +#include <stdint.h>
> +#include <stdlib.h>
> +#include <linux/hw_breakpoint.h>
> +#include <pthread.h>
> +#include <signal.h>
> +#include <sys/ioctl.h>
> +#include <sys/syscall.h>
> +#include <unistd.h>
> +
> +#include "cloexec.h"
> +#include "debug.h"
> +#include "event.h"
> +#include "tests.h"
> +#include "../perf-sys.h"
> +
> +#define NUM_THREADS 5
> +
> +static struct {
> + int tids_want_signal; /* Which threads still want a signal. */
> + int signal_count; /* Sanity check number of signals received. */
> + volatile int iterate_on; /* Variable to set breakpoint on. */
> + siginfo_t first_siginfo; /* First observed siginfo_t. */
> +} ctx;
> +
> +#define TEST_SIG_DATA (~(unsigned long)(&ctx.iterate_on))
> +
> +static struct perf_event_attr make_event_attr(void)
> +{
> + struct perf_event_attr attr = {
> + .type = PERF_TYPE_BREAKPOINT,
> + .size = sizeof(attr),
> + .sample_period = 1,
> + .disabled = 1,
> + .bp_addr = (unsigned long)&ctx.iterate_on,
> + .bp_type = HW_BREAKPOINT_RW,
> + .bp_len = HW_BREAKPOINT_LEN_1,
> + .inherit = 1, /* Children inherit events ... */
> + .inherit_thread = 1, /* ... but only cloned with CLONE_THREAD. */
> + .remove_on_exec = 1, /* Required by sigtrap. */
> + .sigtrap = 1, /* Request synchronous SIGTRAP on event. */
> + .sig_data = TEST_SIG_DATA,
> + };
> + return attr;
> +}
> +
> +static void
> +sigtrap_handler(int signum __maybe_unused, siginfo_t *info, void *ucontext __maybe_unused)
> +{
> + if (!__atomic_fetch_add(&ctx.signal_count, 1, __ATOMIC_RELAXED))
> + ctx.first_siginfo = *info;
> + __atomic_fetch_sub(&ctx.tids_want_signal, syscall(SYS_gettid), __ATOMIC_RELAXED);
> +}
> +
> +static void *test_thread(void *arg)
> +{
> + pthread_barrier_t *barrier = (pthread_barrier_t *)arg;
> + pid_t tid = syscall(SYS_gettid);
> + int i;
> +
> + pthread_barrier_wait(barrier);
> +
> + __atomic_fetch_add(&ctx.tids_want_signal, tid, __ATOMIC_RELAXED);
> + for (i = 0; i < ctx.iterate_on - 1; i++)
> + __atomic_fetch_add(&ctx.tids_want_signal, tid, __ATOMIC_RELAXED);
> +
> + return NULL;
> +}
> +
> +static int run_test_threads(pthread_t *threads, pthread_barrier_t *barrier)
> +{
> + int i;
> +
> + pthread_barrier_wait(barrier);
> + for (i = 0; i < NUM_THREADS; i++)
> + TEST_ASSERT_EQUAL("pthread_join() failed", pthread_join(threads[i], NULL), 0);
> +
> + return TEST_OK;
> +}
> +
> +static int run_stress_test(int fd, pthread_t *threads, pthread_barrier_t *barrier)
> +{
> + int ret;
> +
> + ctx.iterate_on = 3000;
> +
> + TEST_ASSERT_EQUAL("misfired signal?", ctx.signal_count, 0);
> + TEST_ASSERT_EQUAL("enable failed", ioctl(fd, PERF_EVENT_IOC_ENABLE, 0), 0);
> + ret = run_test_threads(threads, barrier);
> + TEST_ASSERT_EQUAL("disable failed", ioctl(fd, PERF_EVENT_IOC_DISABLE, 0), 0);
> +
> + TEST_ASSERT_EQUAL("unexpected sigtraps", ctx.signal_count, NUM_THREADS * ctx.iterate_on);
> + TEST_ASSERT_EQUAL("missing signals or incorrectly delivered", ctx.tids_want_signal, 0);
> + TEST_ASSERT_VAL("unexpected si_addr", ctx.first_siginfo.si_addr == &ctx.iterate_on);
> +#if 0 /* FIXME: enable when libc's signal.h has si_perf_{type,data} */
> + TEST_ASSERT_EQUAL("unexpected si_perf_type", ctx.first_siginfo.si_perf_type,
> + PERF_TYPE_BREAKPOINT);
> + TEST_ASSERT_EQUAL("unexpected si_perf_data", ctx.first_siginfo.si_perf_data,
> + TEST_SIG_DATA);
> +#endif
> +
> + return ret;
> +}
> +
> +static int test__sigtrap(struct test_suite *test __maybe_unused, int subtest __maybe_unused)
> +{
> + struct perf_event_attr attr = make_event_attr();
> + struct sigaction action = {};
> + struct sigaction oldact;
> + pthread_t threads[NUM_THREADS];
> + pthread_barrier_t barrier;
> + int i, fd, ret = TEST_FAIL;
> +
> + pthread_barrier_init(&barrier, NULL, NUM_THREADS + 1);
> +
> + action.sa_flags = SA_SIGINFO | SA_NODEFER;
> + action.sa_sigaction = sigtrap_handler;
> + sigemptyset(&action.sa_mask);
> + if (sigaction(SIGTRAP, &action, &oldact)) {
> + pr_debug("FAILED sigaction()\n");
> + goto out;
> + }
> +
> + fd = sys_perf_event_open(&attr, 0, -1, -1, perf_event_open_cloexec_flag());
> + if (fd < 0) {
> + pr_debug("FAILED sys_perf_event_open()\n");
> + goto out_restore_sigaction;
> + }
> +
> + for (i = 0; i < NUM_THREADS; i++) {
> + if (pthread_create(&threads[i], NULL, test_thread, &barrier)) {
> + pr_debug("FAILED pthread_create()");
> + goto out_close_perf_event;
> + }
> + }
> +
> + ret = run_stress_test(fd, threads, &barrier);
> +
> +out_close_perf_event:
> + close(fd);
> +out_restore_sigaction:
> + sigaction(SIGTRAP, &oldact, NULL);
> +out:
> + pthread_barrier_destroy(&barrier);
> + return ret;
> +}
> +
> +DEFINE_SUITE("Sigtrap", sigtrap);
> diff --git a/tools/perf/tests/tests.h b/tools/perf/tests/tests.h
> index 8f65098110fc..5bbb8f6a48fc 100644
> --- a/tools/perf/tests/tests.h
> +++ b/tools/perf/tests/tests.h
> @@ -146,6 +146,7 @@ DECLARE_SUITE(pe_file_parsing);
> DECLARE_SUITE(expand_cgroup_events);
> DECLARE_SUITE(perf_time_to_tsc);
> DECLARE_SUITE(dlfilter);
> +DECLARE_SUITE(sigtrap);
>
> /*
> * PowerPC and S390 do not support creation of instruction breakpoints using the
> --
> 2.34.0.rc1.387.gb447b232ab-goog
--
- Arnaldo
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