linux/tools/perf/tests/sigtrap.c
John Garry f268088f65 perf test: Skip failing sigtrap test for arm+aarch64
Skip the Sigtrap test for arm + arm64, same as was done for s390 in
commit a840974e96 ("perf test: Test 73 Sig_trap fails on s390"). For
this, reuse BP_SIGNAL_IS_SUPPORTED - meaning that the arch can use BP to
generate signals - instead of BP_ACCOUNT_IS_SUPPORTED, which is
appropriate.

As described by Will at [0], in the test we get stuck in a loop of
handling the HW breakpoint exception and never making progress. GDB
handles this by stepping over the faulting instruction, but with perf
the kernel is expected to handle the step (which it doesn't for arm).

Dmitry made an attempt to get this work, also mentioned in the same
thread as [0], which was appreciated. But the best thing to do is skip
the test for now.

[0] https://lore.kernel.org/linux-perf-users/20220118124343.GC98966@leoy-ThinkPad-X240s/T/#m13b06c39d2a5100d340f009435df6f4d8ee57b5a

Fixes: 5504f67944 ("perf test sigtrap: Add basic stress test for sigtrap handling")
Signed-off-by: John Garry <john.garry@huawei.com>
Tested-by: Leo Yan <leo.yan@linaro.org>
Acked-by: Marco Elver <elver@google.com>
Cc: Dmitriy Vyukov <dvyukov@google.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Marco Elver <elver@google.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Richter <tmricht@linux.ibm.com>
Cc: Will Deacon <will@kernel.org>
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux@armlinux.org.uk
Link: https://lore.kernel.org/r/1645176813-202756-1-git-send-email-john.garry@huawei.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2022-02-18 09:54:50 -03:00

165 lines
4.6 KiB
C

// SPDX-License-Identifier: GPL-2.0
/*
* Basic test for sigtrap support.
*
* 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>
#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,
.exclude_kernel = 1, /* To allow */
.exclude_hv = 1, /* running as !root */
};
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;
char sbuf[STRERR_BUFSIZE];
int i, fd, ret = TEST_FAIL;
if (!BP_SIGNAL_IS_SUPPORTED) {
pr_debug("Test not supported on this architecture");
return TEST_SKIP;
}
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(): %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(): %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(): %s\n", str_error_r(errno, sbuf, sizeof(sbuf)));
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);