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linux-7.2.3/tools/testing/selftests/perf_events/.gitignore

@@ -0,0 +1,5 @@
+# SPDX-License-Identifier: GPL-2.0-only
+sigtrap_threads
+remove_on_exec
+watermark_signal
+mmap

linux-7.2.3/tools/testing/selftests/perf_events/Makefile

@@ -0,0 +1,6 @@
+# SPDX-License-Identifier: GPL-2.0
+CFLAGS += -Wl,-no-as-needed -Wall $(KHDR_INCLUDES)
+LDFLAGS += -lpthread
+
+TEST_GEN_PROGS := sigtrap_threads remove_on_exec watermark_signal mmap
+include ../lib.mk

linux-7.2.3/tools/testing/selftests/perf_events/config

@@ -0,0 +1 @@
+CONFIG_PERF_EVENTS=y

linux-7.2.3/tools/testing/selftests/perf_events/mmap.c

@@ -0,0 +1,236 @@
+// SPDX-License-Identifier: GPL-2.0-only
+#define _GNU_SOURCE
+
+#include <dirent.h>
+#include <sched.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <unistd.h>
+
+#include <sys/ioctl.h>
+#include <sys/mman.h>
+#include <sys/syscall.h>
+#include <sys/types.h>
+
+#include <linux/perf_event.h>
+
+#include "kselftest_harness.h"
+
+#define RB_SIZE		0x3000
+#define AUX_SIZE	0x10000
+#define AUX_OFFS	0x4000
+
+#define HOLE_SIZE	0x1000
+
+/* Reserve space for rb, aux with space for shrink-beyond-vma testing. */
+#define REGION_SIZE	(2 * RB_SIZE + 2 * AUX_SIZE)
+#define REGION_AUX_OFFS (2 * RB_SIZE)
+
+#define MAP_BASE	1
+#define MAP_AUX		2
+
+#define EVENT_SRC_DIR	"/sys/bus/event_source/devices"
+
+FIXTURE(perf_mmap)
+{
+	int		fd;
+	void		*ptr;
+	void		*region;
+};
+
+FIXTURE_VARIANT(perf_mmap)
+{
+	bool		aux;
+	unsigned long	ptr_size;
+};
+
+FIXTURE_VARIANT_ADD(perf_mmap, rb)
+{
+	.aux = false,
+	.ptr_size = RB_SIZE,
+};
+
+FIXTURE_VARIANT_ADD(perf_mmap, aux)
+{
+	.aux = true,
+	.ptr_size = AUX_SIZE,
+};
+
+static bool read_event_type(struct dirent *dent, __u32 *type)
+{
+	char typefn[512];
+	FILE *fp;
+	int res;
+
+	snprintf(typefn, sizeof(typefn), "%s/%s/type", EVENT_SRC_DIR, dent->d_name);
+	fp = fopen(typefn, "r");
+	if (!fp)
+		return false;
+
+	res = fscanf(fp, "%u", type);
+	fclose(fp);
+	return res > 0;
+}
+
+FIXTURE_SETUP(perf_mmap)
+{
+	struct perf_event_attr attr = {
+		.size		= sizeof(attr),
+		.disabled	= 1,
+		.exclude_kernel	= 1,
+		.exclude_hv	= 1,
+	};
+	struct perf_event_attr attr_ok = {};
+	unsigned int eacces = 0, map = 0;
+	struct perf_event_mmap_page *rb;
+	struct dirent *dent;
+	void *aux, *region;
+	DIR *dir;
+
+	self->ptr = NULL;
+
+	dir = opendir(EVENT_SRC_DIR);
+	if (!dir)
+		SKIP(return, "perf not available.");
+
+	region = mmap(NULL, REGION_SIZE, PROT_NONE, MAP_ANON | MAP_PRIVATE, -1, 0);
+	ASSERT_NE(region, MAP_FAILED);
+	self->region = region;
+
+	// Try to find a suitable event on this system
+	while ((dent = readdir(dir))) {
+		int fd;
+
+		if (!read_event_type(dent, &attr.type))
+			continue;
+
+		fd = syscall(SYS_perf_event_open, &attr, 0, -1, -1, 0);
+		if (fd < 0) {
+			if (errno == EACCES)
+				eacces++;
+			continue;
+		}
+
+		// Check whether the event supports mmap()
+		rb = mmap(region, RB_SIZE, PROT_READ | PROT_WRITE, MAP_SHARED | MAP_FIXED, fd, 0);
+		if (rb == MAP_FAILED) {
+			close(fd);
+			continue;
+		}
+
+		if (!map) {
+			// Save the event in case that no AUX capable event is found
+			attr_ok = attr;
+			map = MAP_BASE;
+		}
+
+		if (!variant->aux)
+			continue;
+
+		rb->aux_offset = AUX_OFFS;
+		rb->aux_size = AUX_SIZE;
+
+		// Check whether it supports a AUX buffer
+		aux = mmap(region + REGION_AUX_OFFS, AUX_SIZE, PROT_READ | PROT_WRITE,
+			   MAP_SHARED | MAP_FIXED, fd, AUX_OFFS);
+		if (aux == MAP_FAILED) {
+			munmap(rb, RB_SIZE);
+			close(fd);
+			continue;
+		}
+
+		attr_ok = attr;
+		map = MAP_AUX;
+		munmap(aux, AUX_SIZE);
+		munmap(rb, RB_SIZE);
+		close(fd);
+		break;
+	}
+	closedir(dir);
+
+	if (!map) {
+		if (!eacces)
+			SKIP(return, "No mappable perf event found.");
+		else
+			SKIP(return, "No permissions for perf_event_open()");
+	}
+
+	self->fd = syscall(SYS_perf_event_open, &attr_ok, 0, -1, -1, 0);
+	ASSERT_NE(self->fd, -1);
+
+	rb = mmap(region, RB_SIZE, PROT_READ | PROT_WRITE, MAP_SHARED | MAP_FIXED, self->fd, 0);
+	ASSERT_NE(rb, MAP_FAILED);
+
+	if (!variant->aux) {
+		self->ptr = rb;
+		return;
+	}
+
+	if (map != MAP_AUX)
+		SKIP(return, "No AUX event found.");
+
+	rb->aux_offset = AUX_OFFS;
+	rb->aux_size = AUX_SIZE;
+	aux = mmap(region + REGION_AUX_OFFS, AUX_SIZE, PROT_READ | PROT_WRITE,
+		   MAP_SHARED | MAP_FIXED, self->fd, AUX_OFFS);
+	ASSERT_NE(aux, MAP_FAILED);
+	self->ptr = aux;
+}
+
+FIXTURE_TEARDOWN(perf_mmap)
+{
+	ASSERT_EQ(munmap(self->region, REGION_SIZE), 0);
+	if (self->fd != -1)
+		ASSERT_EQ(close(self->fd), 0);
+}
+
+TEST_F(perf_mmap, remap)
+{
+	void *tmp, *ptr = self->ptr;
+	unsigned long size = variant->ptr_size;
+
+	// Test the invalid remaps
+	ASSERT_EQ(mremap(ptr, size, HOLE_SIZE, MREMAP_MAYMOVE), MAP_FAILED);
+	ASSERT_EQ(mremap(ptr + HOLE_SIZE, size, HOLE_SIZE, MREMAP_MAYMOVE), MAP_FAILED);
+	ASSERT_EQ(mremap(ptr + size - HOLE_SIZE, HOLE_SIZE, size, MREMAP_MAYMOVE), MAP_FAILED);
+	// Shrink the end of the mapping such that we only unmap past end of the VMA,
+	// which should succeed and poke a hole into the PROT_NONE region
+	ASSERT_NE(mremap(ptr + size - HOLE_SIZE, size, HOLE_SIZE, MREMAP_MAYMOVE), MAP_FAILED);
+
+	// Remap the whole buffer to a new address
+	tmp = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_SHARED | MAP_ANONYMOUS, -1, 0);
+	ASSERT_NE(tmp, MAP_FAILED);
+
+	// Try splitting offset 1 hole size into VMA, this should fail
+	ASSERT_EQ(mremap(ptr + HOLE_SIZE, size - HOLE_SIZE, size - HOLE_SIZE,
+			 MREMAP_MAYMOVE | MREMAP_FIXED, tmp), MAP_FAILED);
+	// Remapping the whole thing should succeed fine
+	ptr = mremap(ptr, size, size, MREMAP_MAYMOVE | MREMAP_FIXED, tmp);
+	ASSERT_EQ(ptr, tmp);
+	ASSERT_EQ(munmap(tmp, size), 0);
+}
+
+TEST_F(perf_mmap, unmap)
+{
+	unsigned long size = variant->ptr_size;
+
+	// Try to poke holes into the mappings
+	ASSERT_NE(munmap(self->ptr, HOLE_SIZE), 0);
+	ASSERT_NE(munmap(self->ptr + HOLE_SIZE, HOLE_SIZE), 0);
+	ASSERT_NE(munmap(self->ptr + size - HOLE_SIZE, HOLE_SIZE), 0);
+}
+
+TEST_F(perf_mmap, map)
+{
+	unsigned long size = variant->ptr_size;
+
+	// Try to poke holes into the mappings by mapping anonymous memory over it
+	ASSERT_EQ(mmap(self->ptr, HOLE_SIZE, PROT_READ | PROT_WRITE,
+		       MAP_PRIVATE | MAP_ANON | MAP_FIXED, -1, 0), MAP_FAILED);
+	ASSERT_EQ(mmap(self->ptr + HOLE_SIZE, HOLE_SIZE, PROT_READ | PROT_WRITE,
+		       MAP_PRIVATE | MAP_ANON | MAP_FIXED, -1, 0), MAP_FAILED);
+	ASSERT_EQ(mmap(self->ptr + size - HOLE_SIZE, HOLE_SIZE, PROT_READ | PROT_WRITE,
+		       MAP_PRIVATE | MAP_ANON | MAP_FIXED, -1, 0), MAP_FAILED);
+}
+
+TEST_HARNESS_MAIN

linux-7.2.3/tools/testing/selftests/perf_events/remove_on_exec.c

@@ -0,0 +1,260 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Test for remove_on_exec.
+ *
+ * Copyright (C) 2021, Google LLC.
+ */
+
+#define _GNU_SOURCE
+
+/* We need the latest siginfo from the kernel repo. */
+#include <sys/types.h>
+#include <asm/siginfo.h>
+#define __have_siginfo_t 1
+#define __have_sigval_t 1
+#define __have_sigevent_t 1
+#define __siginfo_t_defined
+#define __sigval_t_defined
+#define __sigevent_t_defined
+#define _BITS_SIGINFO_CONSTS_H 1
+#define _BITS_SIGEVENT_CONSTS_H 1
+
+#include <stdbool.h>
+#include <stddef.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <linux/perf_event.h>
+#include <pthread.h>
+#include <signal.h>
+#include <sys/ioctl.h>
+#include <sys/syscall.h>
+#include <unistd.h>
+
+#include "kselftest_harness.h"
+
+static volatile int signal_count;
+
+static struct perf_event_attr make_event_attr(void)
+{
+	struct perf_event_attr attr = {
+		.type		= PERF_TYPE_HARDWARE,
+		.size		= sizeof(attr),
+		.config		= PERF_COUNT_HW_INSTRUCTIONS,
+		.sample_period	= 1000,
+		.exclude_kernel = 1,
+		.exclude_hv	= 1,
+		.disabled	= 1,
+		.inherit	= 1,
+		/*
+		 * Children normally retain their inherited event on exec; with
+		 * remove_on_exec, we'll remove their event, but the parent and
+		 * any other non-exec'd children will keep their events.
+		 */
+		.remove_on_exec = 1,
+		.sigtrap	= 1,
+	};
+	return attr;
+}
+
+static void sigtrap_handler(int signum, siginfo_t *info, void *ucontext)
+{
+	if (info->si_code != TRAP_PERF) {
+		fprintf(stderr, "%s: unexpected si_code %d\n", __func__, info->si_code);
+		return;
+	}
+
+	signal_count++;
+}
+
+FIXTURE(remove_on_exec)
+{
+	struct sigaction oldact;
+	int fd;
+};
+
+FIXTURE_SETUP(remove_on_exec)
+{
+	struct perf_event_attr attr = make_event_attr();
+	struct sigaction action = {};
+
+	signal_count = 0;
+
+	/* Initialize sigtrap handler. */
+	action.sa_flags = SA_SIGINFO | SA_NODEFER;
+	action.sa_sigaction = sigtrap_handler;
+	sigemptyset(&action.sa_mask);
+	ASSERT_EQ(sigaction(SIGTRAP, &action, &self->oldact), 0);
+
+	/* Initialize perf event. */
+	self->fd = syscall(__NR_perf_event_open, &attr, 0, -1, -1, PERF_FLAG_FD_CLOEXEC);
+	ASSERT_NE(self->fd, -1);
+}
+
+FIXTURE_TEARDOWN(remove_on_exec)
+{
+	close(self->fd);
+	sigaction(SIGTRAP, &self->oldact, NULL);
+}
+
+/* Verify event propagates to fork'd child. */
+TEST_F(remove_on_exec, fork_only)
+{
+	int status;
+	pid_t pid = fork();
+
+	if (pid == 0) {
+		ASSERT_EQ(signal_count, 0);
+		ASSERT_EQ(ioctl(self->fd, PERF_EVENT_IOC_ENABLE, 0), 0);
+		while (!signal_count);
+		_exit(42);
+	}
+
+	while (!signal_count); /* Child enables event. */
+	EXPECT_EQ(waitpid(pid, &status, 0), pid);
+	EXPECT_EQ(WEXITSTATUS(status), 42);
+}
+
+/*
+ * Verify that event does _not_ propagate to fork+exec'd child; event enabled
+ * after fork+exec.
+ */
+TEST_F(remove_on_exec, fork_exec_then_enable)
+{
+	pid_t pid_exec, pid_only_fork;
+	int pipefd[2];
+	int tmp;
+
+	/*
+	 * Non-exec child, to ensure exec does not affect inherited events of
+	 * other children.
+	 */
+	pid_only_fork = fork();
+	if (pid_only_fork == 0) {
+		/* Block until parent enables event. */
+		while (!signal_count);
+		_exit(42);
+	}
+
+	ASSERT_NE(pipe(pipefd), -1);
+	pid_exec = fork();
+	if (pid_exec == 0) {
+		ASSERT_NE(dup2(pipefd[1], STDOUT_FILENO), -1);
+		close(pipefd[0]);
+		execl("/proc/self/exe", "exec_child", NULL);
+		_exit((perror("exec failed"), 1));
+	}
+	close(pipefd[1]);
+
+	ASSERT_EQ(waitpid(pid_exec, &tmp, WNOHANG), 0); /* Child is running. */
+	/* Wait for exec'd child to start spinning. */
+	EXPECT_EQ(read(pipefd[0], &tmp, sizeof(int)), sizeof(int));
+	EXPECT_EQ(tmp, 42);
+	close(pipefd[0]);
+	/* Now we can enable the event, knowing the child is doing work. */
+	EXPECT_EQ(ioctl(self->fd, PERF_EVENT_IOC_ENABLE, 0), 0);
+	/* If the event propagated to the exec'd child, it will exit normally... */
+	usleep(100000); /* ... give time for event to trigger (in case of bug). */
+	EXPECT_EQ(waitpid(pid_exec, &tmp, WNOHANG), 0); /* Should still be running. */
+	EXPECT_EQ(kill(pid_exec, SIGKILL), 0);
+
+	/* Verify removal from child did not affect this task's event. */
+	tmp = signal_count;
+	while (signal_count == tmp); /* Should not hang! */
+	/* Nor should it have affected the first child. */
+	EXPECT_EQ(waitpid(pid_only_fork, &tmp, 0), pid_only_fork);
+	EXPECT_EQ(WEXITSTATUS(tmp), 42);
+}
+
+/*
+ * Verify that event does _not_ propagate to fork+exec'd child; event enabled
+ * before fork+exec.
+ */
+TEST_F(remove_on_exec, enable_then_fork_exec)
+{
+	pid_t pid_exec;
+	int tmp;
+
+	EXPECT_EQ(ioctl(self->fd, PERF_EVENT_IOC_ENABLE, 0), 0);
+
+	pid_exec = fork();
+	if (pid_exec == 0) {
+		execl("/proc/self/exe", "exec_child", NULL);
+		_exit((perror("exec failed"), 1));
+	}
+
+	/*
+	 * The child may exit abnormally at any time if the event propagated and
+	 * a SIGTRAP is sent before the handler was set up.
+	 */
+	usleep(100000); /* ... give time for event to trigger (in case of bug). */
+	EXPECT_EQ(waitpid(pid_exec, &tmp, WNOHANG), 0); /* Should still be running. */
+	EXPECT_EQ(kill(pid_exec, SIGKILL), 0);
+
+	/* Verify removal from child did not affect this task's event. */
+	tmp = signal_count;
+	while (signal_count == tmp); /* Should not hang! */
+}
+
+TEST_F(remove_on_exec, exec_stress)
+{
+	pid_t pids[30];
+	int i, tmp;
+
+	for (i = 0; i < sizeof(pids) / sizeof(pids[0]); i++) {
+		pids[i] = fork();
+		if (pids[i] == 0) {
+			execl("/proc/self/exe", "exec_child", NULL);
+			_exit((perror("exec failed"), 1));
+		}
+
+		/* Some forked with event disabled, rest with enabled. */
+		if (i > 10)
+			EXPECT_EQ(ioctl(self->fd, PERF_EVENT_IOC_ENABLE, 0), 0);
+	}
+
+	usleep(100000); /* ... give time for event to trigger (in case of bug). */
+
+	for (i = 0; i < sizeof(pids) / sizeof(pids[0]); i++) {
+		/* All children should still be running. */
+		EXPECT_EQ(waitpid(pids[i], &tmp, WNOHANG), 0);
+		EXPECT_EQ(kill(pids[i], SIGKILL), 0);
+	}
+
+	/* Verify event is still alive. */
+	tmp = signal_count;
+	while (signal_count == tmp);
+}
+
+/* For exec'd child. */
+static void exec_child(void)
+{
+	struct sigaction action = {};
+	const int val = 42;
+
+	/* Set up sigtrap handler in case we erroneously receive a trap. */
+	action.sa_flags = SA_SIGINFO | SA_NODEFER;
+	action.sa_sigaction = sigtrap_handler;
+	sigemptyset(&action.sa_mask);
+	if (sigaction(SIGTRAP, &action, NULL))
+		_exit((perror("sigaction failed"), 1));
+
+	/* Signal parent that we're starting to spin. */
+	if (write(STDOUT_FILENO, &val, sizeof(int)) == -1)
+		_exit((perror("write failed"), 1));
+
+	/* Should hang here until killed. */
+	while (!signal_count);
+}
+
+#define main test_main
+TEST_HARNESS_MAIN
+#undef main
+int main(int argc, char *argv[])
+{
+	if (!strcmp(argv[0], "exec_child")) {
+		exec_child();
+		return 1;
+	}
+
+	return test_main(argc, argv);
+}

linux-7.2.3/tools/testing/selftests/perf_events/settings

@@ -0,0 +1 @@
+timeout=120

linux-7.2.3/tools/testing/selftests/perf_events/sigtrap_threads.c

@@ -0,0 +1,240 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Test for perf events with SIGTRAP across all threads.
+ *
+ * Copyright (C) 2021, Google LLC.
+ */
+
+#define _GNU_SOURCE
+
+/* We need the latest siginfo from the kernel repo. */
+#include <sys/types.h>
+#include <asm/siginfo.h>
+#define __have_siginfo_t 1
+#define __have_sigval_t 1
+#define __have_sigevent_t 1
+#define __siginfo_t_defined
+#define __sigval_t_defined
+#define __sigevent_t_defined
+#define _BITS_SIGINFO_CONSTS_H 1
+#define _BITS_SIGEVENT_CONSTS_H 1
+
+#include <stdbool.h>
+#include <stddef.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <linux/hw_breakpoint.h>
+#include <linux/perf_event.h>
+#include <pthread.h>
+#include <signal.h>
+#include <sys/ioctl.h>
+#include <sys/syscall.h>
+#include <unistd.h>
+
+#include "kselftest_harness.h"
+
+#define NUM_THREADS 5
+
+/* Data shared between test body, threads, and signal handler. */
+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;
+
+/* Unique value to check si_perf_data is correctly set from perf_event_attr::sig_data. */
+#define TEST_SIG_DATA(addr, id) (~(unsigned long)(addr) + id)
+
+static struct perf_event_attr make_event_attr(bool enabled, volatile void *addr,
+					      unsigned long id)
+{
+	struct perf_event_attr attr = {
+		.type		= PERF_TYPE_BREAKPOINT,
+		.size		= sizeof(attr),
+		.sample_period	= 1,
+		.disabled	= !enabled,
+		.bp_addr	= (unsigned long)addr,
+		.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(addr, id),
+		.exclude_kernel = 1, /* To allow */
+		.exclude_hv     = 1, /* running as !root */
+	};
+	return attr;
+}
+
+static void sigtrap_handler(int signum, siginfo_t *info, void *ucontext)
+{
+	if (info->si_code != TRAP_PERF) {
+		fprintf(stderr, "%s: unexpected si_code %d\n", __func__, info->si_code);
+		return;
+	}
+
+	/*
+	 * The data in siginfo_t we're interested in should all be the same
+	 * across threads.
+	 */
+	if (!__atomic_fetch_add(&ctx.signal_count, 1, __ATOMIC_RELAXED))
+		ctx.first_siginfo = *info;
+	__atomic_fetch_sub(&ctx.tids_want_signal, syscall(__NR_gettid), __ATOMIC_RELAXED);
+}
+
+static void *test_thread(void *arg)
+{
+	pthread_barrier_t *barrier = (pthread_barrier_t *)arg;
+	pid_t tid = syscall(__NR_gettid);
+	int iter;
+	int i;
+
+	pthread_barrier_wait(barrier);
+
+	__atomic_fetch_add(&ctx.tids_want_signal, tid, __ATOMIC_RELAXED);
+	iter = ctx.iterate_on; /* read */
+	if (iter >= 0) {
+		for (i = 0; i < iter - 1; i++) {
+			__atomic_fetch_add(&ctx.tids_want_signal, tid, __ATOMIC_RELAXED);
+			ctx.iterate_on = iter; /* idempotent write */
+		}
+	} else {
+		while (ctx.iterate_on);
+	}
+
+	return NULL;
+}
+
+FIXTURE(sigtrap_threads)
+{
+	struct sigaction oldact;
+	pthread_t threads[NUM_THREADS];
+	pthread_barrier_t barrier;
+	int fd;
+};
+
+FIXTURE_SETUP(sigtrap_threads)
+{
+	struct perf_event_attr attr = make_event_attr(false, &ctx.iterate_on, 0);
+	struct sigaction action = {};
+	int i;
+
+	memset(&ctx, 0, sizeof(ctx));
+
+	/* Initialize sigtrap handler. */
+	action.sa_flags = SA_SIGINFO | SA_NODEFER;
+	action.sa_sigaction = sigtrap_handler;
+	sigemptyset(&action.sa_mask);
+	ASSERT_EQ(sigaction(SIGTRAP, &action, &self->oldact), 0);
+
+	/* Initialize perf event. */
+	self->fd = syscall(__NR_perf_event_open, &attr, 0, -1, -1, PERF_FLAG_FD_CLOEXEC);
+	ASSERT_NE(self->fd, -1);
+
+	/* Spawn threads inheriting perf event. */
+	pthread_barrier_init(&self->barrier, NULL, NUM_THREADS + 1);
+	for (i = 0; i < NUM_THREADS; i++)
+		ASSERT_EQ(pthread_create(&self->threads[i], NULL, test_thread, &self->barrier), 0);
+}
+
+FIXTURE_TEARDOWN(sigtrap_threads)
+{
+	pthread_barrier_destroy(&self->barrier);
+	close(self->fd);
+	sigaction(SIGTRAP, &self->oldact, NULL);
+}
+
+static void run_test_threads(struct __test_metadata *_metadata,
+			     FIXTURE_DATA(sigtrap_threads) *self)
+{
+	int i;
+
+	pthread_barrier_wait(&self->barrier);
+	for (i = 0; i < NUM_THREADS; i++)
+		ASSERT_EQ(pthread_join(self->threads[i], NULL), 0);
+}
+
+TEST_F(sigtrap_threads, remain_disabled)
+{
+	run_test_threads(_metadata, self);
+	EXPECT_EQ(ctx.signal_count, 0);
+	EXPECT_NE(ctx.tids_want_signal, 0);
+}
+
+TEST_F(sigtrap_threads, enable_event)
+{
+	EXPECT_EQ(ioctl(self->fd, PERF_EVENT_IOC_ENABLE, 0), 0);
+	run_test_threads(_metadata, self);
+
+	EXPECT_EQ(ctx.signal_count, NUM_THREADS);
+	EXPECT_EQ(ctx.tids_want_signal, 0);
+	EXPECT_EQ(ctx.first_siginfo.si_addr, &ctx.iterate_on);
+	EXPECT_EQ(ctx.first_siginfo.si_perf_type, PERF_TYPE_BREAKPOINT);
+	EXPECT_EQ(ctx.first_siginfo.si_perf_data, TEST_SIG_DATA(&ctx.iterate_on, 0));
+
+	/* Check enabled for parent. */
+	ctx.iterate_on = 0;
+	EXPECT_EQ(ctx.signal_count, NUM_THREADS + 1);
+}
+
+/* Test that modification propagates to all inherited events. */
+TEST_F(sigtrap_threads, modify_and_enable_event)
+{
+	struct perf_event_attr new_attr = make_event_attr(true, &ctx.iterate_on, 42);
+
+	EXPECT_EQ(ioctl(self->fd, PERF_EVENT_IOC_MODIFY_ATTRIBUTES, &new_attr), 0);
+	run_test_threads(_metadata, self);
+
+	EXPECT_EQ(ctx.signal_count, NUM_THREADS);
+	EXPECT_EQ(ctx.tids_want_signal, 0);
+	EXPECT_EQ(ctx.first_siginfo.si_addr, &ctx.iterate_on);
+	EXPECT_EQ(ctx.first_siginfo.si_perf_type, PERF_TYPE_BREAKPOINT);
+	EXPECT_EQ(ctx.first_siginfo.si_perf_data, TEST_SIG_DATA(&ctx.iterate_on, 42));
+
+	/* Check enabled for parent. */
+	ctx.iterate_on = 0;
+	EXPECT_EQ(ctx.signal_count, NUM_THREADS + 1);
+}
+
+/* Stress test event + signal handling. */
+TEST_F(sigtrap_threads, signal_stress)
+{
+	ctx.iterate_on = 3000;
+
+	EXPECT_EQ(ioctl(self->fd, PERF_EVENT_IOC_ENABLE, 0), 0);
+	run_test_threads(_metadata, self);
+	EXPECT_EQ(ioctl(self->fd, PERF_EVENT_IOC_DISABLE, 0), 0);
+
+	EXPECT_EQ(ctx.signal_count, NUM_THREADS * ctx.iterate_on);
+	EXPECT_EQ(ctx.tids_want_signal, 0);
+	EXPECT_EQ(ctx.first_siginfo.si_addr, &ctx.iterate_on);
+	EXPECT_EQ(ctx.first_siginfo.si_perf_type, PERF_TYPE_BREAKPOINT);
+	EXPECT_EQ(ctx.first_siginfo.si_perf_data, TEST_SIG_DATA(&ctx.iterate_on, 0));
+}
+
+TEST_F(sigtrap_threads, signal_stress_with_disable)
+{
+	const int target_count = NUM_THREADS * 3000;
+	int i;
+
+	ctx.iterate_on = -1;
+
+	EXPECT_EQ(ioctl(self->fd, PERF_EVENT_IOC_ENABLE, 0), 0);
+	pthread_barrier_wait(&self->barrier);
+	while (__atomic_load_n(&ctx.signal_count, __ATOMIC_RELAXED) < target_count) {
+		EXPECT_EQ(ioctl(self->fd, PERF_EVENT_IOC_DISABLE, 0), 0);
+		EXPECT_EQ(ioctl(self->fd, PERF_EVENT_IOC_ENABLE, 0), 0);
+	}
+	ctx.iterate_on = 0;
+	for (i = 0; i < NUM_THREADS; i++)
+		ASSERT_EQ(pthread_join(self->threads[i], NULL), 0);
+	EXPECT_EQ(ioctl(self->fd, PERF_EVENT_IOC_DISABLE, 0), 0);
+
+	EXPECT_EQ(ctx.first_siginfo.si_addr, &ctx.iterate_on);
+	EXPECT_EQ(ctx.first_siginfo.si_perf_type, PERF_TYPE_BREAKPOINT);
+	EXPECT_EQ(ctx.first_siginfo.si_perf_data, TEST_SIG_DATA(&ctx.iterate_on, 0));
+}
+
+TEST_HARNESS_MAIN

linux-7.2.3/tools/testing/selftests/perf_events/watermark_signal.c

@@ -0,0 +1,144 @@
+// SPDX-License-Identifier: GPL-2.0
+#define _GNU_SOURCE
+
+#include <errno.h>
+#include <fcntl.h>
+#include <linux/perf_event.h>
+#include <stddef.h>
+#include <sched.h>
+#include <signal.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/ioctl.h>
+#include <sys/mman.h>
+#include <sys/syscall.h>
+#include <sys/wait.h>
+#include <unistd.h>
+
+#include "kselftest_harness.h"
+
+static int sigio_count;
+
+static void handle_sigio(int signum __maybe_unused,
+			 siginfo_t *oh __maybe_unused,
+			 void *uc __maybe_unused)
+{
+	++sigio_count;
+}
+
+static void do_child(void)
+{
+	raise(SIGSTOP);
+
+	for (int i = 0; i < 20; ++i)
+		sleep(1);
+
+	raise(SIGSTOP);
+
+	exit(0);
+}
+
+TEST(watermark_signal)
+{
+	struct perf_event_attr attr;
+	struct perf_event_mmap_page *p = NULL;
+	struct sigaction previous_sigio, sigio = { 0 };
+	pid_t child = -1;
+	int child_status;
+	int fd = -1;
+	long page_size = sysconf(_SC_PAGE_SIZE);
+
+	sigio.sa_sigaction = handle_sigio;
+	EXPECT_EQ(sigaction(SIGIO, &sigio, &previous_sigio), 0);
+
+	memset(&attr, 0, sizeof(attr));
+	attr.size = sizeof(attr);
+	attr.type = PERF_TYPE_SOFTWARE;
+	attr.config = PERF_COUNT_SW_DUMMY;
+	attr.sample_period = 1;
+	attr.disabled = 1;
+	attr.watermark = 1;
+	attr.context_switch = 1;
+	attr.wakeup_watermark = 1;
+
+	child = fork();
+	EXPECT_GE(child, 0);
+	if (child == 0)
+		do_child();
+	else if (child < 0) {
+		perror("fork()");
+		goto cleanup;
+	}
+
+	if (waitpid(child, &child_status, WSTOPPED) != child ||
+	    !(WIFSTOPPED(child_status) && WSTOPSIG(child_status) == SIGSTOP)) {
+		fprintf(stderr,
+			"failed to synchronize with child errno=%d status=%x\n",
+			errno,
+			child_status);
+		goto cleanup;
+	}
+
+	fd = syscall(__NR_perf_event_open, &attr, child, -1, -1,
+		     PERF_FLAG_FD_CLOEXEC);
+	if (fd < 0) {
+		fprintf(stderr, "failed opening event %llx\n", attr.config);
+		goto cleanup;
+	}
+
+	if (fcntl(fd, F_SETFL, FASYNC)) {
+		perror("F_SETFL FASYNC");
+		goto cleanup;
+	}
+
+	if (fcntl(fd, F_SETOWN, getpid())) {
+		perror("F_SETOWN getpid()");
+		goto cleanup;
+	}
+
+	if (fcntl(fd, F_SETSIG, SIGIO)) {
+		perror("F_SETSIG SIGIO");
+		goto cleanup;
+	}
+
+	p = mmap(NULL, 2 * page_size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
+	if (p == MAP_FAILED) {
+		perror("mmap");
+		goto cleanup;
+	}
+
+	if (ioctl(fd, PERF_EVENT_IOC_ENABLE, 0)) {
+		perror("PERF_EVENT_IOC_ENABLE");
+		goto cleanup;
+	}
+
+	if (kill(child, SIGCONT) < 0) {
+		perror("SIGCONT");
+		goto cleanup;
+	}
+
+	if (waitpid(child, &child_status, WSTOPPED) != -1 || errno != EINTR)
+		fprintf(stderr,
+			"expected SIGIO to terminate wait errno=%d status=%x\n%d",
+			errno,
+			child_status,
+			sigio_count);
+
+	EXPECT_GE(sigio_count, 1);
+
+cleanup:
+	if (p != NULL)
+		munmap(p, 2 * page_size);
+
+	if (fd >= 0)
+		close(fd);
+
+	if (child > 0) {
+		kill(child, SIGKILL);
+		waitpid(child, NULL, 0);
+	}
+
+	sigaction(SIGIO, &previous_sigio, NULL);
+}
+
+TEST_HARNESS_MAIN