// SPDX-License-Identifier: GPL-2.0/* * Ring-buffer memory mapping tests * * Copyright (c) 2024 Vincent Donnefort <vdonnefort@google.com> */#include <fcntl.h>#include <sched.h>#include <stdbool.h>#include <stdio.h>#include <stdlib.h>#include <unistd.h> #include <linux/trace_mmap.h> #include <sys/mman.h>#include <sys/ioctl.h> #include "../user_events/user_events_selftests.h" /* share tracefs setup */#include "../kselftest_harness.h" #define TRACEFS_ROOT "/sys/kernel/tracing" static int __tracefs_write(const char *path, const char *value){	int fd, ret; 	fd = open(path, O_WRONLY | O_TRUNC);	if (fd < 0)		return fd; 	ret = write(fd, value, strlen(value)); 	close(fd); 	return ret == -1 ? -errno : 0;} static int __tracefs_write_int(const char *path, int value){	char *str;	int ret; 	if (asprintf(&str, "%d", value) < 0)		return -1; 	ret = __tracefs_write(path, str); 	free(str); 	return ret;} #define tracefs_write_int(path, value) \	ASSERT_EQ(__tracefs_write_int((path), (value)), 0) #define tracefs_write(path, value) \	ASSERT_EQ(__tracefs_write((path), (value)), 0) static int tracefs_reset(void){	if (__tracefs_write_int(TRACEFS_ROOT"/tracing_on", 0))		return -1;	if (__tracefs_write(TRACEFS_ROOT"/trace", ""))		return -1;	if (__tracefs_write(TRACEFS_ROOT"/set_event", ""))		return -1;	if (__tracefs_write(TRACEFS_ROOT"/current_tracer", "nop"))		return -1; 	return 0;} struct tracefs_cpu_map_desc {	struct trace_buffer_meta	*meta;	int				cpu_fd;}; int tracefs_cpu_map(struct tracefs_cpu_map_desc *desc, int cpu){	int page_size = getpagesize();	char *cpu_path;	void *map; 	if (asprintf(&cpu_path,		     TRACEFS_ROOT"/per_cpu/cpu%d/trace_pipe_raw",		     cpu) < 0)		return -ENOMEM; 	desc->cpu_fd = open(cpu_path, O_RDONLY | O_NONBLOCK);	free(cpu_path);	if (desc->cpu_fd < 0)		return -ENODEV; again:	map = mmap(NULL, page_size, PROT_READ, MAP_SHARED, desc->cpu_fd, 0);	if (map == MAP_FAILED)		return -errno; 	desc->meta = (struct trace_buffer_meta *)map; 	/* the meta-page is bigger than the original mapping */	if (page_size < desc->meta->meta_struct_len) {		int meta_page_size = desc->meta->meta_page_size; 		munmap(desc->meta, page_size);		page_size = meta_page_size;		goto again;	} 	return 0;} void tracefs_cpu_unmap(struct tracefs_cpu_map_desc *desc){	munmap(desc->meta, desc->meta->meta_page_size);	close(desc->cpu_fd);} FIXTURE(map) {	struct tracefs_cpu_map_desc	map_desc;	bool				umount;}; FIXTURE_VARIANT(map) {	int	subbuf_size;}; FIXTURE_VARIANT_ADD(map, subbuf_size_4k) {	.subbuf_size = 4,}; FIXTURE_VARIANT_ADD(map, subbuf_size_8k) {	.subbuf_size = 8,}; FIXTURE_SETUP(map){	int cpu = sched_getcpu();	cpu_set_t cpu_mask;	bool fail, umount;	char *message; 	if (getuid() != 0)		SKIP(return, "Skipping: %s", "Please run the test as root"); 	if (!tracefs_enabled(&message, &fail, &umount)) {		if (fail) {			TH_LOG("Tracefs setup failed: %s", message);			ASSERT_FALSE(fail);		}		SKIP(return, "Skipping: %s", message);	} 	self->umount = umount; 	ASSERT_GE(cpu, 0); 	ASSERT_EQ(tracefs_reset(), 0); 	tracefs_write_int(TRACEFS_ROOT"/buffer_subbuf_size_kb", variant->subbuf_size); 	ASSERT_EQ(tracefs_cpu_map(&self->map_desc, cpu), 0); 	/*	 * Ensure generated events will be found on this very same ring-buffer.	 */	CPU_ZERO(&cpu_mask);	CPU_SET(cpu, &cpu_mask);	ASSERT_EQ(sched_setaffinity(0, sizeof(cpu_mask), &cpu_mask), 0);} FIXTURE_TEARDOWN(map){	tracefs_reset(); 	if (self->umount)		tracefs_unmount(); 	tracefs_cpu_unmap(&self->map_desc);} TEST_F(map, meta_page_check){	struct tracefs_cpu_map_desc *desc = &self->map_desc;	int cnt = 0; 	ASSERT_EQ(desc->meta->entries, 0);	ASSERT_EQ(desc->meta->overrun, 0);	ASSERT_EQ(desc->meta->read, 0); 	ASSERT_EQ(desc->meta->reader.id, 0);	ASSERT_EQ(desc->meta->reader.read, 0); 	ASSERT_EQ(ioctl(desc->cpu_fd, TRACE_MMAP_IOCTL_GET_READER), 0);	ASSERT_EQ(desc->meta->reader.id, 0); 	tracefs_write_int(TRACEFS_ROOT"/tracing_on", 1);	for (int i = 0; i < 16; i++)		tracefs_write_int(TRACEFS_ROOT"/trace_marker", i);again:	ASSERT_EQ(ioctl(desc->cpu_fd, TRACE_MMAP_IOCTL_GET_READER), 0); 	ASSERT_EQ(desc->meta->entries, 16);	ASSERT_EQ(desc->meta->overrun, 0);	ASSERT_EQ(desc->meta->read, 16); 	ASSERT_EQ(desc->meta->reader.id, 1); 	if (!(cnt++))		goto again;} TEST_F(map, data_mmap){	struct tracefs_cpu_map_desc *desc = &self->map_desc;	unsigned long meta_len, data_len;	void *data; 	meta_len = desc->meta->meta_page_size;	data_len = desc->meta->subbuf_size * desc->meta->nr_subbufs; 	/* Map all the available subbufs */	data = mmap(NULL, data_len, PROT_READ, MAP_SHARED,		    desc->cpu_fd, meta_len);	ASSERT_NE(data, MAP_FAILED);	munmap(data, data_len); 	/* Map all the available subbufs - 1 */	data_len -= desc->meta->subbuf_size;	data = mmap(NULL, data_len, PROT_READ, MAP_SHARED,		    desc->cpu_fd, meta_len);	ASSERT_NE(data, MAP_FAILED);	munmap(data, data_len); 	/* Overflow the available subbufs by 1 */	meta_len += desc->meta->subbuf_size * 2;	data = mmap(NULL, data_len, PROT_READ, MAP_SHARED,		    desc->cpu_fd, meta_len);	ASSERT_EQ(data, MAP_FAILED); 	/* Verify meta-page padding */	if (desc->meta->meta_page_size > getpagesize()) {		data_len = desc->meta->meta_page_size;		data = mmap(NULL, data_len,			    PROT_READ, MAP_SHARED, desc->cpu_fd, 0);		ASSERT_NE(data, MAP_FAILED); 		for (int i = desc->meta->meta_struct_len;		     i < desc->meta->meta_page_size; i += sizeof(int))			ASSERT_EQ(*(int *)(data + i), 0); 		munmap(data, data_len);	}} FIXTURE(snapshot) {	bool	umount;}; FIXTURE_SETUP(snapshot){	bool fail, umount;	struct stat sb;	char *message; 	if (getuid() != 0)		SKIP(return, "Skipping: %s", "Please run the test as root"); 	if (stat(TRACEFS_ROOT"/snapshot", &sb))		SKIP(return, "Skipping: %s", "snapshot not available"); 	if (!tracefs_enabled(&message, &fail, &umount)) {		if (fail) {			TH_LOG("Tracefs setup failed: %s", message);			ASSERT_FALSE(fail);		}		SKIP(return, "Skipping: %s", message);	} 	self->umount = umount;} FIXTURE_TEARDOWN(snapshot){	__tracefs_write(TRACEFS_ROOT"/events/sched/sched_switch/trigger",			"!snapshot");	tracefs_reset(); 	if (self->umount)		tracefs_unmount();} TEST_F(snapshot, excludes_map){	struct tracefs_cpu_map_desc map_desc;	int cpu = sched_getcpu(); 	ASSERT_GE(cpu, 0);	tracefs_write(TRACEFS_ROOT"/events/sched/sched_switch/trigger",		      "snapshot");	ASSERT_EQ(tracefs_cpu_map(&map_desc, cpu), -EBUSY);} TEST_F(snapshot, excluded_by_map){	struct tracefs_cpu_map_desc map_desc;	int cpu = sched_getcpu(); 	ASSERT_EQ(tracefs_cpu_map(&map_desc, cpu), 0); 	ASSERT_EQ(__tracefs_write(TRACEFS_ROOT"/events/sched/sched_switch/trigger",				  "snapshot"), -EBUSY);	ASSERT_EQ(__tracefs_write(TRACEFS_ROOT"/snapshot",				  "1"), -EBUSY);} TEST_HARNESS_MAIN