ring-buffer/selftest: Add ring-buffer mapping test
Map a ring-buffer, validate the meta-page before and after emitting few events. Also check ring-buffer mapping boundaries and finally ensure the tracing snapshot is mutually exclusive. Link: https://lore.kernel.org/linux-trace-kernel/20240510140435.3550353-6-vdonnefort@google.com Cc: Shuah Khan <shuah@kernel.org> Cc: Shuah Khan <skhan@linuxfoundation.org> Cc: linux-kselftest@vger.kernel.org Acked-by: Muhammad Usama Anjum <usama.anjum@collabora.com> Signed-off-by: Vincent Donnefort <vdonnefort@google.com> Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
This commit is contained in:
Vincent Donnefort
Steven Rostedt (Google)
parent
a1e0dd7ce3
commit
75961e5541
1
tools/testing/selftests/ring-buffer/.gitignore
vendored
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1
tools/testing/selftests/ring-buffer/.gitignore
vendored
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map_test
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8
tools/testing/selftests/ring-buffer/Makefile
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8
tools/testing/selftests/ring-buffer/Makefile
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# SPDX-License-Identifier: GPL-2.0
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CFLAGS += -Wl,-no-as-needed -Wall
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CFLAGS += $(KHDR_INCLUDES)
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CFLAGS += -D_GNU_SOURCE
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TEST_GEN_PROGS = map_test
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include ../lib.mk
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2
tools/testing/selftests/ring-buffer/config
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tools/testing/selftests/ring-buffer/config
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CONFIG_FTRACE=y
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CONFIG_TRACER_SNAPSHOT=y
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294
tools/testing/selftests/ring-buffer/map_test.c
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tools/testing/selftests/ring-buffer/map_test.c
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// SPDX-License-Identifier: GPL-2.0
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/*
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* Ring-buffer memory mapping tests
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*
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* Copyright (c) 2024 Vincent Donnefort <vdonnefort@google.com>
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*/
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#include <fcntl.h>
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#include <sched.h>
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#include <stdbool.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <unistd.h>
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#include <linux/trace_mmap.h>
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#include <sys/mman.h>
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#include <sys/ioctl.h>
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#include "../user_events/user_events_selftests.h" /* share tracefs setup */
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#include "../kselftest_harness.h"
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#define TRACEFS_ROOT "/sys/kernel/tracing"
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static int __tracefs_write(const char *path, const char *value)
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{
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int fd, ret;
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fd = open(path, O_WRONLY | O_TRUNC);
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if (fd < 0)
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return fd;
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ret = write(fd, value, strlen(value));
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close(fd);
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return ret == -1 ? -errno : 0;
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}
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static int __tracefs_write_int(const char *path, int value)
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{
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char *str;
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int ret;
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if (asprintf(&str, "%d", value) < 0)
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return -1;
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ret = __tracefs_write(path, str);
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free(str);
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return ret;
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}
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#define tracefs_write_int(path, value) \
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ASSERT_EQ(__tracefs_write_int((path), (value)), 0)
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#define tracefs_write(path, value) \
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ASSERT_EQ(__tracefs_write((path), (value)), 0)
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static int tracefs_reset(void)
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{
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if (__tracefs_write_int(TRACEFS_ROOT"/tracing_on", 0))
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return -1;
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if (__tracefs_write(TRACEFS_ROOT"/trace", ""))
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return -1;
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if (__tracefs_write(TRACEFS_ROOT"/set_event", ""))
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return -1;
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if (__tracefs_write(TRACEFS_ROOT"/current_tracer", "nop"))
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return -1;
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return 0;
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}
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struct tracefs_cpu_map_desc {
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struct trace_buffer_meta *meta;
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int cpu_fd;
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};
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int tracefs_cpu_map(struct tracefs_cpu_map_desc *desc, int cpu)
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{
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int page_size = getpagesize();
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char *cpu_path;
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void *map;
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if (asprintf(&cpu_path,
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TRACEFS_ROOT"/per_cpu/cpu%d/trace_pipe_raw",
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cpu) < 0)
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return -ENOMEM;
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desc->cpu_fd = open(cpu_path, O_RDONLY | O_NONBLOCK);
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free(cpu_path);
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if (desc->cpu_fd < 0)
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return -ENODEV;
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map = mmap(NULL, page_size, PROT_READ, MAP_SHARED, desc->cpu_fd, 0);
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if (map == MAP_FAILED)
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return -errno;
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desc->meta = (struct trace_buffer_meta *)map;
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return 0;
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}
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void tracefs_cpu_unmap(struct tracefs_cpu_map_desc *desc)
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{
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munmap(desc->meta, desc->meta->meta_page_size);
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close(desc->cpu_fd);
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}
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FIXTURE(map) {
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struct tracefs_cpu_map_desc map_desc;
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bool umount;
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};
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FIXTURE_VARIANT(map) {
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int subbuf_size;
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};
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FIXTURE_VARIANT_ADD(map, subbuf_size_4k) {
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.subbuf_size = 4,
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};
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FIXTURE_VARIANT_ADD(map, subbuf_size_8k) {
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.subbuf_size = 8,
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};
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FIXTURE_SETUP(map)
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{
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int cpu = sched_getcpu();
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cpu_set_t cpu_mask;
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bool fail, umount;
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char *message;
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if (getuid() != 0)
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SKIP(return, "Skipping: %s", "Please run the test as root");
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if (!tracefs_enabled(&message, &fail, &umount)) {
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if (fail) {
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TH_LOG("Tracefs setup failed: %s", message);
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ASSERT_FALSE(fail);
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}
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SKIP(return, "Skipping: %s", message);
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}
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self->umount = umount;
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ASSERT_GE(cpu, 0);
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ASSERT_EQ(tracefs_reset(), 0);
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tracefs_write_int(TRACEFS_ROOT"/buffer_subbuf_size_kb", variant->subbuf_size);
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ASSERT_EQ(tracefs_cpu_map(&self->map_desc, cpu), 0);
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/*
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* Ensure generated events will be found on this very same ring-buffer.
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*/
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CPU_ZERO(&cpu_mask);
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CPU_SET(cpu, &cpu_mask);
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ASSERT_EQ(sched_setaffinity(0, sizeof(cpu_mask), &cpu_mask), 0);
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}
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FIXTURE_TEARDOWN(map)
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{
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tracefs_reset();
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if (self->umount)
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tracefs_unmount();
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tracefs_cpu_unmap(&self->map_desc);
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}
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TEST_F(map, meta_page_check)
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{
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struct tracefs_cpu_map_desc *desc = &self->map_desc;
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int cnt = 0;
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ASSERT_EQ(desc->meta->entries, 0);
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ASSERT_EQ(desc->meta->overrun, 0);
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ASSERT_EQ(desc->meta->read, 0);
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ASSERT_EQ(desc->meta->reader.id, 0);
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ASSERT_EQ(desc->meta->reader.read, 0);
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ASSERT_EQ(ioctl(desc->cpu_fd, TRACE_MMAP_IOCTL_GET_READER), 0);
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ASSERT_EQ(desc->meta->reader.id, 0);
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tracefs_write_int(TRACEFS_ROOT"/tracing_on", 1);
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for (int i = 0; i < 16; i++)
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tracefs_write_int(TRACEFS_ROOT"/trace_marker", i);
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again:
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ASSERT_EQ(ioctl(desc->cpu_fd, TRACE_MMAP_IOCTL_GET_READER), 0);
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ASSERT_EQ(desc->meta->entries, 16);
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ASSERT_EQ(desc->meta->overrun, 0);
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ASSERT_EQ(desc->meta->read, 16);
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ASSERT_EQ(desc->meta->reader.id, 1);
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if (!(cnt++))
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goto again;
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}
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TEST_F(map, data_mmap)
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{
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struct tracefs_cpu_map_desc *desc = &self->map_desc;
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unsigned long meta_len, data_len;
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void *data;
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meta_len = desc->meta->meta_page_size;
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data_len = desc->meta->subbuf_size * desc->meta->nr_subbufs;
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/* Map all the available subbufs */
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data = mmap(NULL, data_len, PROT_READ, MAP_SHARED,
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desc->cpu_fd, meta_len);
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ASSERT_NE(data, MAP_FAILED);
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munmap(data, data_len);
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/* Map all the available subbufs - 1 */
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data_len -= desc->meta->subbuf_size;
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data = mmap(NULL, data_len, PROT_READ, MAP_SHARED,
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desc->cpu_fd, meta_len);
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ASSERT_NE(data, MAP_FAILED);
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munmap(data, data_len);
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/* Overflow the available subbufs by 1 */
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meta_len += desc->meta->subbuf_size * 2;
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data = mmap(NULL, data_len, PROT_READ, MAP_SHARED,
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desc->cpu_fd, meta_len);
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ASSERT_EQ(data, MAP_FAILED);
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}
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FIXTURE(snapshot) {
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bool umount;
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};
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FIXTURE_SETUP(snapshot)
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{
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bool fail, umount;
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struct stat sb;
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char *message;
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if (getuid() != 0)
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SKIP(return, "Skipping: %s", "Please run the test as root");
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if (stat(TRACEFS_ROOT"/snapshot", &sb))
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SKIP(return, "Skipping: %s", "snapshot not available");
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if (!tracefs_enabled(&message, &fail, &umount)) {
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if (fail) {
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TH_LOG("Tracefs setup failed: %s", message);
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ASSERT_FALSE(fail);
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}
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SKIP(return, "Skipping: %s", message);
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}
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self->umount = umount;
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}
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FIXTURE_TEARDOWN(snapshot)
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{
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__tracefs_write(TRACEFS_ROOT"/events/sched/sched_switch/trigger",
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"!snapshot");
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tracefs_reset();
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if (self->umount)
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tracefs_unmount();
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}
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TEST_F(snapshot, excludes_map)
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{
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struct tracefs_cpu_map_desc map_desc;
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int cpu = sched_getcpu();
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ASSERT_GE(cpu, 0);
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tracefs_write(TRACEFS_ROOT"/events/sched/sched_switch/trigger",
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"snapshot");
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ASSERT_EQ(tracefs_cpu_map(&map_desc, cpu), -EBUSY);
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}
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TEST_F(snapshot, excluded_by_map)
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{
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struct tracefs_cpu_map_desc map_desc;
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int cpu = sched_getcpu();
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ASSERT_EQ(tracefs_cpu_map(&map_desc, cpu), 0);
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ASSERT_EQ(__tracefs_write(TRACEFS_ROOT"/events/sched/sched_switch/trigger",
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"snapshot"), -EBUSY);
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ASSERT_EQ(__tracefs_write(TRACEFS_ROOT"/snapshot",
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"1"), -EBUSY);
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}
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TEST_HARNESS_MAIN
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