This test maps a ring-buffer and validate the meta-page after reset and after emitting few events.

Cc: Shuah Khan shuah@kernel.org Cc: Shuah Khan skhan@linuxfoundation.org Cc: linux-kselftest@vger.kernel.org Signed-off-by: Vincent Donnefort vdonnefort@google.com

diff --git a/tools/testing/selftests/ring-buffer/Makefile b/tools/testing/selftests/ring-buffer/Makefile new file mode 100644 index 000000000000..627c5fa6d1ab --- /dev/null +++ b/tools/testing/selftests/ring-buffer/Makefile @@ -0,0 +1,8 @@ +# SPDX-License-Identifier: GPL-2.0 +CFLAGS += -Wl,-no-as-needed -Wall +CFLAGS += $(KHDR_INCLUDES) +CFLAGS += -D_GNU_SOURCE + +TEST_GEN_PROGS = map_test + +include ../lib.mk diff --git a/tools/testing/selftests/ring-buffer/config b/tools/testing/selftests/ring-buffer/config new file mode 100644 index 000000000000..ef8214661612 --- /dev/null +++ b/tools/testing/selftests/ring-buffer/config @@ -0,0 +1 @@ +CONFIG_FTRACE=y diff --git a/tools/testing/selftests/ring-buffer/map_test.c b/tools/testing/selftests/ring-buffer/map_test.c new file mode 100644 index 000000000000..ec891e956b83 --- /dev/null +++ b/tools/testing/selftests/ring-buffer/map_test.c @@ -0,0 +1,188 @@ +// 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) +{ + FILE *file; + + file = fopen(path, "w"); + if (!file) + return -1; + + fputs(value, file); + fclose(file); + + return 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) + +static int tracefs_reset(void) +{ + if (__tracefs_write_int(TRACEFS_ROOT"/tracing_on", 0)) + return -1; + if (__tracefs_write_int(TRACEFS_ROOT"/trace", 0)) + return -1; + if (__tracefs_write(TRACEFS_ROOT"/set_event", "")) + return -1; + if (__tracefs_write(TRACEFS_ROOT"/current_tracer", "nop")) + return -1; + + return 0; +} + +FIXTURE(map) { + struct trace_buffer_meta *meta; + void *data; + int cpu_fd; + 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(), page_size = getpagesize(); + unsigned long meta_len, data_len; + char *cpu_path, *message; + bool fail, umount; + cpu_set_t cpu_mask; + void *map; + + 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_GE(asprintf(&cpu_path, + TRACEFS_ROOT"/per_cpu/cpu%d/trace_pipe_raw", + cpu), 0); + + self->cpu_fd = open(cpu_path, O_RDONLY | O_NONBLOCK); + ASSERT_GE(self->cpu_fd, 0); + free(cpu_path); + + map = mmap(NULL, page_size, PROT_READ, MAP_SHARED, self->cpu_fd, 0); + ASSERT_NE(map, MAP_FAILED); + self->meta = (struct trace_buffer_meta *)map; + + meta_len = self->meta->meta_page_size; + data_len = self->meta->subbuf_size * self->meta->nr_subbufs; + + map = mmap(NULL, data_len, PROT_READ, MAP_SHARED, self->cpu_fd, meta_len); + ASSERT_NE(map, MAP_FAILED); + self->data = map; + + /* + * 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(); + + munmap(self->data, self->meta->subbuf_size * self->meta->nr_subbufs); + munmap(self->meta, self->meta->meta_page_size); + close(self->cpu_fd); +} + +TEST_F(map, meta_page_check) +{ + int cnt = 0; + + ASSERT_EQ(self->meta->entries, 0); + ASSERT_EQ(self->meta->overrun, 0); + ASSERT_EQ(self->meta->read, 0); + ASSERT_EQ(self->meta->subbufs_touched, 0); + ASSERT_EQ(self->meta->subbufs_lost, 0); + + ASSERT_EQ(self->meta->reader.id, 0); + ASSERT_EQ(self->meta->reader.read, 0); + + ASSERT_EQ(ioctl(self->cpu_fd, TRACE_MMAP_IOCTL_GET_READER), 0); + ASSERT_EQ(self->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(self->cpu_fd, TRACE_MMAP_IOCTL_GET_READER), 0); + + ASSERT_EQ(self->meta->entries, 16); + ASSERT_EQ(self->meta->overrun, 0); + ASSERT_EQ(self->meta->read, 16); + /* subbufs_touched doesn't take into account the commit page */ + ASSERT_EQ(self->meta->subbufs_touched, 0); + ASSERT_EQ(self->meta->subbufs_lost, 0); + + ASSERT_EQ(self->meta->reader.id, 1); + + if (!(cnt++)) + goto again; +} + +TEST_HARNESS_MAIN