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Message-ID: <5da2d9af-7882-49a3-bc39-553e86adf271@collabora.com>
Date: Sun, 7 Apr 2024 01:46:11 +0500
From: Muhammad Usama Anjum <usama.anjum@...labora.com>
To: Vincent Donnefort <vdonnefort@...gle.com>, rostedt@...dmis.org,
mhiramat@...nel.org, linux-kernel@...r.kernel.org,
linux-trace-kernel@...r.kernel.org
Cc: Muhammad Usama Anjum <usama.anjum@...labora.com>,
mathieu.desnoyers@...icios.com, kernel-team@...roid.com,
rdunlap@...radead.org, Shuah Khan <shuah@...nel.org>,
Shuah Khan <skhan@...uxfoundation.org>, linux-kselftest@...r.kernel.org
Subject: Re: [PATCH v20 5/5] ring-buffer/selftest: Add ring-buffer mapping
test
On 4/6/24 10:36 PM, Vincent Donnefort wrote:
> This test maps a ring-buffer and validate the meta-page after reset and
> after emitting few events.
>
> Cc: Shuah Khan <shuah@...nel.org>
> Cc: Shuah Khan <skhan@...uxfoundation.org>
> Cc: linux-kselftest@...r.kernel.org
> Signed-off-by: Vincent Donnefort <vdonnefort@...gle.com>
Acked-by: Muhammad Usama Anjum <usama.anjum@...labora.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
Please add a .gitignore file with map_test in it.
> diff --git a/tools/testing/selftests/ring-buffer/config b/tools/testing/selftests/ring-buffer/config
> new file mode 100644
> index 000000000000..d936f8f00e78
> --- /dev/null
> +++ b/tools/testing/selftests/ring-buffer/config
> @@ -0,0 +1,2 @@
> +CONFIG_FTRACE=y
> +CONFIG_TRACER_SNAPSHOT=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..50a09e1371d4
> --- /dev/null
> +++ b/tools/testing/selftests/ring-buffer/map_test.c
> @@ -0,0 +1,302 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Ring-buffer memory mapping tests
> + *
> + * Copyright (c) 2024 Vincent Donnefort <vdonnefort@...gle.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;
> +
> + 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;
> +
> + 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 (!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()) {
> + void *addr;
> +
> + 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);
> +
> + addr = (void *)((unsigned long)data + getpagesize());
> + ASSERT_EQ(*((int *)addr), 0);
> + munmap(data, data_len);
> + }
> +}
> +
> +FIXTURE(snapshot) {
> + bool umount;
> +};
> +
> +FIXTURE_SETUP(snapshot)
> +{
> + bool fail, umount;
> + struct stat sb;
> + char *message;
> +
> + 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
--
BR,
Muhammad Usama Anjum
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