// SPDX-License-Identifier: GPL-2.0
/*
* Ring-buffer memory mapping tests
*
* Copyright (c) 2024 Vincent Donnefort <[email protected]>
*/
#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
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