This test maps a ring-buffer and validate the meta-page after reset and
after emitting few events.
Cc: Shuah Khan <sh...@kernel.org>
Cc: Shuah Khan <sk...@linuxfoundation.org>
Cc: linux-kselftest@vger.kernel.org
Signed-off-by: Vincent Donnefort <vdonnef...@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..49107e8da5e9
--- /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 <vdonnef...@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;
+
+ 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->subbufs_read, 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->subbufs_read, 1);
+
+ ASSERT_EQ(self->meta->reader.id, 1);
+
+ if (!(cnt++))
+ goto again;
+}
+
+TEST_HARNESS_MAIN
--
2.43.0.275.g3460e3d667-goog
