linux-kernel - [PATCH RFC bpf-next 2/2] selftests/bpf: Test mmapable task local storage.

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Date:   Thu, 24 Mar 2022 16:41:23 -0700
From:   Hao Luo <haoluo@...gle.com>
To:     Alexei Starovoitov <ast@...nel.org>,
        Andrii Nakryiko <andrii@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>
Cc:     yhs@...com, KP Singh <kpsingh@...nel.org>,
        Martin KaFai Lau <kafai@...com>,
        Song Liu <songliubraving@...com>, bpf@...r.kernel.org,
        linux-kernel@...r.kernel.org, Hao Luo <haoluo@...gle.com>
Subject: [PATCH RFC bpf-next 2/2] selftests/bpf: Test mmapable task local storage.

Tests mmapable task local storage.

Signed-off-by: Hao Luo <haoluo@...gle.com>
---
 .../bpf/prog_tests/task_local_storage.c       | 38 +++++++++++++++++++
 .../bpf/progs/task_local_storage_mmapable.c   | 38 +++++++++++++++++++
 2 files changed, 76 insertions(+)
 create mode 100644 tools/testing/selftests/bpf/progs/task_local_storage_mmapable.c

diff --git a/tools/testing/selftests/bpf/prog_tests/task_local_storage.c b/tools/testing/selftests/bpf/prog_tests/task_local_storage.c
index 035c263aab1b..24e6edd32a78 100644
--- a/tools/testing/selftests/bpf/prog_tests/task_local_storage.c
+++ b/tools/testing/selftests/bpf/prog_tests/task_local_storage.c
@@ -6,8 +6,10 @@
 #include <sys/syscall.h>   /* For SYS_xxx definitions */
 #include <sys/types.h>
 #include <test_progs.h>
+#include <sys/mman.h>
 #include "task_local_storage.skel.h"
 #include "task_local_storage_exit_creds.skel.h"
+#include "task_local_storage_mmapable.skel.h"
 #include "task_ls_recursion.skel.h"
 
 static void test_sys_enter_exit(void)
@@ -81,6 +83,40 @@ static void test_recursion(void)
 	task_ls_recursion__destroy(skel);
 }
 
+#define MAGIC_VALUE 0xabcd1234
+
+static void test_mmapable(void)
+{
+	struct task_local_storage_mmapable *skel;
+	const long page_size = sysconf(_SC_PAGE_SIZE);
+	int fd, err;
+	void *ptr;
+
+	skel = task_local_storage_mmapable__open_and_load();
+	if (!ASSERT_OK_PTR(skel, "skel_open_and_load"))
+		return;
+
+	fd = bpf_map__fd(skel->maps.mmapable_map);
+	ptr = mmap(NULL, page_size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
+	if (!ASSERT_NEQ(ptr, MAP_FAILED, "mmap"))
+		goto out;
+
+	skel->bss->target_pid = syscall(SYS_gettid);
+
+	err = task_local_storage_mmapable__attach(skel);
+	if (!ASSERT_OK(err, "skel_attach"))
+		goto unmap;
+
+	syscall(SYS_gettid);
+
+	ASSERT_EQ(*(u64 *)ptr, MAGIC_VALUE, "value");
+
+unmap:
+	munmap(ptr, page_size);
+out:
+	task_local_storage_mmapable__destroy(skel);
+}
+
 void test_task_local_storage(void)
 {
 	if (test__start_subtest("sys_enter_exit"))
@@ -89,4 +125,6 @@ void test_task_local_storage(void)
 		test_exit_creds();
 	if (test__start_subtest("recursion"))
 		test_recursion();
+	if (test__start_subtest("mmapable"))
+		test_mmapable();
 }
diff --git a/tools/testing/selftests/bpf/progs/task_local_storage_mmapable.c b/tools/testing/selftests/bpf/progs/task_local_storage_mmapable.c
new file mode 100644
index 000000000000..8cd82bb7336a
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/task_local_storage_mmapable.c
@@ -0,0 +1,38 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2022 Google */
+
+#include "vmlinux.h"
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+
+char _license[] SEC("license") = "GPL";
+
+struct {
+	__uint(type, BPF_MAP_TYPE_TASK_STORAGE);
+	__uint(map_flags, BPF_F_NO_PREALLOC | BPF_F_MMAPABLE);
+	__type(key, int);
+	__type(value, long);
+} mmapable_map SEC(".maps");
+
+#define MAGIC_VALUE 0xabcd1234
+
+pid_t target_pid = 0;
+
+SEC("tp_btf/sys_enter")
+int BPF_PROG(on_enter, struct pt_regs *regs, long id)
+{
+	struct task_struct *task;
+	long *ptr;
+
+	task = bpf_get_current_task_btf();
+	if (task->pid != target_pid)
+		return 0;
+
+	ptr = bpf_task_storage_get(&mmapable_map, task, 0,
+				   BPF_LOCAL_STORAGE_GET_F_CREATE);
+	if (!ptr)
+		return 0;
+
+	*ptr = MAGIC_VALUE;
+	return 0;
+}
-- 
2.35.1.1021.g381101b075-goog