linux-kernel - [PATCH bpf-next 2/2] selftests/bpf: Add selftests for bpf_task_cwd_from

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Message-ID: <tencent_2B46D7106B0DB285B4B2242FFB55685EF309@qq.com>
Date: Thu, 29 May 2025 11:32:50 +0800
From: Rong Tao <rtoax@...mail.com>
To: ast@...nel.org,
	daniel@...earbox.net
Cc: rtoax@...mail.com,
	rongtao@...tc.cn,
	Andrii Nakryiko <andrii@...nel.org>,
	Martin KaFai Lau <martin.lau@...ux.dev>,
	Eduard Zingerman <eddyz87@...il.com>,
	Song Liu <song@...nel.org>,
	Yonghong Song <yonghong.song@...ux.dev>,
	John Fastabend <john.fastabend@...il.com>,
	KP Singh <kpsingh@...nel.org>,
	Stanislav Fomichev <sdf@...ichev.me>,
	Hao Luo <haoluo@...gle.com>,
	Jiri Olsa <jolsa@...nel.org>,
	Mykola Lysenko <mykolal@...com>,
	Shuah Khan <shuah@...nel.org>,
	Juntong Deng <juntong.deng@...look.com>,
	Amery Hung <amery.hung@...edance.com>,
	Dave Marchevsky <davemarchevsky@...com>,
	Hou Tao <houtao1@...wei.com>,
	bpf@...r.kernel.org (open list:BPF [GENERAL] (Safe Dynamic Programs and Tools)),
	linux-kernel@...r.kernel.org (open list),
	linux-kselftest@...r.kernel.org (open list:KERNEL SELFTEST FRAMEWORK)
Subject: [PATCH bpf-next 2/2] selftests/bpf: Add selftests for bpf_task_cwd_from_pid()

From: Rong Tao <rongtao@...tc.cn>

Add some selftest testcases that validate the expected behavior of the
bpf_task_cwd_from_pid() kfunc that was added in the prior patch.

Signed-off-by: Rong Tao <rongtao@...tc.cn>
---
 .../selftests/bpf/prog_tests/task_kfunc.c     |  3 ++
 .../selftests/bpf/progs/task_kfunc_common.h   |  1 +
 .../selftests/bpf/progs/task_kfunc_success.c  | 47 +++++++++++++++++++
 3 files changed, 51 insertions(+)

diff --git a/tools/testing/selftests/bpf/prog_tests/task_kfunc.c b/tools/testing/selftests/bpf/prog_tests/task_kfunc.c
index 83b90335967a..c18a0cb67164 100644
--- a/tools/testing/selftests/bpf/prog_tests/task_kfunc.c
+++ b/tools/testing/selftests/bpf/prog_tests/task_kfunc.c
@@ -149,6 +149,9 @@ static const char * const success_tests[] = {
 	"task_kfunc_acquire_trusted_walked",
 	"test_task_kfunc_flavor_relo",
 	"test_task_kfunc_flavor_relo_not_found",
+	"test_task_cwd_from_pid_arg",
+	"test_task_cwd_from_pid",
+	"test_task_cwd_from_pid_current",
 };
 
 static const char * const vpid_success_tests[] = {
diff --git a/tools/testing/selftests/bpf/progs/task_kfunc_common.h b/tools/testing/selftests/bpf/progs/task_kfunc_common.h
index e9c4fea7a4bb..b762054a1825 100644
--- a/tools/testing/selftests/bpf/progs/task_kfunc_common.h
+++ b/tools/testing/selftests/bpf/progs/task_kfunc_common.h
@@ -24,6 +24,7 @@ struct task_struct *bpf_task_acquire(struct task_struct *p) __ksym;
 void bpf_task_release(struct task_struct *p) __ksym;
 struct task_struct *bpf_task_from_pid(s32 pid) __ksym;
 struct task_struct *bpf_task_from_vpid(s32 vpid) __ksym;
+int bpf_task_cwd_from_pid(s32 pid, char *buf, u32 buf_len) __ksym;
 void bpf_rcu_read_lock(void) __ksym;
 void bpf_rcu_read_unlock(void) __ksym;
 
diff --git a/tools/testing/selftests/bpf/progs/task_kfunc_success.c b/tools/testing/selftests/bpf/progs/task_kfunc_success.c
index 5fb4fc19d26a..6424cf5c151e 100644
--- a/tools/testing/selftests/bpf/progs/task_kfunc_success.c
+++ b/tools/testing/selftests/bpf/progs/task_kfunc_success.c
@@ -351,6 +351,53 @@ int BPF_PROG(test_task_from_pid_invalid, struct task_struct *task, u64 clone_fla
 	return 0;
 }
 
+SEC("tp_btf/task_newtask")
+int BPF_PROG(test_task_cwd_from_pid_arg, struct task_struct *task, u64 clone_flags)
+{
+	char cwd[256];
+
+	if (!is_test_kfunc_task())
+		return 0;
+
+	err = 0;
+	err += bpf_task_cwd_from_pid(task->pid, NULL, sizeof(cwd)) != -EINVAL;
+	err += bpf_task_cwd_from_pid(task->pid, cwd, 0) != -EINVAL;
+	err += bpf_task_cwd_from_pid(-1, cwd, sizeof(cwd)) != -ESRCH;
+	return 0;
+}
+
+SEC("tp_btf/task_newtask")
+int BPF_PROG(test_task_cwd_from_pid, struct task_struct *task, u64 clone_flags)
+{
+	char cwd[256];
+
+	if (!is_test_kfunc_task())
+		return 0;
+
+	err = bpf_task_cwd_from_pid(task->pid, cwd, sizeof(cwd));
+	return 0;
+}
+
+SEC("tp_btf/task_newtask")
+int BPF_PROG(test_task_cwd_from_pid_current, struct task_struct *task, u64 clone_flags)
+{
+	char cwd[128], cwd2[128];
+	struct task_struct *current;
+
+	if (!is_test_kfunc_task())
+		return 0;
+
+	current = bpf_get_current_task_btf();
+
+	err = 0;
+	err += bpf_task_cwd_from_pid(task->pid, cwd, sizeof(cwd));
+	err += bpf_task_cwd_from_pid(current->pid, cwd2, sizeof(cwd2));
+
+	err += bpf_strncmp(cwd, sizeof(cwd), cwd2) != 0;
+
+	return 0;
+}
+
 SEC("tp_btf/task_newtask")
 int BPF_PROG(task_kfunc_acquire_trusted_walked, struct task_struct *task, u64 clone_flags)
 {
-- 
2.49.0