linux-kernel - [PATCH RFC bpf-next 3/3] selftests/bpf: add testcase for probe read fault

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Message-ID: <20250927061210.194502-4-menglong.dong@linux.dev>
Date: Sat, 27 Sep 2025 14:12:10 +0800
From: Menglong Dong <menglong8.dong@...il.com>
To: ast@...nel.org
Cc: bpf@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	linux-trace-kernel@...r.kernel.org,
	jiang.biao@...ux.dev
Subject: [PATCH RFC bpf-next 3/3] selftests/bpf: add testcase for probe read fault

Add testcase for probe read fault to stream.c.

Signed-off-by: Menglong Dong <menglong.dong@...ux.dev>
---
 .../testing/selftests/bpf/prog_tests/stream.c | 22 ++++++++++++++++++-
 tools/testing/selftests/bpf/progs/stream.c    | 21 ++++++++++++++++++
 2 files changed, 42 insertions(+), 1 deletion(-)

diff --git a/tools/testing/selftests/bpf/prog_tests/stream.c b/tools/testing/selftests/bpf/prog_tests/stream.c
index c3cce5c292bd..81fd258b97e0 100644
--- a/tools/testing/selftests/bpf/prog_tests/stream.c
+++ b/tools/testing/selftests/bpf/prog_tests/stream.c
@@ -72,7 +72,8 @@ static void test_address(struct bpf_program *prog, unsigned long *fault_addr_p)
 	ASSERT_OK(ret, "ret");
 	ASSERT_OK(opts.retval, "retval");
 
-	sprintf(fault_addr, "0x%lx", *fault_addr_p);
+	if (fault_addr_p)
+		sprintf(fault_addr, "0x%lx", *fault_addr_p);
 
 	ret = bpf_prog_stream_read(prog_fd, BPF_STREAM_STDERR, buf, sizeof(buf), &ropts);
 	ASSERT_GT(ret, 0, "stream read");
@@ -106,3 +107,22 @@ void test_stream_arena_fault_address(void)
 
 	stream__destroy(skel);
 }
+
+void test_stream_probe_read_fault(void)
+{
+	struct stream *skel;
+
+#if !defined(__x86_64__)
+	printf("%s:SKIP: probe fault reporting not supported\n", __func__);
+	test__skip();
+	return;
+#endif
+
+	skel = stream__open_and_load();
+	if (!ASSERT_OK_PTR(skel, "stream__open_and_load"))
+		return;
+
+	test_address(skel->progs.stream_probe_read_fault, NULL);
+
+	stream__destroy(skel);
+}
diff --git a/tools/testing/selftests/bpf/progs/stream.c b/tools/testing/selftests/bpf/progs/stream.c
index 4a5bd852f10c..290c40463522 100644
--- a/tools/testing/selftests/bpf/progs/stream.c
+++ b/tools/testing/selftests/bpf/progs/stream.c
@@ -7,6 +7,8 @@
 #include "bpf_experimental.h"
 #include "bpf_arena_common.h"
 
+#define READ_ONCE(x) (*(volatile typeof(x) *)&(x))
+
 struct arr_elem {
 	struct bpf_res_spin_lock lock;
 };
@@ -234,4 +236,23 @@ int stream_arena_callback_fault(void *ctx)
 	return 0;
 }
 
+SEC("syscall")
+__arch_x86_64
+__success __retval(0)
+__stderr("ERROR: Probe READ access faule, insn=0x[0-9a-fA-F]+")
+__stderr("CPU: {{[0-9]+}} UID: 0 PID: {{[0-9]+}} Comm: {{.*}}")
+__stderr("Call trace:\n"
+"{{([a-zA-Z_][a-zA-Z0-9_]*\\+0x[0-9a-fA-F]+/0x[0-9a-fA-F]+\n"
+"|[ \t]+[^\n]+\n)*}}")
+int stream_probe_read_fault(void *ctx)
+{
+	struct sk_buff *skb = bpf_core_cast((void *)0xFFFFFFFF00000000,
+					    struct sk_buff);
+
+	/* do the memory read */
+	READ_ONCE(skb->network_header);
+
+	return 0;
+}
+
 char _license[] SEC("license") = "GPL";
-- 
2.51.0