From: Jiri Olsa <jolsa@kernel.org>
To: Oleg Nesterov <oleg@redhat.com>,
Masami Hiramatsu <mhiramat@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Andrii Nakryiko <andrii@kernel.org>
Cc: bpf@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-trace-kernel@vger.kernel.org, x86@kernel.org,
Song Liu <songliubraving@fb.com>, Yonghong Song <yhs@fb.com>,
John Fastabend <john.fastabend@gmail.com>,
Hao Luo <haoluo@google.com>, Steven Rostedt <rostedt@goodmis.org>,
Ingo Molnar <mingo@kernel.org>
Subject: [PATCHv4 bpf-next 5/6] selftests/bpf: Add kprobe write ctx attach test
Date: Tue, 16 Sep 2025 23:53:00 +0200 [thread overview]
Message-ID: <20250916215301.664963-6-jolsa@kernel.org> (raw)
In-Reply-To: <20250916215301.664963-1-jolsa@kernel.org>
Adding test to check we can't attach standard kprobe program that
writes to the context.
It's x86_64 specific test.
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
---
.../selftests/bpf/prog_tests/attach_probe.c | 28 +++++++++++++++++++
.../selftests/bpf/progs/kprobe_write_ctx.c | 15 ++++++++++
2 files changed, 43 insertions(+)
create mode 100644 tools/testing/selftests/bpf/progs/kprobe_write_ctx.c
diff --git a/tools/testing/selftests/bpf/prog_tests/attach_probe.c b/tools/testing/selftests/bpf/prog_tests/attach_probe.c
index cabc51c2ca6b..9e77e5da7097 100644
--- a/tools/testing/selftests/bpf/prog_tests/attach_probe.c
+++ b/tools/testing/selftests/bpf/prog_tests/attach_probe.c
@@ -3,6 +3,7 @@
#include "test_attach_kprobe_sleepable.skel.h"
#include "test_attach_probe_manual.skel.h"
#include "test_attach_probe.skel.h"
+#include "kprobe_write_ctx.skel.h"
/* this is how USDT semaphore is actually defined, except volatile modifier */
volatile unsigned short uprobe_ref_ctr __attribute__((unused)) __attribute((section(".probes")));
@@ -201,6 +202,31 @@ static void test_attach_kprobe_long_event_name(void)
test_attach_probe_manual__destroy(skel);
}
+#ifdef __x86_64__
+/* attach kprobe/kretprobe long event name testings */
+static void test_attach_kprobe_write_ctx(void)
+{
+ struct kprobe_write_ctx *skel = NULL;
+ struct bpf_link *link = NULL;
+
+ skel = kprobe_write_ctx__open_and_load();
+ if (!ASSERT_OK_PTR(skel, "kprobe_write_ctx__open_and_load"))
+ return;
+
+ link = bpf_program__attach_kprobe_opts(skel->progs.kprobe_write_ctx,
+ "bpf_fentry_test1", NULL);
+ if (!ASSERT_ERR_PTR(link, "bpf_program__attach_kprobe_opts"))
+ bpf_link__destroy(link);
+
+ kprobe_write_ctx__destroy(skel);
+}
+#else
+static void test_attach_kprobe_write_ctx(void)
+{
+ test__skip();
+}
+#endif
+
static void test_attach_probe_auto(struct test_attach_probe *skel)
{
struct bpf_link *uprobe_err_link;
@@ -406,6 +432,8 @@ void test_attach_probe(void)
test_attach_uprobe_long_event_name();
if (test__start_subtest("kprobe-long_name"))
test_attach_kprobe_long_event_name();
+ if (test__start_subtest("kprobe-write-ctx"))
+ test_attach_kprobe_write_ctx();
cleanup:
test_attach_probe__destroy(skel);
diff --git a/tools/testing/selftests/bpf/progs/kprobe_write_ctx.c b/tools/testing/selftests/bpf/progs/kprobe_write_ctx.c
new file mode 100644
index 000000000000..4621a5bef4e2
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/kprobe_write_ctx.c
@@ -0,0 +1,15 @@
+// SPDX-License-Identifier: GPL-2.0
+#include "vmlinux.h"
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+
+char _license[] SEC("license") = "GPL";
+
+#if defined(__TARGET_ARCH_x86)
+SEC("kprobe")
+int kprobe_write_ctx(struct pt_regs *ctx)
+{
+ ctx->ax = 0;
+ return 0;
+}
+#endif
--
2.51.0
next prev parent reply other threads:[~2025-09-16 21:54 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-09-16 21:52 [PATCHv4 bpf-next 0/6] uprobe,bpf: Allow to change app registers from uprobe registers Jiri Olsa
2025-09-16 21:52 ` [PATCHv4 bpf-next 1/6] bpf: Allow uprobe program to change context registers Jiri Olsa
2025-09-16 21:52 ` [PATCHv4 bpf-next 2/6] uprobe: Do not emulate/sstep original instruction when ip is changed Jiri Olsa
2025-09-16 22:28 ` Andrii Nakryiko
2025-09-22 20:47 ` Andrii Nakryiko
2025-09-24 8:49 ` Peter Zijlstra
2025-09-24 9:47 ` Alexei Starovoitov
2025-09-24 10:23 ` Jiri Olsa
2025-09-16 21:52 ` [PATCHv4 bpf-next 3/6] selftests/bpf: Add uprobe context registers changes test Jiri Olsa
2025-09-16 21:52 ` [PATCHv4 bpf-next 4/6] selftests/bpf: Add uprobe context ip register change test Jiri Olsa
2025-09-16 21:53 ` Jiri Olsa [this message]
2025-09-16 21:53 ` [PATCHv4 bpf-next 6/6] selftests/bpf: Add kprobe multi write ctx attach test Jiri Olsa
2025-09-24 9:50 ` [PATCHv4 bpf-next 0/6] uprobe,bpf: Allow to change app registers from uprobe registers patchwork-bot+netdevbpf
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