[PATCHv4 bpf-next 5/6] selftests/bpf: Add kprobe write ctx attach test
From: Jiri Olsa <jolsa@kernel.org>
Date: 2025-09-16 21:54:11
Also in:
bpf, lkml
Subsystem:
bpf [general] (safe dynamic programs and tools), bpf [selftests] (test runners & infrastructure), kernel selftest framework, the rest · Maintainers:
Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko, Eduard Zingerman, Kumar Kartikeya Dwivedi, Shuah Khan, Shuah Khan, Linus Torvalds
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