selftests/bpf: Add kprobe multi write ctx attach test

Adding test to check we can't attach kprobe multi 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>
Link: https://lore.kernel.org/r/20250916215301.664963-7-jolsa@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

diff --git a/tools/testing/selftests/bpf/prog_tests/kprobe_multi_test.c b/tools/testing/selftests/bpf/prog_tests/kprobe_multi_test.c
index 171706e78da88cbe9e7196dd8a9545cc7ddfced7..6cfaa978bc9af26e88e89d9f8ce3e96c55245da0 100644 (file)
--- a/tools/testing/selftests/bpf/prog_tests/kprobe_multi_test.c
+++ b/tools/testing/selftests/bpf/prog_tests/kprobe_multi_test.c
@@ -7,6 +7,7 @@
 #include "kprobe_multi_session.skel.h"
 #include "kprobe_multi_session_cookie.skel.h"
 #include "kprobe_multi_verifier.skel.h"
+#include "kprobe_write_ctx.skel.h"
 #include "bpf/libbpf_internal.h"
 #include "bpf/hashmap.h"
 
@@ -539,6 +540,30 @@ cleanup:
        kprobe_multi_override__destroy(skel);
 }
 
+#ifdef __x86_64__
+static void test_attach_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_multi_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_write_ctx(void)
+{
+       test__skip();
+}
+#endif
+
 void serial_test_kprobe_multi_bench_attach(void)
 {
        if (test__start_subtest("kernel"))
@@ -578,5 +603,7 @@ void test_kprobe_multi_test(void)
                test_session_cookie_skel_api();
        if (test__start_subtest("unique_match"))
                test_unique_match();
+       if (test__start_subtest("attach_write_ctx"))
+               test_attach_write_ctx();
        RUN_TESTS(kprobe_multi_verifier);
 }

diff --git a/tools/testing/selftests/bpf/progs/kprobe_write_ctx.c b/tools/testing/selftests/bpf/progs/kprobe_write_ctx.c
index 4621a5bef4e295eb062c1b7c03b006e953caf2c6..f77aef0474d3b61cd048a0207fbcdd4f6d82aa57 100644 (file)
--- a/tools/testing/selftests/bpf/progs/kprobe_write_ctx.c
+++ b/tools/testing/selftests/bpf/progs/kprobe_write_ctx.c
@@ -12,4 +12,11 @@ int kprobe_write_ctx(struct pt_regs *ctx)
        ctx->ax = 0;
        return 0;
 }
+
+SEC("kprobe.multi")
+int kprobe_multi_write_ctx(struct pt_regs *ctx)
+{
+       ctx->ax = 0;
+       return 0;
+}
 #endif