From 698181b2d5fda2192eeab4029e4e02646201d471 Mon Sep 17 00:00:00 2001 From: Tiezhu Yang Date: Tue, 8 Sep 2026 15:35:06 +0800 Subject: [PATCH] selftests/bpf: Add test for indirect struct_ops trampoline Add a test case to verify that arguments passed on the stack are correctly read by an indirect struct_ops trampoline. This test ensures the correctness of stack offsets across various architectures. It is particularly critical for architectures like LoongArch, RISC-V, ARM64, and PowerPC where arguments beyond the first 8 registers are passed on the stack, as well as x86_64 and s390x which have lower register argument limits. Signed-off-by: Tiezhu Yang Link: https://lore.kernel.org/r/20260908073506.29734-1-yangtiezhu@loongson.cn Signed-off-by: Alexei Starovoitov --- .../prog_tests/test_struct_ops_multi_args.c | 57 ++++++++++++++++++- .../bpf/progs/struct_ops_multi_args.c | 14 ++++- .../selftests/bpf/test_kmods/bpf_testmod.c | 10 ++++ .../selftests/bpf/test_kmods/bpf_testmod.h | 5 ++ 4 files changed, 84 insertions(+), 2 deletions(-) diff --git a/tools/testing/selftests/bpf/prog_tests/test_struct_ops_multi_args.c b/tools/testing/selftests/bpf/prog_tests/test_struct_ops_multi_args.c index 0f321e889862..8767e5f8bcc7 100644 --- a/tools/testing/selftests/bpf/prog_tests/test_struct_ops_multi_args.c +++ b/tools/testing/selftests/bpf/prog_tests/test_struct_ops_multi_args.c @@ -3,7 +3,62 @@ #include #include "struct_ops_multi_args.skel.h" +static void test_refcounted_multi(void) +{ + struct struct_ops_multi_args *skel; + char log_buf[4096] = {}; + int err; + + skel = struct_ops_multi_args__open(); + if (!ASSERT_OK_PTR(skel, "struct_ops_multi_args__open")) + return; + + bpf_program__set_log_buf(skel->progs.test_refcounted_multi, log_buf, sizeof(log_buf)); + + err = struct_ops_multi_args__load(skel); + if (!ASSERT_EQ(err, -EINVAL, "struct_ops_multi_args__load")) + goto out; + + ASSERT_HAS_SUBSTR(log_buf, "program with __ref argument cannot tail call", + "check_verifier_log_message"); + +out: + struct_ops_multi_args__destroy(skel); +} + +static void test_trampoline_stack_args(void) +{ + struct struct_ops_multi_args *skel; + struct bpf_link *link = NULL; + int err; + + skel = struct_ops_multi_args__open(); + if (!ASSERT_OK_PTR(skel, "struct_ops_multi_args__open")) + return; + + bpf_program__set_autoload(skel->progs.test_refcounted_multi, false); + skel->struct_ops.testmod_ref_acquire->test_refcounted_multi = NULL; + + err = struct_ops_multi_args__load(skel); + if (!ASSERT_OK(err, "struct_ops_multi_args__load")) + goto out; + + link = bpf_map__attach_struct_ops(skel->maps.testmod_ref_acquire); + if (!ASSERT_OK_PTR(link, "bpf_map__attach_struct_ops")) + goto out; + + ASSERT_EQ(skel->bss->trampoline_stack_arg9, 9999, "check_stack_passed_arg9"); + +out: + bpf_link__destroy(link); + struct_ops_multi_args__destroy(skel); +} + void test_struct_ops_multi_args(void) { - RUN_TESTS(struct_ops_multi_args); + if (test__start_subtest("test_refcounted_multi")) + test_refcounted_multi(); + + if (test__start_subtest("test_trampoline_stack_args")) + test_trampoline_stack_args(); } diff --git a/tools/testing/selftests/bpf/progs/struct_ops_multi_args.c b/tools/testing/selftests/bpf/progs/struct_ops_multi_args.c index c62be15757f0..9d290f22b492 100644 --- a/tools/testing/selftests/bpf/progs/struct_ops_multi_args.c +++ b/tools/testing/selftests/bpf/progs/struct_ops_multi_args.c @@ -17,7 +17,6 @@ struct { } prog_array SEC(".maps"); SEC("struct_ops/test_refcounted_multi") -__failure __msg("program with __ref argument cannot tail call") int test_refcounted_multi(unsigned long long *ctx) { /* ctx[2] is used because the refcounted variable is the third argument */ @@ -29,7 +28,20 @@ int test_refcounted_multi(unsigned long long *ctx) return 0; } +__u64 trampoline_stack_arg9 = 0; + +SEC("struct_ops/test_trampoline_stack_args") +int BPF_PROG(test_trampoline_stack_args, int arg1, int arg2, int arg3, + int arg4, int arg5, int arg6, + int arg7, int arg8, int arg9) +{ + trampoline_stack_arg9 = arg9; + + return 0; +} + SEC(".struct_ops.link") struct bpf_testmod_ops testmod_ref_acquire = { .test_refcounted_multi = (void *)test_refcounted_multi, + .test_trampoline_stack_args = (void *)test_trampoline_stack_args, }; diff --git a/tools/testing/selftests/bpf/test_kmods/bpf_testmod.c b/tools/testing/selftests/bpf/test_kmods/bpf_testmod.c index 66b14168566a..fd2c0cdc91b1 100644 --- a/tools/testing/selftests/bpf/test_kmods/bpf_testmod.c +++ b/tools/testing/selftests/bpf/test_kmods/bpf_testmod.c @@ -1831,6 +1831,8 @@ static int bpf_dummy_reg(void *kdata, struct bpf_link *link) */ if (ops->test_2) ops->test_2(4, ops->data); + if (ops->test_trampoline_stack_args) + ops->test_trampoline_stack_args(1, 2, 3, 4, 5, 6, 7, 8, 9999); return 0; } @@ -1878,6 +1880,13 @@ bpf_testmod_ops__test_return_ref_kptr(int dummy, struct task_struct *task__ref, return NULL; } +static int bpf_testmod_ops__test_trampoline_stack_args(int arg1, int arg2, int arg3, + int arg4, int arg5, int arg6, + int arg7, int arg8, int arg9) +{ + return arg9; +} + static struct bpf_testmod_ops __bpf_testmod_ops = { .test_1 = bpf_testmod_test_1, .test_2 = bpf_testmod_test_2, @@ -1885,6 +1894,7 @@ static struct bpf_testmod_ops __bpf_testmod_ops = { .test_refcounted = bpf_testmod_ops__test_refcounted, .test_refcounted_multi = bpf_testmod_ops__test_refcounted_multi, .test_return_ref_kptr = bpf_testmod_ops__test_return_ref_kptr, + .test_trampoline_stack_args = bpf_testmod_ops__test_trampoline_stack_args, }; struct bpf_struct_ops bpf_bpf_testmod_ops = { diff --git a/tools/testing/selftests/bpf/test_kmods/bpf_testmod.h b/tools/testing/selftests/bpf/test_kmods/bpf_testmod.h index 210b919290cc..2b12f81bf748 100644 --- a/tools/testing/selftests/bpf/test_kmods/bpf_testmod.h +++ b/tools/testing/selftests/bpf/test_kmods/bpf_testmod.h @@ -46,6 +46,11 @@ struct bpf_testmod_ops { struct task_struct *(*test_return_ref_kptr)(int dummy, struct task_struct *task, struct cgroup *cgrp); + /* Used to test indirect struct_ops trampoline with stack-passed arguments. */ + int (*test_trampoline_stack_args)(int arg1, int arg2, int arg3, + int arg4, int arg5, int arg6, + int arg7, int arg8, int arg9); + /* The following fields are used to test shadow copies. */ char onebyte; struct {