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selftests/bpf: Add tests for BPF function stack arguments

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Add selftests covering stack argument passing for both BPF-to-BPF
subprog calls and kfunc calls with more than 5 arguments. All tests
are guarded by __BPF_FEATURE_STACK_ARGUMENT and __TARGET_ARCH_x86.

BPF-to-BPF subprog call tests (stack_arg.c):
  - Scalar stack args
  - Pointer stack args
  - Mixed pointer/scalar stack args
  - Nested calls
  - Dynptr stack arg
  - Two callees with different stack arg counts
  - Async callback

Kfunc call tests (stack_arg_kfunc.c, with bpf_testmod kfuncs):
  - Scalar stack args
  - Pointer stack args
  - Mixed pointer/scalar stack args
  - Dynptr stack arg
  - Memory buffer + size pair
  - Iterator
  - Const string pointer
  - Timer pointer

Acked-by: Puranjay Mohan <puranjay@kernel.org>
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20260513045127.2397187-1-yonghong.song@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Yonghong Song
2026-05-12 21:51:27 -07:00
committed by Alexei Starovoitov
parent 324c3ca6ee
commit 79e7ec0063
5 changed files with 638 additions and 1 deletions
Download Patch File Download Diff File Expand all files Collapse all files

139
tools/testing/selftests/bpf/prog_tests/stack_arg.c Normal file
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@@ -0,0 +1,139 @@
// SPDX-License-Identifier: GPL-2.0
/* Copyright (c) 2026 Meta Platforms, Inc. and affiliates. */
#include <test_progs.h>
#include <network_helpers.h>
#include "stack_arg.skel.h"
#include "stack_arg_kfunc.skel.h"
static void run_subtest(struct bpf_program *prog, int expected)
{
int err, prog_fd;
LIBBPF_OPTS(bpf_test_run_opts, topts,
.data_in = &pkt_v4,
.data_size_in = sizeof(pkt_v4),
.repeat = 1,
);
prog_fd = bpf_program__fd(prog);
err = bpf_prog_test_run_opts(prog_fd, &topts);
ASSERT_OK(err, "test_run");
ASSERT_EQ(topts.retval, expected, "retval");
}
static void test_global_many(void)
{
struct stack_arg *skel;
skel = stack_arg__open();
if (!ASSERT_OK_PTR(skel, "open"))
return;
if (!skel->rodata->has_stack_arg) {
test__skip();
goto out;
}
if (!ASSERT_OK(stack_arg__load(skel), "load"))
goto out;
run_subtest(skel->progs.test_global_many_args, 36);
out:
stack_arg__destroy(skel);
}
static void test_async_cb_many(void)
{
struct stack_arg *skel;
skel = stack_arg__open();
if (!ASSERT_OK_PTR(skel, "open"))
return;
if (!skel->rodata->has_stack_arg) {
test__skip();
goto out;
}
if (!ASSERT_OK(stack_arg__load(skel), "load"))
goto out;
run_subtest(skel->progs.test_async_cb_many_args, 0);
/* Wait for the timer callback to fire and verify the result.
* 10+20+30+40+50+60+70+80 = 360
*/
usleep(50);
ASSERT_EQ(skel->bss->timer_result, 360, "timer_result");
out:
stack_arg__destroy(skel);
}
static void test_bpf2bpf(void)
{
struct stack_arg *skel;
skel = stack_arg__open();
if (!ASSERT_OK_PTR(skel, "open"))
return;
if (!skel->rodata->has_stack_arg) {
test__skip();
goto out;
}
if (!ASSERT_OK(stack_arg__load(skel), "load"))
goto out;
run_subtest(skel->progs.test_bpf2bpf_ptr_stack_arg, 45);
run_subtest(skel->progs.test_bpf2bpf_mix_stack_args, 51);
run_subtest(skel->progs.test_bpf2bpf_nesting_stack_arg, 50);
run_subtest(skel->progs.test_bpf2bpf_dynptr_stack_arg, 69);
run_subtest(skel->progs.test_two_callees, 91);
out:
stack_arg__destroy(skel);
}
static void test_kfunc(void)
{
struct stack_arg_kfunc *skel;
skel = stack_arg_kfunc__open();
if (!ASSERT_OK_PTR(skel, "open"))
return;
if (!skel->rodata->has_stack_arg) {
test__skip();
goto out;
}
if (!ASSERT_OK(stack_arg_kfunc__load(skel), "load"))
goto out;
run_subtest(skel->progs.test_stack_arg_scalar, 36);
run_subtest(skel->progs.test_stack_arg_ptr, 45);
run_subtest(skel->progs.test_stack_arg_mix, 51);
run_subtest(skel->progs.test_stack_arg_dynptr, 69);
run_subtest(skel->progs.test_stack_arg_mem, 151);
run_subtest(skel->progs.test_stack_arg_iter, 115);
run_subtest(skel->progs.test_stack_arg_const_str, 15);
run_subtest(skel->progs.test_stack_arg_timer, 15);
out:
stack_arg_kfunc__destroy(skel);
}
void test_stack_arg(void)
{
if (test__start_subtest("global_many_args"))
test_global_many();
if (test__start_subtest("async_cb_many_args"))
test_async_cb_many();
if (test__start_subtest("bpf2bpf"))
test_bpf2bpf();
if (test__start_subtest("kfunc"))
test_kfunc();
}

252
tools/testing/selftests/bpf/progs/stack_arg.c Normal file
View File

@@ -0,0 +1,252 @@
// SPDX-License-Identifier: GPL-2.0
/* Copyright (c) 2026 Meta Platforms, Inc. and affiliates. */
#include <vmlinux.h>
#include <stdbool.h>
#include <bpf/bpf_helpers.h>
#include "bpf_kfuncs.h"
#define CLOCK_MONOTONIC 1
struct timer_elem {
struct bpf_timer timer;
};
struct {
__uint(type, BPF_MAP_TYPE_ARRAY);
__uint(max_entries, 1);
__type(key, int);
__type(value, struct timer_elem);
} timer_map SEC(".maps");
int timer_result;
#if defined(__TARGET_ARCH_x86) && defined(__BPF_FEATURE_STACK_ARGUMENT)
const volatile bool has_stack_arg = true;
__noinline static int static_func_many_args(int a, int b, int c, int d,
int e, int f, int g, int h)
{
return a + b + c + d + e + f + g + h;
}
__noinline int global_calls_many_args(int a, int b, int c)
{
return static_func_many_args(a, b, c, 4, 5, 6, 7, 8);
}
SEC("tc")
int test_global_many_args(void)
{
return global_calls_many_args(1, 2, 3);
}
struct test_data {
long x;
long y;
};
/* 1 + 2 + 3 + 4 + 5 + 10 + 20 = 45 */
__noinline static long func_with_ptr_stack_arg(long a, long b, long c, long d,
long e, struct test_data *p)
{
return a + b + c + d + e + p->x + p->y;
}
__noinline long global_ptr_stack_arg(long a, long b, long c, long d, long e)
{
struct test_data data = { .x = 10, .y = 20 };
return func_with_ptr_stack_arg(a, b, c, d, e, &data);
}
SEC("tc")
int test_bpf2bpf_ptr_stack_arg(void)
{
return global_ptr_stack_arg(1, 2, 3, 4, 5);
}
/* 1 + 2 + 3 + 4 + 5 + 10 + 6 + 20 = 51 */
__noinline static long func_with_mix_stack_args(long a, long b, long c, long d,
long e, struct test_data *p,
long f, struct test_data *q)
{
return a + b + c + d + e + p->x + f + q->y;
}
__noinline long global_mix_stack_args(long a, long b, long c, long d, long e)
{
struct test_data p = { .x = 10 };
struct test_data q = { .y = 20 };
return func_with_mix_stack_args(a, b, c, d, e, &p, e + 1, &q);
}
SEC("tc")
int test_bpf2bpf_mix_stack_args(void)
{
return global_mix_stack_args(1, 2, 3, 4, 5);
}
/*
* Nesting test: func_outer calls func_inner, both with struct pointer
* as stack arg.
*
* func_inner: (a+1) + (b+1) + (c+1) + (d+1) + (e+1) + p->x + p->y
* = 2 + 3 + 4 + 5 + 6 + 10 + 20 = 50
*/
__noinline static long func_inner_ptr(long a, long b, long c, long d,
long e, struct test_data *p)
{
return a + b + c + d + e + p->x + p->y;
}
__noinline static long func_outer_ptr(long a, long b, long c, long d,
long e, struct test_data *p)
{
return func_inner_ptr(a + 1, b + 1, c + 1, d + 1, e + 1, p);
}
__noinline long global_nesting_ptr(long a, long b, long c, long d, long e)
{
struct test_data data = { .x = 10, .y = 20 };
return func_outer_ptr(a, b, c, d, e, &data);
}
SEC("tc")
int test_bpf2bpf_nesting_stack_arg(void)
{
return global_nesting_ptr(1, 2, 3, 4, 5);
}
/* 1 + 2 + 3 + 4 + 5 + sizeof(pkt_v4) = 15 + 54 = 69 */
__noinline static long func_with_dynptr(long a, long b, long c, long d,
long e, struct bpf_dynptr *ptr)
{
return a + b + c + d + e + bpf_dynptr_size(ptr);
}
__noinline long global_dynptr_stack_arg(void *ctx __arg_ctx, long a, long b,
long c, long d)
{
struct bpf_dynptr ptr;
bpf_dynptr_from_skb(ctx, 0, &ptr);
return func_with_dynptr(a, b, c, d, d + 1, &ptr);
}
SEC("tc")
int test_bpf2bpf_dynptr_stack_arg(struct __sk_buff *skb)
{
return global_dynptr_stack_arg(skb, 1, 2, 3, 4);
}
/* foo1: a+b+c+d+e+f+g+h */
__noinline static int foo1(int a, int b, int c, int d,
int e, int f, int g, int h)
{
return a + b + c + d + e + f + g + h;
}
/* foo2: a+b+c+d+e+f+g+h+i+j */
__noinline static int foo2(int a, int b, int c, int d, int e,
int f, int g, int h, int i, int j)
{
return a + b + c + d + e + f + g + h + i + j;
}
/* global_two_callees calls foo1 (3 stack args) and foo2 (5 stack args).
* The outgoing stack arg area is sized for foo2 (the larger callee).
* Stores for foo1 are a subset of the area used by foo2.
* Result: foo1(1,2,3,4,5,6,7,8) + foo2(1,2,3,4,5,6,7,8,9,10) = 36 + 55 = 91
*
* Pass a-e through so the compiler can't constant-fold the stack args away.
*/
__noinline int global_two_callees(int a, int b, int c, int d, int e)
{
int ret;
ret = foo1(a, b, c, d, e, a + 5, a + 6, a + 7);
ret += foo2(a, b, c, d, e, a + 5, a + 6, a + 7, a + 8, a + 9);
return ret;
}
SEC("tc")
int test_two_callees(void)
{
return global_two_callees(1, 2, 3, 4, 5);
}
static int timer_cb_many_args(void *map, int *key, struct bpf_timer *timer)
{
timer_result = static_func_many_args(10, 20, 30, 40, 50, 60, 70, 80);
return 0;
}
SEC("tc")
int test_async_cb_many_args(void)
{
struct timer_elem *elem;
int key = 0;
elem = bpf_map_lookup_elem(&timer_map, &key);
if (!elem)
return -1;
bpf_timer_init(&elem->timer, &timer_map, CLOCK_MONOTONIC);
bpf_timer_set_callback(&elem->timer, timer_cb_many_args);
bpf_timer_start(&elem->timer, 1, 0);
return 0;
}
#else
const volatile bool has_stack_arg = false;
SEC("tc")
int test_global_many_args(void)
{
return 0;
}
SEC("tc")
int test_bpf2bpf_ptr_stack_arg(void)
{
return 0;
}
SEC("tc")
int test_bpf2bpf_mix_stack_args(void)
{
return 0;
}
SEC("tc")
int test_bpf2bpf_nesting_stack_arg(void)
{
return 0;
}
SEC("tc")
int test_bpf2bpf_dynptr_stack_arg(struct __sk_buff *skb)
{
return 0;
}
SEC("tc")
int test_two_callees(void)
{
return 0;
}
SEC("tc")
int test_async_cb_many_args(void)
{
return 0;
}
#endif
char _license[] SEC("license") = "GPL";

163
tools/testing/selftests/bpf/progs/stack_arg_kfunc.c Normal file
View File

@@ -0,0 +1,163 @@
// SPDX-License-Identifier: GPL-2.0
/* Copyright (c) 2026 Meta Platforms, Inc. and affiliates. */
#include <vmlinux.h>
#include <bpf/bpf_helpers.h>
#include "bpf_kfuncs.h"
#include "../test_kmods/bpf_testmod_kfunc.h"
#if defined(__TARGET_ARCH_x86) && defined(__BPF_FEATURE_STACK_ARGUMENT)
const volatile bool has_stack_arg = true;
struct bpf_iter_testmod_seq {
u64 :64;
u64 :64;
};
extern int bpf_iter_testmod_seq_new(struct bpf_iter_testmod_seq *it, s64 value, int cnt) __ksym;
extern void bpf_iter_testmod_seq_destroy(struct bpf_iter_testmod_seq *it) __ksym;
struct timer_map_value {
struct bpf_timer timer;
};
struct {
__uint(type, BPF_MAP_TYPE_ARRAY);
__uint(max_entries, 1);
__type(key, int);
__type(value, struct timer_map_value);
} kfunc_timer_map SEC(".maps");
SEC("tc")
int test_stack_arg_scalar(struct __sk_buff *skb)
{
return bpf_kfunc_call_stack_arg(1, 2, 3, 4, 5, 6, 7, 8);
}
SEC("tc")
int test_stack_arg_ptr(struct __sk_buff *skb)
{
struct prog_test_pass1 p = { .x0 = 10, .x1 = 20 };
return bpf_kfunc_call_stack_arg_ptr(1, 2, 3, 4, 5, &p);
}
SEC("tc")
int test_stack_arg_mix(struct __sk_buff *skb)
{
struct prog_test_pass1 p = { .x0 = 10 };
struct prog_test_pass1 q = { .x1 = 20 };
return bpf_kfunc_call_stack_arg_mix(1, 2, 3, 4, 5, &p, 6, &q);
}
/* 1 + 2 + 3 + 4 + 5 + sizeof(pkt_v4) = 15 + 54 = 69 */
SEC("tc")
int test_stack_arg_dynptr(struct __sk_buff *skb)
{
struct bpf_dynptr ptr;
bpf_dynptr_from_skb(skb, 0, &ptr);
return bpf_kfunc_call_stack_arg_dynptr(1, 2, 3, 4, 5, &ptr);
}
/* 1 + 2 + 3 + 4 + 5 + (1 + 2 + ... + 16) = 15 + 136 = 151 */
SEC("tc")
int test_stack_arg_mem(struct __sk_buff *skb)
{
char buf[16] = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16};
return bpf_kfunc_call_stack_arg_mem(1, 2, 3, 4, 5, buf, sizeof(buf));
}
/* 1 + 2 + 3 + 4 + 5 + 100 = 115 */
SEC("tc")
int test_stack_arg_iter(struct __sk_buff *skb)
{
struct bpf_iter_testmod_seq it;
u64 ret;
bpf_iter_testmod_seq_new(&it, 100, 10);
ret = bpf_kfunc_call_stack_arg_iter(1, 2, 3, 4, 5, &it);
bpf_iter_testmod_seq_destroy(&it);
return ret;
}
const char cstr[] = "hello";
/* 1 + 2 + 3 + 4 + 5 = 15 */
SEC("tc")
int test_stack_arg_const_str(struct __sk_buff *skb)
{
return bpf_kfunc_call_stack_arg_const_str(1, 2, 3, 4, 5, cstr);
}
/* 1 + 2 + 3 + 4 + 5 = 15 */
SEC("tc")
int test_stack_arg_timer(struct __sk_buff *skb)
{
struct timer_map_value *val;
int key = 0;
val = bpf_map_lookup_elem(&kfunc_timer_map, &key);
if (!val)
return 0;
return bpf_kfunc_call_stack_arg_timer(1, 2, 3, 4, 5, &val->timer);
}
#else
const volatile bool has_stack_arg = false;
SEC("tc")
int test_stack_arg_scalar(struct __sk_buff *skb)
{
return 0;
}
SEC("tc")
int test_stack_arg_ptr(struct __sk_buff *skb)
{
return 0;
}
SEC("tc")
int test_stack_arg_mix(struct __sk_buff *skb)
{
return 0;
}
SEC("tc")
int test_stack_arg_dynptr(struct __sk_buff *skb)
{
return 0;
}
SEC("tc")
int test_stack_arg_mem(struct __sk_buff *skb)
{
return 0;
}
SEC("tc")
int test_stack_arg_iter(struct __sk_buff *skb)
{
return 0;
}
SEC("tc")
int test_stack_arg_const_str(struct __sk_buff *skb)
{
return 0;
}
SEC("tc")
int test_stack_arg_timer(struct __sk_buff *skb)
{
return 0;
}
#endif
char _license[] SEC("license") = "GPL";

65
tools/testing/selftests/bpf/test_kmods/bpf_testmod.c
View File

@@ -825,6 +825,63 @@ __bpf_kfunc int bpf_kfunc_call_test5(u8 a, u16 b, u32 c)
return 0;
}
__bpf_kfunc u64 bpf_kfunc_call_stack_arg(u64 a, u64 b, u64 c, u64 d,
u64 e, u64 f, u64 g, u64 h)
{
return a + b + c + d + e + f + g + h;
}
__bpf_kfunc u64 bpf_kfunc_call_stack_arg_ptr(u64 a, u64 b, u64 c, u64 d, u64 e,
struct prog_test_pass1 *p)
{
return a + b + c + d + e + p->x0 + p->x1;
}
__bpf_kfunc u64 bpf_kfunc_call_stack_arg_mix(u64 a, u64 b, u64 c, u64 d, u64 e,
struct prog_test_pass1 *p, u64 f,
struct prog_test_pass1 *q)
{
return a + b + c + d + e + p->x0 + f + q->x1;
}
__bpf_kfunc u64 bpf_kfunc_call_stack_arg_dynptr(u64 a, u64 b, u64 c, u64 d, u64 e,
struct bpf_dynptr *ptr)
{
const struct bpf_dynptr_kern *kern_ptr = (void *)ptr;
return a + b + c + d + e + (kern_ptr->size & 0xFFFFFF);
}
__bpf_kfunc u64 bpf_kfunc_call_stack_arg_mem(u64 a, u64 b, u64 c, u64 d, u64 e,
void *mem, int mem__sz)
{
const unsigned char *p = mem;
u64 sum = a + b + c + d + e;
int i;
for (i = 0; i < mem__sz; i++)
sum += p[i];
return sum;
}
__bpf_kfunc u64 bpf_kfunc_call_stack_arg_iter(u64 a, u64 b, u64 c, u64 d, u64 e,
struct bpf_iter_testmod_seq *it__iter)
{
return a + b + c + d + e + it__iter->value;
}
__bpf_kfunc u64 bpf_kfunc_call_stack_arg_const_str(u64 a, u64 b, u64 c, u64 d, u64 e,
const char *str__str)
{
return a + b + c + d + e;
}
__bpf_kfunc u64 bpf_kfunc_call_stack_arg_timer(u64 a, u64 b, u64 c, u64 d, u64 e,
struct bpf_timer *timer)
{
return a + b + c + d + e;
}
static struct prog_test_ref_kfunc prog_test_struct = {
.a = 42,
.b = 108,
@@ -1288,6 +1345,14 @@ BTF_ID_FLAGS(func, bpf_kfunc_call_test2)
BTF_ID_FLAGS(func, bpf_kfunc_call_test3)
BTF_ID_FLAGS(func, bpf_kfunc_call_test4)
BTF_ID_FLAGS(func, bpf_kfunc_call_test5)
BTF_ID_FLAGS(func, bpf_kfunc_call_stack_arg)
BTF_ID_FLAGS(func, bpf_kfunc_call_stack_arg_ptr)
BTF_ID_FLAGS(func, bpf_kfunc_call_stack_arg_mix)
BTF_ID_FLAGS(func, bpf_kfunc_call_stack_arg_dynptr)
BTF_ID_FLAGS(func, bpf_kfunc_call_stack_arg_mem)
BTF_ID_FLAGS(func, bpf_kfunc_call_stack_arg_iter)
BTF_ID_FLAGS(func, bpf_kfunc_call_stack_arg_const_str)
BTF_ID_FLAGS(func, bpf_kfunc_call_stack_arg_timer)
BTF_ID_FLAGS(func, bpf_kfunc_call_test_mem_len_fail1)
BTF_ID_FLAGS(func, bpf_kfunc_call_test_mem_len_fail2)
BTF_ID_FLAGS(func, bpf_kfunc_call_test_acquire, KF_ACQUIRE | KF_RET_NULL)

20
tools/testing/selftests/bpf/test_kmods/bpf_testmod_kfunc.h
View File

@@ -26,6 +26,8 @@ struct prog_test_ref_kfunc {
};
#endif
struct bpf_iter_testmod_seq;
struct prog_test_pass1 {
int x0;
struct {
@@ -111,7 +113,23 @@ int bpf_kfunc_call_test2(struct sock *sk, __u32 a, __u32 b) __ksym;
struct sock *bpf_kfunc_call_test3(struct sock *sk) __ksym;
long bpf_kfunc_call_test4(signed char a, short b, int c, long d) __ksym;
int bpf_kfunc_call_test5(__u8 a, __u16 b, __u32 c) __ksym;
__u64 bpf_kfunc_call_stack_arg(__u64 a, __u64 b, __u64 c, __u64 d,
__u64 e, __u64 f, __u64 g, __u64 h) __ksym;
__u64 bpf_kfunc_call_stack_arg_ptr(__u64 a, __u64 b, __u64 c, __u64 d, __u64 e,
struct prog_test_pass1 *p) __ksym;
__u64 bpf_kfunc_call_stack_arg_mix(__u64 a, __u64 b, __u64 c, __u64 d, __u64 e,
struct prog_test_pass1 *p, __u64 f,
struct prog_test_pass1 *q) __ksym;
__u64 bpf_kfunc_call_stack_arg_dynptr(__u64 a, __u64 b, __u64 c, __u64 d, __u64 e,
struct bpf_dynptr *ptr) __ksym;
__u64 bpf_kfunc_call_stack_arg_mem(__u64 a, __u64 b, __u64 c, __u64 d, __u64 e,
void *mem, int mem__sz) __ksym;
__u64 bpf_kfunc_call_stack_arg_iter(__u64 a, __u64 b, __u64 c, __u64 d, __u64 e,
struct bpf_iter_testmod_seq *it__iter) __ksym;
__u64 bpf_kfunc_call_stack_arg_const_str(__u64 a, __u64 b, __u64 c, __u64 d, __u64 e,
const char *str__str) __ksym;
__u64 bpf_kfunc_call_stack_arg_timer(__u64 a, __u64 b, __u64 c, __u64 d, __u64 e,
struct bpf_timer *timer) __ksym;
void bpf_kfunc_call_test_pass_ctx(struct __sk_buff *skb) __ksym;
void bpf_kfunc_call_test_pass1(struct prog_test_pass1 *p) __ksym;
void bpf_kfunc_call_test_pass2(struct prog_test_pass2 *p) __ksym;