1 files changed, 273 insertions, 0 deletions
diff --git a/tools/testing/selftests/bpf/progs/stack_arg.c b/tools/testing/selftests/bpf/progs/stack_arg.c
new file mode 100644
index 000000000000..944e3bb603e7
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/stack_arg.c
@@ -0,0 +1,273 @@
+// 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(__TARGET_ARCH_arm64)) && \
+	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,
+					    int i, int j)
+{
+	return a + b + c + d + e + f + g + h + i + j;
+}
+
+__noinline int global_calls_many_args(int a, int b, int c)
+{
+	return static_func_many_args(a, b, c, a + 3, a + 4, a + 5, a + 6,
+				     a + 7, a + 8, a + 9);
+}
+
+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+6+7+8+9+10+20 = 75 */
+__noinline static long func_with_ptr_stack_arg(long a, long b, long c, long d,
+					       long e, long f, long g, long h,
+					       long i, struct test_data *p)
+{
+	return a + b + c + d + e + f + g + h + i + 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, a + 5, a + 6, a + 7,
+				      a + 8, &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+6+7+10+8+20 = 66 */
+__noinline static long func_with_mix_stack_args(long a, long b, long c, long d,
+						long e, long f, long g,
+						struct test_data *p,
+						long h, struct test_data *q)
+{
+	return a + b + c + d + e + f + g + p->x + h + 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, e + 1, e + 2, &p,
+					e + 3, &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)+...+(i+1) + p->x + p->y
+ *           = 2+3+4+5+6+7+8+9+10+10+20 = 84
+ */
+__noinline static long func_inner_ptr(long a, long b, long c, long d,
+				      long e, long f, long g, long h,
+				      long i, struct test_data *p)
+{
+	return a + b + c + d + e + f + g + h + i + p->x + p->y;
+}
+
+__noinline static long func_outer_ptr(long a, long b, long c, long d,
+				      long e, long f, long g, long h,
+				      long i, struct test_data *p)
+{
+	return func_inner_ptr(a + 1, b + 1, c + 1, d + 1, e + 1,
+			      f + 1, g + 1, h + 1, i + 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, a + 5, a + 6, a + 7, a + 8,
+			      &data);
+}
+
+SEC("tc")
+int test_bpf2bpf_nesting_stack_arg(void)
+{
+	return global_nesting_ptr(1, 2, 3, 4, 5);
+}
+
+/* 1+2+3+4+5+6+7+8+9+sizeof(pkt_v4) = 45+54 = 99 */
+__noinline static long func_with_dynptr(long a, long b, long c, long d,
+					long e, long f, long g, long h,
+					long i, struct bpf_dynptr *ptr)
+{
+	return a + b + c + d + e + f + g + h + i + 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, d + 2, d + 3, d + 4,
+				d + 5, &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+i+j */
+__noinline static int foo1(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;
+}
+
+/* foo2: a+b+c+d+e+f+g+h+i+j+k+l */
+__noinline static int foo2(int a, int b, int c, int d, int e,
+			   int f, int g, int h, int i, int j,
+			   int k, int l)
+{
+	return a + b + c + d + e + f + g + h + i + j + k + l;
+}
+
+/* global_two_callees calls foo1 (5 stack args) and foo2 (7 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..10) + foo2(1..12) = 55 + 78 = 133
+ *
+ * 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, a + 8, a + 9);
+	ret += foo2(a, b, c, d, e, a + 5, a + 6, a + 7, a + 8, a + 9,
+		    a + 10, a + 11);
+	return ret;
+}
+
+SEC("tc")
+int test_two_callees(void)
+{
+	return global_two_callees(1, 2, 3, 4, 5);
+}
+
+const volatile int timer_base = 10;
+
+static int timer_cb_many_args(void *map, int *key, struct bpf_timer *timer)
+{
+	int v = timer_base;
+
+	timer_result = static_func_many_args(v, v * 2, v * 3, v * 4, v * 5,
+					     v * 6, v * 7, v * 8, v * 9,
+					     v * 10);
+	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";