From 9fd5bf96ac4be2ec784598c818f672422182042c Mon Sep 17 00:00:00 2001
From: Emil Tsalapatis <emil@etsalapatis.com>
Date: Mon, 1 Jun 2026 20:41:20 -0400
Subject: [PATCH] selftests/bpf: Add tests for the new type-tag based __arena
 identifier

Add selftests that combine the new type-based __arena identifier with
the volatile qualifier both in functions' arguments and return values.
This way we test both that they are recognized as arena arguments and
that they are not sensitive to the position they are placed in the type
compared to other qualifiers.

Signed-off-by: Emil Tsalapatis <emil@etsalapatis.com>
Link: https://lore.kernel.org/r/20260602004120.17087-7-emil@etsalapatis.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
---
 .../selftests/bpf/progs/verifier_arena.c      | 67 +++++++++++++++++++
 1 file changed, 67 insertions(+)

diff --git a/tools/testing/selftests/bpf/progs/verifier_arena.c b/tools/testing/selftests/bpf/progs/verifier_arena.c
index 89d72c8d756a..df0e22d1a29b 100644
--- a/tools/testing/selftests/bpf/progs/verifier_arena.c
+++ b/tools/testing/selftests/bpf/progs/verifier_arena.c
@@ -607,4 +607,71 @@ int non_arena_ptr_add_to_arena_ptr(void *ctx)
 
 #endif
 
+static __noinline
+u32 __arena *check_arena_arg_nonglobal(u32 __arena *arg)
+{
+	volatile u32 val = *arg;
+
+	*arg = val + 1;
+
+	return arg;
+}
+
+__weak
+u32 __arena *check_arena_arg_global(u32 __arena *arg)
+{
+	volatile u32 val = *arg;
+
+	*arg = val + 1;
+
+	return arg;
+}
+
+__weak
+u32 volatile __arena *check_arena_arg_quals1(u32 volatile __arena *arg1, u32 __arena volatile *arg2)
+{
+	*arg1 = *arg1 + 1;
+	*arg2 = *arg1 + 1;
+
+	return arg2;
+}
+
+__weak
+u32 __arena volatile *check_arena_arg_quals2(u32 volatile __arena *arg1, u32 __arena volatile *arg2)
+{
+	*arg1 = *arg1 + 1;
+	*arg2 = *arg2 + 1;
+
+	return arg2;
+}
+
+SEC("syscall")
+__success __retval(0)
+int check_arena_arg_ret(void *ctx)
+{
+	u32 __arena *page = bpf_arena_alloc_pages(&arena, NULL, 1, NUMA_NO_NODE, 0);
+	u32 __arena *arg = page;
+	u32 __arena volatile *arg1;
+	u32 __arena volatile *ret1;
+	u32 volatile __arena *arg2;
+	u32 volatile __arena *ret2;
+
+	if (!arg)
+		return 1;
+
+	/* Make sure we use {arg, ret}{1, 2}. */
+
+	arg = check_arena_arg_nonglobal(page);
+	arg = check_arena_arg_global(arg);
+
+	arg1 = arg2 = page;
+	ret1 = check_arena_arg_quals1(arg1, arg2);
+	ret2 = check_arena_arg_quals2(arg1, arg2);
+
+	if (!(*ret1 ||*ret2))
+		return -EINVAL;
+
+	return 0;
+}
+
 char _license[] SEC("license") = "GPL";