From: Yonghong Song <yonghong.song@linux.dev>
To: bpf@vger.kernel.org
Cc: Alexei Starovoitov <ast@kernel.org>,
Andrii Nakryiko <andrii@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Eduard Zingerman <eddyz87@gmail.com>,
kernel-team@fb.com
Subject: [PATCH bpf-next v2 10/10] selftests/bpf: Test kfuncs returning arena pointers by value
Date: Tue, 25 Aug 2026 13:55:03 -0700 [thread overview]
Message-ID: <20260825205503.1327012-1-yonghong.song@linux.dev> (raw)
In-Reply-To: <20260825205412.1320099-1-yonghong.song@linux.dev>
Cover the by-value struct returns a kfunc may now make: two arena
pointers filling R0:R2, and an arena pointer beside a scalar. The
existing cases for a struct and a nested struct carrying a plain pointer
stay rejected.
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
---
.../selftests/bpf/prog_tests/aggregate_ret.c | 42 +++++++++++++++++
.../bpf/progs/aggregate_ret_kfunc_arena.c | 47 +++++++++++++++++++
.../selftests/bpf/test_kmods/bpf_testmod.c | 16 +++++++
.../bpf/test_kmods/bpf_testmod_kfunc.h | 18 +++++++
4 files changed, 123 insertions(+)
create mode 100644 tools/testing/selftests/bpf/progs/aggregate_ret_kfunc_arena.c
diff --git a/tools/testing/selftests/bpf/prog_tests/aggregate_ret.c b/tools/testing/selftests/bpf/prog_tests/aggregate_ret.c
index e0b94ed10f94..07d9d6e1d6b8 100644
--- a/tools/testing/selftests/bpf/prog_tests/aggregate_ret.c
+++ b/tools/testing/selftests/bpf/prog_tests/aggregate_ret.c
@@ -1,11 +1,53 @@
// SPDX-License-Identifier: GPL-2.0
/* Copyright (c) 2026 Meta Platforms, Inc. and affiliates. */
#include <test_progs.h>
+#include <bpf/btf.h>
#include "aggregate_ret_func.skel.h"
#include "aggregate_ret_kfunc.skel.h"
+#include "aggregate_ret_kfunc_arena.skel.h"
+
+static bool testmod_has_arena_tagged_member(void)
+{
+ struct btf *vmlinux_btf, *module_btf = NULL;
+ const struct btf_type *t;
+ bool tagged = false;
+ __s32 id;
+
+ vmlinux_btf = btf__load_vmlinux_btf();
+ if (!vmlinux_btf)
+ return false;
+
+ module_btf = btf__load_module_btf("bpf_testmod", vmlinux_btf);
+ if (!module_btf)
+ goto out;
+
+ /* prog_test_ret_arena::a is 'void __arena_tag *': PTR -> TYPE_TAG -> void */
+ id = btf__find_by_name_kind(module_btf, "prog_test_ret_arena", BTF_KIND_STRUCT);
+ if (id <= 0)
+ goto out;
+
+ t = btf__type_by_id(module_btf, btf_members(btf__type_by_id(module_btf, id))[0].type);
+ if (!t || !btf_is_ptr(t))
+ goto out;
+
+ t = btf__type_by_id(module_btf, t->type);
+ tagged = t && btf_is_type_tag(t) &&
+ !strcmp(btf__name_by_offset(module_btf, t->name_off), "arena");
+
+out:
+ btf__free(module_btf);
+ btf__free(vmlinux_btf);
+
+ return tagged;
+}
void test_aggregate_ret(void)
{
RUN_TESTS(aggregate_ret_func);
RUN_TESTS(aggregate_ret_kfunc);
+
+ if (testmod_has_arena_tagged_member())
+ RUN_TESTS(aggregate_ret_kfunc_arena);
+ else
+ test__skip();
}
diff --git a/tools/testing/selftests/bpf/progs/aggregate_ret_kfunc_arena.c b/tools/testing/selftests/bpf/progs/aggregate_ret_kfunc_arena.c
new file mode 100644
index 000000000000..f68deae6c900
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/aggregate_ret_kfunc_arena.c
@@ -0,0 +1,47 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2026 Meta Platforms, Inc. and affiliates. */
+#include <vmlinux.h>
+#include <bpf/bpf_helpers.h>
+#include "bpf_misc.h"
+#include "../test_kmods/bpf_testmod_kfunc.h"
+
+void __kfunc_btf_root(void)
+{
+ asm volatile (""
+ :
+ : "r"(&bpf_kfunc_call_test_ret_arena),
+ "r"(&bpf_kfunc_call_test_ret_arena_mixed));
+}
+
+SEC("tc")
+__arch_x86_64 __arch_arm64
+__load_if_JITed()
+__success __retval(0)
+__naked int aggregate_ret_kfunc_arena(void)
+{
+ asm volatile (
+ "call %[bpf_kfunc_call_test_ret_arena];"
+ "r0 = 0;"
+ "exit;"
+ :
+ : __imm(bpf_kfunc_call_test_ret_arena)
+ : __clobber_all);
+}
+
+SEC("tc")
+__arch_x86_64 __arch_arm64
+__load_if_JITed()
+__success __retval(0)
+__naked int aggregate_ret_kfunc_arena_mixed(void)
+{
+ asm volatile (
+ "r1 = 0;"
+ "call %[bpf_kfunc_call_test_ret_arena_mixed];"
+ "r0 = 0;"
+ "exit;"
+ :
+ : __imm(bpf_kfunc_call_test_ret_arena_mixed)
+ : __clobber_all);
+}
+
+char _license[] SEC("license") = "GPL";
diff --git a/tools/testing/selftests/bpf/test_kmods/bpf_testmod.c b/tools/testing/selftests/bpf/test_kmods/bpf_testmod.c
index 76acbe29054a..81fb93ea466e 100644
--- a/tools/testing/selftests/bpf/test_kmods/bpf_testmod.c
+++ b/tools/testing/selftests/bpf/test_kmods/bpf_testmod.c
@@ -981,6 +981,20 @@ __bpf_kfunc struct prog_test_ret_ptr bpf_kfunc_call_test_ret_ptr(u64 tag)
return r;
}
+__bpf_kfunc struct prog_test_ret_arena bpf_kfunc_call_test_ret_arena(void)
+{
+ struct prog_test_ret_arena r = { .a = NULL, .b = NULL };
+
+ return r;
+}
+
+__bpf_kfunc struct prog_test_ret_arena_mixed bpf_kfunc_call_test_ret_arena_mixed(u64 tag)
+{
+ struct prog_test_ret_arena_mixed r = { .p = NULL, .tag = tag };
+
+ return r;
+}
+
__bpf_kfunc struct prog_test_ret_nested bpf_kfunc_call_test_ret_nested(u64 tag)
{
struct prog_test_ret_nested r = { .in = { .p = NULL }, .tag = tag };
@@ -1553,6 +1567,8 @@ BTF_ID_FLAGS(func, bpf_kfunc_call_test_i128)
BTF_ID_FLAGS(func, bpf_kfunc_call_test_ret_pair)
BTF_ID_FLAGS(func, bpf_kfunc_call_test_ret_fastcall, KF_FASTCALL)
BTF_ID_FLAGS(func, bpf_kfunc_call_test_ret_ptr)
+BTF_ID_FLAGS(func, bpf_kfunc_call_test_ret_arena)
+BTF_ID_FLAGS(func, bpf_kfunc_call_test_ret_arena_mixed)
BTF_ID_FLAGS(func, bpf_kfunc_call_test_ret_nested)
BTF_ID_FLAGS(func, bpf_kfunc_call_test_ret_deep)
BTF_ID_FLAGS(func, bpf_kfunc_call_test_ret_ii)
diff --git a/tools/testing/selftests/bpf/test_kmods/bpf_testmod_kfunc.h b/tools/testing/selftests/bpf/test_kmods/bpf_testmod_kfunc.h
index 52227129a49e..aebf88102dc6 100644
--- a/tools/testing/selftests/bpf/test_kmods/bpf_testmod_kfunc.h
+++ b/tools/testing/selftests/bpf/test_kmods/bpf_testmod_kfunc.h
@@ -26,6 +26,12 @@ struct prog_test_ref_kfunc {
};
#endif
+#if __has_attribute(btf_type_tag)
+#define __arena_tag __attribute__((btf_type_tag("arena")))
+#else
+#define __arena_tag
+#endif
+
struct bpf_iter_testmod_seq;
struct prog_test_pass1 {
@@ -70,6 +76,16 @@ struct prog_test_ret_ptr { /* 16 bytes: contains a pointer */
__u64 tag;
};
+struct prog_test_ret_arena { /* 16 bytes: two arena pointers */
+ void __arena_tag *a;
+ void __arena_tag *b;
+};
+
+struct prog_test_ret_arena_mixed { /* 16 bytes: an arena pointer and a scalar */
+ void __arena_tag *p;
+ __u64 tag;
+};
+
struct prog_test_ret_nested { /* 16 bytes: the pointer hides one level down */
struct {
void *p;
@@ -179,6 +195,8 @@ struct prog_test_ret_pair bpf_kfunc_call_test_ret_fastcall(__u64 a, __u64 b) __k
struct prog_test_ret_ii bpf_kfunc_call_test_ret_ii(int a, int b) __ksym;
struct prog_test_ret_ptr bpf_kfunc_call_test_ret_ptr(__u64 tag) __ksym;
struct prog_test_ret_nested bpf_kfunc_call_test_ret_nested(__u64 tag) __ksym;
+struct prog_test_ret_arena bpf_kfunc_call_test_ret_arena(void) __ksym;
+struct prog_test_ret_arena_mixed bpf_kfunc_call_test_ret_arena_mixed(__u64 tag) __ksym;
struct prog_test_ret_deep bpf_kfunc_call_test_ret_deep(__u64 v) __ksym;
struct prog_test_ret_big bpf_kfunc_call_test_ret_big(void) __ksym;
__u64 bpf_kfunc_call_stack_arg(__u64 a, __u64 b, __u64 c, __u64 d,
--
2.53.0-Meta
next prev parent reply other threads:[~2026-08-25 20:55 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-08-25 20:54 [PATCH bpf-next v2 00/10] bpf: Allow arena pointers in by-value returns Yonghong Song
2026-08-25 20:54 ` [PATCH bpf-next v2 01/10] bpf: Record each half of a paired return value in verifier diagnostics Yonghong Song
2026-08-25 21:59 ` bot+bpf-ci
2026-08-26 17:08 ` Yonghong Song
2026-08-25 20:54 ` [PATCH bpf-next v2 02/10] bpf: Drop the recursion depth argument of btf_type_is_scalar_struct() Yonghong Song
2026-08-25 20:54 ` [PATCH bpf-next v2 03/10] bpf: Add btf_type_is_arena_ptr() Yonghong Song
2026-08-25 21:59 ` bot+bpf-ci
2026-08-26 17:28 ` Yonghong Song
2026-08-25 20:54 ` [PATCH bpf-next v2 04/10] bpf: Let the by-value struct walk take the kinds of member it accepts Yonghong Song
2026-08-25 21:59 ` bot+bpf-ci
2026-08-26 17:39 ` Yonghong Song
2026-08-25 20:54 ` [PATCH bpf-next v2 05/10] bpf: Report which member makes a kfunc return type unsupported Yonghong Song
2026-08-25 21:59 ` bot+bpf-ci
2026-08-26 17:59 ` Yonghong Song
2026-08-25 20:54 ` [PATCH bpf-next v2 06/10] bpf: Allow a global function to return arena pointers by value Yonghong Song
2026-08-25 21:12 ` sashiko-bot
2026-08-26 18:40 ` Yonghong Song
2026-08-25 20:54 ` [PATCH bpf-next v2 07/10] bpf: Allow arena pointers in a by-value kfunc return Yonghong Song
2026-08-25 22:13 ` bot+bpf-ci
2026-08-26 18:57 ` Yonghong Song
2026-08-25 20:54 ` [PATCH bpf-next v2 08/10] selftests/bpf: Check the member named for an unsupported kfunc return type Yonghong Song
2026-08-25 20:54 ` [PATCH bpf-next v2 09/10] selftests/bpf: Test global functions returning arena pointers by value Yonghong Song
2026-08-25 21:59 ` bot+bpf-ci
2026-08-27 3:46 ` Yonghong Song
2026-08-25 20:55 ` Yonghong Song [this message]
2026-08-25 21:59 ` [PATCH bpf-next v2 10/10] selftests/bpf: Test kfuncs " bot+bpf-ci
2026-08-27 3:58 ` Yonghong Song
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