[PATCH bpf-next v4] selftests/bpf: Negative test case for tail call map

[PATCH bpf-next v4] selftests/bpf: Negative test case for tail call map

[Paul Chaignon]

This patch adds a negative test case for the following verifier error.

    expected prog array map for tail call

Acked-by: Yonghong Song <yonghong.song@linux.dev>
Signed-off-by: Paul Chaignon <paul.chaignon@gmail.com>
---
Changes in v4:
  - Sent an earlier version as v3 by mistake. Monday is hard...
Changes in v3:
  - Removed BPF_F_ANY_ALIGNMENT flag as suggested by Yonghong.
Changes in v2:
  - Moved the test to prog_tests format as suggested by Eduard.
  - Rebased.
  - v1: https://lore.kernel.org/bpf/7cec754c8d4cc2d93a50e9091d7ccc7f33d454d4.1751578055.git.paul.chaignon@gmail.com/

 .../selftests/bpf/prog_tests/verifier.c       |  2 ++
 .../selftests/bpf/progs/verifier_tailcall.c   | 31 +++++++++++++++++++
 2 files changed, 33 insertions(+)
 create mode 100644 tools/testing/selftests/bpf/progs/verifier_tailcall.c

diff --git a/tools/testing/selftests/bpf/prog_tests/verifier.c b/tools/testing/selftests/bpf/prog_tests/verifier.c
index c9da06741104..77ec95d4ffaa 100644
--- a/tools/testing/selftests/bpf/prog_tests/verifier.c
+++ b/tools/testing/selftests/bpf/prog_tests/verifier.c
@@ -85,6 +85,7 @@
 #include "verifier_store_release.skel.h"
 #include "verifier_subprog_precision.skel.h"
 #include "verifier_subreg.skel.h"
+#include "verifier_tailcall.skel.h"
 #include "verifier_tailcall_jit.skel.h"
 #include "verifier_typedef.skel.h"
 #include "verifier_uninit.skel.h"
@@ -219,6 +220,7 @@ void test_verifier_stack_ptr(void)            { RUN(verifier_stack_ptr); }
 void test_verifier_store_release(void)        { RUN(verifier_store_release); }
 void test_verifier_subprog_precision(void)    { RUN(verifier_subprog_precision); }
 void test_verifier_subreg(void)               { RUN(verifier_subreg); }
+void test_verifier_tailcall(void)             { RUN(verifier_tailcall); }
 void test_verifier_tailcall_jit(void)         { RUN(verifier_tailcall_jit); }
 void test_verifier_typedef(void)              { RUN(verifier_typedef); }
 void test_verifier_uninit(void)               { RUN(verifier_uninit); }
diff --git a/tools/testing/selftests/bpf/progs/verifier_tailcall.c b/tools/testing/selftests/bpf/progs/verifier_tailcall.c
new file mode 100644
index 000000000000..b4acce60fb9b
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/verifier_tailcall.c
@@ -0,0 +1,31 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/bpf.h>
+#include <bpf/bpf_helpers.h>
+#include "bpf_misc.h"
+
+struct {
+	__uint(type, BPF_MAP_TYPE_ARRAY);
+	__uint(max_entries, 1);
+	__type(key, __u32);
+	__type(value, __u32);
+} map_array SEC(".maps");
+
+SEC("socket")
+__description("invalid map type for tail call")
+__failure __msg("expected prog array map for tail call")
+__failure_unpriv
+__naked void invalid_map_for_tail_call(void)
+{
+	asm volatile ("			\
+	r2 = %[map_array] ll;	\
+	r3 = 0;				\
+	call %[bpf_tail_call];		\
+	exit;				\
+"	:
+	: __imm(bpf_tail_call),
+	  __imm_addr(map_array)
+	: __clobber_all);
+}
+
+char _license[] SEC("license") = "GPL";
-- 
2.43.0

Re: [PATCH bpf-next v4] selftests/bpf: Negative test case for tail call map

[Daniel Borkmann]

On 7/7/25 1:50 PM, Paul Chaignon wrote:
> This patch adds a negative test case for the following verifier error.
> 
>      expected prog array map for tail call
> 
> Acked-by: Yonghong Song <yonghong.song@linux.dev>
> Signed-off-by: Paul Chaignon <paul.chaignon@gmail.com>

Acked-by: Daniel Borkmann <daniel@iogearbox.net>

Re: [PATCH bpf-next v4] selftests/bpf: Negative test case for tail call map

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to bpf/bpf-next.git (master)
by Alexei Starovoitov <ast@kernel.org>:

On Mon, 7 Jul 2025 13:50:35 +0200 you wrote:
> This patch adds a negative test case for the following verifier error.
> 
>     expected prog array map for tail call
> 
> Acked-by: Yonghong Song <yonghong.song@linux.dev>
> Signed-off-by: Paul Chaignon <paul.chaignon@gmail.com>
> 
> [...]

Here is the summary with links:
  - [bpf-next,v4] selftests/bpf: Negative test case for tail call map
    https://git.kernel.org/bpf/bpf-next/c/192e3aa14529

You are awesome, thank you!
-- 
Deet-doot-dot, I am a bot.
https://korg.docs.kernel.org/patchwork/pwbot.html