[PATCH bpf v2 08/11] selftests/bpf: Test for mixed arena/nonarena code paths
From: Emil Tsalapatis <emil@etsalapatis.com>
Date: 2026-09-22 17:20:47
Also in:
bpf
Subsystem:
bpf [general] (safe dynamic programs and tools), bpf [selftests] (test runners & infrastructure), kernel selftest framework, the rest · Maintainers:
Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko, Eduard Zingerman, Kumar Kartikeya Dwivedi, Shuah Khan, Shuah Khan, Linus Torvalds
Add a selftest to confirm the verifier rejects ALU operations that return arena or non-arena results depending on code path. Signed-off-by: Emil Tsalapatis <emil@etsalapatis.com> --- .../selftests/bpf/progs/verifier_arena.c | 49 +++++++++++++++++++ 1 file changed, 49 insertions(+)
diff --git a/tools/testing/selftests/bpf/progs/verifier_arena.c b/tools/testing/selftests/bpf/progs/verifier_arena.c
index 332322c9b..1ce9c4b78 100644
--- a/tools/testing/selftests/bpf/progs/verifier_arena.c
+++ b/tools/testing/selftests/bpf/progs/verifier_arena.c@@ -561,6 +561,55 @@ int arena_ptr_add_arena_ptr(void *ctx) return 0; } +SEC("syscall") +__failure __msg("same insn cannot be used with and without arena pointer") +int mixed_arena_scalar_alu64_scalar_first(void *ctx) +{ + volatile register __u64 reg asm("r3"); + __u32 pick_arena = bpf_get_prandom_u32(); + + reg = 1ULL << 32; + + if (pick_arena) { + asm volatile ( + "r9 = %[arena] ll;" + "%[reg] = 0;" + "%[reg] = addr_space_cast(%[reg], 0x0, 0x1);" + : [reg] "=r"(reg) + : __imm_addr(arena) + : "r9" + ); + } + + reg += 1; + + return 0; +} + +SEC("syscall") +__failure __msg("same insn cannot be used with and without arena pointer") +int mixed_arena_scalar_alu64_arena_first(void *ctx) +{ + volatile register __u64 reg asm("r3"); + __u32 pick_scalar = bpf_get_prandom_u32(); + + asm volatile ( + "r9 = %[arena] ll;" + "%[reg] = 0;" + "%[reg] = addr_space_cast(%[reg], 0x0, 0x1);" + : [reg] "=r"(reg) + : __imm_addr(arena) + : "r9" + ); + + if (pick_scalar) + reg = 1ULL << 32; + + reg += 1; + + return 0; +} + SEC("syscall") __success __retval(0) int scalar_xor_arena_ptr(void *ctx)
--
2.54.0