linux-kernel - [PATCH bpf-next v4 4/4] bpf, arm64: Emit BTI for indirect jump target

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Message-ID: <20260114093914.2403982-5-xukuohai@huaweicloud.com>
Date: Wed, 14 Jan 2026 17:39:14 +0800
From: Xu Kuohai <xukuohai@...weicloud.com>
To: bpf@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org
Cc: Alexei Starovoitov <ast@...nel.org>,
	Daniel Borkmann <daniel@...earbox.net>,
	Andrii Nakryiko <andrii@...nel.org>,
	Martin KaFai Lau <martin.lau@...ux.dev>,
	Eduard Zingerman <eddyz87@...il.com>,
	Yonghong Song <yonghong.song@...ux.dev>,
	Puranjay Mohan <puranjay@...nel.org>,
	Anton Protopopov <a.s.protopopov@...il.com>
Subject: [PATCH bpf-next v4 4/4] bpf, arm64: Emit BTI for indirect jump target

From: Xu Kuohai <xukuohai@...wei.com>

On CPUs that support BTI, the indirect jump selftest triggers a kernel
panic because there is no BTI instructions at the indirect jump targets.

Fix it by emitting a BTI instruction for each indirect jump target.

For reference, below is a sample panic log.

Internal error: Oops - BTI: 0000000036000003 [#1]  SMP
...
Call trace:
 bpf_prog_2e5f1c71c13ac3e0_big_jump_table+0x54/0xf8 (P)
 bpf_prog_run_pin_on_cpu+0x140/0x468
 bpf_prog_test_run_syscall+0x280/0x3b8
 bpf_prog_test_run+0x22c/0x2c0

Fixes: f4a66cf1cb14 ("bpf: arm64: Add support for indirect jumps")
Signed-off-by: Xu Kuohai <xukuohai@...wei.com>
---
 arch/arm64/net/bpf_jit_comp.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/arch/arm64/net/bpf_jit_comp.c b/arch/arm64/net/bpf_jit_comp.c
index 0c4d44bcfbf4..370ae0751b9e 100644
--- a/arch/arm64/net/bpf_jit_comp.c
+++ b/arch/arm64/net/bpf_jit_comp.c
@@ -1231,6 +1231,9 @@ static int build_insn(const struct bpf_insn *insn, struct jit_ctx *ctx,
 	int ret;
 	bool sign_extend;
 
+	if (bpf_insn_is_indirect_target(ctx->prog, i))
+		emit_bti(A64_BTI_J, ctx);
+
 	switch (code) {
 	/* dst = src */
 	case BPF_ALU | BPF_MOV | BPF_X:
-- 
2.47.3