From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mta0.migadu.com (out-198.mta0.migadu.com [91.218.175.198]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 8C09C4E13FD for ; Fri, 25 Sep 2026 17:54:21 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.198 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790358868; cv=none; b=P87zyZplpFkNwACzXSx0VkZ/tu23Jqjt+mk0n6CvxR+sApdgMxgmqsDekprdQauDLR3brBg0Er9N2EH0PaSwzHOZ7o670RnqCe+A/hFncnL1c6BYAhWbY7xYoNqZ8OZcnk0MK8gLCouMYuxnPSNrL5z/W8i+Tr3EY/jTBRjf1ko= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790358868; c=relaxed/simple; bh=p67gamRmEwkUu95LFXAoYMitz/njw63lJRtWJbeZLy4=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:To:Cc; b=YTaIBYN8VgbKsNNo2FrvY62ewASLLkoW2u8+AjY+qQtSIAtI8mxsaG1EdwRZcvABMyHSbxAbFicR6WYT7yRqPgPUi9wO22dFh4tbHJMjmOCHpp68nbCzSSlNcjvMqM3tvtSkKSEn0m14BGaEAcFwG+3ntaS6OtHjXH0I/UW3QAM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=nZ6TWux4; arc=none smtp.client-ip=91.218.175.198 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="nZ6TWux4" X-Envelope-To: linux-kernel@vger.kernel.org DKIM-Signature: a=rsa-sha256; bh=p67gamRmEwkUu95LFXAoYMitz/njw63lJRtWJbeZLy4=; c=simple/simple; d=linux.dev; h=from:to:subject:date:message-id:mime-version:content-type; s=key1; t=1790358857; v=1; x=1790963657; b=nZ6TWux4hEkIuyUUuz62ChOXqadne3nZcyxhChnRoUTy83si/kH855Kp0oqCjfoXKzfFrhQu 1rERs5x2xiCxeKDTmQ4oad/S2LKhGzqsW9cjNjJD1jPHL3ZkwVcZedL2FCYri09rR9jBG6YmEPB 8ZVtYPddGXISW1JsSQnPHdbE= X-Envelope-To: linux-kernel@vger.kernel.org Received: by smtp.migadu.com with ESMTPS id c0aea6dd7cc8ad8e; Fri, 25 Sep 2026 17:54:06 +0000 X-Mizu-Trace-ID: c0aea6dd7cc8ad8e X-Migadu-Flow: FLOW_OUT From: "Jose Fernandez (Anthropic)" Date: Fri, 25 Sep 2026 17:53:21 +0000 Subject: [PATCH bpf] bpf, arm64: Fix jited line info off by kCFI hash Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20260925-b4-arm64-bpf-linfo-cfi-v1-1-e930ab335170@linux.dev> X-B4-Tracking: v=1; b=H4sIABC1tmoC/22NzQ6CMBCEX4Xs2Q2IgOCrGA/tupVVbMnWv4Tw7 ha8epyZb2YmiKzCEQ7ZBMoviRJ8EttNBtQbf2GUc9JQFmVTdGWNtkKj96ZCOzocxLuA5ARdTbu 223NVtASpPCo7+azDR0gonH5mfNor02OZXDBrIqNV46lfrGHMKbyD3ljzNfpzBfP8BektMb+2A AAA X-Change-ID: 20260925-b4-arm64-bpf-linfo-cfi-f5c3897e408c To: Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Eduard Zingerman , Kumar Kartikeya Dwivedi , Martin KaFai Lau , Song Liu , Yonghong Song , Jiri Olsa , Emil Tsalapatis , Ihor Solodrai , Puranjay Mohan , Xu Kuohai , Catalin Marinas , Will Deacon , Mark Rutland , Maxwell Bland , Sami Tolvanen Cc: bpf@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Sashiko , "Jose Fernandez (Anthropic)" X-Mailer: b4 0.15.2 With CONFIG_CFI=y, the jited line info of every arm64 BPF program is off by one instruction, so tools that use it show the wrong source line. The JIT counts ctx.offset[] from ctx.ro_image. Since commit 710618c760c0 ("arm64/cfi,bpf: Support kCFI + BPF on arm64"), prog->bpf_func starts past the 4-byte kCFI hash, and bpf_prog_fill_jited_linfo() adds the offsets to prog->bpf_func. Subtract cfi_get_offset() from the offsets before the fill, and move the fill after bpf_prog_update_insn_ptrs(), which needs the offsets relative to ctx.ro_image. Fixes: 710618c760c0 ("arm64/cfi,bpf: Support kCFI + BPF on arm64") Reported-by: Sashiko Closes: https://lore.kernel.org/all/20260904014748.C04AA1F000E9@smtp.kernel.org/ Reported-by: Alexei Starovoitov Closes: https://lore.kernel.org/all/DLNXZ2WK7TPD.2RZBUNRS4FA4L@gmail.com/ Assisted-by: LLM Signed-off-by: Jose Fernandez (Anthropic) --- Tested in an arm64 KVM guest with CONFIG_CFI=y. Without this patch every line info entry after a function's first was off by one instruction, and with it every entry was correct. --- arch/arm64/net/bpf_jit_comp.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) diff --git a/arch/arm64/net/bpf_jit_comp.c b/arch/arm64/net/bpf_jit_comp.c index c5f55d6161fee..cdc98efc1acf0 100644 --- a/arch/arm64/net/bpf_jit_comp.c +++ b/arch/arm64/net/bpf_jit_comp.c @@ -2345,14 +2345,21 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_verifier_env *env, struct bpf_pr /* offset[prog->len] is the size of program */ for (i = 0; i <= prog->len; i++) ctx.offset[i] *= AARCH64_INSN_SIZE; - bpf_prog_fill_jited_linfo(prog, ctx.offset + 1); /* * The bpf_prog_update_insn_ptrs function expects offsets to * point to the first byte of the jitted instruction (unlike - * the bpf_prog_fill_jited_linfo above, which, for historical + * the bpf_prog_fill_jited_linfo below, which, for historical * reasons, expects to point to the next instruction) */ bpf_prog_update_insn_ptrs(prog, ctx.offset, ctx.ro_image); + /* + * Line info is relative to prog->bpf_func, which starts + * cfi_get_offset() bytes into ro_image. Shift the offsets here, + * after bpf_prog_update_insn_ptrs(), which needs them unshifted. + */ + for (i = 0; i <= prog->len; i++) + ctx.offset[i] -= cfi_get_offset(); + bpf_prog_fill_jited_linfo(prog, ctx.offset + 1); out_off: if (!ro_header && priv_stack_ptr) { free_percpu(priv_stack_ptr); --- base-commit: ad139384ecddb6f3e7e3c3c12765aafae0e39670 change-id: 20260925-b4-arm64-bpf-linfo-cfi-f5c3897e408c Best regards, -- Jose Fernandez (Anthropic)