From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail.loongson.cn (mail.loongson.cn [114.242.206.163]) by smtp.subspace.kernel.org (Postfix) with ESMTP id BF60E1DA32 for ; Tue, 30 Jul 2024 10:57:52 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=114.242.206.163 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1722337075; cv=none; b=Cq7VKsBa3MiIyM7AffNa1Qcm7hIDDJXB0qnR15SmldAMVBgQ3IumtTNkEH4QWB+HyGwWmzHY+nFSDvSOoHQswmr7y84oDZT2MoL16G4X61MwhpDx8GSriNcxpEAvH3t5ETpxqxy6+azwt5gfP+wZ70tyP/YVe49nr73jROf9zdA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1722337075; c=relaxed/simple; bh=fDp1d/mg0Zzqb9iZx2iJYS7OWCBh7c2Kr/tOqv+/pqE=; h=Subject:To:Cc:References:From:Message-ID:Date:MIME-Version: In-Reply-To:Content-Type; b=S2xBYEQYif/Nwr4FoR3eCGfGEsbHVsGKo+E+cBqyR/dXjRCtOtL5maN16T1igi9g7f+KebHRAakUmZytXkn0n9pCUl/wkCC9cT9aLlWXw/vkX1bdP+5JMuOhClMm2Pnu3rWp0S2nZAW8FpZJVZGjfKLyUc+Gw6IbxPElJzyChzE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=loongson.cn; spf=pass smtp.mailfrom=loongson.cn; arc=none smtp.client-ip=114.242.206.163 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=loongson.cn Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=loongson.cn Received: from loongson.cn (unknown [111.9.175.10]) by gateway (Coremail) with SMTP id _____8Cxe+oux6hmmGwEAA--.15664S3; Tue, 30 Jul 2024 18:57:50 +0800 (CST) Received: from [10.136.12.26] (unknown [111.9.175.10]) by front1 (Coremail) with SMTP id qMiowMAxX8csx6hm5XMGAA--.32005S3; Tue, 30 Jul 2024 18:57:50 +0800 (CST) Subject: Re: [PATCH 1/2] objtool/LoongArch: Restrict stack operation instruction To: Tiezhu Yang , Josh Poimboeuf , Peter Zijlstra , Huacai Chen Cc: loongarch@lists.linux.dev, linux-kernel@vger.kernel.org References: <20240730061901.21485-1-yangtiezhu@loongson.cn> <20240730061901.21485-2-yangtiezhu@loongson.cn> <4ac60afc-de6b-acf6-c9e6-1f45c0680dbe@loongson.cn> <6ee45e77-eb22-c4ac-ee47-6a329236eeb7@loongson.cn> From: Jinyang He Message-ID: Date: Tue, 30 Jul 2024 18:57:48 +0800 User-Agent: Mozilla/5.0 (X11; Linux loongarch64; rv:68.0) Gecko/20100101 Thunderbird/68.7.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 In-Reply-To: <6ee45e77-eb22-c4ac-ee47-6a329236eeb7@loongson.cn> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US X-CM-TRANSID:qMiowMAxX8csx6hm5XMGAA--.32005S3 X-CM-SenderInfo: pkhmx0p1dqwqxorr0wxvrqhubq/ X-Coremail-Antispam: 1Uk129KBj93XoW7ZF17Cr45Jr13uw17GF45Jwc_yoW8Kw18pF 97J3Z8JFWkG34IkrnFqF1DWa4qyrW7Xw1UGr15ta4Fyrs8AF12gr4rXFW29FnxXrs3Jw1j krWfZrWxuFyqqFXCm3ZEXasCq-sJn29KB7ZKAUJUUUU5529EdanIXcx71UUUUU7KY7ZEXa sCq-sGcSsGvfJ3Ic02F40EFcxC0VAKzVAqx4xG6I80ebIjqfuFe4nvWSU5nxnvy29KBjDU 0xBIdaVrnRJUUUv2b4IE77IF4wAFF20E14v26r1j6r4UM7CY07I20VC2zVCF04k26cxKx2 IYs7xG6rWj6s0DM7CIcVAFz4kK6r1Y6r17M28lY4IEw2IIxxk0rwA2F7IY1VAKz4vEj48v e4kI8wA2z4x0Y4vE2Ix0cI8IcVAFwI0_Jr0_JF4l84ACjcxK6xIIjxv20xvEc7CjxVAFwI 0_Gr0_Cr1l84ACjcxK6I8E87Iv67AKxVW8Jr0_Cr1UM28EF7xvwVC2z280aVCY1x0267AK xVW8Jr0_Cr1UM2AIxVAIcxkEcVAq07x20xvEncxIr21l57IF6xkI12xvs2x26I8E6xACxx 1l5I8CrVACY4xI64kE6c02F40Ex7xfMcIj6xIIjxv20xvE14v26r1Y6r17McIj6I8E87Iv 67AKxVWUJVW8JwAm72CE4IkC6x0Yz7v_Jr0_Gr1lF7xvr2IY64vIr41lc7I2V7IY0VAS07 AlzVAYIcxG8wCF04k20xvY0x0EwIxGrwCFx2IqxVCFs4IE7xkEbVWUJVW8JwC20s026c02 F40E14v26r1j6r18MI8I3I0E7480Y4vE14v26r106r1rMI8E67AF67kF1VAFwI0_JF0_Jw 1lIxkGc2Ij64vIr41lIxAIcVC0I7IYx2IY67AKxVWUJVWUCwCI42IY6xIIjxv20xvEc7Cj xVAFwI0_Jr0_Gr1lIxAIcVCF04k26cxKx2IYs7xG6r1j6r1xMIIF0xvEx4A2jsIE14v26r 1j6r4UMIIF0xvEx4A2jsIEc7CjxVAFwI0_Jr0_GrUvcSsGvfC2KfnxnUUI43ZEXa7IU8zw Z7UUUUU== On 2024-07-30 17:49, Tiezhu Yang wrote: > On 07/30/2024 05:28 PM, Jinyang He wrote: >> On 2024-07-30 14:19, Tiezhu Yang wrote: >> >>> After commit a0f7085f6a63 ("LoongArch: Add RANDOMIZE_KSTACK_OFFSET >>> support"), the code flow of do_syscall() was changed when compiled >>> with GCC due to the secondary stack of add_random_kstack_offset(), >>> something like this: >>> >>>    addi.d          $sp, $sp, -32 >>>    st.d            $fp, $sp, 16 >>>    st.d            $ra, $sp, 24 >>>    addi.d          $fp, $sp, 32 >>>    ... >>>    sub.d           $sp, $sp, $t1 >> Have you checked the ORC info whether is right or tried backtrace which >> passed do_syscall? The "sub.d $sp, $sp, $t1" has modified the $sp so the >> $sp cannot express CFA here. This patch just clear the warning but >> ignore >> the validity of ORC info. The wrong ORC info may cause illegally access >> memory when backtrace. > > I did testing many times before submitting, the call trace is > expected when testing "echo l > /proc/sysrq-trigger". Make sure the RANDOMIZE_KSTACK_OFFSET is enable. I tested it by CONFIG_RANDOMIZE_KSTACK_OFFSET_DEFAULT=y on qemu and it did not show the frame about handle_syscall. On the other hand, $ ./tools/objtool/objtool --dump arch/loongarch/kernel/syscall.o .noinstr.text+0:type:call sp:sp +   0 fp: (und)  ra: (und)  signal:0 .noinstr.text+4:type:call sp:sp +  32 fp: (und)  ra: (und)  signal:0 .noinstr.text+8:type:call sp:sp +  32 fp:prevsp + -16 ra: (und) signal:0 .noinstr.text+c:type:call sp:sp +  32 fp:prevsp + -16 ra:prevsp + -8 signal:0 .noinstr.text+e4:type:call sp:sp +  32 fp:prevsp + -16 ra: (und) signal:0 .noinstr.text+e8:type:call sp:sp +  32 fp: (und)  ra: (und) signal:0 .noinstr.text+ec:type:call sp:sp +   0 fp: (und)  ra: (und) signal:0 .noinstr.text+f0:type:? sp: (und)  fp: (und)  ra: (und)  signal:0 .noinstr.text+100:type:call sp:sp +  32 fp:prevsp + -16 ra:prevsp + -8 signal:0 .noinstr.text+118:type:? sp: (und)  fp: (und)  ra: (und)  signal:0 $ objdump -d arch/loongarch/kernel/syscall.o | grep "sub.*sp.*sp"   70:    0011b463     sub.d           $sp, $sp, $t1 Obviously the ORC info is wrong. (Assume the backtrace PC is 0x74, how to find the previous frame?)