From nobody Tue Feb 10 17:03:02 2026 Received: from mail.loongson.cn (mail.loongson.cn [114.242.206.163]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 0369D15FCEB for ; Tue, 30 Jul 2024 06:19:09 +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=1722320352; cv=none; b=XIW5VgwSeu+mrz7R3hLQZs+/bnFJvI2KKbHBJ/BRQ8RdGk6ef1PWtuELY8GeNNaxdyU1EjoG7fImkTOgCFOWIk/WqCWDTtYJCoTanEsfrdatr3TMv2Fzr8nKaAi4lf3NJ72LCE+llXZATBeEThT/A1zpgWqdqj1hL7NWx8cRCDY= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1722320352; c=relaxed/simple; bh=vz2hKdAFp86DZHllck2S/sUsgOdMhETXVboVbB5vGXk=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=nTs/pzDv1dUiWI0XeTDm6bOn0pOpyQs51g0aAQO9knZY+H2IBI8xn7OGKPIl5asUP7HJozQYDBY2rJuoCeYyorXWKGX2FkhJwJPl6zfIEfMvYrdr2K60pXyAOgCM9e8W00qJ5MrtrmJban00PwdVbUvQ5zEk2sKfOcoE3ulKYbE= 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 [113.200.148.30]) by gateway (Coremail) with SMTP id _____8CxruvXhahmz0MEAA--.14804S3; Tue, 30 Jul 2024 14:19:03 +0800 (CST) Received: from linux.localdomain (unknown [113.200.148.30]) by front1 (Coremail) with SMTP id qMiowMAxX8fVhahmehYGAA--.30051S3; Tue, 30 Jul 2024 14:19:02 +0800 (CST) From: Tiezhu Yang To: Josh Poimboeuf , Peter Zijlstra , Huacai Chen Cc: loongarch@lists.linux.dev, linux-kernel@vger.kernel.org Subject: [PATCH 1/2] objtool/LoongArch: Restrict stack operation instruction Date: Tue, 30 Jul 2024 14:19:00 +0800 Message-ID: <20240730061901.21485-2-yangtiezhu@loongson.cn> X-Mailer: git-send-email 2.42.0 In-Reply-To: <20240730061901.21485-1-yangtiezhu@loongson.cn> References: <20240730061901.21485-1-yangtiezhu@loongson.cn> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-CM-TRANSID: qMiowMAxX8fVhahmehYGAA--.30051S3 X-CM-SenderInfo: p1dqw3xlh2x3gn0dqz5rrqw2lrqou0/ X-Coremail-Antispam: 1Uk129KBj93XoW7ZF17Cr4UCw1kXr4fZw4DWrX_yoW8Kryfpr Zru3W3GFWUurn7Zw1vqayUWrZxGFs3XrySgF4fJa4xCr13Xrn7Xr1Ig3WYkFyvqw45K3y0 grWfAry7JF4qvagCm3ZEXasCq-sJn29KB7ZKAUJUUUUr529EdanIXcx71UUUUU7KY7ZEXa sCq-sGcSsGvfJ3Ic02F40EFcxC0VAKzVAqx4xG6I80ebIjqfuFe4nvWSU5nxnvy29KBjDU 0xBIdaVrnRJUUU9Yb4IE77IF4wAFF20E14v26r1j6r4UM7CY07I20VC2zVCF04k26cxKx2 IYs7xG6rWj6s0DM7CIcVAFz4kK6r1Y6r17M28lY4IEw2IIxxk0rwA2F7IY1VAKz4vEj48v e4kI8wA2z4x0Y4vE2Ix0cI8IcVAFwI0_Gr0_Xr1l84ACjcxK6xIIjxv20xvEc7CjxVAFwI 0_Gr0_Cr1l84ACjcxK6I8E87Iv67AKxVW8Jr0_Cr1UM28EF7xvwVC2z280aVCY1x0267AK xVW8Jr0_Cr1UM2kKe7AKxVWUXVWUAwAS0I0E0xvYzxvE52x082IY62kv0487Mc804VCY07 AIYIkI8VC2zVCFFI0UMc02F40EFcxC0VAKzVAqx4xG6I80ewAv7VC0I7IYx2IY67AKxVWU AVWUtwAv7VC2z280aVAFwI0_Jr0_Gr1lOx8S6xCaFVCjc4AY6r1j6r4UM4x0Y48IcxkI7V AKI48JMxAIw28IcxkI7VAKI48JMxC20s026xCaFVCjc4AY6r1j6r4UMxCIbckI1I0E14v2 6r1Y6r17MI8I3I0E5I8CrVAFwI0_Jr0_Jr4lx2IqxVCjr7xvwVAFwI0_JrI_JrWlx4CE17 CEb7AF67AKxVWUAVWUtwCIc40Y0x0EwIxGrwCI42IY6xIIjxv20xvE14v26r1I6r4UMIIF 0xvE2Ix0cI8IcVCY1x0267AKxVWUJVW8JwCI42IY6xAIw20EY4v20xvaj40_Jr0_JF4lIx AIcVC2z280aVAFwI0_Jr0_Gr1lIxAIcVC2z280aVCY1x0267AKxVWUJVW8JbIYCTnIWIev Ja73UjIFyTuYvjxUc0eHDUUUU Content-Type: text/plain; charset="utf-8" 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 ... addi.d $sp, $fp, -32 ld.d $ra, $sp, 24 ld.d $fp, $sp, 16 addi.d $sp, $sp, 32 fp points to the stack top, it is only used to save and restore the original sp and is not used as cfa base for arch_callee_saved_reg(). In the case OP_SRC_ADD of update_cfi_state(), the above rare case is not handled so that lead to a wrong stack size, then there exists a objtool warning "do_syscall+0x11c: return with modified stack frame". Because the fp related instructions do not modify the stack frame, no need to decode them, just restrict stack operation instruction only with the single case "addi.d sp,sp,si12". By the way, if fp is used as cfa base for arch_callee_saved_reg() (there is no this behavior on LoongArch at present), then it needs to decode the related instructions and modify update_cfi_state(). Reported-by: kernel test robot Closes: https://lore.kernel.org/oe-kbuild-all/202407201336.mW8dj1VB-lkp@int= el.com/ Fixes: b2d23158e6c8 ("objtool/LoongArch: Implement instruction decoder") Signed-off-by: Tiezhu Yang --- tools/objtool/arch/loongarch/decode.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/tools/objtool/arch/loongarch/decode.c b/tools/objtool/arch/loo= ngarch/decode.c index aee479d2191c..6a34af675cee 100644 --- a/tools/objtool/arch/loongarch/decode.c +++ b/tools/objtool/arch/loongarch/decode.c @@ -121,8 +121,8 @@ static bool decode_insn_reg2i12_fomat(union loongarch_i= nstruction inst, { switch (inst.reg2i12_format.opcode) { case addid_op: - if ((inst.reg2i12_format.rd =3D=3D CFI_SP) || (inst.reg2i12_format.rj = =3D=3D CFI_SP)) { - /* addi.d sp,sp,si12 or addi.d fp,sp,si12 */ + if ((inst.reg2i12_format.rd =3D=3D CFI_SP) && (inst.reg2i12_format.rj = =3D=3D CFI_SP)) { + /* addi.d sp,sp,si12 */ insn->immediate =3D sign_extend64(inst.reg2i12_format.immediate, 11); ADD_OP(op) { op->src.type =3D OP_SRC_ADD; --=20 2.42.0