From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id D7BA4C433F5 for ; Mon, 10 Oct 2022 10:47:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:Date: Message-ID:From:References:CC:To:Subject:Reply-To:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:List-Owner; bh=75Q3j5ntIYAhct79+xFU+xTQsEBz17zXp/bV9dKZnNE=; b=ESyqlwhxViygyQsQeP4mywNCNz 5eObrQILg1PmhVI1PYhrvVQpB7ez9j1O+I8TlF+3l7VxYtnc9yFJd22NS7XDkM7wv0KbMdyOOg4s0 HGv33r1tumqLU7DS8gtlOmIuC3I0hvFvRyQywRC2CGhPogtsf8ydCMwo2CjZns9MD8krKWTmU2jqC 85PI8lWtRtsP0K3UAnTNi8OD386QIQdvF5SGImn4GxcYjk0kZ2UTDTWWkUI6sxB+XmHdyBvA96mKo xI+h8k65yvfG6otQ5WgfYCNmxNJxiwF1JXGfUSE/9JATNtgBMLV7Qvd1a2ETTFBeA47IG+rlxapgY 1QU5/hsg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1ohqIy-000SQg-KP; Mon, 10 Oct 2022 10:46:40 +0000 Received: from szxga02-in.huawei.com ([45.249.212.188]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1ohqIu-000SN5-8G for linux-arm-kernel@lists.infradead.org; Mon, 10 Oct 2022 10:46:38 +0000 Received: from dggpemm500023.china.huawei.com (unknown [172.30.72.57]) by szxga02-in.huawei.com (SkyGuard) with ESMTP id 4MmFpc6h1yzVhsM; Mon, 10 Oct 2022 18:42:00 +0800 (CST) Received: from dggpemm500006.china.huawei.com (7.185.36.236) by dggpemm500023.china.huawei.com (7.185.36.83) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.31; Mon, 10 Oct 2022 18:46:24 +0800 Received: from [10.174.178.55] (10.174.178.55) by dggpemm500006.china.huawei.com (7.185.36.236) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.31; Mon, 10 Oct 2022 18:46:24 +0800 Subject: Re: [PATCH v2 2/2] ARM: Make the dumped instructions are consistent with the disassembled ones To: Ard Biesheuvel CC: Russell King , , References: <20221010095346.1957-1-thunder.leizhen@huawei.com> <20221010095346.1957-3-thunder.leizhen@huawei.com> From: "Leizhen (ThunderTown)" Message-ID: <08054412-06de-3c3e-48b8-1a7eb327a2d0@huawei.com> Date: Mon, 10 Oct 2022 18:46:12 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.7.0 MIME-Version: 1.0 In-Reply-To: Content-Language: en-US X-Originating-IP: [10.174.178.55] X-ClientProxiedBy: dggems701-chm.china.huawei.com (10.3.19.178) To dggpemm500006.china.huawei.com (7.185.36.236) X-CFilter-Loop: Reflected X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20221010_034636_663906_F4555FC7 X-CRM114-Status: GOOD ( 18.63 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 2022/10/10 18:10, Ard Biesheuvel wrote: > On Mon, 10 Oct 2022 at 11:56, Zhen Lei wrote: >> >> In ARM, the mapping of instruction memory is always little-endian, except >> some BE-32 supported ARM architectures. Such as ARMv7-R, its instruction >> endianness may be BE-32. Of course, its data endianness will also be BE-32 >> mode. Due to two negatives make a positive, the instruction stored in the >> register after reading is in little-endian format. But for the case of >> BE-8, the instruction endianness is LE, the instruction stored in the >> register after reading is in big-endian format, which is inconsistent >> with the disassembled one. >> >> For example: >> The content of disassembly: >> c0429ee8: e3500000 cmp r0, #0 >> c0429eec: 159f2044 ldrne r2, [pc, #68] >> c0429ef0: 108f2002 addne r2, pc, r2 >> c0429ef4: 1882000a stmne r2, {r1, r3} >> c0429ef8: e7f000f0 udf #0 >> >> The output of undefined instruction exception: >> Internal error: Oops - undefined instruction: 0 [#1] SMP ARM >> ... ... >> Code: 000050e3 44209f15 02208f10 0a008218 (f000f0e7) >> >> This inconveniences the checking of instructions. What's worse is that, >> for somebody who don't know about this, might think the instructions are >> all broken. >> >> So, when CONFIG_CPU_ENDIAN_BE8=y, let's convert the instructions to >> little-endian format before they are printed. The conversion result is >> as follows: >> Code: e3500000 159f2044 108f2002 1882000a (e7f000f0) >> >> Signed-off-by: Zhen Lei >> --- >> arch/arm/kernel/traps.c | 7 +++++++ >> 1 file changed, 7 insertions(+) >> >> diff --git a/arch/arm/kernel/traps.c b/arch/arm/kernel/traps.c >> index 34aa80c09c508c1..50b00c9091f079d 100644 >> --- a/arch/arm/kernel/traps.c >> +++ b/arch/arm/kernel/traps.c >> @@ -193,6 +193,13 @@ static void dump_instr(const char *lvl, struct pt_regs *regs) >> bad = get_user(val, &((u32 __user *)addr)[i]); >> } >> >> + if (IS_ENABLED(CONFIG_CPU_ENDIAN_BE8)) { >> + if (thumb) >> + val = (__force unsigned int)cpu_to_le16(val); > > Better use swab16() here instead of the ugly __force cast, given that > the swab is going to occur unconditionally here. Good idea. > > >> + else >> + val = (__force unsigned int)cpu_to_le32(val); > > and swab32() here OK > > >> + } >> + >> if (!bad) >> p += sprintf(p, i == 0 ? "(%0*x) " : "%0*x ", >> width, val); >> -- >> 2.25.1 >> >> >> _______________________________________________ >> linux-arm-kernel mailing list >> linux-arm-kernel@lists.infradead.org >> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel > . > -- Regards, Zhen Lei _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel