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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1C77AC433F5 for ; Fri, 15 Oct 2021 03:12:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E788361056 for ; Fri, 15 Oct 2021 03:12:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233109AbhJODOQ (ORCPT ); Thu, 14 Oct 2021 23:14:16 -0400 Received: from out30-56.freemail.mail.aliyun.com ([115.124.30.56]:40478 "EHLO out30-56.freemail.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229526AbhJODOL (ORCPT ); Thu, 14 Oct 2021 23:14:11 -0400 X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R651e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e04357;MF=tianjia.zhang@linux.alibaba.com;NM=1;PH=DS;RN=5;SR=0;TI=SMTPD_---0Us2T59N_1634267522; Received: from B-455UMD6M-2027.local(mailfrom:tianjia.zhang@linux.alibaba.com fp:SMTPD_---0Us2T59N_1634267522) by smtp.aliyun-inc.com(127.0.0.1); Fri, 15 Oct 2021 11:12:03 +0800 Subject: Re: [RFC] crypto/sm4: Fix objtool/libelf warning To: Peter Zijlstra Cc: herbert@gondor.apana.org.au, linux-kernel@vger.kernel.org, Josh Poimboeuf , x86@kernel.org References: <20211007202204.GT174703@worktop.programming.kicks-ass.net> <8e35ba6d-f876-4726-a8e7-a0d80b0186f2@linux.alibaba.com> From: Tianjia Zhang Message-ID: <6759f51a-4f35-5a68-4934-24947f07e85b@linux.alibaba.com> Date: Fri, 15 Oct 2021 11:12:02 +0800 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:78.0) Gecko/20100101 Thunderbird/78.14.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Peter, On 10/14/21 10:56 PM, Peter Zijlstra wrote: > On Thu, Oct 14, 2021 at 06:29:55PM +0800, Tianjia Zhang wrote: >> Hi Peter, >> >> On 10/8/21 4:22 AM, Peter Zijlstra wrote: >>> Hi, >>> >>> objtool is yielding the obscure libelf warning: >>> >>> vmlinux.o: warning: objtool: elf_update: invalid section entry size >>> >>> Which I tracked down to section: >>> >>> [3023] .rodata.cst164 PROGBITS 0000000000000000 1ab501e0 000154 a4 AM 0 0 16 >>> >>> Which has a section size of 0x154 (340) and an entry size of 0xa4 (164). >>> An obvious mis-match. >>> >>> From there, git-grep quickly yields: >>> >>> arch/x86/crypto/sm4-aesni-avx-asm_64.S:.section .rodata.cst164, "aM", @progbits, 164 >>> arch/x86/crypto/sm4-aesni-avx2-asm_64.S:.section .rodata.cst164, "aM", @progbits, 164 >>> >>> So those files create this .rodata section with an explicit entry size, >>> but then don't respect it themselves. Removing the entry size makes the >>> warning go away, but I can't tell if that's right or not, given there is >>> zero clue as to why that entry size was specified to begin with. >>> >>> Please explain... >>> >>> --- >>> diff --git a/arch/x86/crypto/sm4-aesni-avx-asm_64.S b/arch/x86/crypto/sm4-aesni-avx-asm_64.S >>> index 18d2f5199194..d089cccf4db7 100644 >>> --- a/arch/x86/crypto/sm4-aesni-avx-asm_64.S >>> +++ b/arch/x86/crypto/sm4-aesni-avx-asm_64.S >>> @@ -78,7 +78,7 @@ >>> vpxor tmp0, x, x; >>> -.section .rodata.cst164, "aM", @progbits, 164 >>> +.section .rodata.cst164, "aM", @progbits >>> .align 16 >>> /* >>> diff --git a/arch/x86/crypto/sm4-aesni-avx2-asm_64.S b/arch/x86/crypto/sm4-aesni-avx2-asm_64.S >>> index d2ffd7f76ee2..a0f7541c2246 100644 >>> --- a/arch/x86/crypto/sm4-aesni-avx2-asm_64.S >>> +++ b/arch/x86/crypto/sm4-aesni-avx2-asm_64.S >>> @@ -93,7 +93,7 @@ >>> vpxor tmp0, x, x; >>> -.section .rodata.cst164, "aM", @progbits, 164 >>> +.section .rodata.cst164, "aM", @progbits >>> .align 16 >>> /* >>> >> >> Thanks for pointing it out, We have also reproduced this error. If the M >> flag is specified, the entry_size argument is required. > > Correct. > >> We also need to >> consider the clang compiler. This requires a more thorough method to fix it. >> I will post another patch later. > > If the purpose is to share the whole section, such that there is only a > single copy of those tables between the two sm4 implementations, then > you need to set the entry size to the total size of the section. > > Otoh, almost every entry (with exception of the very last one) seems to > be 16 bytes, so you might just get away with setting the entry size to > 16. > > Given this is only a very small data table, why the need to share? Any > one machine will only use a single one of these implementations at any > one time. > The main purpose is not to share the whole section, but to prevent clang from causing errors. It seems that the clang compiler has stricter restrictions on this entry_size. Best regards, Tianjia