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 X-Spam-Level: X-Spam-Status: No, score=-25.2 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 054F8C433EF for ; Fri, 10 Sep 2021 23:56:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D5F536101D for ; Fri, 10 Sep 2021 23:56:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234920AbhIJX5M (ORCPT ); Fri, 10 Sep 2021 19:57:12 -0400 Received: from mail.kernel.org ([198.145.29.99]:46854 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233946AbhIJX5K (ORCPT ); Fri, 10 Sep 2021 19:57:10 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 270AC6052B; Fri, 10 Sep 2021 23:55:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1631318158; bh=DNbYPXmd3IEaN88m25hO+5ZGRjkmqcd4V/ITcTDtlJ8=; h=Subject:To:Cc:References:From:Date:In-Reply-To:From; b=ZthXR82/C9yEorBA8YiAX0b2E2fFmoJkua0IZVv/q72g2apayUeTCMDZEL+8Dy9g4 LDII2t6/ey5bAQgqpVdbft6M8C4dsR2cWvqFwwL5xxxJCj0iU2cuNOyUCiJ2TgKvZs QXFeAzkv62k9eEuqzlUtXlcMRV8qh2PuGwMTmRWq4CJds1gcSvvKs9WYrlOK4ApSYm Leuo6iDnpBV4ATweXcRxEY5j0C0YHlIhAvmtB0Ew9bZRZ0KTVlE9XIyfBQwsYqioen GXiIuzme6LkBFx6fIxiLoYrkQJIPT0d4jcOrDOOzH3MNucVYhLoXIYX6nsfgppHP1L aotqFKwOA3R3Q== Subject: Re: [PATCH 01/10] Documentation: raise minimum supported version of GCC to 5.1 To: Nick Desaulniers , Andrew Morton Cc: Linus Torvalds , Rasmus Villemoes , Masahiro Yamada , Joe Perches , Arnd Bergmann , Stephen Rothwell , llvm@lists.linux.dev, linux-kernel@vger.kernel.org References: <20210910234047.1019925-1-ndesaulniers@google.com> <20210910234047.1019925-2-ndesaulniers@google.com> From: Nathan Chancellor Message-ID: Date: Fri, 10 Sep 2021 16:55:55 -0700 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.13.0 MIME-Version: 1.0 In-Reply-To: <20210910234047.1019925-2-ndesaulniers@google.com> 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 On 9/10/2021 4:40 PM, Nick Desaulniers wrote: > commit fad7cd3310db ("nbd: add the check to prevent overflow in > __nbd_ioctl()") > > raised an issue from the fallback helpers added in > > commit f0907827a8a9 ("compiler.h: enable builtin overflow checkers and add fallback code") > > Specifically, the helpers for checking whether the results of a > multiplication overflowed (__unsigned_mul_overflow, > __signed_add_overflow) use the division operator when > !COMPILER_HAS_GENERIC_BUILTIN_OVERFLOW. This is problematic for 64b > operands on 32b hosts. "hosts" -> "targets" or "architectures"? It might be worth putting the error that Stephen found here? > Also, because the macro is type agnostic, it is very difficult to write > a similarly type generic macro that dispatches to one of: > * div64_s64 > * div64_u64 > * div_s64 > * div_u64 > > Raising the minimum supported versions allows us to remove all of the > fallback helpers for !COMPILER_HAS_GENERIC_BUILTIN_OVERFLOW, instead > dispatching the compiler builtins. > > arm64 has already raised the minimum supported GCC version to 5.1, do > this for all targets now. See the link below for the previous > discussion. > > Link: https://lore.kernel.org/all/20210909182525.372ee687@canb.auug.org.au/ > Link: https://lore.kernel.org/lkml/CAK7LNASs6dvU6D3jL2GG3jW58fXfaj6VNOe55NJnTB8UPuk2pA@mail.gmail.com/ > Link: https://github.com/ClangBuiltLinux/linux/issues/1438 > Reported-by: Stephen Rothwell > Reported-by: Nathan Chancellor > Suggested-by: Rasmus Villemoes > Signed-off-by: Nick Desaulniers Reviewed-by: Nathan Chancellor > --- > Documentation/process/changes.rst | 2 +- > scripts/min-tool-version.sh | 8 +------- > 2 files changed, 2 insertions(+), 8 deletions(-) > > diff --git a/Documentation/process/changes.rst b/Documentation/process/changes.rst > index d3a8557b66a1..e35ab74a0f80 100644 > --- a/Documentation/process/changes.rst > +++ b/Documentation/process/changes.rst > @@ -29,7 +29,7 @@ you probably needn't concern yourself with pcmciautils. > ====================== =============== ======================================== > Program Minimal version Command to check the version > ====================== =============== ======================================== > -GNU C 4.9 gcc --version > +GNU C 5.1 gcc --version > Clang/LLVM (optional) 10.0.1 clang --version > GNU make 3.81 make --version > binutils 2.23 ld -v > diff --git a/scripts/min-tool-version.sh b/scripts/min-tool-version.sh > index 319f92104f56..4edc708baa63 100755 > --- a/scripts/min-tool-version.sh > +++ b/scripts/min-tool-version.sh > @@ -17,13 +17,7 @@ binutils) > echo 2.23.0 > ;; > gcc) > - # https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63293 > - # https://lore.kernel.org/r/20210107111841.GN1551@shell.armlinux.org.uk > - if [ "$SRCARCH" = arm64 ]; then > - echo 5.1.0 > - else > - echo 4.9.0 > - fi > + echo 5.1.0 > ;; > icc) > # temporary >