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=-15.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 43A87C2B9F2 for ; Sun, 23 May 2021 00:42:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 276F26052B for ; Sun, 23 May 2021 00:42:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231486AbhEWAna (ORCPT ); Sat, 22 May 2021 20:43:30 -0400 Received: from mail.kernel.org ([198.145.29.99]:52680 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231451AbhEWAn3 (ORCPT ); Sat, 22 May 2021 20:43:29 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id B8E2E611AD; Sun, 23 May 2021 00:42:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1621730523; bh=hYMTAfZ7OEEBL9VjuayqgjAnEgC6b6SzyTVACnGRZnQ=; h=Date:From:To:Subject:In-Reply-To:From; b=WkCqDxEjbQyq2ZTrJzhh/EBs45Gm2r2YZ18NtFeJmB3LTRwD1fQPWjj8LvAFXfMFN G9UQHhkFPa0cqJ16DDoq3gdIf3DVqjxAJ0KjLVVKJx+lWN1Yoe0XIo2jyFCXD9ppbn QuFDFHw34LYHLeezuZmv6avLdPtS7jWdFmfOOF4o= Date: Sat, 22 May 2021 17:42:02 -0700 From: Andrew Morton To: akpm@linux-foundation.org, andy.shevchenko@gmail.com, ardb@kernel.org, arnd@arndb.de, linux-mm@kvack.org, mm-commits@vger.kernel.org, penguin-kernel@I-love.SAKURA.ne.jp, peterz@infradead.org, rikard.falkeborn@gmail.com, torvalds@linux-foundation.org, yury.norov@gmail.com Subject: [patch 07/10] linux/bits.h: fix compilation error with GENMASK Message-ID: <20210523004202.MOjiaAIxA%akpm@linux-foundation.org> In-Reply-To: <20210522174113.47fd4c853c0a1470c57deefa@linux-foundation.org> User-Agent: s-nail v14.8.16 Precedence: bulk Reply-To: linux-kernel@vger.kernel.org List-ID: X-Mailing-List: mm-commits@vger.kernel.org From: Rikard Falkeborn Subject: linux/bits.h: fix compilation error with GENMASK GENMASK() has an input check which uses __builtin_choose_expr() to enable a compile time sanity check of its inputs if they are known at compile time. However, it turns out that __builtin_constant_p() does not always return a compile time constant [0]. It was thought this problem was fixed with gcc 4.9 [1], but apparently this is not the case [2]. Switch to use __is_constexpr() instead which always returns a compile time constant, regardless of its inputs. [0]: https://lore.kernel.org/lkml/42b4342b-aefc-a16a-0d43-9f9c0d63ba7a@rasmusvillemoes.dk [1]: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=19449 [2]: https://lore.kernel.org/lkml/1ac7bbc2-45d9-26ed-0b33-bf382b8d858b@I-love.SAKURA.ne.jp Link: https://lkml.kernel.org/r/20210511203716.117010-1-rikard.falkeborn@gmail.com Signed-off-by: Rikard Falkeborn Reported-by: Tetsuo Handa Acked-by: Arnd Bergmann Reviewed-by: Andy Shevchenko Cc: Ard Biesheuvel Cc: Yury Norov Cc: Peter Zijlstra Signed-off-by: Andrew Morton --- include/linux/bits.h | 2 +- include/linux/const.h | 8 ++++++++ include/linux/minmax.h | 10 ++-------- tools/include/linux/bits.h | 2 +- tools/include/linux/const.h | 8 ++++++++ 5 files changed, 20 insertions(+), 10 deletions(-) --- a/include/linux/bits.h~linux-bitsh-fix-compilation-error-with-genmask +++ a/include/linux/bits.h @@ -22,7 +22,7 @@ #include #define GENMASK_INPUT_CHECK(h, l) \ (BUILD_BUG_ON_ZERO(__builtin_choose_expr( \ - __builtin_constant_p((l) > (h)), (l) > (h), 0))) + __is_constexpr((l) > (h)), (l) > (h), 0))) #else /* * BUILD_BUG_ON_ZERO is not available in h files included from asm files, --- a/include/linux/const.h~linux-bitsh-fix-compilation-error-with-genmask +++ a/include/linux/const.h @@ -3,4 +3,12 @@ #include +/* + * This returns a constant expression while determining if an argument is + * a constant expression, most importantly without evaluating the argument. + * Glory to Martin Uecker + */ +#define __is_constexpr(x) \ + (sizeof(int) == sizeof(*(8 ? ((void *)((long)(x) * 0l)) : (int *)8))) + #endif /* _LINUX_CONST_H */ --- a/include/linux/minmax.h~linux-bitsh-fix-compilation-error-with-genmask +++ a/include/linux/minmax.h @@ -2,6 +2,8 @@ #ifndef _LINUX_MINMAX_H #define _LINUX_MINMAX_H +#include + /* * min()/max()/clamp() macros must accomplish three things: * @@ -17,14 +19,6 @@ #define __typecheck(x, y) \ (!!(sizeof((typeof(x) *)1 == (typeof(y) *)1))) -/* - * This returns a constant expression while determining if an argument is - * a constant expression, most importantly without evaluating the argument. - * Glory to Martin Uecker - */ -#define __is_constexpr(x) \ - (sizeof(int) == sizeof(*(8 ? ((void *)((long)(x) * 0l)) : (int *)8))) - #define __no_side_effects(x, y) \ (__is_constexpr(x) && __is_constexpr(y)) --- a/tools/include/linux/bits.h~linux-bitsh-fix-compilation-error-with-genmask +++ a/tools/include/linux/bits.h @@ -22,7 +22,7 @@ #include #define GENMASK_INPUT_CHECK(h, l) \ (BUILD_BUG_ON_ZERO(__builtin_choose_expr( \ - __builtin_constant_p((l) > (h)), (l) > (h), 0))) + __is_constexpr((l) > (h)), (l) > (h), 0))) #else /* * BUILD_BUG_ON_ZERO is not available in h files included from asm files, --- a/tools/include/linux/const.h~linux-bitsh-fix-compilation-error-with-genmask +++ a/tools/include/linux/const.h @@ -3,4 +3,12 @@ #include +/* + * This returns a constant expression while determining if an argument is + * a constant expression, most importantly without evaluating the argument. + * Glory to Martin Uecker + */ +#define __is_constexpr(x) \ + (sizeof(int) == sizeof(*(8 ? ((void *)((long)(x) * 0l)) : (int *)8))) + #endif /* _LINUX_CONST_H */ _