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=-15.8 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_RED autolearn=unavailable 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 814D9C43331 for ; Sat, 13 Mar 2021 05:08:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6B15864FC4 for ; Sat, 13 Mar 2021 05:08:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231383AbhCMFIM (ORCPT ); Sat, 13 Mar 2021 00:08:12 -0500 Received: from mail.kernel.org ([198.145.29.99]:41944 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231723AbhCMFHs (ORCPT ); Sat, 13 Mar 2021 00:07:48 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id B141064F91; Sat, 13 Mar 2021 05:07:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1615612068; bh=KKTkhef31fR4JMNYj70z9BZaxZrdISCGvo1YJFQCLDg=; h=Date:From:To:Subject:In-Reply-To:From; b=gH1W4eakRO5NY2uDhlwpxuufWQwrrK7IH/nD/EGCMCuw7tsta/mdN84TX6MNP1dms XVnrGhprRxoWdAEO1mjE9CwjwbictbpJZNmN/+wzCPTyxmhGy7zVfuwRVLJJhZqbK0 V5624aMI46v3Yf3672kV1Y/pmLNYC0BzCMnnrtFE= Date: Fri, 12 Mar 2021 21:07:47 -0800 From: Andrew Morton To: akpm@linux-foundation.org, aou@eecs.berkeley.edu, arnd@arndb.de, deanbo422@gmail.com, elver@google.com, green.hu@gmail.com, guoren@kernel.org, keescook@chromium.org, linux-mm@kvack.org, luc.vanoostenryck@gmail.com, masahiroy@kernel.org, mm-commits@vger.kernel.org, nathan@kernel.org, ndesaulniers@google.com, nickhu@andestech.com, nivedita@alum.mit.edu, ojeda@kernel.org, palmer@dabbelt.com, paul.walmsley@sifive.com, rdunlap@infradead.org, samitolvanen@google.com, stable@vger.kernel.org, torvalds@linux-foundation.org Subject: [patch 14/29] linux/compiler-clang.h: define HAVE_BUILTIN_BSWAP* Message-ID: <20210313050747.ZSth0fs8-%akpm@linux-foundation.org> In-Reply-To: <20210312210632.9b7d62973d72a56fb13c7a03@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: Arnd Bergmann Subject: linux/compiler-clang.h: define HAVE_BUILTIN_BSWAP* Separating compiler-clang.h from compiler-gcc.h inadventently dropped the definitions of the three HAVE_BUILTIN_BSWAP macros, which requires falling back to the open-coded version and hoping that the compiler detects it. Since all versions of clang support the __builtin_bswap interfaces, add back the flags and have the headers pick these up automatically. This results in a 4% improvement of compilation speed for arm defconfig. Note: it might also be worth revisiting which architectures set CONFIG_ARCH_USE_BUILTIN_BSWAP for one compiler or the other, today this is set on six architectures (arm32, csky, mips, powerpc, s390, x86), while another ten architectures define custom helpers (alpha, arc, ia64, m68k, mips, nios2, parisc, sh, sparc, xtensa), and the rest (arm64, h8300, hexagon, microblaze, nds32, openrisc, riscv) just get the unoptimized version and rely on the compiler to detect it. A long time ago, the compiler builtins were architecture specific, but nowadays, all compilers that are able to build the kernel have correct implementations of them, though some may not be as optimized as the inline asm versions. The patch that dropped the optimization landed in v4.19, so as discussed it would be fairly safe to backport this revert to stable kernels to the 4.19/5.4/5.10 stable kernels, but there is a remaining risk for regressions, and it has no known side-effects besides compile speed. Link: https://lkml.kernel.org/r/20210226161151.2629097-1-arnd@kernel.org Link: https://lore.kernel.org/lkml/20210225164513.3667778-1-arnd@kernel.org/ Fixes: 815f0ddb346c ("include/linux/compiler*.h: make compiler-*.h mutually exclusive") Signed-off-by: Arnd Bergmann Reviewed-by: Nathan Chancellor Reviewed-by: Kees Cook Acked-by: Miguel Ojeda Acked-by: Nick Desaulniers Acked-by: Luc Van Oostenryck Cc: Masahiro Yamada Cc: Nick Hu Cc: Greentime Hu Cc: Vincent Chen Cc: Paul Walmsley Cc: Palmer Dabbelt Cc: Albert Ou Cc: Guo Ren Cc: Randy Dunlap Cc: Sami Tolvanen Cc: Marco Elver Cc: Arvind Sankar Cc: Signed-off-by: Andrew Morton --- include/linux/compiler-clang.h | 6 ++++++ 1 file changed, 6 insertions(+) --- a/include/linux/compiler-clang.h~linux-compiler-clangh-define-have_builtin_bswap +++ a/include/linux/compiler-clang.h @@ -31,6 +31,12 @@ #define __no_sanitize_thread #endif +#if defined(CONFIG_ARCH_USE_BUILTIN_BSWAP) +#define __HAVE_BUILTIN_BSWAP32__ +#define __HAVE_BUILTIN_BSWAP64__ +#define __HAVE_BUILTIN_BSWAP16__ +#endif /* CONFIG_ARCH_USE_BUILTIN_BSWAP */ + #if __has_feature(undefined_behavior_sanitizer) /* GCC does not have __SANITIZE_UNDEFINED__ */ #define __no_sanitize_undefined \ _