From patchwork Mon Aug 7 05:57:32 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Zhangjin Wu X-Patchwork-Id: 711420 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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id F10F9EB64DD for ; Mon, 7 Aug 2023 05:58:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229704AbjHGF6E (ORCPT ); Mon, 7 Aug 2023 01:58:04 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57264 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230483AbjHGF57 (ORCPT ); Mon, 7 Aug 2023 01:57:59 -0400 Received: from bg4.exmail.qq.com (bg4.exmail.qq.com [43.155.65.254]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id DAC2C170B; Sun, 6 Aug 2023 22:57:55 -0700 (PDT) X-QQ-mid: bizesmtp70t1691387853tz776qn7 Received: from linux-lab-host.localdomain ( [116.30.130.12]) by bizesmtp.qq.com (ESMTP) with id ; Mon, 07 Aug 2023 13:57:32 +0800 (CST) X-QQ-SSF: 01200000000000E0X000000A0000000 X-QQ-FEAT: 7jw2iSiCazrDRCkOXuADr5FHLOFZXWkxZuDnONNhh+oqJ3Wt3OCZM/MgwcO+4 SdEQqXlZfjCMNUfrOjH6EsTZNBaCEFYx3otcNH7v5TDzYW7FWNZWS261/ej8VXbXpYCCd1u Kw+KjhyW45sQPfcOrJvzb3X9Zco/k868fgrfmk2KKzl+dY/omThbOAgqqsUQ4DVUYkDWE9s j3pLbl3UNGMlO6CeOBQWyubYCqgdwfS4qkQcMxaH1Lq7uChjjUC632J8PR1sbXU82/v/4LT 1RFhMtFgl1aK1kkzgn/Gc2jdODnpPOsXzNcQniiVjzpJC3GkYRnHrC3jxy1lZEQTtA/kPXi YG6EESBIXs5g/inWtWhT/oxSqvRQrGCypjQI3lblntTdTUtlNOiwiBz5Up/dzlwUSPg7nUb X-QQ-GoodBg: 0 X-BIZMAIL-ID: 8095711180092042174 From: Zhangjin Wu To: w@1wt.eu Cc: falcon@tinylab.org, arnd@arndb.de, david.laight@aculab.com, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, thomas@t-8ch.de Subject: [PATCH v3] tools/nolibc: fix up size inflate regression Date: Mon, 7 Aug 2023 13:57:32 +0800 Message-Id: <8eaab5da2dcbba42e3f3efc2ae686a22c95f84f0.1691386601.git.falcon@tinylab.org> X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 X-QQ-SENDSIZE: 520 Feedback-ID: bizesmtp:tinylab.org:qybglogicsvrgz:qybglogicsvrgz5a-1 Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org As reported and suggested by Willy, the inline __sysret() helper introduces three types of conversions and increases the size: (1) the "unsigned long" argument to __sysret() forces a sign extension from all sys_* functions that used to return 'int' (2) the comparison with the error range now has to be performed on a 'unsigned long' instead of an 'int' (3) the return value from __sysret() is a 'long' (note, a signed long) which then has to be turned back to an 'int' before being returned by the caller to satisfy the caller's prototype. To fix up this, firstly, let's use macro instead of inline function to preserves the input type and avoids these useless conversions (1), (3). Secondly, comparison to -MAX_ERRNO inflicts on all integer returns where we could previously keep a simple sign comparison, let's use a new is_signed_type() macro from include/linux/compiler.h to limit the comparision to -MAX_ERRNO (2) only on demand and preserves a simple sign comparision for most of the cases as before. Thirdly, fix up the following warning by an explicit conversion and let __sysret() be able to accept the (void *) type of argument and return value with the same (void *) type: sysroot/powerpc/include/sys.h: In function 'sbrk': sysroot/powerpc/include/sys.h:104:16: warning: cast to pointer from integer of different size [-Wint-to-pointer-cast] 104 | return (void *)__sysret(-ENOMEM); Fourthly, to further workaround the argument type with 'const', must use __auto_type for a new enough gcc versions and use 'long' for the old gcc versions as before. Here reports the size testing result with nolibc-test: before: // ppc64le $ size nolibc-test text data bss dec hex filename 27916 8 80 28004 6d64 nolibc-test // mips $ size nolibc-test text data bss dec hex filename 23276 64 64 23404 5b6c nolibc-test after: // ppc64le $ size nolibc-test text data bss dec hex filename 27736 8 80 27824 6cb0 nolibc-test // mips $ size nolibc-test text data bss dec hex filename 23036 64 64 23164 5a7c nolibc-test Suggested-by: Willy Tarreau Link: https://lore.kernel.org/lkml/20230806095846.GB10627@1wt.eu/ Link: https://lore.kernel.org/lkml/20230806134348.GA19145@1wt.eu/ Signed-off-by: Zhangjin Wu --- Hi, Willy To increase readability, v3 further defines a __GXX_HAS_AUTO_TYPE_WITH_CONST_SUPPORT macro for gcc >= 11.0 (ABI_VERSION >= 1016) who has __auto_type with 'const' support. When this macro is defined, provides a __sysret version with __auto_type, otherwise, use a fixed 'long' type as a fallback. Tested for all of the nolibc supported architectures with Arnd's 13.2.0 toolchains. and also for x86_64 with gcc-4.8 and gcc-9, no compile failures, no compile warnings, no running failures. Changes from v2 --> v3: * define a __GXX_HAS_AUTO_TYPE_WITH_CONST_SUPPORT for gcc >= 11.0 (ABI_VERSION >= 1016) * split __sysret() to two versions by the macro instead of a mixed unified and unreadable version * use shorter __ret instead of __sysret_arg Changes from v1 --> v2: * fix up argument with 'const' in the type * support "void *" argument v2: https://lore.kernel.org/lkml/95fe3e732f455fab653fe1427118d905e4d04257.1691339836.git.falcon@tinylab.org/ v1: https://lore.kernel.org/lkml/20230806131921.52453-1-falcon@tinylab.org/ --- tools/include/nolibc/sys.h | 66 +++++++++++++++++++++++++++++++------- 1 file changed, 55 insertions(+), 11 deletions(-) diff --git a/tools/include/nolibc/sys.h b/tools/include/nolibc/sys.h index 56f63eb48a1b..b137f7771db9 100644 --- a/tools/include/nolibc/sys.h +++ b/tools/include/nolibc/sys.h @@ -35,15 +35,59 @@ * (src/internal/syscall_ret.c) and glibc (sysdeps/unix/sysv/linux/sysdep.h) */ -static __inline__ __attribute__((unused, always_inline)) -long __sysret(unsigned long ret) -{ - if (ret >= (unsigned long)-MAX_ERRNO) { - SET_ERRNO(-(long)ret); - return -1; - } - return ret; -} +/* + * Whether 'type' is a signed type or an unsigned type. Supports scalar types, + * bool and also pointer types. (from include/linux/compiler.h) + */ +#define __is_signed_type(type) (((type)(-1)) < (type)1) + +/* __auto_type is used instead of __typeof__ to workaround the build error + * 'error: assignment of read-only variable' when the argument has 'const' in + * the type, but __auto_type is a new feature from newer gcc version and it + * only works with 'const' from gcc 11.0 (__GXX_ABI_VERSION = 1016) + * https://gcc.gnu.org/legacy-ml/gcc-patches/2013-11/msg01378.html + */ + +#if __GXX_ABI_VERSION >= 1016 +#define __GXX_HAS_AUTO_TYPE_WITH_CONST_SUPPORT +#endif + +#ifdef __GXX_HAS_AUTO_TYPE_WITH_CONST_SUPPORT +#define __sysret(arg) \ +({ \ + __auto_type __ret = (arg); \ + if (__is_signed_type(__typeof__(arg))) { \ + if (__ret < 0) { \ + SET_ERRNO(-(long)__ret); \ + __ret = (__typeof__(arg))(-1L); \ + } \ + } else { \ + if ((unsigned long)__ret >= (unsigned long)-MAX_ERRNO) { \ + SET_ERRNO(-(long)__ret); \ + __ret = (__typeof__(arg))(-1L); \ + } \ + } \ + __ret; \ +}) + +#else /* ! __GXX_HAS_AUTO_TYPE_WITH_CONST_SUPPORT */ +#define __sysret(arg) \ +({ \ + long __ret = (long)(arg); \ + if (__is_signed_type(__typeof__(arg))) { \ + if (__ret < 0) { \ + SET_ERRNO(-__ret); \ + __ret = -1L; \ + } \ + } else { \ + if ((unsigned long)__ret >= (unsigned long)-MAX_ERRNO) { \ + SET_ERRNO(-__ret); \ + __ret = -1L; \ + } \ + } \ + (__typeof__(arg))__ret; \ +}) +#endif /* ! __GXX_HAS_AUTO_TYPE_WITH_CONST_SUPPORT */ /* Functions in this file only describe syscalls. They're declared static so * that the compiler usually decides to inline them while still being allowed @@ -94,7 +138,7 @@ void *sbrk(intptr_t inc) if (ret && sys_brk(ret + inc) == ret + inc) return ret + inc; - return (void *)__sysret(-ENOMEM); + return __sysret((void *)-ENOMEM); } @@ -682,7 +726,7 @@ void *sys_mmap(void *addr, size_t length, int prot, int flags, int fd, static __attribute__((unused)) void *mmap(void *addr, size_t length, int prot, int flags, int fd, off_t offset) { - return (void *)__sysret((unsigned long)sys_mmap(addr, length, prot, flags, fd, offset)); + return __sysret(sys_mmap(addr, length, prot, flags, fd, offset)); } static __attribute__((unused))