From patchwork Sun Mar 20 16:58:35 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Thomas Petazzoni X-Patchwork-Id: 599862 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from whitealder.osuosl.org (smtp1.osuosl.org [140.211.166.138]) by ozlabs.org (Postfix) with ESMTP id 3qSlXq4pSHz9s9N for ; Mon, 21 Mar 2016 03:58:51 +1100 (AEDT) Received: from localhost (localhost [127.0.0.1]) by whitealder.osuosl.org (Postfix) with ESMTP id 8667E923C2; Sun, 20 Mar 2016 16:58:49 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from whitealder.osuosl.org ([127.0.0.1]) by localhost (.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id r1yVi9-o0vpf; Sun, 20 Mar 2016 16:58:46 +0000 (UTC) Received: from ash.osuosl.org (ash.osuosl.org [140.211.166.34]) by whitealder.osuosl.org (Postfix) with ESMTP id 614BA923B7; Sun, 20 Mar 2016 16:58:46 +0000 (UTC) X-Original-To: uclibc@lists.busybox.net Delivered-To: uclibc@osuosl.org Received: from hemlock.osuosl.org (smtp2.osuosl.org [140.211.166.133]) by ash.osuosl.org (Postfix) with ESMTP id 0D18A1C0B41 for ; Sun, 20 Mar 2016 16:58:45 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by hemlock.osuosl.org (Postfix) with ESMTP id 08DA49604E for ; Sun, 20 Mar 2016 16:58:45 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from hemlock.osuosl.org ([127.0.0.1]) by localhost (.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id d41pDGvzYT3n for ; Sun, 20 Mar 2016 16:58:44 +0000 (UTC) X-Greylist: domain auto-whitelisted by SQLgrey-1.7.6 Received: from mail.free-electrons.com (down.free-electrons.com [37.187.137.238]) by hemlock.osuosl.org (Postfix) with ESMTP id EB8359604C for ; Sun, 20 Mar 2016 16:58:43 +0000 (UTC) Received: by mail.free-electrons.com (Postfix, from userid 110) id 5429A1F5; Sun, 20 Mar 2016 17:58:36 +0100 (CET) Received: from localhost (AToulouse-657-1-41-6.w92-146.abo.wanadoo.fr [92.146.39.6]) by mail.free-electrons.com (Postfix) with ESMTPSA id 1C19BB0; Sun, 20 Mar 2016 17:58:36 +0100 (CET) From: Thomas Petazzoni To: devel@uclibc-ng.org Subject: [PATCH] arm: simplify handling of Thumb related options Date: Sun, 20 Mar 2016 17:58:35 +0100 Message-Id: <1458493115-26904-1-git-send-email-thomas.petazzoni@free-electrons.com> X-Mailer: git-send-email 2.6.4 Cc: uclibc@uclibc.org X-BeenThere: uclibc@uclibc.org X-Mailman-Version: 2.1.18-1 Precedence: list List-Id: "Discussion and development of uClibc \(the embedded C library\)" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Errors-To: uclibc-bounces@uclibc.org Sender: "uClibc" Currently, the Thumb support on ARM has three related Config.in options, which are not trivial for users to understand, and are in fact not needed: - The USE_BX option is not needed: knowing whether BX is available or not is easy. If you have an ARM > v4 or ARMv4T, then BX is available, otherwise it's not. This is the logic used in glibc. - The USE_LDREXSTREX option is not needed: whenever Thumb2 is available, ldrex/strex are available, so we can simply rely on __thumb2__ to determine whether ldrex/strex should be used, without requiring a Config.in option. - Once USE_BX and USE_LDREXSTREX are removed, the only thing left that COMPILE_IN_THUMB does is to set -mthumb. This makes the option unnecessary, as on ARM at least, the user is already supposed to pass -march= or other compiler options tuning the library for a specific ARM variant. There is no reason to do otherwise for Thumb, which allows to get rid of the COMPILE_IN_THUMB option. Signed-off-by: Thomas Petazzoni --- Rules.mak | 1 - extra/Configs/Config.arm | 22 ---------------------- libc/sysdeps/linux/arm/bits/arm_bx.h | 10 ++++------ libc/sysdeps/linux/arm/clone.S | 2 +- .../linuxthreads.old/sysdeps/arm/pt-machine.h | 7 +++---- 5 files changed, 8 insertions(+), 34 deletions(-) diff --git a/Rules.mak b/Rules.mak index b1cecec..0ae3bb1 100644 --- a/Rules.mak +++ b/Rules.mak @@ -392,7 +392,6 @@ endif ifeq ($(TARGET_ARCH),arm) CPU_CFLAGS-$(ARCH_LITTLE_ENDIAN)+=-mlittle-endian CPU_CFLAGS-$(ARCH_BIG_ENDIAN)+=-mbig-endian - CPU_CFLAGS-$(COMPILE_IN_THUMB_MODE)+=-mthumb endif ifeq ($(TARGET_ARCH),metag) diff --git a/extra/Configs/Config.arm b/extra/Configs/Config.arm index 00cf982..0d02e3f 100644 --- a/extra/Configs/Config.arm +++ b/extra/Configs/Config.arm @@ -24,25 +24,3 @@ config CONFIG_ARM_EABI If you say 'n' here, then the library will be built for the old Linux ABI. - -config COMPILE_IN_THUMB_MODE - bool "Build using Thumb mode" - select USE_BX - select USE_LDREXSTREX - help - Say 'y' here to force building uClibc in thumb mode. - Say 'n' to use your compiler's default mode. - -config USE_BX - bool "Use BX in function return" - help - Say 'y' to use BX to return from functions on your thumb-aware - processor. Say 'y' if you need to use interworking. Say 'n' if not. - It is safe to say 'y' even if you're not doing interworking. - -config USE_LDREXSTREX - bool "Use load-store exclusive ASM ops (not supported in SmartFusion)" - depends on COMPILE_IN_THUMB_MODE - default n - help - Say 'y' to use LDREX/STREX ASM ops. diff --git a/libc/sysdeps/linux/arm/bits/arm_bx.h b/libc/sysdeps/linux/arm/bits/arm_bx.h index 2c29089..1c775b6 100644 --- a/libc/sysdeps/linux/arm/bits/arm_bx.h +++ b/libc/sysdeps/linux/arm/bits/arm_bx.h @@ -23,13 +23,11 @@ #error Please include features.h first #endif /* features.h not yet included */ -#if defined(__USE_BX__) -# if (__ARM_ARCH <= 4 && !defined __ARM_ARCH_4T__) -# error Use of BX was requested, but is not available on the target processor. -# endif /* ARCH level */ -#endif /* __USE_BX__ */ +#if __ARM_ARCH > 4 || defined (__ARM_ARCH_4T__) +# define ARCH_HAS_BX +#endif -#if defined(__USE_BX__) && (__ARM_ARCH > 4 || (__ARM_ARCH == 4 && defined __ARM_ARCH_4T__)) +#if defined(ARCH_HAS_BX) # define BX(reg) bx reg # define BXC(cond, reg) bx##cond reg #else diff --git a/libc/sysdeps/linux/arm/clone.S b/libc/sysdeps/linux/arm/clone.S index b4c7d8a..fd7590d 100644 --- a/libc/sysdeps/linux/arm/clone.S +++ b/libc/sysdeps/linux/arm/clone.S @@ -69,7 +69,7 @@ __clone: @ pick the function arg and call address off the stack and execute ldr r0, [sp, #4] -#if defined(__USE_BX__) +#if defined(ARCH_HAS_BX) ldr r1, [sp] bl 2f @ blx r1 #else diff --git a/libpthread/linuxthreads.old/sysdeps/arm/pt-machine.h b/libpthread/linuxthreads.old/sysdeps/arm/pt-machine.h index 2b877f9..fc17e9b 100644 --- a/libpthread/linuxthreads.old/sysdeps/arm/pt-machine.h +++ b/libpthread/linuxthreads.old/sysdeps/arm/pt-machine.h @@ -28,8 +28,7 @@ # define PT_EI __extern_always_inline #endif -#if defined(__thumb__) -#if defined(__USE_LDREXSTREX__) +#if defined(__thumb2__) PT_EI long int ldrex(int *spinlock) { long int ret; @@ -63,7 +62,7 @@ testandset (int *spinlock) return ret; } -#else /* __USE_LDREXSTREX__ */ +#elif defined(__thumb__) /* This will not work on ARM1 or ARM2 because SWP is lacking on those machines. Unfortunately we have no way to detect this at compile @@ -88,7 +87,7 @@ PT_EI long int testandset (int *spinlock) : "0"(1), "r"(spinlock)); return ret; } -#endif + #else /* __thumb__ */ PT_EI long int testandset (int *spinlock);