From patchwork Sat Jan 26 04:01:13 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Nathan Chancellor X-Patchwork-Id: 10782305 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 13BF16C2 for ; Sat, 26 Jan 2019 04:07:09 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id DE4BF30133 for ; Sat, 26 Jan 2019 04:07:08 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id D028E30632; Sat, 26 Jan 2019 04:07:08 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.2 required=2.0 tests=BAYES_00,DKIM_ADSP_CUSTOM_MED, DKIM_SIGNED,DKIM_VALID,FREEMAIL_FROM,MAILING_LIST_MULTI,RCVD_IN_DNSWL_MED autolearn=ham version=3.3.1 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id 4698F30133 for ; Sat, 26 Jan 2019 04:07:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Message-Id:Date:Subject:To:From:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=01oLhjARk/yABiA9f2r2oBG/yaXTsa/CSLynyhgFPUE=; b=sMIjgHlDuR5Qh5 lRH1PEI/qEt8SYCbx0CDQwd9VVXavozav4S7ZKWumcDpCaPVL3rrzDX2IwaUiKPlEIM3rnD302CFI jbHZUJxTesRjN/Dt6+7b/Vbk3MKDx5JOSYjN5afgNlDMKPX7aISCIxaAjl3VGD71RhQ7v9oWB3IJr VcqTrlUmZdbrHCUwF1/oVfZ242UdXSNOq4RggX+oSUMNJCdwMvlbQSv7rPKHq+JceGyxJt1RhS2EL X2GkiQ+wYJpMsgXh0KVXOYXOtqltHDgxy5pkap70lRQDK6lmxkyT/qc6Vf5qY/2MA7e2t7dSaZrNO HjkxVBEM3e1RONSWpM6Q==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1gnFFI-0001QU-TO; Sat, 26 Jan 2019 04:07:04 +0000 Received: from mail-ed1-x541.google.com ([2a00:1450:4864:20::541]) by bombadil.infradead.org with esmtps (Exim 4.90_1 #2 (Red Hat Linux)) id 1gnFFE-0001PY-LO for linux-arm-kernel@lists.infradead.org; Sat, 26 Jan 2019 04:07:02 +0000 Received: by mail-ed1-x541.google.com with SMTP id g22so8910752edr.7 for ; Fri, 25 Jan 2019 20:06:59 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=bzGp4f5mj60UhOCZqN/eEORXWRoInqsbZGO2akYdCy0=; b=h+bujeUeE17D0y8QwbvANrZPFPrItuMxLv41QWHuHQe7jZxsqQoTg/QafkQp36HV8W r3ndwX/etR3BfSi/GkeCpKUx4ABXQ1JT74yW7aozIImuFau803R/L+J9jOGtusMEz5Pi Qfh95S2bYYTyy9JrT2TpZdYiAgsgbhrRNMvx602yVwUAvbM5/9qBq4TZKybXm4KBVU8X mIC720jVoOn/UhPRuwKPZijb4Pjpao1qToD7j4hs/cu5nuFZ5t/vW5EUhjx/eCoS4w14 wnGMegSGGNqHcjALkFIOotIHGUoHiqcz0p7dQAMMxTH2MdbV7I4bj5hrHQavAs/LyK5K 9uJg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=bzGp4f5mj60UhOCZqN/eEORXWRoInqsbZGO2akYdCy0=; b=BnxuYKXt7+IHhzzggO/RSXlRbu/9gmYJmEXeebVwSCf6lv53OD2FVWf6NnOiwcW9WM vDRkM0LzMw1mHniOrAMWQuL87i06xA/R1nGONN/p6FDp6cbeP7hz6+UsvX74J20fHdsq HIdq8qKnhvtHfCukMqQb1paHUNywOkOFXHMLlcPgJ4+bImwR7NmNmqjpJbnd1CEEO6Ko fM2HRFXxhidW/lGUz9a5HJJerqu0DUU0FdPKnK+w4c5Y8Ru9og6fQQWSDgtlFRLowNaI lL0HdajnTdC/PKGAlzcBeUyy2fyELzTIy8B+/eud2OJk5lrIF2wd6Up+KsSwvzZazemf A4hA== X-Gm-Message-State: AJcUukcQbFiQUOP5S/crURjqc9yjDsxemKmr+P0o4DgzAZ3kJXEzjkSv w/OvYqJsm+YwIUtoc/CTkqM= X-Google-Smtp-Source: ALg8bN53xR6ipP+cZObsAMMommYUAv3P6GEQwW2RXGorZmvuAPPXcmhaLuts5aIImEo5svuz/9oCNw== X-Received: by 2002:a50:8863:: with SMTP id c32mr12583176edc.156.1548475618118; Fri, 25 Jan 2019 20:06:58 -0800 (PST) Received: from localhost.localdomain ([2a01:4f9:2a:1fae::2]) by smtp.gmail.com with ESMTPSA id s46sm12047978edd.9.2019.01.25.20.06.56 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 25 Jan 2019 20:06:57 -0800 (PST) From: Nathan Chancellor To: Russell King , Ard Biesheuvel , Jonathan Corbet Subject: [PATCH RESEND] ARM: Ensure that NEON code always compiles with Clang Date: Fri, 25 Jan 2019 21:01:13 -0700 Message-Id: <20190126040111.9013-1-natechancellor@gmail.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20181215212304.19390-1-natechancellor@gmail.com> References: <20181215212304.19390-1-natechancellor@gmail.com> MIME-Version: 1.0 X-Patchwork-Bot: notify X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190125_200700_729836_4D81B5EF X-CRM114-Status: GOOD ( 17.92 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Nicolas Pitre , Tri Vo , linux-doc@vger.kernel.org, Nicolas Pitre , Nick Desaulniers , linux-kernel@vger.kernel.org, Stefan Agner , Nathan Chancellor , linux-arm-kernel@lists.infradead.org Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org X-Virus-Scanned: ClamAV using ClamSMTP While building arm32 allyesconfig, I ran into the following errors: arch/arm/lib/xor-neon.c:17:2: error: You should compile this file with '-mfloat-abi=softfp -mfpu=neon' In file included from lib/raid6/neon1.c:27: /home/nathan/cbl/prebuilt/lib/clang/8.0.0/include/arm_neon.h:28:2: error: "NEON support not enabled" Building V=1 showed NEON_FLAGS getting passed along to Clang but __ARM_NEON__ was not getting defined. Ultimately, it boils down to Clang only defining __ARM_NEON__ when targeting armv7, rather than armv6k, which is the '-march' value for allyesconfig. >From lib/Basic/Targets/ARM.cpp in the Clang source: // This only gets set when Neon instructions are actually available, unlike // the VFP define, hence the soft float and arch check. This is subtly // different from gcc, we follow the intent which was that it should be set // when Neon instructions are actually available. if ((FPU & NeonFPU) && !SoftFloat && ArchVersion >= 7) { Builder.defineMacro("__ARM_NEON", "1"); Builder.defineMacro("__ARM_NEON__"); // current AArch32 NEON implementations do not support double-precision // floating-point even when it is present in VFP. Builder.defineMacro("__ARM_NEON_FP", "0x" + Twine::utohexstr(HW_FP & ~HW_FP_DP)); } Ard Biesheuvel recommended explicitly adding '-march=armv7-a' at the beginning of the NEON_FLAGS definitions so that __ARM_NEON__ always gets definined by Clang. This doesn't functionally change anything because that code will only run where NEON is supported, which is implicitly armv7. Link: https://github.com/ClangBuiltLinux/linux/issues/287 Suggested-by: Ard Biesheuvel Signed-off-by: Nathan Chancellor Acked-by: Nicolas Pitre Reviewed-by: Nick Desaulniers Reviewed-by: Stefan Agner --- Resending with Nicolas's ack and Nick's review, to give others a chance to pitch in with review/testing before submitting it to the patch system (specifically Stefan, sorry I should have included you in the previous posting). With this patch and: * A tip of tree LLVM build (I used apt.llvm.org) * Clang GCOV support: https://lore.kernel.org/lkml/20190122233749.42220-1-trong@android.com/ * Two minor hacks for unrelated issues that are still being worked through: * https://raw.githubusercontent.com/nathanchance/patches/c313b2fa0efb/linux/build-hax/0003-DO-NOT-UPSTREAM-ARM-Don-t-select-HAVE_FUNCTION_TRACE.patch (see https://github.com/ClangBuiltLinux/linux/issues/35) * https://gist.githubusercontent.com/nathanchance/b2f5a4015abade1a41e78d5fc3235c5b/raw/744321882ab05511331f26896bad7c9f0056a6a5/gistfile1.txt (see https://github.com/ClangBuiltLinux/linux/issues/325) I can build and link a little endian allyesconfig ARM kernel. This patch alone works with GCC 8.2.0 and binutils 2.31.1. Documentation/arm/kernel_mode_neon.txt | 4 ++-- arch/arm/lib/Makefile | 2 +- arch/arm/lib/xor-neon.c | 2 +- lib/raid6/Makefile | 2 +- 4 files changed, 5 insertions(+), 5 deletions(-) diff --git a/Documentation/arm/kernel_mode_neon.txt b/Documentation/arm/kernel_mode_neon.txt index 525452726d31..b9e060c5b61e 100644 --- a/Documentation/arm/kernel_mode_neon.txt +++ b/Documentation/arm/kernel_mode_neon.txt @@ -6,7 +6,7 @@ TL;DR summary * Use only NEON instructions, or VFP instructions that don't rely on support code * Isolate your NEON code in a separate compilation unit, and compile it with - '-mfpu=neon -mfloat-abi=softfp' + '-march=armv7-a -mfpu=neon -mfloat-abi=softfp' * Put kernel_neon_begin() and kernel_neon_end() calls around the calls into your NEON code * Don't sleep in your NEON code, and be aware that it will be executed with @@ -87,7 +87,7 @@ instructions appearing in unexpected places if no special care is taken. Therefore, the recommended and only supported way of using NEON/VFP in the kernel is by adhering to the following rules: * isolate the NEON code in a separate compilation unit and compile it with - '-mfpu=neon -mfloat-abi=softfp'; + '-march=armv7-a -mfpu=neon -mfloat-abi=softfp'; * issue the calls to kernel_neon_begin(), kernel_neon_end() as well as the calls into the unit containing the NEON code from a compilation unit which is *not* built with the GCC flag '-mfpu=neon' set. diff --git a/arch/arm/lib/Makefile b/arch/arm/lib/Makefile index ad25fd1872c7..0bff0176db2c 100644 --- a/arch/arm/lib/Makefile +++ b/arch/arm/lib/Makefile @@ -39,7 +39,7 @@ $(obj)/csumpartialcopy.o: $(obj)/csumpartialcopygeneric.S $(obj)/csumpartialcopyuser.o: $(obj)/csumpartialcopygeneric.S ifeq ($(CONFIG_KERNEL_MODE_NEON),y) - NEON_FLAGS := -mfloat-abi=softfp -mfpu=neon + NEON_FLAGS := -march=armv7-a -mfloat-abi=softfp -mfpu=neon CFLAGS_xor-neon.o += $(NEON_FLAGS) obj-$(CONFIG_XOR_BLOCKS) += xor-neon.o endif diff --git a/arch/arm/lib/xor-neon.c b/arch/arm/lib/xor-neon.c index 2c40aeab3eaa..c691b901092f 100644 --- a/arch/arm/lib/xor-neon.c +++ b/arch/arm/lib/xor-neon.c @@ -14,7 +14,7 @@ MODULE_LICENSE("GPL"); #ifndef __ARM_NEON__ -#error You should compile this file with '-mfloat-abi=softfp -mfpu=neon' +#error You should compile this file with '-march=armv7-a -mfloat-abi=softfp -mfpu=neon' #endif /* diff --git a/lib/raid6/Makefile b/lib/raid6/Makefile index 4e90d443d1b0..e723eacf7868 100644 --- a/lib/raid6/Makefile +++ b/lib/raid6/Makefile @@ -39,7 +39,7 @@ endif ifeq ($(CONFIG_KERNEL_MODE_NEON),y) NEON_FLAGS := -ffreestanding ifeq ($(ARCH),arm) -NEON_FLAGS += -mfloat-abi=softfp -mfpu=neon +NEON_FLAGS += -march=armv7-a -mfloat-abi=softfp -mfpu=neon endif CFLAGS_recov_neon_inner.o += $(NEON_FLAGS) ifeq ($(ARCH),arm64)