From patchwork Wed Feb 14 13:44:34 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Woodhouse, David" X-Patchwork-Id: 10218907 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 86FD9601D7 for ; Wed, 14 Feb 2018 13:45:59 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 7670728FAE for ; Wed, 14 Feb 2018 13:45:59 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 6A46828FDE; Wed, 14 Feb 2018 13:45:59 +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=-7.0 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, RCVD_IN_DNSWL_HI autolearn=unavailable version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 0978E28FAE for ; Wed, 14 Feb 2018 13:45:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1030407AbeBNNp0 (ORCPT ); Wed, 14 Feb 2018 08:45:26 -0500 Received: from smtp-fw-4101.amazon.com ([72.21.198.25]:40868 "EHLO smtp-fw-4101.amazon.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1030252AbeBNNo4 (ORCPT ); Wed, 14 Feb 2018 08:44:56 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=amazon.co.uk; i=@amazon.co.uk; q=dns/txt; s=amazon201209; t=1518615896; x=1550151896; h=from:to:subject:date:message-id:in-reply-to:references; bh=7GUIRWILo0LT/aL4M47T6JJhUWbPNOoYuvv+uvYQDkM=; b=V+hua1qvMaIoPqzA98wM7vAiZcjLWH/zraNWZvN4cka5MTQCRTBkvDb5 Mj9amLSE2S4JLe2NDIj8PuAtLY4tq2uP+DEI3Fmzx2bu758MWfQ2y+dSX lfkvQeUPDqauEEqQHWoHuef4tPzvGvL1UaLd4UMD9LQggC+czwDnkn/J1 M=; X-IronPort-AV: E=Sophos;i="5.46,512,1511827200"; d="scan'208";a="708104511" Received: from iad6-co-svc-p1-lb1-vlan3.amazon.com (HELO email-inbound-relay-1a-807d4a99.us-east-1.amazon.com) ([10.124.125.6]) by smtp-border-fw-out-4101.iad4.amazon.com with ESMTP/TLS/DHE-RSA-AES256-SHA; 14 Feb 2018 13:44:55 +0000 Received: from uc8d3ff76b9bc5848a9cc.ant.amazon.com (iad1-ws-svc-lb91-vlan2.amazon.com [10.0.103.146]) by email-inbound-relay-1a-807d4a99.us-east-1.amazon.com (8.14.7/8.14.7) with ESMTP id w1EDiiJb102378 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); Wed, 14 Feb 2018 13:44:47 GMT Received: from uc8d3ff76b9bc5848a9cc.ant.amazon.com (localhost [127.0.0.1]) by uc8d3ff76b9bc5848a9cc.ant.amazon.com (8.15.2/8.15.2/Debian-3) with ESMTP id w1EDih8s014281; Wed, 14 Feb 2018 13:44:44 GMT Received: (from dwmw@localhost) by uc8d3ff76b9bc5848a9cc.ant.amazon.com (8.15.2/8.15.2/Submit) id w1EDiher014280; Wed, 14 Feb 2018 13:44:43 GMT From: David Woodhouse To: tglx@linutronix.de, karahmed@amazon.de, x86@kernel.org, kvm@vger.kernel.org, torvalds@linux-foundation.org, pbonzini@redhat.com, linux-kernel@vger.kernel.org, bp@alien8.de, peterz@infradead.org, jmattson@google.com, rkrcmar@redhat.com, arjan.van.de.ven@intel.com, dave.hansen@intel.com, mingo@kernel.org Subject: [PATCH 4/4] x86/retpoline: Support retpoline build with Clang Date: Wed, 14 Feb 2018 13:44:34 +0000 Message-Id: <1518615874-13806-5-git-send-email-dwmw@amazon.co.uk> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1518615874-13806-1-git-send-email-dwmw@amazon.co.uk> References: <1518615874-13806-1-git-send-email-dwmw@amazon.co.uk> Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Signed-off-by: David Woodhouse --- arch/x86/Makefile | 5 ++++- include/linux/compiler-clang.h | 5 +++++ include/linux/compiler-gcc.h | 4 ++++ include/linux/init.h | 8 ++++---- 4 files changed, 17 insertions(+), 5 deletions(-) diff --git a/arch/x86/Makefile b/arch/x86/Makefile index fad5516..dbc7d0e 100644 --- a/arch/x86/Makefile +++ b/arch/x86/Makefile @@ -232,7 +232,10 @@ KBUILD_CFLAGS += -fno-asynchronous-unwind-tables # Avoid indirect branches in kernel to deal with Spectre ifdef CONFIG_RETPOLINE - RETPOLINE_CFLAGS += $(call cc-option,-mindirect-branch=thunk-extern -mindirect-branch-register) + RETPOLINE_CFLAGS_GCC := -mindirect-branch=thunk-extern -mindirect-branch-register + RETPOLINE_CFLAGS_CLANG := -mretpoline-external-thunk + + RETPOLINE_CFLAGS += $(call cc-option,$(RETPOLINE_CFLAGS_GCC),$(call cc-option,$(RETPOLINE_CFLAGS_CLANG))) ifneq ($(RETPOLINE_CFLAGS),) KBUILD_CFLAGS += $(RETPOLINE_CFLAGS) -DRETPOLINE endif diff --git a/include/linux/compiler-clang.h b/include/linux/compiler-clang.h index 3b609ed..be3aef6 100644 --- a/include/linux/compiler-clang.h +++ b/include/linux/compiler-clang.h @@ -19,3 +19,8 @@ #define randomized_struct_fields_start struct { #define randomized_struct_fields_end }; + +/* Clang doesn't have a way to turn it off per-function, yet. */ +#ifdef __noretpoline +#undef __noretpoline +#endif diff --git a/include/linux/compiler-gcc.h b/include/linux/compiler-gcc.h index 631354a..2e8a287 100644 --- a/include/linux/compiler-gcc.h +++ b/include/linux/compiler-gcc.h @@ -93,6 +93,10 @@ #define __weak __attribute__((weak)) #define __alias(symbol) __attribute__((alias(#symbol))) +#ifdef RETPOLINE +#define __noretpoline __attribute__((indirect_branch("keep"))) +#endif + /* * it doesn't make sense on ARM (currently the only user of __naked) * to trace naked functions because then mcount is called without diff --git a/include/linux/init.h b/include/linux/init.h index 506a981..bc27cf0 100644 --- a/include/linux/init.h +++ b/include/linux/init.h @@ -6,10 +6,10 @@ #include /* Built-in __init functions needn't be compiled with retpoline */ -#if defined(RETPOLINE) && !defined(MODULE) -#define __noretpoline __attribute__((indirect_branch("keep"))) +#if defined(__noretpoline) && !defined(MODULE) +#define __noinitretpoline __noretpoline #else -#define __noretpoline +#define __noinitretpoline #endif /* These macros are used to mark some functions or @@ -47,7 +47,7 @@ /* These are for everybody (although not all archs will actually discard it in modules) */ -#define __init __section(.init.text) __cold __latent_entropy __noretpoline +#define __init __section(.init.text) __cold __latent_entropy __noinitretpoline #define __initdata __section(.init.data) #define __initconst __section(.init.rodata) #define __exitdata __section(.exit.data)