From patchwork Thu Jun 21 16:23:24 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Nick Desaulniers X-Patchwork-Id: 10480177 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 5E6C360365 for ; Thu, 21 Jun 2018 16:26:21 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 4C00320407 for ; Thu, 21 Jun 2018 16:26:21 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 48DC429059; Thu, 21 Jun 2018 16:26:21 +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=-7.8 required=2.0 tests=BAYES_00, DKIM_ADSP_CUSTOM_MED, DKIM_SIGNED, MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI, T_DKIM_INVALID autolearn=ham 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 6177920407 for ; Thu, 21 Jun 2018 16:24:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933396AbeFUQXq (ORCPT ); Thu, 21 Jun 2018 12:23:46 -0400 Received: from mail-qk0-f201.google.com ([209.85.220.201]:54181 "EHLO mail-qk0-f201.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933417AbeFUQXn (ORCPT ); Thu, 21 Jun 2018 12:23:43 -0400 Received: by mail-qk0-f201.google.com with SMTP id u20-v6so3007898qkk.20 for ; Thu, 21 Jun 2018 09:23:42 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:date:in-reply-to:message-id:references:subject:from:to :cc; bh=69zGo/r6+0irgRW+5JOoApDxQgRAUSTQ2lETVwGDrV0=; b=YrTPqyFVtXsMAvvC5f5FlE1rzB5VeSdti6iX58Isa6cVmz2PRckosBrTZ5w2rs4uIj hXbElK+IDt19xVxdp6+Ej58/YGBIfozLYxh4cNMmpMiK7BTcUWNRnmgP7RvhL7ut0v9w THXUgfYFZ3axU7uHsYtg4A02xPDbqJ7Yp/ai0w3SHqGBfnObeJYV7cpyMMd1LtmUsY5g ydsE9E5eJIAoa61wuBIoljqU6MLCCgC+mlBEe3umrKVOe9ddAGyFw+/nVP/tnjy+oj4P CEVNylQy2JGqrLErk4nK+FB0hicYy5w0SbPDo4Vqt8PQc03syxJdEPDGHgCOscG95Eeq et2w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:date:in-reply-to:message-id :references:subject:from:to:cc; bh=69zGo/r6+0irgRW+5JOoApDxQgRAUSTQ2lETVwGDrV0=; b=PA+uMUhmn9lTlDoe+gPTOJk+eXQKj8D4DegLFenW234M0oRZGEQl+U422W8MZHcwbw VlrY7axBsYfS62k0CUhsiVxlWvZpLnwYAd39PW79nRv+RfENfFhK450AfLjuKya5EEjP 7OynmAG7diVWTIsIWVF5CdxdTzjQ2Oz7bEXyckc4/ofjZag0x/X27Br9Y9kHe8YJY0QW nWKlJELIXUJxEndK5EFQoFTHXZFE4XvX7BE8JQM2grr+77RmV5jGf6ryUTjT2/AvrNB7 i/1DnGhNIsliAivmTNx0x1X35PIegCMl8ONMwvEJ+jzsnwQveH2nozsNv6xtV9Hh0/co qbGA== X-Gm-Message-State: APt69E3rPiq1Qxn1OUsW0SSoP+P3A2DoDt3UmF7yn9a6E3EqAVX5JpjD lq/FS8FxEYKHah4u0c2k1I/EwS/WkH7+D/Fari8= X-Google-Smtp-Source: ADUXVKLDjcBLaZU3T6NBtD9qXhtx8YPSSonWXRKDxUZLixu0q5c66xT5K2h1Rgk/eX4EAfXz0AOTD/gjUC1MiYZGZBQ= MIME-Version: 1.0 X-Received: by 2002:a0c:89ed:: with SMTP id 42-v6mr13747177qvs.36.1529598221996; Thu, 21 Jun 2018 09:23:41 -0700 (PDT) Date: Thu, 21 Jun 2018 09:23:24 -0700 In-Reply-To: <20180621162324.36656-1-ndesaulniers@google.com> Message-Id: <20180621162324.36656-4-ndesaulniers@google.com> References: <20180621162324.36656-1-ndesaulniers@google.com> X-Mailer: git-send-email 2.18.0.rc2.346.g013aa6912e-goog Subject: [PATCH v6 3/3] x86: paravirt: make native_save_fl extern inline From: Nick Desaulniers To: mingo@redhat.com, tglx@linutronix.de Cc: akpm@linux-foundation.org, hpa@zytor.com, linux-efi@vger.kernel.org, linux-kernel@vger.kernel.org, x86@kernel.org, virtualization@lists.linux-foundation.org, astrachan@google.com, manojgupta@google.com, ghackmann@google.com, sedat.dilek@gmail.com, tstellar@redhat.com, keescook@google.com, yamada.masahiro@socionext.com, michal.lkml@markovi.net, linux-kbuild@vger.kernel.org, geert@linux-m68k.org, will.deacon@arm.com, mawilcox@microsoft.com, arnd@arndb.de, rientjes@google.com, acme@redhat.com, pombredanne@nexb.com, aryabinin@virtuozzo.com, kstewart@linuxfoundation.org, boris.ostrovsky@oracle.com, jan.kiszka@siemens.com, rostedt@goodmis.org, kirill.shutemov@linux.intel.com, ard.biesheuvel@linaro.org, akataria@vmware.com, brijesh.singh@amd.com, caoj.fnst@cn.fujitsu.com, gregkh@linuxfoundation.org, jarkko.sakkinen@linux.intel.com, jgross@suse.com, jpoimboe@redhat.com, mka@chromium.org, ndesaulniers@google.com, thomas.lendacky@amd.com, tweek@google.com, mjg59@google.com, joe@perches.com, andrea.parri@amarulasolutions.com Sender: linux-kbuild-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kbuild@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP native_save_fl() is marked static inline, but by using it as a function pointer in arch/x86/kernel/paravirt.c, it MUST be outlined. paravirt's use of native_save_fl() also requires that no GPRs other than %rax are clobbered. Compilers have different heuristics which they use to emit stack guard code, the emittance of which can break paravirt's callee saved assumption by clobbering %rcx. Marking a function definition extern inline means that if this version cannot be inlined, then the out-of-line version will be preferred. By having the out-of-line version be implemented in assembly, it cannot be instrumented with a stack protector, which might violate custom calling conventions that code like paravirt rely on. The semantics of extern inline has changed since gnu89. This means that folks using GCC versions >= 5.1 may see symbol redefinition errors at link time for subdirs that override KBUILD_CFLAGS (making the C standard used implicit) regardless of this patch. This has been cleaned up earlier in the patch set, but is left as a note in the commit message for future travelers. Reports: https://lkml.org/lkml/2018/5/7/534 https://github.com/ClangBuiltLinux/linux/issues/16 Discussion: https://bugs.llvm.org/show_bug.cgi?id=37512 https://lkml.org/lkml/2018/5/24/1371 Thanks to the many folks that participated in the discussion. Acked-by: Juergen Gross Debugged-by: Alistair Strachan Debugged-by: Matthias Kaehlcke Reported-by: Sedat Dilek Signed-off-by: Nick Desaulniers Suggested-by: Arnd Bergmann Suggested-by: H. Peter Anvin Suggested-by: Tom Stellar Tested-by: Sedat Dilek Acked-by: Ingo Molnar --- arch/x86/include/asm/irqflags.h | 2 +- arch/x86/kernel/Makefile | 1 + arch/x86/kernel/irqflags.S | 26 ++++++++++++++++++++++++++ 3 files changed, 28 insertions(+), 1 deletion(-) create mode 100644 arch/x86/kernel/irqflags.S diff --git a/arch/x86/include/asm/irqflags.h b/arch/x86/include/asm/irqflags.h index 89f08955fff7..c4fc17220df9 100644 --- a/arch/x86/include/asm/irqflags.h +++ b/arch/x86/include/asm/irqflags.h @@ -13,7 +13,7 @@ * Interrupt control: */ -static inline unsigned long native_save_fl(void) +extern inline unsigned long native_save_fl(void) { unsigned long flags; diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile index 02d6f5cf4e70..8824d01c0c35 100644 --- a/arch/x86/kernel/Makefile +++ b/arch/x86/kernel/Makefile @@ -61,6 +61,7 @@ obj-y += alternative.o i8253.o hw_breakpoint.o obj-y += tsc.o tsc_msr.o io_delay.o rtc.o obj-y += pci-iommu_table.o obj-y += resource.o +obj-y += irqflags.o obj-y += process.o obj-y += fpu/ diff --git a/arch/x86/kernel/irqflags.S b/arch/x86/kernel/irqflags.S new file mode 100644 index 000000000000..ddeeaac8adda --- /dev/null +++ b/arch/x86/kernel/irqflags.S @@ -0,0 +1,26 @@ +/* SPDX-License-Identifier: GPL-2.0 */ + +#include +#include +#include + +/* + * unsigned long native_save_fl(void) + */ +ENTRY(native_save_fl) + pushf + pop %_ASM_AX + ret +ENDPROC(native_save_fl) +EXPORT_SYMBOL(native_save_fl) + +/* + * void native_restore_fl(unsigned long flags) + * %eax/%rdi: flags + */ +ENTRY(native_restore_fl) + push %_ASM_ARG1 + popf + ret +ENDPROC(native_restore_fl) +EXPORT_SYMBOL(native_restore_fl)