From mboxrd@z Thu Jan 1 00:00:00 1970 From: Bjorn Helgaas Subject: Re: [PATCH 11/22] pci: lto: fix PREL32 relocations Date: Fri, 17 Jul 2020 15:26:20 -0500 Message-ID: <20200717202620.GA768846@bjorn-Precision-5520> References: <20200624203200.78870-12-samitolvanen@google.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20200624203200.78870-12-samitolvanen@google.com> Sender: linux-kbuild-owner@vger.kernel.org To: Sami Tolvanen Cc: Masahiro Yamada , Will Deacon , Greg Kroah-Hartman , "Paul E. McKenney" , Kees Cook , Nick Desaulniers , clang-built-linux@googlegroups.com, kernel-hardening@lists.openwall.com, linux-arch@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kbuild@vger.kernel.org, linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org, x86@kernel.org List-Id: linux-arch.vger.kernel.org OK by me, but please update the subject to match convention: PCI: Fix PREL32 relocations for LTO and include a hint in the commit log about what LTO is. At least expand the initialism once. Googling for "LTO" isn't very useful. With Clang's Link Time Optimization (LTO), the compiler ... ? On Wed, Jun 24, 2020 at 01:31:49PM -0700, Sami Tolvanen wrote: > With LTO, the compiler can rename static functions to avoid global > naming collisions. As PCI fixup functions are typically static, > renaming can break references to them in inline assembly. This > change adds a global stub to DECLARE_PCI_FIXUP_SECTION to fix the > issue when PREL32 relocations are used. > > Signed-off-by: Sami Tolvanen Acked-by: Bjorn Helgaas > --- > include/linux/pci.h | 15 ++++++++++----- > 1 file changed, 10 insertions(+), 5 deletions(-) > > diff --git a/include/linux/pci.h b/include/linux/pci.h > index c79d83304e52..1e65e16f165a 100644 > --- a/include/linux/pci.h > +++ b/include/linux/pci.h > @@ -1909,19 +1909,24 @@ enum pci_fixup_pass { > }; > > #ifdef CONFIG_HAVE_ARCH_PREL32_RELOCATIONS > -#define __DECLARE_PCI_FIXUP_SECTION(sec, name, vendor, device, class, \ > - class_shift, hook) \ > - __ADDRESSABLE(hook) \ > +#define ___DECLARE_PCI_FIXUP_SECTION(sec, name, vendor, device, class, \ > + class_shift, hook, stub) \ > + void stub(struct pci_dev *dev) { hook(dev); } \ > asm(".section " #sec ", \"a\" \n" \ > ".balign 16 \n" \ > ".short " #vendor ", " #device " \n" \ > ".long " #class ", " #class_shift " \n" \ > - ".long " #hook " - . \n" \ > + ".long " #stub " - . \n" \ > ".previous \n"); > + > +#define __DECLARE_PCI_FIXUP_SECTION(sec, name, vendor, device, class, \ > + class_shift, hook, stub) \ > + ___DECLARE_PCI_FIXUP_SECTION(sec, name, vendor, device, class, \ > + class_shift, hook, stub) > #define DECLARE_PCI_FIXUP_SECTION(sec, name, vendor, device, class, \ > class_shift, hook) \ > __DECLARE_PCI_FIXUP_SECTION(sec, name, vendor, device, class, \ > - class_shift, hook) > + class_shift, hook, __UNIQUE_ID(hook)) > #else > /* Anonymous variables would be nice... */ > #define DECLARE_PCI_FIXUP_SECTION(section, name, vendor, device, class, \ > -- > 2.27.0.212.ge8ba1cc988-goog > From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.kernel.org ([198.145.29.99]:32944 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726510AbgGQU0W (ORCPT ); Fri, 17 Jul 2020 16:26:22 -0400 Date: Fri, 17 Jul 2020 15:26:20 -0500 From: Bjorn Helgaas Subject: Re: [PATCH 11/22] pci: lto: fix PREL32 relocations Message-ID: <20200717202620.GA768846@bjorn-Precision-5520> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200624203200.78870-12-samitolvanen@google.com> Sender: linux-arch-owner@vger.kernel.org List-ID: To: Sami Tolvanen Cc: Masahiro Yamada , Will Deacon , Greg Kroah-Hartman , "Paul E. McKenney" , Kees Cook , Nick Desaulniers , clang-built-linux@googlegroups.com, kernel-hardening@lists.openwall.com, linux-arch@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kbuild@vger.kernel.org, linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org, x86@kernel.org Message-ID: <20200717202620._IQNT6VXNHUkvA1fgRrIO_dGyxvV4j3Ky3mC_4PKnx8@z> OK by me, but please update the subject to match convention: PCI: Fix PREL32 relocations for LTO and include a hint in the commit log about what LTO is. At least expand the initialism once. Googling for "LTO" isn't very useful. With Clang's Link Time Optimization (LTO), the compiler ... ? On Wed, Jun 24, 2020 at 01:31:49PM -0700, Sami Tolvanen wrote: > With LTO, the compiler can rename static functions to avoid global > naming collisions. As PCI fixup functions are typically static, > renaming can break references to them in inline assembly. This > change adds a global stub to DECLARE_PCI_FIXUP_SECTION to fix the > issue when PREL32 relocations are used. > > Signed-off-by: Sami Tolvanen Acked-by: Bjorn Helgaas > --- > include/linux/pci.h | 15 ++++++++++----- > 1 file changed, 10 insertions(+), 5 deletions(-) > > diff --git a/include/linux/pci.h b/include/linux/pci.h > index c79d83304e52..1e65e16f165a 100644 > --- a/include/linux/pci.h > +++ b/include/linux/pci.h > @@ -1909,19 +1909,24 @@ enum pci_fixup_pass { > }; > > #ifdef CONFIG_HAVE_ARCH_PREL32_RELOCATIONS > -#define __DECLARE_PCI_FIXUP_SECTION(sec, name, vendor, device, class, \ > - class_shift, hook) \ > - __ADDRESSABLE(hook) \ > +#define ___DECLARE_PCI_FIXUP_SECTION(sec, name, vendor, device, class, \ > + class_shift, hook, stub) \ > + void stub(struct pci_dev *dev) { hook(dev); } \ > asm(".section " #sec ", \"a\" \n" \ > ".balign 16 \n" \ > ".short " #vendor ", " #device " \n" \ > ".long " #class ", " #class_shift " \n" \ > - ".long " #hook " - . \n" \ > + ".long " #stub " - . \n" \ > ".previous \n"); > + > +#define __DECLARE_PCI_FIXUP_SECTION(sec, name, vendor, device, class, \ > + class_shift, hook, stub) \ > + ___DECLARE_PCI_FIXUP_SECTION(sec, name, vendor, device, class, \ > + class_shift, hook, stub) > #define DECLARE_PCI_FIXUP_SECTION(sec, name, vendor, device, class, \ > class_shift, hook) \ > __DECLARE_PCI_FIXUP_SECTION(sec, name, vendor, device, class, \ > - class_shift, hook) > + class_shift, hook, __UNIQUE_ID(hook)) > #else > /* Anonymous variables would be nice... */ > #define DECLARE_PCI_FIXUP_SECTION(section, name, vendor, device, class, \ > -- > 2.27.0.212.ge8ba1cc988-goog >