| Message ID | 20200624203200.78870-12-samitolvanen@google.com |
|---|---|
| State | New |
| Headers | show |
| Series | add support for Clang LTO | expand |
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 <samitolvanen@google.com> Acked-by: Bjorn Helgaas <bhelgaas@google.com> > --- > 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 >
Hi Bjorn, On Fri, Jul 17, 2020 at 1:26 PM Bjorn Helgaas <helgaas@kernel.org> wrote: > > 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 ... ? Sure, I'll change this in the next version. Thanks for taking a look! Sami
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, \
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 <samitolvanen@google.com> --- include/linux/pci.h | 15 ++++++++++----- 1 file changed, 10 insertions(+), 5 deletions(-)