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    SubjectRe: [PATCH v6 17/25] PCI: Fix PREL32 relocations for LTO
    On Mon, Oct 12, 2020 at 05:31:55PM -0700, Sami Tolvanen wrote:
    > With Clang's Link Time Optimization (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>
    > Reviewed-by: Kees Cook <keescook@chromium.org>

    Another independent patch! :) Bjorn, since you've already Acked this
    patch, would be be willing to pick it up for your tree?

    -Kees

    > ---
    > include/linux/pci.h | 19 ++++++++++++++-----
    > 1 file changed, 14 insertions(+), 5 deletions(-)
    >
    > diff --git a/include/linux/pci.h b/include/linux/pci.h
    > index 835530605c0d..4e64421981c7 100644
    > --- a/include/linux/pci.h
    > +++ b/include/linux/pci.h
    > @@ -1909,19 +1909,28 @@ 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); \
    > + 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, \
    > --
    > 2.28.0.1011.ga647a8990f-goog
    >

    --
    Kees Cook

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