diff mbox series

[v6,17/25] PCI: Fix PREL32 relocations for LTO

Message ID 20201013003203.4168817-18-samitolvanen@google.com
State New, archived
Headers show
Series Add support for Clang LTO | expand

Commit Message

Sami Tolvanen Oct. 13, 2020, 12:31 a.m. UTC
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>
---
 include/linux/pci.h | 19 ++++++++++++++-----
 1 file changed, 14 insertions(+), 5 deletions(-)

Comments

Kees Cook Oct. 14, 2020, 10:58 p.m. UTC | #1
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
>
diff mbox series

Patch

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,	\