diff mbox series

[v7,05/10] PCI: Add support for relative addressing in quirk tables

Message ID 20180102200549.22984-6-ard.biesheuvel@linaro.org
State Not Applicable
Delegated to: David Miller
Headers show
Series add support for relative references in special sections | expand

Commit Message

Ard Biesheuvel Jan. 2, 2018, 8:05 p.m. UTC 
Allow the PCI quirk tables to be emitted in a way that avoids absolute
references to the hook functions. This reduces the size of the entries,
and, more importantly, makes them invariant under runtime relocation
(e.g., for KASLR)

Acked-by: Bjorn Helgaas <bhelgaas@google.com>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
---
 drivers/pci/quirks.c | 13 ++++++++++---
 include/linux/pci.h  | 20 ++++++++++++++++++++
 2 files changed, 30 insertions(+), 3 deletions(-)

Comments

Catalin Marinas Jan. 5, 2018, 5:41 p.m. UTC | #1 
On Tue, Jan 02, 2018 at 08:05:44PM +0000, Ard Biesheuvel wrote:
> diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
> index 10684b17d0bd..b6d51b4d5ce1 100644
> --- a/drivers/pci/quirks.c
> +++ b/drivers/pci/quirks.c
> @@ -3556,9 +3556,16 @@ static void pci_do_fixups(struct pci_dev *dev, struct pci_fixup *f,
>  		     f->vendor == (u16) PCI_ANY_ID) &&
>  		    (f->device == dev->device ||
>  		     f->device == (u16) PCI_ANY_ID)) {
> -			calltime = fixup_debug_start(dev, f->hook);
> -			f->hook(dev);
> -			fixup_debug_report(dev, calltime, f->hook);
> +			void (*hook)(struct pci_dev *dev);
> +#ifdef CONFIG_HAVE_ARCH_PREL32_RELOCATIONS
> +			hook = (void *)((unsigned long)&f->hook_offset +
> +					f->hook_offset);
> +#else
> +			hook = f->hook;
> +#endif

More of a nitpick but I've seen this pattern in several places in your
code, maybe worth defining a macro (couldn't come up with a better
name):

#define offset_to_ptr(off) \
	((void *)((unsigned long)&(off) + (off)))
Ard Biesheuvel Jan. 5, 2018, 5:45 p.m. UTC | #2 
On 5 January 2018 at 17:41, Catalin Marinas <catalin.marinas@arm.com> wrote:
> On Tue, Jan 02, 2018 at 08:05:44PM +0000, Ard Biesheuvel wrote:
>> diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
>> index 10684b17d0bd..b6d51b4d5ce1 100644
>> --- a/drivers/pci/quirks.c
>> +++ b/drivers/pci/quirks.c
>> @@ -3556,9 +3556,16 @@ static void pci_do_fixups(struct pci_dev *dev, struct pci_fixup *f,
>>                    f->vendor == (u16) PCI_ANY_ID) &&
>>                   (f->device == dev->device ||
>>                    f->device == (u16) PCI_ANY_ID)) {
>> -                     calltime = fixup_debug_start(dev, f->hook);
>> -                     f->hook(dev);
>> -                     fixup_debug_report(dev, calltime, f->hook);
>> +                     void (*hook)(struct pci_dev *dev);
>> +#ifdef CONFIG_HAVE_ARCH_PREL32_RELOCATIONS
>> +                     hook = (void *)((unsigned long)&f->hook_offset +
>> +                                     f->hook_offset);
>> +#else
>> +                     hook = f->hook;
>> +#endif
>
> More of a nitpick but I've seen this pattern in several places in your
> code, maybe worth defining a macro (couldn't come up with a better
> name):
>
> #define offset_to_ptr(off) \
>         ((void *)((unsigned long)&(off) + (off)))
>

Yeah, good point. Or even

static inline void *offset_to_ptr(const s32 *off)
{
    return (void *)((unsigned long)off + *off);
}
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diff mbox series

Patch

diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
index 10684b17d0bd..b6d51b4d5ce1 100644
--- a/drivers/pci/quirks.c
+++ b/drivers/pci/quirks.c
@@ -3556,9 +3556,16 @@  static void pci_do_fixups(struct pci_dev *dev, struct pci_fixup *f,
 		     f->vendor == (u16) PCI_ANY_ID) &&
 		    (f->device == dev->device ||
 		     f->device == (u16) PCI_ANY_ID)) {
-			calltime = fixup_debug_start(dev, f->hook);
-			f->hook(dev);
-			fixup_debug_report(dev, calltime, f->hook);
+			void (*hook)(struct pci_dev *dev);
+#ifdef CONFIG_HAVE_ARCH_PREL32_RELOCATIONS
+			hook = (void *)((unsigned long)&f->hook_offset +
+					f->hook_offset);
+#else
+			hook = f->hook;
+#endif
+			calltime = fixup_debug_start(dev, hook);
+			hook(dev);
+			fixup_debug_report(dev, calltime, hook);
 		}
 }
 
diff --git a/include/linux/pci.h b/include/linux/pci.h
index c170c9250c8b..086c3965710b 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -1792,7 +1792,11 @@  struct pci_fixup {
 	u16 device;		/* You can use PCI_ANY_ID here of course */
 	u32 class;		/* You can use PCI_ANY_ID here too */
 	unsigned int class_shift;	/* should be 0, 8, 16 */
+#ifdef CONFIG_HAVE_ARCH_PREL32_RELOCATIONS
+	int hook_offset;
+#else
 	void (*hook)(struct pci_dev *dev);
+#endif
 };
 
 enum pci_fixup_pass {
@@ -1806,12 +1810,28 @@  enum pci_fixup_pass {
 	pci_fixup_suspend_late,	/* pci_device_suspend_late() */
 };
 
+#ifdef CONFIG_HAVE_ARCH_PREL32_RELOCATIONS
+#define __DECLARE_PCI_FIXUP_SECTION(sec, name, vendor, device, class,	\
+				    class_shift, hook)			\
+	__ADDRESSABLE(hook)						\
+	asm(".section "	#sec ", \"a\"				\n"	\
+	    ".balign	16					\n"	\
+	    ".short "	#vendor ", " #device "			\n"	\
+	    ".long "	#class ", " #class_shift "		\n"	\
+	    ".long "	VMLINUX_SYMBOL_STR(hook) " - .		\n"	\
+	    ".previous						\n");
+#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)
+#else
 /* Anonymous variables would be nice... */
 #define DECLARE_PCI_FIXUP_SECTION(section, name, vendor, device, class,	\
 				  class_shift, hook)			\
 	static const struct pci_fixup __PASTE(__pci_fixup_##name,__LINE__) __used	\
 	__attribute__((__section__(#section), aligned((sizeof(void *)))))    \
 		= { vendor, device, class, class_shift, hook };
+#endif
 
 #define DECLARE_PCI_FIXUP_CLASS_EARLY(vendor, device, class,		\
 					 class_shift, hook)		\