diff mbox series

[v2,1/2] lib/xor: make xor prototypes more friendely to compiler vectorization

Message ID 20220129224529.76887-2-ardb@kernel.org
State Superseded
Headers show
Series xor: enable auto-vectorization in Clang | expand

Commit Message

Ard Biesheuvel Jan. 29, 2022, 10:45 p.m. UTC 
Modern compilers are perfectly capable of extracting parallelism from
the XOR routines, provided that the prototypes reflect the nature of the
input accurately, in particular, the fact that the input vectors are
expected not to overlap. This is not documented explicitly, but is
implied by the interchangeability of the various C routines, some of
which use temporary variables while others don't: this means that these
routines only behave identically for non-overlapping inputs.

So let's decorate these input vectors with the __restrict modifier,
which informs the compiler that there is no overlap. While at it, make
the input-only vectors pointer-to-const as well.

Tested-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
---
 arch/alpha/include/asm/xor.h           | 53 ++++++++----
 arch/arm/include/asm/xor.h             | 42 ++++++----
 arch/arm64/include/asm/xor.h           | 21 +++--
 arch/arm64/lib/xor-neon.c              | 23 +++---
 arch/ia64/include/asm/xor.h            | 21 +++--
 arch/powerpc/include/asm/xor_altivec.h | 25 +++---
 arch/powerpc/lib/xor_vmx.c             | 28 ++++---
 arch/powerpc/lib/xor_vmx.h             | 27 ++++---
 arch/powerpc/lib/xor_vmx_glue.c        | 32 ++++----
 arch/s390/lib/xor.c                    | 21 +++--
 arch/sparc/include/asm/xor_32.h        | 21 +++--
 arch/sparc/include/asm/xor_64.h        | 42 ++++++----
 arch/x86/include/asm/xor.h             | 42 ++++++----
 arch/x86/include/asm/xor_32.h          | 42 ++++++----
 arch/x86/include/asm/xor_avx.h         | 21 +++--
 include/asm-generic/xor.h              | 84 +++++++++++++-------
 include/linux/raid/xor.h               | 21 +++--
 17 files changed, 366 insertions(+), 200 deletions(-)

Comments

Nick Desaulniers Jan. 31, 2022, 6:13 p.m. UTC | #1 
On Sat, Jan 29, 2022 at 2:45 PM Ard Biesheuvel <ardb@kernel.org> wrote:
>
> Modern compilers are perfectly capable of extracting parallelism from
> the XOR routines, provided that the prototypes reflect the nature of the
> input accurately, in particular, the fact that the input vectors are
> expected not to overlap. This is not documented explicitly, but is
> implied by the interchangeability of the various C routines, some of
> which use temporary variables while others don't: this means that these
> routines only behave identically for non-overlapping inputs.
>
> So let's decorate these input vectors with the __restrict modifier,
> which informs the compiler that there is no overlap. While at it, make
> the input-only vectors pointer-to-const as well.
>
> Tested-by: Nathan Chancellor <nathan@kernel.org>
> Signed-off-by: Ard Biesheuvel <ardb@kernel.org>

Thanks for the patch!
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>

I like how you renamed the parameters in
arch/powerpc/include/asm/xor_altivec.h, arch/powerpc/lib/xor_vmx.h,
and arch/powerpc/lib/xor_vmx_glue.c.  It's not befitting for the
suffix _in to be used when the first param is technically more of an
"inout" param.  Though, you might also want to update the parameter
names in arch/powerpc/lib/xor_vmx.c.
Nick Desaulniers Jan. 31, 2022, 6:17 p.m. UTC | #2 
On Mon, Jan 31, 2022 at 10:13 AM Nick Desaulniers
<ndesaulniers@google.com> wrote:
>
> On Sat, Jan 29, 2022 at 2:45 PM Ard Biesheuvel <ardb@kernel.org> wrote:
> >
> > Modern compilers are perfectly capable of extracting parallelism from
> > the XOR routines, provided that the prototypes reflect the nature of the
> > input accurately, in particular, the fact that the input vectors are
> > expected not to overlap. This is not documented explicitly, but is
> > implied by the interchangeability of the various C routines, some of
> > which use temporary variables while others don't: this means that these
> > routines only behave identically for non-overlapping inputs.
> >
> > So let's decorate these input vectors with the __restrict modifier,
> > which informs the compiler that there is no overlap. While at it, make
> > the input-only vectors pointer-to-const as well.
> >
> > Tested-by: Nathan Chancellor <nathan@kernel.org>
> > Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
>
> Thanks for the patch!
> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
>
> I like how you renamed the parameters in
> arch/powerpc/include/asm/xor_altivec.h, arch/powerpc/lib/xor_vmx.h,
> and arch/powerpc/lib/xor_vmx_glue.c.  It's not befitting for the
> suffix _in to be used when the first param is technically more of an
> "inout" param.  Though, you might also want to update the parameter
> names in arch/powerpc/lib/xor_vmx.c.

Also, this patch fixes an instance of -Wframe-larger-than we observed with ppc:

Link: https://github.com/ClangBuiltLinux/linux/issues/563
Herbert Xu Feb. 5, 2022, 4:33 a.m. UTC | #3 
On Sat, Jan 29, 2022 at 11:45:28PM +0100, Ard Biesheuvel wrote:
>
> diff --git a/arch/arm64/lib/xor-neon.c b/arch/arm64/lib/xor-neon.c
> index d189cf4e70ea..e8d189f3897f 100644
> --- a/arch/arm64/lib/xor-neon.c
> +++ b/arch/arm64/lib/xor-neon.c

I think this still fails to build on arm64:

../arch/arm64/lib/xor-neon.c:13:6: warning: no previous prototype for ‘xor_arm64_neon_2’ [-Wmissing-prototypes]
   13 | void xor_arm64_neon_2(unsigned long bytes, unsigned long * __restrict p1,
      |      ^~~~~~~~~~~~~~~~
../arch/arm64/lib/xor-neon.c:40:6: warning: no previous prototype for ‘xor_arm64_neon_3’ [-Wmissing-prototypes]
   40 | void xor_arm64_neon_3(unsigned long bytes, unsigned long * __restrict p1,
      |      ^~~~~~~~~~~~~~~~
../arch/arm64/lib/xor-neon.c:76:6: warning: no previous prototype for ‘xor_arm64_neon_4’ [-Wmissing-prototypes]
   76 | void xor_arm64_neon_4(unsigned long bytes, unsigned long * __restrict p1,
      |      ^~~~~~~~~~~~~~~~
../arch/arm64/lib/xor-neon.c:121:6: warning: no previous prototype for ‘xor_arm64_neon_5’ [-Wmissing-prototypes]
  121 | void xor_arm64_neon_5(unsigned long bytes, unsigned long * __restrict p1,
      |      ^~~~~~~~~~~~~~~~
../arch/arm64/lib/xor-neon.c: In function ‘xor_neon_init’:
../arch/arm64/lib/xor-neon.c:316:29: error: assignment to ‘void (*)(long unsigned int,  long unsigned int * __restrict__,  const long unsigned int * __restrict__,  const long unsigned int * __restrict__)’ from incompatible pointer type ‘void (*)(long unsigned int,  long unsigned int *, long unsigned int *, long unsigned int *)’ [-Werror=incompatible-pointer-types]
  316 |   xor_block_inner_neon.do_3 = xor_arm64_eor3_3;
      |                             ^
../arch/arm64/lib/xor-neon.c:317:29: error: assignment to ‘void (*)(long unsigned int,  long unsigned int * __restrict__,  const long unsigned int * __restrict__,  const long unsigned int * __restrict__,  const long unsigned int * __restrict__)’ from incompatible pointer type ‘void (*)(long unsigned int,  long unsigned int *, long unsigned int *, long unsigned int *, long unsigned int *)’ [-Werror=incompatible-pointer-types]
  317 |   xor_block_inner_neon.do_4 = xor_arm64_eor3_4;
      |                             ^
../arch/arm64/lib/xor-neon.c:318:29: error: assignment to ‘void (*)(long unsigned int,  long unsigned int * __restrict__,  const long unsigned int * __restrict__,  const long unsigned int * __restrict__,  const long unsigned int * __restrict__,  const long unsigned int * __restrict__)’ from incompatible pointer type ‘void (*)(long unsigned int,  long unsigned int *, long unsigned int *, long unsigned int *, long unsigned int *, long unsigned int *)’ [-Werror=incompatible-pointer-types]
  318 |   xor_block_inner_neon.do_5 = xor_arm64_eor3_5;
      |                             ^
cc1: some warnings being treated as errors

Cheers,
Ard Biesheuvel Feb. 5, 2022, 7:56 a.m. UTC | #4 
On Sat, 5 Feb 2022 at 05:34, Herbert Xu <herbert@gondor.apana.org.au> wrote:
>
> On Sat, Jan 29, 2022 at 11:45:28PM +0100, Ard Biesheuvel wrote:
> >
> > diff --git a/arch/arm64/lib/xor-neon.c b/arch/arm64/lib/xor-neon.c
> > index d189cf4e70ea..e8d189f3897f 100644
> > --- a/arch/arm64/lib/xor-neon.c
> > +++ b/arch/arm64/lib/xor-neon.c
>
> I think this still fails to build on arm64:
>

Oops, failed to rebase onto the arm64 tree, which carries another XOR
patch of mine.


> ../arch/arm64/lib/xor-neon.c:13:6: warning: no previous prototype for ‘xor_arm64_neon_2’ [-Wmissing-prototypes]
>    13 | void xor_arm64_neon_2(unsigned long bytes, unsigned long * __restrict p1,
>       |      ^~~~~~~~~~~~~~~~
> ../arch/arm64/lib/xor-neon.c:40:6: warning: no previous prototype for ‘xor_arm64_neon_3’ [-Wmissing-prototypes]
>    40 | void xor_arm64_neon_3(unsigned long bytes, unsigned long * __restrict p1,
>       |      ^~~~~~~~~~~~~~~~
> ../arch/arm64/lib/xor-neon.c:76:6: warning: no previous prototype for ‘xor_arm64_neon_4’ [-Wmissing-prototypes]
>    76 | void xor_arm64_neon_4(unsigned long bytes, unsigned long * __restrict p1,
>       |      ^~~~~~~~~~~~~~~~
> ../arch/arm64/lib/xor-neon.c:121:6: warning: no previous prototype for ‘xor_arm64_neon_5’ [-Wmissing-prototypes]
>   121 | void xor_arm64_neon_5(unsigned long bytes, unsigned long * __restrict p1,
>       |      ^~~~~~~~~~~~~~~~
> ../arch/arm64/lib/xor-neon.c: In function ‘xor_neon_init’:
> ../arch/arm64/lib/xor-neon.c:316:29: error: assignment to ‘void (*)(long unsigned int,  long unsigned int * __restrict__,  const long unsigned int * __restrict__,  const long unsigned int * __restrict__)’ from incompatible pointer type ‘void (*)(long unsigned int,  long unsigned int *, long unsigned int *, long unsigned int *)’ [-Werror=incompatible-pointer-types]
>   316 |   xor_block_inner_neon.do_3 = xor_arm64_eor3_3;
>       |                             ^
> ../arch/arm64/lib/xor-neon.c:317:29: error: assignment to ‘void (*)(long unsigned int,  long unsigned int * __restrict__,  const long unsigned int * __restrict__,  const long unsigned int * __restrict__,  const long unsigned int * __restrict__)’ from incompatible pointer type ‘void (*)(long unsigned int,  long unsigned int *, long unsigned int *, long unsigned int *, long unsigned int *)’ [-Werror=incompatible-pointer-types]
>   317 |   xor_block_inner_neon.do_4 = xor_arm64_eor3_4;
>       |                             ^
> ../arch/arm64/lib/xor-neon.c:318:29: error: assignment to ‘void (*)(long unsigned int,  long unsigned int * __restrict__,  const long unsigned int * __restrict__,  const long unsigned int * __restrict__,  const long unsigned int * __restrict__,  const long unsigned int * __restrict__)’ from incompatible pointer type ‘void (*)(long unsigned int,  long unsigned int *, long unsigned int *, long unsigned int *, long unsigned int *, long unsigned int *)’ [-Werror=incompatible-pointer-types]
>   318 |   xor_block_inner_neon.do_5 = xor_arm64_eor3_5;
>       |                             ^
> cc1: some warnings being treated as errors
>
> Cheers,
> --
> Email: Herbert Xu <herbert@gondor.apana.org.au>
> Home Page: http://gondor.apana.org.au/~herbert/
> PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt
diff mbox series

Patch

diff --git a/arch/alpha/include/asm/xor.h b/arch/alpha/include/asm/xor.h
index 5aeb4fb3cb7c..e0de0c233ab9 100644
--- a/arch/alpha/include/asm/xor.h
+++ b/arch/alpha/include/asm/xor.h
@@ -5,24 +5,43 @@ 
  * Optimized RAID-5 checksumming functions for alpha EV5 and EV6
  */
 
-extern void xor_alpha_2(unsigned long, unsigned long *, unsigned long *);
-extern void xor_alpha_3(unsigned long, unsigned long *, unsigned long *,
-		        unsigned long *);
-extern void xor_alpha_4(unsigned long, unsigned long *, unsigned long *,
-		        unsigned long *, unsigned long *);
-extern void xor_alpha_5(unsigned long, unsigned long *, unsigned long *,
-		        unsigned long *, unsigned long *, unsigned long *);
+extern void
+xor_alpha_2(unsigned long bytes, unsigned long * __restrict p1,
+	    const unsigned long * __restrict p2);
+extern void
+xor_alpha_3(unsigned long bytes, unsigned long * __restrict p1,
+	    const unsigned long * __restrict p2,
+	    const unsigned long * __restrict p3);
+extern void
+xor_alpha_4(unsigned long bytes, unsigned long * __restrict p1,
+	    const unsigned long * __restrict p2,
+	    const unsigned long * __restrict p3,
+	    const unsigned long * __restrict p4);
+extern void
+xor_alpha_5(unsigned long bytes, unsigned long * __restrict p1,
+	    const unsigned long * __restrict p2,
+	    const unsigned long * __restrict p3,
+	    const unsigned long * __restrict p4,
+	    const unsigned long * __restrict p5);
 
-extern void xor_alpha_prefetch_2(unsigned long, unsigned long *,
-				 unsigned long *);
-extern void xor_alpha_prefetch_3(unsigned long, unsigned long *,
-				 unsigned long *, unsigned long *);
-extern void xor_alpha_prefetch_4(unsigned long, unsigned long *,
-				 unsigned long *, unsigned long *,
-				 unsigned long *);
-extern void xor_alpha_prefetch_5(unsigned long, unsigned long *,
-				 unsigned long *, unsigned long *,
-				 unsigned long *, unsigned long *);
+extern void
+xor_alpha_prefetch_2(unsigned long bytes, unsigned long * __restrict p1,
+		     const unsigned long * __restrict p2);
+extern void
+xor_alpha_prefetch_3(unsigned long bytes, unsigned long * __restrict p1,
+		     const unsigned long * __restrict p2,
+		     const unsigned long * __restrict p3);
+extern void
+xor_alpha_prefetch_4(unsigned long bytes, unsigned long * __restrict p1,
+		     const unsigned long * __restrict p2,
+		     const unsigned long * __restrict p3,
+		     const unsigned long * __restrict p4);
+extern void
+xor_alpha_prefetch_5(unsigned long bytes, unsigned long * __restrict p1,
+		     const unsigned long * __restrict p2,
+		     const unsigned long * __restrict p3,
+		     const unsigned long * __restrict p4,
+		     const unsigned long * __restrict p5);
 
 asm("								\n\
 	.text							\n\
diff --git a/arch/arm/include/asm/xor.h b/arch/arm/include/asm/xor.h
index aefddec79286..669cad5194d3 100644
--- a/arch/arm/include/asm/xor.h
+++ b/arch/arm/include/asm/xor.h
@@ -44,7 +44,8 @@ 
 		: "0" (dst), "r" (a1), "r" (a2), "r" (a3), "r" (a4))
 
 static void
-xor_arm4regs_2(unsigned long bytes, unsigned long *p1, unsigned long *p2)
+xor_arm4regs_2(unsigned long bytes, unsigned long * __restrict p1,
+	       const unsigned long * __restrict p2)
 {
 	unsigned int lines = bytes / sizeof(unsigned long) / 4;
 	register unsigned int a1 __asm__("r4");
@@ -64,8 +65,9 @@  xor_arm4regs_2(unsigned long bytes, unsigned long *p1, unsigned long *p2)
 }
 
 static void
-xor_arm4regs_3(unsigned long bytes, unsigned long *p1, unsigned long *p2,
-		unsigned long *p3)
+xor_arm4regs_3(unsigned long bytes, unsigned long * __restrict p1,
+	       const unsigned long * __restrict p2,
+	       const unsigned long * __restrict p3)
 {
 	unsigned int lines = bytes / sizeof(unsigned long) / 4;
 	register unsigned int a1 __asm__("r4");
@@ -86,8 +88,10 @@  xor_arm4regs_3(unsigned long bytes, unsigned long *p1, unsigned long *p2,
 }
 
 static void
-xor_arm4regs_4(unsigned long bytes, unsigned long *p1, unsigned long *p2,
-		unsigned long *p3, unsigned long *p4)
+xor_arm4regs_4(unsigned long bytes, unsigned long * __restrict p1,
+	       const unsigned long * __restrict p2,
+	       const unsigned long * __restrict p3,
+	       const unsigned long * __restrict p4)
 {
 	unsigned int lines = bytes / sizeof(unsigned long) / 2;
 	register unsigned int a1 __asm__("r8");
@@ -105,8 +109,11 @@  xor_arm4regs_4(unsigned long bytes, unsigned long *p1, unsigned long *p2,
 }
 
 static void
-xor_arm4regs_5(unsigned long bytes, unsigned long *p1, unsigned long *p2,
-		unsigned long *p3, unsigned long *p4, unsigned long *p5)
+xor_arm4regs_5(unsigned long bytes, unsigned long * __restrict p1,
+	       const unsigned long * __restrict p2,
+	       const unsigned long * __restrict p3,
+	       const unsigned long * __restrict p4,
+	       const unsigned long * __restrict p5)
 {
 	unsigned int lines = bytes / sizeof(unsigned long) / 2;
 	register unsigned int a1 __asm__("r8");
@@ -146,7 +153,8 @@  static struct xor_block_template xor_block_arm4regs = {
 extern struct xor_block_template const xor_block_neon_inner;
 
 static void
-xor_neon_2(unsigned long bytes, unsigned long *p1, unsigned long *p2)
+xor_neon_2(unsigned long bytes, unsigned long * __restrict p1,
+	   const unsigned long * __restrict p2)
 {
 	if (in_interrupt()) {
 		xor_arm4regs_2(bytes, p1, p2);
@@ -158,8 +166,9 @@  xor_neon_2(unsigned long bytes, unsigned long *p1, unsigned long *p2)
 }
 
 static void
-xor_neon_3(unsigned long bytes, unsigned long *p1, unsigned long *p2,
-		unsigned long *p3)
+xor_neon_3(unsigned long bytes, unsigned long * __restrict p1,
+	   const unsigned long * __restrict p2,
+	   const unsigned long * __restrict p3)
 {
 	if (in_interrupt()) {
 		xor_arm4regs_3(bytes, p1, p2, p3);
@@ -171,8 +180,10 @@  xor_neon_3(unsigned long bytes, unsigned long *p1, unsigned long *p2,
 }
 
 static void
-xor_neon_4(unsigned long bytes, unsigned long *p1, unsigned long *p2,
-		unsigned long *p3, unsigned long *p4)
+xor_neon_4(unsigned long bytes, unsigned long * __restrict p1,
+	   const unsigned long * __restrict p2,
+	   const unsigned long * __restrict p3,
+	   const unsigned long * __restrict p4)
 {
 	if (in_interrupt()) {
 		xor_arm4regs_4(bytes, p1, p2, p3, p4);
@@ -184,8 +195,11 @@  xor_neon_4(unsigned long bytes, unsigned long *p1, unsigned long *p2,
 }
 
 static void
-xor_neon_5(unsigned long bytes, unsigned long *p1, unsigned long *p2,
-		unsigned long *p3, unsigned long *p4, unsigned long *p5)
+xor_neon_5(unsigned long bytes, unsigned long * __restrict p1,
+	   const unsigned long * __restrict p2,
+	   const unsigned long * __restrict p3,
+	   const unsigned long * __restrict p4,
+	   const unsigned long * __restrict p5)
 {
 	if (in_interrupt()) {
 		xor_arm4regs_5(bytes, p1, p2, p3, p4, p5);
diff --git a/arch/arm64/include/asm/xor.h b/arch/arm64/include/asm/xor.h
index 947f6a4f1aa0..befcd8a7abc9 100644
--- a/arch/arm64/include/asm/xor.h
+++ b/arch/arm64/include/asm/xor.h
@@ -16,7 +16,8 @@ 
 extern struct xor_block_template const xor_block_inner_neon;
 
 static void
-xor_neon_2(unsigned long bytes, unsigned long *p1, unsigned long *p2)
+xor_neon_2(unsigned long bytes, unsigned long * __restrict p1,
+	   const unsigned long * __restrict p2)
 {
 	kernel_neon_begin();
 	xor_block_inner_neon.do_2(bytes, p1, p2);
@@ -24,8 +25,9 @@  xor_neon_2(unsigned long bytes, unsigned long *p1, unsigned long *p2)
 }
 
 static void
-xor_neon_3(unsigned long bytes, unsigned long *p1, unsigned long *p2,
-		unsigned long *p3)
+xor_neon_3(unsigned long bytes, unsigned long * __restrict p1,
+	   const unsigned long * __restrict p2,
+	   const unsigned long * __restrict p3)
 {
 	kernel_neon_begin();
 	xor_block_inner_neon.do_3(bytes, p1, p2, p3);
@@ -33,8 +35,10 @@  xor_neon_3(unsigned long bytes, unsigned long *p1, unsigned long *p2,
 }
 
 static void
-xor_neon_4(unsigned long bytes, unsigned long *p1, unsigned long *p2,
-		unsigned long *p3, unsigned long *p4)
+xor_neon_4(unsigned long bytes, unsigned long * __restrict p1,
+	   const unsigned long * __restrict p2,
+	   const unsigned long * __restrict p3,
+	   const unsigned long * __restrict p4)
 {
 	kernel_neon_begin();
 	xor_block_inner_neon.do_4(bytes, p1, p2, p3, p4);
@@ -42,8 +46,11 @@  xor_neon_4(unsigned long bytes, unsigned long *p1, unsigned long *p2,
 }
 
 static void
-xor_neon_5(unsigned long bytes, unsigned long *p1, unsigned long *p2,
-		unsigned long *p3, unsigned long *p4, unsigned long *p5)
+xor_neon_5(unsigned long bytes, unsigned long * __restrict p1,
+	   const unsigned long * __restrict p2,
+	   const unsigned long * __restrict p3,
+	   const unsigned long * __restrict p4,
+	   const unsigned long * __restrict p5)
 {
 	kernel_neon_begin();
 	xor_block_inner_neon.do_5(bytes, p1, p2, p3, p4, p5);
diff --git a/arch/arm64/lib/xor-neon.c b/arch/arm64/lib/xor-neon.c
index d189cf4e70ea..e8d189f3897f 100644
--- a/arch/arm64/lib/xor-neon.c
+++ b/arch/arm64/lib/xor-neon.c
@@ -10,8 +10,8 @@ 
 #include <linux/module.h>
 #include <asm/neon-intrinsics.h>
 
-void xor_arm64_neon_2(unsigned long bytes, unsigned long *p1,
-	unsigned long *p2)
+void xor_arm64_neon_2(unsigned long bytes, unsigned long * __restrict p1,
+	const unsigned long * __restrict p2)
 {
 	uint64_t *dp1 = (uint64_t *)p1;
 	uint64_t *dp2 = (uint64_t *)p2;
@@ -37,8 +37,9 @@  void xor_arm64_neon_2(unsigned long bytes, unsigned long *p1,
 	} while (--lines > 0);
 }
 
-void xor_arm64_neon_3(unsigned long bytes, unsigned long *p1,
-	unsigned long *p2, unsigned long *p3)
+void xor_arm64_neon_3(unsigned long bytes, unsigned long * __restrict p1,
+	const unsigned long * __restrict p2,
+	const unsigned long * __restrict p3)
 {
 	uint64_t *dp1 = (uint64_t *)p1;
 	uint64_t *dp2 = (uint64_t *)p2;
@@ -72,8 +73,10 @@  void xor_arm64_neon_3(unsigned long bytes, unsigned long *p1,
 	} while (--lines > 0);
 }
 
-void xor_arm64_neon_4(unsigned long bytes, unsigned long *p1,
-	unsigned long *p2, unsigned long *p3, unsigned long *p4)
+void xor_arm64_neon_4(unsigned long bytes, unsigned long * __restrict p1,
+	const unsigned long * __restrict p2,
+	const unsigned long * __restrict p3,
+	const unsigned long * __restrict p4)
 {
 	uint64_t *dp1 = (uint64_t *)p1;
 	uint64_t *dp2 = (uint64_t *)p2;
@@ -115,9 +118,11 @@  void xor_arm64_neon_4(unsigned long bytes, unsigned long *p1,
 	} while (--lines > 0);
 }
 
-void xor_arm64_neon_5(unsigned long bytes, unsigned long *p1,
-	unsigned long *p2, unsigned long *p3,
-	unsigned long *p4, unsigned long *p5)
+void xor_arm64_neon_5(unsigned long bytes, unsigned long * __restrict p1,
+	const unsigned long * __restrict p2,
+	const unsigned long * __restrict p3,
+	const unsigned long * __restrict p4,
+	const unsigned long * __restrict p5)
 {
 	uint64_t *dp1 = (uint64_t *)p1;
 	uint64_t *dp2 = (uint64_t *)p2;
diff --git a/arch/ia64/include/asm/xor.h b/arch/ia64/include/asm/xor.h
index 673051bf9d7d..6785f70d3208 100644
--- a/arch/ia64/include/asm/xor.h
+++ b/arch/ia64/include/asm/xor.h
@@ -4,13 +4,20 @@ 
  */
 
 
-extern void xor_ia64_2(unsigned long, unsigned long *, unsigned long *);
-extern void xor_ia64_3(unsigned long, unsigned long *, unsigned long *,
-		       unsigned long *);
-extern void xor_ia64_4(unsigned long, unsigned long *, unsigned long *,
-		       unsigned long *, unsigned long *);
-extern void xor_ia64_5(unsigned long, unsigned long *, unsigned long *,
-		       unsigned long *, unsigned long *, unsigned long *);
+extern void xor_ia64_2(unsigned long bytes, unsigned long * __restrict p1,
+		       const unsigned long * __restrict p2);
+extern void xor_ia64_3(unsigned long bytes, unsigned long * __restrict p1,
+		       const unsigned long * __restrict p2,
+		       const unsigned long * __restrict p3);
+extern void xor_ia64_4(unsigned long bytes, unsigned long * __restrict p1,
+		       const unsigned long * __restrict p2,
+		       const unsigned long * __restrict p3,
+		       const unsigned long * __restrict p4);
+extern void xor_ia64_5(unsigned long bytes, unsigned long * __restrict p1,
+		       const unsigned long * __restrict p2,
+		       const unsigned long * __restrict p3,
+		       const unsigned long * __restrict p4,
+		       const unsigned long * __restrict p5);
 
 static struct xor_block_template xor_block_ia64 = {
 	.name =	"ia64",
diff --git a/arch/powerpc/include/asm/xor_altivec.h b/arch/powerpc/include/asm/xor_altivec.h
index 6ca923510b59..294620a25f80 100644
--- a/arch/powerpc/include/asm/xor_altivec.h
+++ b/arch/powerpc/include/asm/xor_altivec.h
@@ -3,17 +3,20 @@ 
 #define _ASM_POWERPC_XOR_ALTIVEC_H
 
 #ifdef CONFIG_ALTIVEC
-
-void xor_altivec_2(unsigned long bytes, unsigned long *v1_in,
-		   unsigned long *v2_in);
-void xor_altivec_3(unsigned long bytes, unsigned long *v1_in,
-		   unsigned long *v2_in, unsigned long *v3_in);
-void xor_altivec_4(unsigned long bytes, unsigned long *v1_in,
-		   unsigned long *v2_in, unsigned long *v3_in,
-		   unsigned long *v4_in);
-void xor_altivec_5(unsigned long bytes, unsigned long *v1_in,
-		   unsigned long *v2_in, unsigned long *v3_in,
-		   unsigned long *v4_in, unsigned long *v5_in);
+void xor_altivec_2(unsigned long bytes, unsigned long * __restrict p1,
+		   const unsigned long * __restrict p2);
+void xor_altivec_3(unsigned long bytes, unsigned long * __restrict p1,
+		   const unsigned long * __restrict p2,
+		   const unsigned long * __restrict p3);
+void xor_altivec_4(unsigned long bytes, unsigned long * __restrict p1,
+		   const unsigned long * __restrict p2,
+		   const unsigned long * __restrict p3,
+		   const unsigned long * __restrict p4);
+void xor_altivec_5(unsigned long bytes, unsigned long * __restrict p1,
+		   const unsigned long * __restrict p2,
+		   const unsigned long * __restrict p3,
+		   const unsigned long * __restrict p4,
+		   const unsigned long * __restrict p5);
 
 #endif
 #endif /* _ASM_POWERPC_XOR_ALTIVEC_H */
diff --git a/arch/powerpc/lib/xor_vmx.c b/arch/powerpc/lib/xor_vmx.c
index 54e61979e80e..aab49d056d18 100644
--- a/arch/powerpc/lib/xor_vmx.c
+++ b/arch/powerpc/lib/xor_vmx.c
@@ -49,8 +49,9 @@  typedef vector signed char unative_t;
 		V1##_3 = vec_xor(V1##_3, V2##_3);	\
 	} while (0)
 
-void __xor_altivec_2(unsigned long bytes, unsigned long *v1_in,
-		     unsigned long *v2_in)
+void __xor_altivec_2(unsigned long bytes,
+		     unsigned long * __restrict v1_in,
+		     const unsigned long * __restrict v2_in)
 {
 	DEFINE(v1);
 	DEFINE(v2);
@@ -67,8 +68,10 @@  void __xor_altivec_2(unsigned long bytes, unsigned long *v1_in,
 	} while (--lines > 0);
 }
 
-void __xor_altivec_3(unsigned long bytes, unsigned long *v1_in,
-		     unsigned long *v2_in, unsigned long *v3_in)
+void __xor_altivec_3(unsigned long bytes,
+		     unsigned long * __restrict v1_in,
+		     const unsigned long * __restrict v2_in,
+		     const unsigned long * __restrict v3_in)
 {
 	DEFINE(v1);
 	DEFINE(v2);
@@ -89,9 +92,11 @@  void __xor_altivec_3(unsigned long bytes, unsigned long *v1_in,
 	} while (--lines > 0);
 }
 
-void __xor_altivec_4(unsigned long bytes, unsigned long *v1_in,
-		     unsigned long *v2_in, unsigned long *v3_in,
-		     unsigned long *v4_in)
+void __xor_altivec_4(unsigned long bytes,
+		     unsigned long * __restrict v1_in,
+		     const unsigned long * __restrict v2_in,
+		     const unsigned long * __restrict v3_in,
+		     const unsigned long * __restrict v4_in)
 {
 	DEFINE(v1);
 	DEFINE(v2);
@@ -116,9 +121,12 @@  void __xor_altivec_4(unsigned long bytes, unsigned long *v1_in,
 	} while (--lines > 0);
 }
 
-void __xor_altivec_5(unsigned long bytes, unsigned long *v1_in,
-		     unsigned long *v2_in, unsigned long *v3_in,
-		     unsigned long *v4_in, unsigned long *v5_in)
+void __xor_altivec_5(unsigned long bytes,
+		     unsigned long * __restrict v1_in,
+		     const unsigned long * __restrict v2_in,
+		     const unsigned long * __restrict v3_in,
+		     const unsigned long * __restrict v4_in,
+		     const unsigned long * __restrict v5_in)
 {
 	DEFINE(v1);
 	DEFINE(v2);
diff --git a/arch/powerpc/lib/xor_vmx.h b/arch/powerpc/lib/xor_vmx.h
index 5c2b0839b179..573c41d90dac 100644
--- a/arch/powerpc/lib/xor_vmx.h
+++ b/arch/powerpc/lib/xor_vmx.h
@@ -6,16 +6,17 @@ 
  * outside of the enable/disable altivec block.
  */
 
-void __xor_altivec_2(unsigned long bytes, unsigned long *v1_in,
-			     unsigned long *v2_in);
-
-void __xor_altivec_3(unsigned long bytes, unsigned long *v1_in,
-			     unsigned long *v2_in, unsigned long *v3_in);
-
-void __xor_altivec_4(unsigned long bytes, unsigned long *v1_in,
-			     unsigned long *v2_in, unsigned long *v3_in,
-			     unsigned long *v4_in);
-
-void __xor_altivec_5(unsigned long bytes, unsigned long *v1_in,
-			     unsigned long *v2_in, unsigned long *v3_in,
-			     unsigned long *v4_in, unsigned long *v5_in);
+void __xor_altivec_2(unsigned long bytes, unsigned long * __restrict p1,
+		     const unsigned long * __restrict p2);
+void __xor_altivec_3(unsigned long bytes, unsigned long * __restrict p1,
+		     const unsigned long * __restrict p2,
+		     const unsigned long * __restrict p3);
+void __xor_altivec_4(unsigned long bytes, unsigned long * __restrict p1,
+		     const unsigned long * __restrict p2,
+		     const unsigned long * __restrict p3,
+		     const unsigned long * __restrict p4);
+void __xor_altivec_5(unsigned long bytes, unsigned long * __restrict p1,
+		     const unsigned long * __restrict p2,
+		     const unsigned long * __restrict p3,
+		     const unsigned long * __restrict p4,
+		     const unsigned long * __restrict p5);
diff --git a/arch/powerpc/lib/xor_vmx_glue.c b/arch/powerpc/lib/xor_vmx_glue.c
index 80dba916c367..35d917ece4d1 100644
--- a/arch/powerpc/lib/xor_vmx_glue.c
+++ b/arch/powerpc/lib/xor_vmx_glue.c
@@ -12,47 +12,51 @@ 
 #include <asm/xor_altivec.h>
 #include "xor_vmx.h"
 
-void xor_altivec_2(unsigned long bytes, unsigned long *v1_in,
-		   unsigned long *v2_in)
+void xor_altivec_2(unsigned long bytes, unsigned long * __restrict p1,
+		   const unsigned long * __restrict p2)
 {
 	preempt_disable();
 	enable_kernel_altivec();
-	__xor_altivec_2(bytes, v1_in, v2_in);
+	__xor_altivec_2(bytes, p1, p2);
 	disable_kernel_altivec();
 	preempt_enable();
 }
 EXPORT_SYMBOL(xor_altivec_2);
 
-void xor_altivec_3(unsigned long bytes,  unsigned long *v1_in,
-		   unsigned long *v2_in, unsigned long *v3_in)
+void xor_altivec_3(unsigned long bytes, unsigned long * __restrict p1,
+		   const unsigned long * __restrict p2,
+		   const unsigned long * __restrict p3)
 {
 	preempt_disable();
 	enable_kernel_altivec();
-	__xor_altivec_3(bytes, v1_in, v2_in, v3_in);
+	__xor_altivec_3(bytes, p1, p2, p3);
 	disable_kernel_altivec();
 	preempt_enable();
 }
 EXPORT_SYMBOL(xor_altivec_3);
 
-void xor_altivec_4(unsigned long bytes,  unsigned long *v1_in,
-		   unsigned long *v2_in, unsigned long *v3_in,
-		   unsigned long *v4_in)
+void xor_altivec_4(unsigned long bytes, unsigned long * __restrict p1,
+		   const unsigned long * __restrict p2,
+		   const unsigned long * __restrict p3,
+		   const unsigned long * __restrict p4)
 {
 	preempt_disable();
 	enable_kernel_altivec();
-	__xor_altivec_4(bytes, v1_in, v2_in, v3_in, v4_in);
+	__xor_altivec_4(bytes, p1, p2, p3, p4);
 	disable_kernel_altivec();
 	preempt_enable();
 }
 EXPORT_SYMBOL(xor_altivec_4);
 
-void xor_altivec_5(unsigned long bytes,  unsigned long *v1_in,
-		   unsigned long *v2_in, unsigned long *v3_in,
-		   unsigned long *v4_in, unsigned long *v5_in)
+void xor_altivec_5(unsigned long bytes, unsigned long * __restrict p1,
+		   const unsigned long * __restrict p2,
+		   const unsigned long * __restrict p3,
+		   const unsigned long * __restrict p4,
+		   const unsigned long * __restrict p5)
 {
 	preempt_disable();
 	enable_kernel_altivec();
-	__xor_altivec_5(bytes, v1_in, v2_in, v3_in, v4_in, v5_in);
+	__xor_altivec_5(bytes, p1, p2, p3, p4, p5);
 	disable_kernel_altivec();
 	preempt_enable();
 }
diff --git a/arch/s390/lib/xor.c b/arch/s390/lib/xor.c
index a963c3d8ad0d..fb924a8041dc 100644
--- a/arch/s390/lib/xor.c
+++ b/arch/s390/lib/xor.c
@@ -11,7 +11,8 @@ 
 #include <linux/raid/xor.h>
 #include <asm/xor.h>
 
-static void xor_xc_2(unsigned long bytes, unsigned long *p1, unsigned long *p2)
+static void xor_xc_2(unsigned long bytes, unsigned long * __restrict p1,
+		     const unsigned long * __restrict p2)
 {
 	asm volatile(
 		"	larl	1,2f\n"
@@ -32,8 +33,9 @@  static void xor_xc_2(unsigned long bytes, unsigned long *p1, unsigned long *p2)
 		: "0", "1", "cc", "memory");
 }
 
-static void xor_xc_3(unsigned long bytes, unsigned long *p1, unsigned long *p2,
-		     unsigned long *p3)
+static void xor_xc_3(unsigned long bytes, unsigned long * __restrict p1,
+		     const unsigned long * __restrict p2,
+		     const unsigned long * __restrict p3)
 {
 	asm volatile(
 		"	larl	1,2f\n"
@@ -58,8 +60,10 @@  static void xor_xc_3(unsigned long bytes, unsigned long *p1, unsigned long *p2,
 		: : "0", "1", "cc", "memory");
 }
 
-static void xor_xc_4(unsigned long bytes, unsigned long *p1, unsigned long *p2,
-		     unsigned long *p3, unsigned long *p4)
+static void xor_xc_4(unsigned long bytes, unsigned long * __restrict p1,
+		     const unsigned long * __restrict p2,
+		     const unsigned long * __restrict p3,
+		     const unsigned long * __restrict p4)
 {
 	asm volatile(
 		"	larl	1,2f\n"
@@ -88,8 +92,11 @@  static void xor_xc_4(unsigned long bytes, unsigned long *p1, unsigned long *p2,
 		: : "0", "1", "cc", "memory");
 }
 
-static void xor_xc_5(unsigned long bytes, unsigned long *p1, unsigned long *p2,
-		     unsigned long *p3, unsigned long *p4, unsigned long *p5)
+static void xor_xc_5(unsigned long bytes, unsigned long * __restrict p1,
+		     const unsigned long * __restrict p2,
+		     const unsigned long * __restrict p3,
+		     const unsigned long * __restrict p4,
+		     const unsigned long * __restrict p5)
 {
 	asm volatile(
 		"	larl	1,2f\n"
diff --git a/arch/sparc/include/asm/xor_32.h b/arch/sparc/include/asm/xor_32.h
index 3e5af37e4b9c..0351813cf3af 100644
--- a/arch/sparc/include/asm/xor_32.h
+++ b/arch/sparc/include/asm/xor_32.h
@@ -13,7 +13,8 @@ 
  */
 
 static void
-sparc_2(unsigned long bytes, unsigned long *p1, unsigned long *p2)
+sparc_2(unsigned long bytes, unsigned long * __restrict p1,
+	const unsigned long * __restrict p2)
 {
 	int lines = bytes / (sizeof (long)) / 8;
 
@@ -50,8 +51,9 @@  sparc_2(unsigned long bytes, unsigned long *p1, unsigned long *p2)
 }
 
 static void
-sparc_3(unsigned long bytes, unsigned long *p1, unsigned long *p2,
-	unsigned long *p3)
+sparc_3(unsigned long bytes, unsigned long * __restrict p1,
+	const unsigned long * __restrict p2,
+	const unsigned long * __restrict p3)
 {
 	int lines = bytes / (sizeof (long)) / 8;
 
@@ -101,8 +103,10 @@  sparc_3(unsigned long bytes, unsigned long *p1, unsigned long *p2,
 }
 
 static void
-sparc_4(unsigned long bytes, unsigned long *p1, unsigned long *p2,
-	unsigned long *p3, unsigned long *p4)
+sparc_4(unsigned long bytes, unsigned long * __restrict p1,
+	const unsigned long * __restrict p2,
+	const unsigned long * __restrict p3,
+	const unsigned long * __restrict p4)
 {
 	int lines = bytes / (sizeof (long)) / 8;
 
@@ -165,8 +169,11 @@  sparc_4(unsigned long bytes, unsigned long *p1, unsigned long *p2,
 }
 
 static void
-sparc_5(unsigned long bytes, unsigned long *p1, unsigned long *p2,
-	unsigned long *p3, unsigned long *p4, unsigned long *p5)
+sparc_5(unsigned long bytes, unsigned long * __restrict p1,
+	const unsigned long * __restrict p2,
+	const unsigned long * __restrict p3,
+	const unsigned long * __restrict p4,
+	const unsigned long * __restrict p5)
 {
 	int lines = bytes / (sizeof (long)) / 8;
 
diff --git a/arch/sparc/include/asm/xor_64.h b/arch/sparc/include/asm/xor_64.h
index 16169f3edcd5..caaddea8ad79 100644
--- a/arch/sparc/include/asm/xor_64.h
+++ b/arch/sparc/include/asm/xor_64.h
@@ -12,13 +12,20 @@ 
 
 #include <asm/spitfire.h>
 
-void xor_vis_2(unsigned long, unsigned long *, unsigned long *);
-void xor_vis_3(unsigned long, unsigned long *, unsigned long *,
-	       unsigned long *);
-void xor_vis_4(unsigned long, unsigned long *, unsigned long *,
-	       unsigned long *, unsigned long *);
-void xor_vis_5(unsigned long, unsigned long *, unsigned long *,
-	       unsigned long *, unsigned long *, unsigned long *);
+void xor_vis_2(unsigned long bytes, unsigned long * __restrict p1,
+	       const unsigned long * __restrict p2);
+void xor_vis_3(unsigned long bytes, unsigned long * __restrict p1,
+	       const unsigned long * __restrict p2,
+	       const unsigned long * __restrict p3);
+void xor_vis_4(unsigned long bytes, unsigned long * __restrict p1,
+	       const unsigned long * __restrict p2,
+	       const unsigned long * __restrict p3,
+	       const unsigned long * __restrict p4);
+void xor_vis_5(unsigned long bytes, unsigned long * __restrict p1,
+	       const unsigned long * __restrict p2,
+	       const unsigned long * __restrict p3,
+	       const unsigned long * __restrict p4,
+	       const unsigned long * __restrict p5);
 
 /* XXX Ugh, write cheetah versions... -DaveM */
 
@@ -30,13 +37,20 @@  static struct xor_block_template xor_block_VIS = {
         .do_5	= xor_vis_5,
 };
 
-void xor_niagara_2(unsigned long, unsigned long *, unsigned long *);
-void xor_niagara_3(unsigned long, unsigned long *, unsigned long *,
-		   unsigned long *);
-void xor_niagara_4(unsigned long, unsigned long *, unsigned long *,
-		   unsigned long *, unsigned long *);
-void xor_niagara_5(unsigned long, unsigned long *, unsigned long *,
-		   unsigned long *, unsigned long *, unsigned long *);
+void xor_niagara_2(unsigned long bytes, unsigned long * __restrict p1,
+		   const unsigned long * __restrict p2);
+void xor_niagara_3(unsigned long bytes, unsigned long * __restrict p1,
+		   const unsigned long * __restrict p2,
+		   const unsigned long * __restrict p3);
+void xor_niagara_4(unsigned long bytes, unsigned long * __restrict p1,
+		   const unsigned long * __restrict p2,
+		   const unsigned long * __restrict p3,
+		   const unsigned long * __restrict p4);
+void xor_niagara_5(unsigned long bytes, unsigned long * __restrict p1,
+		   const unsigned long * __restrict p2,
+		   const unsigned long * __restrict p3,
+		   const unsigned long * __restrict p4,
+		   const unsigned long * __restrict p5);
 
 static struct xor_block_template xor_block_niagara = {
         .name	= "Niagara",
diff --git a/arch/x86/include/asm/xor.h b/arch/x86/include/asm/xor.h
index 2ee95a7769e6..7b0307acc410 100644
--- a/arch/x86/include/asm/xor.h
+++ b/arch/x86/include/asm/xor.h
@@ -57,7 +57,8 @@ 
 					op(i + 3, 3)
 
 static void
-xor_sse_2(unsigned long bytes, unsigned long *p1, unsigned long *p2)
+xor_sse_2(unsigned long bytes, unsigned long * __restrict p1,
+	  const unsigned long * __restrict p2)
 {
 	unsigned long lines = bytes >> 8;
 
@@ -108,7 +109,8 @@  xor_sse_2(unsigned long bytes, unsigned long *p1, unsigned long *p2)
 }
 
 static void
-xor_sse_2_pf64(unsigned long bytes, unsigned long *p1, unsigned long *p2)
+xor_sse_2_pf64(unsigned long bytes, unsigned long * __restrict p1,
+	       const unsigned long * __restrict p2)
 {
 	unsigned long lines = bytes >> 8;
 
@@ -142,8 +144,9 @@  xor_sse_2_pf64(unsigned long bytes, unsigned long *p1, unsigned long *p2)
 }
 
 static void
-xor_sse_3(unsigned long bytes, unsigned long *p1, unsigned long *p2,
-	  unsigned long *p3)
+xor_sse_3(unsigned long bytes, unsigned long * __restrict p1,
+	  const unsigned long * __restrict p2,
+	  const unsigned long * __restrict p3)
 {
 	unsigned long lines = bytes >> 8;
 
@@ -201,8 +204,9 @@  xor_sse_3(unsigned long bytes, unsigned long *p1, unsigned long *p2,
 }
 
 static void
-xor_sse_3_pf64(unsigned long bytes, unsigned long *p1, unsigned long *p2,
-	       unsigned long *p3)
+xor_sse_3_pf64(unsigned long bytes, unsigned long * __restrict p1,
+	       const unsigned long * __restrict p2,
+	       const unsigned long * __restrict p3)
 {
 	unsigned long lines = bytes >> 8;
 
@@ -238,8 +242,10 @@  xor_sse_3_pf64(unsigned long bytes, unsigned long *p1, unsigned long *p2,
 }
 
 static void
-xor_sse_4(unsigned long bytes, unsigned long *p1, unsigned long *p2,
-	  unsigned long *p3, unsigned long *p4)
+xor_sse_4(unsigned long bytes, unsigned long * __restrict p1,
+	  const unsigned long * __restrict p2,
+	  const unsigned long * __restrict p3,
+	  const unsigned long * __restrict p4)
 {
 	unsigned long lines = bytes >> 8;
 
@@ -304,8 +310,10 @@  xor_sse_4(unsigned long bytes, unsigned long *p1, unsigned long *p2,
 }
 
 static void
-xor_sse_4_pf64(unsigned long bytes, unsigned long *p1, unsigned long *p2,
-	       unsigned long *p3, unsigned long *p4)
+xor_sse_4_pf64(unsigned long bytes, unsigned long * __restrict p1,
+	       const unsigned long * __restrict p2,
+	       const unsigned long * __restrict p3,
+	       const unsigned long * __restrict p4)
 {
 	unsigned long lines = bytes >> 8;
 
@@ -343,8 +351,11 @@  xor_sse_4_pf64(unsigned long bytes, unsigned long *p1, unsigned long *p2,
 }
 
 static void
-xor_sse_5(unsigned long bytes, unsigned long *p1, unsigned long *p2,
-	  unsigned long *p3, unsigned long *p4, unsigned long *p5)
+xor_sse_5(unsigned long bytes, unsigned long * __restrict p1,
+	  const unsigned long * __restrict p2,
+	  const unsigned long * __restrict p3,
+	  const unsigned long * __restrict p4,
+	  const unsigned long * __restrict p5)
 {
 	unsigned long lines = bytes >> 8;
 
@@ -416,8 +427,11 @@  xor_sse_5(unsigned long bytes, unsigned long *p1, unsigned long *p2,
 }
 
 static void
-xor_sse_5_pf64(unsigned long bytes, unsigned long *p1, unsigned long *p2,
-	       unsigned long *p3, unsigned long *p4, unsigned long *p5)
+xor_sse_5_pf64(unsigned long bytes, unsigned long * __restrict p1,
+	       const unsigned long * __restrict p2,
+	       const unsigned long * __restrict p3,
+	       const unsigned long * __restrict p4,
+	       const unsigned long * __restrict p5)
 {
 	unsigned long lines = bytes >> 8;
 
diff --git a/arch/x86/include/asm/xor_32.h b/arch/x86/include/asm/xor_32.h
index 67ceb790e639..7a6b9474591e 100644
--- a/arch/x86/include/asm/xor_32.h
+++ b/arch/x86/include/asm/xor_32.h
@@ -21,7 +21,8 @@ 
 #include <asm/fpu/api.h>
 
 static void
-xor_pII_mmx_2(unsigned long bytes, unsigned long *p1, unsigned long *p2)
+xor_pII_mmx_2(unsigned long bytes, unsigned long * __restrict p1,
+	      const unsigned long * __restrict p2)
 {
 	unsigned long lines = bytes >> 7;
 
@@ -64,8 +65,9 @@  xor_pII_mmx_2(unsigned long bytes, unsigned long *p1, unsigned long *p2)
 }
 
 static void
-xor_pII_mmx_3(unsigned long bytes, unsigned long *p1, unsigned long *p2,
-	      unsigned long *p3)
+xor_pII_mmx_3(unsigned long bytes, unsigned long * __restrict p1,
+	      const unsigned long * __restrict p2,
+	      const unsigned long * __restrict p3)
 {
 	unsigned long lines = bytes >> 7;
 
@@ -113,8 +115,10 @@  xor_pII_mmx_3(unsigned long bytes, unsigned long *p1, unsigned long *p2,
 }
 
 static void
-xor_pII_mmx_4(unsigned long bytes, unsigned long *p1, unsigned long *p2,
-	      unsigned long *p3, unsigned long *p4)
+xor_pII_mmx_4(unsigned long bytes, unsigned long * __restrict p1,
+	      const unsigned long * __restrict p2,
+	      const unsigned long * __restrict p3,
+	      const unsigned long * __restrict p4)
 {
 	unsigned long lines = bytes >> 7;
 
@@ -168,8 +172,11 @@  xor_pII_mmx_4(unsigned long bytes, unsigned long *p1, unsigned long *p2,
 
 
 static void
-xor_pII_mmx_5(unsigned long bytes, unsigned long *p1, unsigned long *p2,
-	      unsigned long *p3, unsigned long *p4, unsigned long *p5)
+xor_pII_mmx_5(unsigned long bytes, unsigned long * __restrict p1,
+	      const unsigned long * __restrict p2,
+	      const unsigned long * __restrict p3,
+	      const unsigned long * __restrict p4,
+	      const unsigned long * __restrict p5)
 {
 	unsigned long lines = bytes >> 7;
 
@@ -248,7 +255,8 @@  xor_pII_mmx_5(unsigned long bytes, unsigned long *p1, unsigned long *p2,
 #undef BLOCK
 
 static void
-xor_p5_mmx_2(unsigned long bytes, unsigned long *p1, unsigned long *p2)
+xor_p5_mmx_2(unsigned long bytes, unsigned long * __restrict p1,
+	     const unsigned long * __restrict p2)
 {
 	unsigned long lines = bytes >> 6;
 
@@ -295,8 +303,9 @@  xor_p5_mmx_2(unsigned long bytes, unsigned long *p1, unsigned long *p2)
 }
 
 static void
-xor_p5_mmx_3(unsigned long bytes, unsigned long *p1, unsigned long *p2,
-	     unsigned long *p3)
+xor_p5_mmx_3(unsigned long bytes, unsigned long * __restrict p1,
+	     const unsigned long * __restrict p2,
+	     const unsigned long * __restrict p3)
 {
 	unsigned long lines = bytes >> 6;
 
@@ -352,8 +361,10 @@  xor_p5_mmx_3(unsigned long bytes, unsigned long *p1, unsigned long *p2,
 }
 
 static void
-xor_p5_mmx_4(unsigned long bytes, unsigned long *p1, unsigned long *p2,
-	     unsigned long *p3, unsigned long *p4)
+xor_p5_mmx_4(unsigned long bytes, unsigned long * __restrict p1,
+	     const unsigned long * __restrict p2,
+	     const unsigned long * __restrict p3,
+	     const unsigned long * __restrict p4)
 {
 	unsigned long lines = bytes >> 6;
 
@@ -418,8 +429,11 @@  xor_p5_mmx_4(unsigned long bytes, unsigned long *p1, unsigned long *p2,
 }
 
 static void
-xor_p5_mmx_5(unsigned long bytes, unsigned long *p1, unsigned long *p2,
-	     unsigned long *p3, unsigned long *p4, unsigned long *p5)
+xor_p5_mmx_5(unsigned long bytes, unsigned long * __restrict p1,
+	     const unsigned long * __restrict p2,
+	     const unsigned long * __restrict p3,
+	     const unsigned long * __restrict p4,
+	     const unsigned long * __restrict p5)
 {
 	unsigned long lines = bytes >> 6;
 
diff --git a/arch/x86/include/asm/xor_avx.h b/arch/x86/include/asm/xor_avx.h
index 0c4e5b5e3852..7f81dd5897f4 100644
--- a/arch/x86/include/asm/xor_avx.h
+++ b/arch/x86/include/asm/xor_avx.h
@@ -26,7 +26,8 @@ 
 		BLOCK4(8) \
 		BLOCK4(12)
 
-static void xor_avx_2(unsigned long bytes, unsigned long *p0, unsigned long *p1)
+static void xor_avx_2(unsigned long bytes, unsigned long * __restrict p0,
+		      const unsigned long * __restrict p1)
 {
 	unsigned long lines = bytes >> 9;
 
@@ -52,8 +53,9 @@  do { \
 	kernel_fpu_end();
 }
 
-static void xor_avx_3(unsigned long bytes, unsigned long *p0, unsigned long *p1,
-	unsigned long *p2)
+static void xor_avx_3(unsigned long bytes, unsigned long * __restrict p0,
+		      const unsigned long * __restrict p1,
+		      const unsigned long * __restrict p2)
 {
 	unsigned long lines = bytes >> 9;
 
@@ -82,8 +84,10 @@  do { \
 	kernel_fpu_end();
 }
 
-static void xor_avx_4(unsigned long bytes, unsigned long *p0, unsigned long *p1,
-	unsigned long *p2, unsigned long *p3)
+static void xor_avx_4(unsigned long bytes, unsigned long * __restrict p0,
+		      const unsigned long * __restrict p1,
+		      const unsigned long * __restrict p2,
+		      const unsigned long * __restrict p3)
 {
 	unsigned long lines = bytes >> 9;
 
@@ -115,8 +119,11 @@  do { \
 	kernel_fpu_end();
 }
 
-static void xor_avx_5(unsigned long bytes, unsigned long *p0, unsigned long *p1,
-	unsigned long *p2, unsigned long *p3, unsigned long *p4)
+static void xor_avx_5(unsigned long bytes, unsigned long * __restrict p0,
+	     const unsigned long * __restrict p1,
+	     const unsigned long * __restrict p2,
+	     const unsigned long * __restrict p3,
+	     const unsigned long * __restrict p4)
 {
 	unsigned long lines = bytes >> 9;
 
diff --git a/include/asm-generic/xor.h b/include/asm-generic/xor.h
index b62a2a56a4d4..44509d48fca2 100644
--- a/include/asm-generic/xor.h
+++ b/include/asm-generic/xor.h
@@ -8,7 +8,8 @@ 
 #include <linux/prefetch.h>
 
 static void
-xor_8regs_2(unsigned long bytes, unsigned long *p1, unsigned long *p2)
+xor_8regs_2(unsigned long bytes, unsigned long * __restrict p1,
+	    const unsigned long * __restrict p2)
 {
 	long lines = bytes / (sizeof (long)) / 8;
 
@@ -27,8 +28,9 @@  xor_8regs_2(unsigned long bytes, unsigned long *p1, unsigned long *p2)
 }
 
 static void
-xor_8regs_3(unsigned long bytes, unsigned long *p1, unsigned long *p2,
-	    unsigned long *p3)
+xor_8regs_3(unsigned long bytes, unsigned long * __restrict p1,
+	    const unsigned long * __restrict p2,
+	    const unsigned long * __restrict p3)
 {
 	long lines = bytes / (sizeof (long)) / 8;
 
@@ -48,8 +50,10 @@  xor_8regs_3(unsigned long bytes, unsigned long *p1, unsigned long *p2,
 }
 
 static void
-xor_8regs_4(unsigned long bytes, unsigned long *p1, unsigned long *p2,
-	    unsigned long *p3, unsigned long *p4)
+xor_8regs_4(unsigned long bytes, unsigned long * __restrict p1,
+	    const unsigned long * __restrict p2,
+	    const unsigned long * __restrict p3,
+	    const unsigned long * __restrict p4)
 {
 	long lines = bytes / (sizeof (long)) / 8;
 
@@ -70,8 +74,11 @@  xor_8regs_4(unsigned long bytes, unsigned long *p1, unsigned long *p2,
 }
 
 static void
-xor_8regs_5(unsigned long bytes, unsigned long *p1, unsigned long *p2,
-	    unsigned long *p3, unsigned long *p4, unsigned long *p5)
+xor_8regs_5(unsigned long bytes, unsigned long * __restrict p1,
+	    const unsigned long * __restrict p2,
+	    const unsigned long * __restrict p3,
+	    const unsigned long * __restrict p4,
+	    const unsigned long * __restrict p5)
 {
 	long lines = bytes / (sizeof (long)) / 8;
 
@@ -93,7 +100,8 @@  xor_8regs_5(unsigned long bytes, unsigned long *p1, unsigned long *p2,
 }
 
 static void
-xor_32regs_2(unsigned long bytes, unsigned long *p1, unsigned long *p2)
+xor_32regs_2(unsigned long bytes, unsigned long * __restrict p1,
+	     const unsigned long * __restrict p2)
 {
 	long lines = bytes / (sizeof (long)) / 8;
 
@@ -129,8 +137,9 @@  xor_32regs_2(unsigned long bytes, unsigned long *p1, unsigned long *p2)
 }
 
 static void
-xor_32regs_3(unsigned long bytes, unsigned long *p1, unsigned long *p2,
-	    unsigned long *p3)
+xor_32regs_3(unsigned long bytes, unsigned long * __restrict p1,
+	     const unsigned long * __restrict p2,
+	     const unsigned long * __restrict p3)
 {
 	long lines = bytes / (sizeof (long)) / 8;
 
@@ -175,8 +184,10 @@  xor_32regs_3(unsigned long bytes, unsigned long *p1, unsigned long *p2,
 }
 
 static void
-xor_32regs_4(unsigned long bytes, unsigned long *p1, unsigned long *p2,
-	    unsigned long *p3, unsigned long *p4)
+xor_32regs_4(unsigned long bytes, unsigned long * __restrict p1,
+	     const unsigned long * __restrict p2,
+	     const unsigned long * __restrict p3,
+	     const unsigned long * __restrict p4)
 {
 	long lines = bytes / (sizeof (long)) / 8;
 
@@ -230,8 +241,11 @@  xor_32regs_4(unsigned long bytes, unsigned long *p1, unsigned long *p2,
 }
 
 static void
-xor_32regs_5(unsigned long bytes, unsigned long *p1, unsigned long *p2,
-	    unsigned long *p3, unsigned long *p4, unsigned long *p5)
+xor_32regs_5(unsigned long bytes, unsigned long * __restrict p1,
+	     const unsigned long * __restrict p2,
+	     const unsigned long * __restrict p3,
+	     const unsigned long * __restrict p4,
+	     const unsigned long * __restrict p5)
 {
 	long lines = bytes / (sizeof (long)) / 8;
 
@@ -294,7 +308,8 @@  xor_32regs_5(unsigned long bytes, unsigned long *p1, unsigned long *p2,
 }
 
 static void
-xor_8regs_p_2(unsigned long bytes, unsigned long *p1, unsigned long *p2)
+xor_8regs_p_2(unsigned long bytes, unsigned long * __restrict p1,
+	      const unsigned long * __restrict p2)
 {
 	long lines = bytes / (sizeof (long)) / 8 - 1;
 	prefetchw(p1);
@@ -320,8 +335,9 @@  xor_8regs_p_2(unsigned long bytes, unsigned long *p1, unsigned long *p2)
 }
 
 static void
-xor_8regs_p_3(unsigned long bytes, unsigned long *p1, unsigned long *p2,
-	    unsigned long *p3)
+xor_8regs_p_3(unsigned long bytes, unsigned long * __restrict p1,
+	      const unsigned long * __restrict p2,
+	      const unsigned long * __restrict p3)
 {
 	long lines = bytes / (sizeof (long)) / 8 - 1;
 	prefetchw(p1);
@@ -350,8 +366,10 @@  xor_8regs_p_3(unsigned long bytes, unsigned long *p1, unsigned long *p2,
 }
 
 static void
-xor_8regs_p_4(unsigned long bytes, unsigned long *p1, unsigned long *p2,
-	    unsigned long *p3, unsigned long *p4)
+xor_8regs_p_4(unsigned long bytes, unsigned long * __restrict p1,
+	      const unsigned long * __restrict p2,
+	      const unsigned long * __restrict p3,
+	      const unsigned long * __restrict p4)
 {
 	long lines = bytes / (sizeof (long)) / 8 - 1;
 
@@ -384,8 +402,11 @@  xor_8regs_p_4(unsigned long bytes, unsigned long *p1, unsigned long *p2,
 }
 
 static void
-xor_8regs_p_5(unsigned long bytes, unsigned long *p1, unsigned long *p2,
-	    unsigned long *p3, unsigned long *p4, unsigned long *p5)
+xor_8regs_p_5(unsigned long bytes, unsigned long * __restrict p1,
+	      const unsigned long * __restrict p2,
+	      const unsigned long * __restrict p3,
+	      const unsigned long * __restrict p4,
+	      const unsigned long * __restrict p5)
 {
 	long lines = bytes / (sizeof (long)) / 8 - 1;
 
@@ -421,7 +442,8 @@  xor_8regs_p_5(unsigned long bytes, unsigned long *p1, unsigned long *p2,
 }
 
 static void
-xor_32regs_p_2(unsigned long bytes, unsigned long *p1, unsigned long *p2)
+xor_32regs_p_2(unsigned long bytes, unsigned long * __restrict p1,
+	       const unsigned long * __restrict p2)
 {
 	long lines = bytes / (sizeof (long)) / 8 - 1;
 
@@ -466,8 +488,9 @@  xor_32regs_p_2(unsigned long bytes, unsigned long *p1, unsigned long *p2)
 }
 
 static void
-xor_32regs_p_3(unsigned long bytes, unsigned long *p1, unsigned long *p2,
-	    unsigned long *p3)
+xor_32regs_p_3(unsigned long bytes, unsigned long * __restrict p1,
+	       const unsigned long * __restrict p2,
+	       const unsigned long * __restrict p3)
 {
 	long lines = bytes / (sizeof (long)) / 8 - 1;
 
@@ -523,8 +546,10 @@  xor_32regs_p_3(unsigned long bytes, unsigned long *p1, unsigned long *p2,
 }
 
 static void
-xor_32regs_p_4(unsigned long bytes, unsigned long *p1, unsigned long *p2,
-	    unsigned long *p3, unsigned long *p4)
+xor_32regs_p_4(unsigned long bytes, unsigned long * __restrict p1,
+	       const unsigned long * __restrict p2,
+	       const unsigned long * __restrict p3,
+	       const unsigned long * __restrict p4)
 {
 	long lines = bytes / (sizeof (long)) / 8 - 1;
 
@@ -591,8 +616,11 @@  xor_32regs_p_4(unsigned long bytes, unsigned long *p1, unsigned long *p2,
 }
 
 static void
-xor_32regs_p_5(unsigned long bytes, unsigned long *p1, unsigned long *p2,
-	    unsigned long *p3, unsigned long *p4, unsigned long *p5)
+xor_32regs_p_5(unsigned long bytes, unsigned long * __restrict p1,
+	       const unsigned long * __restrict p2,
+	       const unsigned long * __restrict p3,
+	       const unsigned long * __restrict p4,
+	       const unsigned long * __restrict p5)
 {
 	long lines = bytes / (sizeof (long)) / 8 - 1;
 
diff --git a/include/linux/raid/xor.h b/include/linux/raid/xor.h
index 2a9fee8ddae3..51b811b62322 100644
--- a/include/linux/raid/xor.h
+++ b/include/linux/raid/xor.h
@@ -11,13 +11,20 @@  struct xor_block_template {
         struct xor_block_template *next;
         const char *name;
         int speed;
-	void (*do_2)(unsigned long, unsigned long *, unsigned long *);
-	void (*do_3)(unsigned long, unsigned long *, unsigned long *,
-		     unsigned long *);
-	void (*do_4)(unsigned long, unsigned long *, unsigned long *,
-		     unsigned long *, unsigned long *);
-	void (*do_5)(unsigned long, unsigned long *, unsigned long *,
-		     unsigned long *, unsigned long *, unsigned long *);
+	void (*do_2)(unsigned long, unsigned long * __restrict,
+		     const unsigned long * __restrict);
+	void (*do_3)(unsigned long, unsigned long * __restrict,
+		     const unsigned long * __restrict,
+		     const unsigned long * __restrict);
+	void (*do_4)(unsigned long, unsigned long * __restrict,
+		     const unsigned long * __restrict,
+		     const unsigned long * __restrict,
+		     const unsigned long * __restrict);
+	void (*do_5)(unsigned long, unsigned long * __restrict,
+		     const unsigned long * __restrict,
+		     const unsigned long * __restrict,
+		     const unsigned long * __restrict,
+		     const unsigned long * __restrict);
 };
 
 #endif