lib/xor: make xor prototypes more friendly to compiler vectorization

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>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Link: https://github.com/ClangBuiltLinux/linux/issues/563
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

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
-extern void xor_alpha_3(unsigned long, unsigned long *, unsigned long *,
+xor_alpha_2(unsigned long bytes, unsigned long * __restrict p1,
-		        unsigned long *);
+	    const unsigned long * __restrict p2);
-extern void xor_alpha_4(unsigned long, unsigned long *, unsigned long *,
+extern void
-		        unsigned long *, unsigned long *);
+xor_alpha_3(unsigned long bytes, unsigned long * __restrict p1,
-extern void xor_alpha_5(unsigned long, unsigned long *, unsigned long *,
+	    const unsigned long * __restrict p2,
-		        unsigned long *, unsigned long *, unsigned long *);
+	    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 *,
+extern void
-				 unsigned long *);
+xor_alpha_prefetch_2(unsigned long bytes, unsigned long * __restrict p1,
-extern void xor_alpha_prefetch_3(unsigned long, unsigned long *,
+		     const unsigned long * __restrict p2);
-				 unsigned long *, unsigned long *);
+extern void
-extern void xor_alpha_prefetch_4(unsigned long, unsigned long *,
+xor_alpha_prefetch_3(unsigned long bytes, unsigned long * __restrict p1,
-				 unsigned long *, unsigned long *,
+		     const unsigned long * __restrict p2,
-				 unsigned long *);
+		     const unsigned long * __restrict p3);
-extern void xor_alpha_prefetch_5(unsigned long, unsigned long *,
+extern void
-				 unsigned long *, unsigned long *,
+xor_alpha_prefetch_4(unsigned long bytes, unsigned long * __restrict p1,
-				 unsigned long *, unsigned long *);
+		     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\

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,
+xor_arm4regs_3(unsigned long bytes, unsigned long * __restrict p1,
-		unsigned long *p3)
+	       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,
+xor_arm4regs_4(unsigned long bytes, unsigned long * __restrict p1,
-		unsigned long *p3, unsigned long *p4)
+	       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,
+xor_arm4regs_5(unsigned long bytes, unsigned long * __restrict p1,
-		unsigned long *p3, unsigned long *p4, unsigned long *p5)
+	       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,
+xor_neon_3(unsigned long bytes, unsigned long * __restrict p1,
-		unsigned long *p3)
+	   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,
+xor_neon_4(unsigned long bytes, unsigned long * __restrict p1,
-		unsigned long *p3, unsigned long *p4)
+	   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,
+xor_neon_5(unsigned long bytes, unsigned long * __restrict p1,
-		unsigned long *p3, unsigned long *p4, unsigned long *p5)
+	   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);

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,
+xor_neon_3(unsigned long bytes, unsigned long * __restrict p1,
-		unsigned long *p3)
+	   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,
+xor_neon_4(unsigned long bytes, unsigned long * __restrict p1,
-		unsigned long *p3, unsigned long *p4)
+	   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,
+xor_neon_5(unsigned long bytes, unsigned long * __restrict p1,
-		unsigned long *p3, unsigned long *p4, unsigned long *p5)
+	   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);

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,
+void xor_arm64_neon_2(unsigned long bytes, unsigned long * __restrict p1,
-	unsigned long *p2)
+	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,
+void xor_arm64_neon_3(unsigned long bytes, unsigned long * __restrict p1,
-	unsigned long *p2, unsigned long *p3)
+	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,
+void xor_arm64_neon_4(unsigned long bytes, unsigned long * __restrict p1,
-	unsigned long *p2, unsigned long *p3, unsigned long *p4)
+	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,
+void xor_arm64_neon_5(unsigned long bytes, unsigned long * __restrict p1,
-	unsigned long *p2, unsigned long *p3,
+	const unsigned long * __restrict p2,
-	unsigned long *p4, unsigned long *p5)
+	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;
@@ -186,8 +191,10 @@ static inline uint64x2_t eor3(uint64x2_t p, uint64x2_t q, uint64x2_t r)
 	return res;
 }
 
-static void xor_arm64_eor3_3(unsigned long bytes, unsigned long *p1,
+static void xor_arm64_eor3_3(unsigned long bytes,
-			     unsigned long *p2, unsigned long *p3)
+	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;
@@ -219,9 +226,11 @@ static void xor_arm64_eor3_3(unsigned long bytes, unsigned long *p1,
 	} while (--lines > 0);
 }
 
-static void xor_arm64_eor3_4(unsigned long bytes, unsigned long *p1,
+static void xor_arm64_eor3_4(unsigned long bytes,
-			     unsigned long *p2, unsigned long *p3,
+	unsigned long * __restrict p1,
-			     unsigned long *p4)
+	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;
@@ -261,9 +270,12 @@ static void xor_arm64_eor3_4(unsigned long bytes, unsigned long *p1,
 	} while (--lines > 0);
 }
 
-static void xor_arm64_eor3_5(unsigned long bytes, unsigned long *p1,
+static void xor_arm64_eor3_5(unsigned long bytes,
-			     unsigned long *p2, unsigned long *p3,
+	unsigned long * __restrict p1,
-			     unsigned long *p4, unsigned long *p5)
+	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;

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_2(unsigned long bytes, unsigned long * __restrict p1,
-extern void xor_ia64_3(unsigned long, unsigned long *, unsigned long *,
+		       const unsigned long * __restrict p2);
-		       unsigned long *);
+extern void xor_ia64_3(unsigned long bytes, unsigned long * __restrict p1,
-extern void xor_ia64_4(unsigned long, unsigned long *, unsigned long *,
+		       const unsigned long * __restrict p2,
-		       unsigned long *, unsigned long *);
+		       const unsigned long * __restrict p3);
-extern void xor_ia64_5(unsigned long, unsigned long *, unsigned long *,
+extern void xor_ia64_4(unsigned long bytes, unsigned long * __restrict p1,
-		       unsigned long *, unsigned long *, unsigned long *);
+		       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",

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 * __restrict p1,
-void xor_altivec_2(unsigned long bytes, unsigned long *v1_in,
+		   const unsigned long * __restrict p2);
-		   unsigned long *v2_in);
+void xor_altivec_3(unsigned long bytes, unsigned long * __restrict p1,
-void xor_altivec_3(unsigned long bytes, unsigned long *v1_in,
+		   const unsigned long * __restrict p2,
-		   unsigned long *v2_in, unsigned long *v3_in);
+		   const unsigned long * __restrict p3);
-void xor_altivec_4(unsigned long bytes, unsigned long *v1_in,
+void xor_altivec_4(unsigned long bytes, unsigned long * __restrict p1,
-		   unsigned long *v2_in, unsigned long *v3_in,
+		   const unsigned long * __restrict p2,
-		   unsigned long *v4_in);
+		   const unsigned long * __restrict p3,
-void xor_altivec_5(unsigned long bytes, unsigned long *v1_in,
+		   const unsigned long * __restrict p4);
-		   unsigned long *v2_in, unsigned long *v3_in,
+void xor_altivec_5(unsigned long bytes, unsigned long * __restrict p1,
-		   unsigned long *v4_in, unsigned long *v5_in);
+		   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 */

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,
+void __xor_altivec_2(unsigned long bytes,
-		     unsigned long *v2_in)
+		     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,
+void __xor_altivec_3(unsigned long bytes,
-		     unsigned long *v2_in, unsigned long *v3_in)
+		     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,
+void __xor_altivec_4(unsigned long bytes,
-		     unsigned long *v2_in, unsigned long *v3_in,
+		     unsigned long * __restrict v1_in,
-		     unsigned long *v4_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,
+void __xor_altivec_5(unsigned long bytes,
-		     unsigned long *v2_in, unsigned long *v3_in,
+		     unsigned long * __restrict v1_in,
-		     unsigned long *v4_in, unsigned long *v5_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);

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,
+void __xor_altivec_2(unsigned long bytes, unsigned long * __restrict p1,
-			     unsigned long *v2_in);
+		     const unsigned long * __restrict p2);
-
+void __xor_altivec_3(unsigned long bytes, unsigned long * __restrict p1,
-void __xor_altivec_3(unsigned long bytes, unsigned long *v1_in,
+		     const unsigned long * __restrict p2,
-			     unsigned long *v2_in, unsigned long *v3_in);
+		     const unsigned long * __restrict p3);
-
+void __xor_altivec_4(unsigned long bytes, unsigned long * __restrict p1,
-void __xor_altivec_4(unsigned long bytes, unsigned long *v1_in,
+		     const unsigned long * __restrict p2,
-			     unsigned long *v2_in, unsigned long *v3_in,
+		     const unsigned long * __restrict p3,
-			     unsigned long *v4_in);
+		     const unsigned long * __restrict p4);
-
+void __xor_altivec_5(unsigned long bytes, unsigned long * __restrict p1,
-void __xor_altivec_5(unsigned long bytes, unsigned long *v1_in,
+		     const unsigned long * __restrict p2,
-			     unsigned long *v2_in, unsigned long *v3_in,
+		     const unsigned long * __restrict p3,
-			     unsigned long *v4_in, unsigned long *v5_in);
+		     const unsigned long * __restrict p4,
+		     const unsigned long * __restrict p5);

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,
+void xor_altivec_2(unsigned long bytes, unsigned long * __restrict p1,
-		   unsigned long *v2_in)
+		   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,
+void xor_altivec_3(unsigned long bytes, unsigned long * __restrict p1,
-		   unsigned long *v2_in, unsigned long *v3_in)
+		   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,
+void xor_altivec_4(unsigned long bytes, unsigned long * __restrict p1,
-		   unsigned long *v2_in, unsigned long *v3_in,
+		   const unsigned long * __restrict p2,
-		   unsigned long *v4_in)
+		   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,
+void xor_altivec_5(unsigned long bytes, unsigned long * __restrict p1,
-		   unsigned long *v2_in, unsigned long *v3_in,
+		   const unsigned long * __restrict p2,
-		   unsigned long *v4_in, unsigned long *v5_in)
+		   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();
 }

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,
+static void xor_xc_3(unsigned long bytes, unsigned long * __restrict p1,
-		     unsigned long *p3)
+		     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,
+static void xor_xc_4(unsigned long bytes, unsigned long * __restrict p1,
-		     unsigned long *p3, unsigned long *p4)
+		     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,
+static void xor_xc_5(unsigned long bytes, unsigned long * __restrict p1,
-		     unsigned long *p3, unsigned long *p4, unsigned long *p5)
+		     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"

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,
+sparc_3(unsigned long bytes, unsigned long * __restrict p1,
-	unsigned long *p3)
+	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,
+sparc_4(unsigned long bytes, unsigned long * __restrict p1,
-	unsigned long *p3, unsigned long *p4)
+	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,
+sparc_5(unsigned long bytes, unsigned long * __restrict p1,
-	unsigned long *p3, unsigned long *p4, unsigned long *p5)
+	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;
 

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_2(unsigned long bytes, unsigned long * __restrict p1,
-void xor_vis_3(unsigned long, unsigned long *, unsigned long *,
+	       const unsigned long * __restrict p2);
-	       unsigned long *);
+void xor_vis_3(unsigned long bytes, unsigned long * __restrict p1,
-void xor_vis_4(unsigned long, unsigned long *, unsigned long *,
+	       const unsigned long * __restrict p2,
-	       unsigned long *, unsigned long *);
+	       const unsigned long * __restrict p3);
-void xor_vis_5(unsigned long, unsigned long *, unsigned long *,
+void xor_vis_4(unsigned long bytes, unsigned long * __restrict p1,
-	       unsigned long *, unsigned long *, unsigned long *);
+	       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_2(unsigned long bytes, unsigned long * __restrict p1,
-void xor_niagara_3(unsigned long, unsigned long *, unsigned long *,
+		   const unsigned long * __restrict p2);
-		   unsigned long *);
+void xor_niagara_3(unsigned long bytes, unsigned long * __restrict p1,
-void xor_niagara_4(unsigned long, unsigned long *, unsigned long *,
+		   const unsigned long * __restrict p2,
-		   unsigned long *, unsigned long *);
+		   const unsigned long * __restrict p3);
-void xor_niagara_5(unsigned long, unsigned long *, unsigned long *,
+void xor_niagara_4(unsigned long bytes, unsigned long * __restrict p1,
-		   unsigned long *, unsigned long *, unsigned long *);
+		   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",

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,
+xor_sse_3(unsigned long bytes, unsigned long * __restrict p1,
-	  unsigned long *p3)
+	  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,
+xor_sse_3_pf64(unsigned long bytes, unsigned long * __restrict p1,
-	       unsigned long *p3)
+	       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,
+xor_sse_4(unsigned long bytes, unsigned long * __restrict p1,
-	  unsigned long *p3, unsigned long *p4)
+	  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,
+xor_sse_4_pf64(unsigned long bytes, unsigned long * __restrict p1,
-	       unsigned long *p3, unsigned long *p4)
+	       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,
+xor_sse_5(unsigned long bytes, unsigned long * __restrict p1,
-	  unsigned long *p3, unsigned long *p4, unsigned long *p5)
+	  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,
+xor_sse_5_pf64(unsigned long bytes, unsigned long * __restrict p1,
-	       unsigned long *p3, unsigned long *p4, unsigned long *p5)
+	       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;
 

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,
+xor_pII_mmx_3(unsigned long bytes, unsigned long * __restrict p1,
-	      unsigned long *p3)
+	      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,
+xor_pII_mmx_4(unsigned long bytes, unsigned long * __restrict p1,
-	      unsigned long *p3, unsigned long *p4)
+	      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,
+xor_pII_mmx_5(unsigned long bytes, unsigned long * __restrict p1,
-	      unsigned long *p3, unsigned long *p4, unsigned long *p5)
+	      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,
+xor_p5_mmx_3(unsigned long bytes, unsigned long * __restrict p1,
-	     unsigned long *p3)
+	     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,
+xor_p5_mmx_4(unsigned long bytes, unsigned long * __restrict p1,
-	     unsigned long *p3, unsigned long *p4)
+	     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,
+xor_p5_mmx_5(unsigned long bytes, unsigned long * __restrict p1,
-	     unsigned long *p3, unsigned long *p4, unsigned long *p5)
+	     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;
 

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,
+static void xor_avx_3(unsigned long bytes, unsigned long * __restrict p0,
-	unsigned long *p2)
+		      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,
+static void xor_avx_4(unsigned long bytes, unsigned long * __restrict p0,
-	unsigned long *p2, unsigned long *p3)
+		      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,
+static void xor_avx_5(unsigned long bytes, unsigned long * __restrict p0,
-	unsigned long *p2, unsigned long *p3, unsigned long *p4)
+	     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;
 

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,
+xor_8regs_3(unsigned long bytes, unsigned long * __restrict p1,
-	    unsigned long *p3)
+	    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,
+xor_8regs_4(unsigned long bytes, unsigned long * __restrict p1,
-	    unsigned long *p3, unsigned long *p4)
+	    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,
+xor_8regs_5(unsigned long bytes, unsigned long * __restrict p1,
-	    unsigned long *p3, unsigned long *p4, unsigned long *p5)
+	    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,
+xor_32regs_3(unsigned long bytes, unsigned long * __restrict p1,
-	    unsigned long *p3)
+	     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,
+xor_32regs_4(unsigned long bytes, unsigned long * __restrict p1,
-	    unsigned long *p3, unsigned long *p4)
+	     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,
+xor_32regs_5(unsigned long bytes, unsigned long * __restrict p1,
-	    unsigned long *p3, unsigned long *p4, unsigned long *p5)
+	     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,
+xor_8regs_p_3(unsigned long bytes, unsigned long * __restrict p1,
-	    unsigned long *p3)
+	      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,
+xor_8regs_p_4(unsigned long bytes, unsigned long * __restrict p1,
-	    unsigned long *p3, unsigned long *p4)
+	      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,
+xor_8regs_p_5(unsigned long bytes, unsigned long * __restrict p1,
-	    unsigned long *p3, unsigned long *p4, unsigned long *p5)
+	      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,
+xor_32regs_p_3(unsigned long bytes, unsigned long * __restrict p1,
-	    unsigned long *p3)
+	       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,
+xor_32regs_p_4(unsigned long bytes, unsigned long * __restrict p1,
-	    unsigned long *p3, unsigned long *p4)
+	       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,
+xor_32regs_p_5(unsigned long bytes, unsigned long * __restrict p1,
-	    unsigned long *p3, unsigned long *p4, unsigned long *p5)
+	       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;
 

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_2)(unsigned long, unsigned long * __restrict,
-	void (*do_3)(unsigned long, unsigned long *, unsigned long *,
+		     const unsigned long * __restrict);
-		     unsigned long *);
+	void (*do_3)(unsigned long, unsigned long * __restrict,
-	void (*do_4)(unsigned long, unsigned long *, unsigned long *,
+		     const unsigned long * __restrict,
-		     unsigned long *, unsigned long *);
+		     const unsigned long * __restrict);
-	void (*do_5)(unsigned long, unsigned long *, unsigned long *,
+	void (*do_4)(unsigned long, unsigned long * __restrict,
-		     unsigned long *, unsigned long *, unsigned long *);
+		     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