Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 08c7dd1b authored by Daniel Axtens's avatar Daniel Axtens Committed by Herbert Xu
Browse files

crypto: powerpc - Re-enable non-REFLECTed CRCs 

When CRC32c was included in the kernel, Anton ripped out
the #ifdefs around reflected polynomials, because CRC32c
is always reflected. However, not all CRCs use reflection
so we'd like to make it optional.

Restore the REFLECT parts from Anton's original CRC32
implementation (https://github.com/antonblanchard/crc32-vpmsum)

That implementation is available under GPLv2+, so we're OK
from a licensing point of view:
https://github.com/antonblanchard/crc32-vpmsum/blob/master/LICENSE.TXT



As CRC32c requires REFLECT, add that #define.

Cc: Anton Blanchard <anton@samba.org>
Signed-off-by: default avatarDaniel Axtens <dja@axtens.net>
Signed-off-by: default avatarHerbert Xu <herbert@gondor.apana.org.au>
parent de696a26

arch/powerpc/crypto/crc32-vpmsum_core.S

+30 −1
Original line number Diff line number Diff line
@@ -35,7 +35,9 @@ 


	.text



#if defined(__BIG_ENDIAN__)

#if defined(__BIG_ENDIAN__) && defined(REFLECT)

#define BYTESWAP_DATA

#elif defined(__LITTLE_ENDIAN__) && !defined(REFLECT)

#define BYTESWAP_DATA

#else

#undef BYTESWAP_DATA
@@ -108,7 +110,11 @@ FUNC_START(CRC_FUNCTION_NAME) 
	/* Get the initial value into v8 */

	vxor	v8,v8,v8

	MTVRD(v8, R3)

#ifdef REFLECT

	vsldoi	v8,zeroes,v8,8	/* shift into bottom 32 bits */

#else

	vsldoi	v8,v8,zeroes,4	/* shift into top 32 bits */

#endif



#ifdef BYTESWAP_DATA

	addis	r3,r2,.byteswap_constant@toc@ha
@@ -354,6 +360,7 @@ FUNC_START(CRC_FUNCTION_NAME) 
	vxor	v6,v6,v14

	vxor	v7,v7,v15



#ifdef REFLECT

	/*

	 * vpmsumd produces a 96 bit result in the least significant bits

	 * of the register. Since we are bit reflected we have to shift it
@@ -368,6 +375,7 @@ FUNC_START(CRC_FUNCTION_NAME) 
	vsldoi	v5,v5,zeroes,4

	vsldoi	v6,v6,zeroes,4

	vsldoi	v7,v7,zeroes,4

#endif



	/* xor with last 1024 bits */

	lvx	v8,0,r4
@@ -511,12 +519,32 @@ FUNC_START(CRC_FUNCTION_NAME) 
	vsldoi	v1,v0,v0,8

	vxor	v0,v0,v1		/* xor two 64 bit results together */



#ifdef REFLECT

	/* shift left one bit */

	vspltisb v1,1

	vsl	v0,v0,v1

#endif



	vand	v0,v0,mask_64bit

#ifndef REFLECT

	/*

	 * Now for the Barrett reduction algorithm. The idea is to calculate q,

	 * the multiple of our polynomial that we need to subtract. By

	 * doing the computation 2x bits higher (ie 64 bits) and shifting the

	 * result back down 2x bits, we round down to the nearest multiple.

	 */

	VPMSUMD(v1,v0,const1)	/* ma */

	vsldoi	v1,zeroes,v1,8	/* q = floor(ma/(2^64)) */

	VPMSUMD(v1,v1,const2)	/* qn */

	vxor	v0,v0,v1	/* a - qn, subtraction is xor in GF(2) */



	/*

	 * Get the result into r3. We need to shift it left 8 bytes:

	 * V0 [ 0 1 2 X ]

	 * V0 [ 0 X 2 3 ]

	 */

	vsldoi	v0,v0,zeroes,8	/* shift result into top 64 bits */

#else

	/*

	 * The reflected version of Barrett reduction. Instead of bit

	 * reflecting our data (which is expensive to do), we bit reflect our
@@ -537,6 +565,7 @@ FUNC_START(CRC_FUNCTION_NAME) 
	 * V0 [ 0 X 2 3 ]

	 */

	vsldoi	v0,v0,zeroes,4		/* shift result into top 64 bits of */

#endif



	/* Get it into r3 */

	MFVRD(R3, v0)

arch/powerpc/crypto/crc32c-vpmsum_asm.S

+1 −0
Original line number Diff line number Diff line
@@ -842,4 +842,5 @@ 
	.octa 0x00000000000000000000000105ec76f1



#define CRC_FUNCTION_NAME __crc32c_vpmsum

#define REFLECT

#include "crc32-vpmsum_core.S"