// SPDX-License-Identifier: GPL-2.0-or-later/* * Copyright 2002 H. Peter Anvin - All Rights Reserved * * RAID-6 data recovery in dual failure mode.  In single failure mode, use the * RAID-5 algorithm (or, in the case of Q failure, just reconstruct the * syndrome.) */ #include <linux/mm.h>#include <linux/raid/pq.h>#include "algos.h" /* Recover two failed data blocks. */static void raid6_2data_recov_intx1(int disks, size_t bytes, int faila,		int failb, void **ptrs){	u8 *p, *q, *dp, *dq;	u8 px, qx, db;	const u8 *pbmul;	/* P multiplier table for B data */	const u8 *qmul;		/* Q multiplier table (for both) */ 	p = (u8 *)ptrs[disks-2];	q = (u8 *)ptrs[disks-1]; 	/* Compute syndrome with zero for the missing data pages	   Use the dead data pages as temporary storage for	   delta p and delta q */	dp = (u8 *)ptrs[faila];	ptrs[faila] = page_address(ZERO_PAGE(0));	ptrs[disks-2] = dp;	dq = (u8 *)ptrs[failb];	ptrs[failb] = page_address(ZERO_PAGE(0));	ptrs[disks-1] = dq; 	raid6_gen_syndrome(disks, bytes, ptrs); 	/* Restore pointer table */	ptrs[faila]   = dp;	ptrs[failb]   = dq;	ptrs[disks-2] = p;	ptrs[disks-1] = q; 	/* Now, pick the proper data tables */	pbmul = raid6_gfmul[raid6_gfexi[failb-faila]];	qmul  = raid6_gfmul[raid6_gfinv[raid6_gfexp[faila]^raid6_gfexp[failb]]]; 	/* Now do it... */	while ( bytes-- ) {		px    = *p ^ *dp;		qx    = qmul[*q ^ *dq];		*dq++ = db = pbmul[px] ^ qx; /* Reconstructed B */		*dp++ = db ^ px; /* Reconstructed A */		p++; q++;	}} /* Recover failure of one data block plus the P block */static void raid6_datap_recov_intx1(int disks, size_t bytes, int faila,		void **ptrs){	u8 *p, *q, *dq;	const u8 *qmul;		/* Q multiplier table */ 	p = (u8 *)ptrs[disks-2];	q = (u8 *)ptrs[disks-1]; 	/* Compute syndrome with zero for the missing data page	   Use the dead data page as temporary storage for delta q */	dq = (u8 *)ptrs[faila];	ptrs[faila] = page_address(ZERO_PAGE(0));	ptrs[disks-1] = dq; 	raid6_gen_syndrome(disks, bytes, ptrs); 	/* Restore pointer table */	ptrs[faila]   = dq;	ptrs[disks-1] = q; 	/* Now, pick the proper data tables */	qmul  = raid6_gfmul[raid6_gfinv[raid6_gfexp[faila]]]; 	/* Now do it... */	while ( bytes-- ) {		*p++ ^= *dq = qmul[*q ^ *dq];		q++; dq++;	}}  const struct raid6_recov_calls raid6_recov_intx1 = {	.data2 = raid6_2data_recov_intx1,	.datap = raid6_datap_recov_intx1,	.name = "intx1",};