Git Repo - linux.git/blame_incremental - lib/raid6/recov

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Commit	Line	Data
	1	// SPDX-License-Identifier: GPL-2.0
	2	/*
	3	* RAID-6 data recovery in dual failure mode based on the XC instruction.
	4	*
	5	* Copyright IBM Corp. 2016
	6	* Author(s): Martin Schwidefsky <[email protected]>
	7	*/
	8
	9	#include <linux/export.h>
	10	#include <linux/raid/pq.h>
	11
	12	static inline void xor_block(u8 p1, u8 p2)
	13	{
	14	typedef struct { u8 _[256]; } addrtype;
	15
	16	asm volatile(
	17	" xc 0(256,%[p1]),0(%[p2])\n"
	18	: "+m" ((addrtype ) p1) : "m" ((addrtype ) p2),
	19	[p1] "a" (p1), [p2] "a" (p2) : "cc");
	20	}
	21
	22	/* Recover two failed data blocks. */
	23	static void raid6_2data_recov_s390xc(int disks, size_t bytes, int faila,
	24	int failb, void **ptrs)
	25	{
	26	u8 p, q, dp, dq;
	27	const u8 pbmul; / P multiplier table for B data */
	28	const u8 qmul; / Q multiplier table (for both) */
	29	int i;
	30
	31	p = (u8 *)ptrs[disks-2];
	32	q = (u8 *)ptrs[disks-1];
	33
	34	/* Compute syndrome with zero for the missing data pages
	35	Use the dead data pages as temporary storage for
	36	delta p and delta q */
	37	dp = (u8 *)ptrs[faila];
	38	ptrs[faila] = (void *)raid6_empty_zero_page;
	39	ptrs[disks-2] = dp;
	40	dq = (u8 *)ptrs[failb];
	41	ptrs[failb] = (void *)raid6_empty_zero_page;
	42	ptrs[disks-1] = dq;
	43
	44	raid6_call.gen_syndrome(disks, bytes, ptrs);
	45
	46	/* Restore pointer table */
	47	ptrs[faila] = dp;
	48	ptrs[failb] = dq;
	49	ptrs[disks-2] = p;
	50	ptrs[disks-1] = q;
	51
	52	/* Now, pick the proper data tables */
	53	pbmul = raid6_gfmul[raid6_gfexi[failb-faila]];
	54	qmul = raid6_gfmul[raid6_gfinv[raid6_gfexp[faila]^raid6_gfexp[failb]]];
	55
	56	/* Now do it... */
	57	while (bytes) {
	58	xor_block(dp, p);
	59	xor_block(dq, q);
	60	for (i = 0; i < 256; i++)
	61	dq[i] = pbmul[dp[i]] ^ qmul[dq[i]];
	62	xor_block(dp, dq);
	63	p += 256;
	64	q += 256;
	65	dp += 256;
	66	dq += 256;
	67	bytes -= 256;
	68	}
	69	}
	70
	71	/* Recover failure of one data block plus the P block */
	72	static void raid6_datap_recov_s390xc(int disks, size_t bytes, int faila,
	73	void **ptrs)
	74	{
	75	u8 p, q, *dq;
	76	const u8 qmul; / Q multiplier table */
	77	int i;
	78
	79	p = (u8 *)ptrs[disks-2];
	80	q = (u8 *)ptrs[disks-1];
	81
	82	/* Compute syndrome with zero for the missing data page
	83	Use the dead data page as temporary storage for delta q */
	84	dq = (u8 *)ptrs[faila];
	85	ptrs[faila] = (void *)raid6_empty_zero_page;
	86	ptrs[disks-1] = dq;
	87
	88	raid6_call.gen_syndrome(disks, bytes, ptrs);
	89
	90	/* Restore pointer table */
	91	ptrs[faila] = dq;
	92	ptrs[disks-1] = q;
	93
	94	/* Now, pick the proper data tables */
	95	qmul = raid6_gfmul[raid6_gfinv[raid6_gfexp[faila]]];
	96
	97	/* Now do it... */
	98	while (bytes) {
	99	xor_block(dq, q);
	100	for (i = 0; i < 256; i++)
	101	dq[i] = qmul[dq[i]];
	102	xor_block(p, dq);
	103	p += 256;
	104	q += 256;
	105	dq += 256;
	106	bytes -= 256;
	107	}
	108	}
	109
	110
	111	const struct raid6_recov_calls raid6_recov_s390xc = {
	112	.data2 = raid6_2data_recov_s390xc,
	113	.datap = raid6_datap_recov_s390xc,
	114	.valid = NULL,
	115	.name = "s390xc",
	116	.priority = 1,
	117	};