sse1.c

Go to the documentation of this file.

/* -*- linux-c -*- ------------------------------------------------------- *
 *
 *   Copyright 2002 H. Peter Anvin - All Rights Reserved
 *
 *   This program is free software; you can redistribute it and/or modify
 *   it under the terms of the GNU General Public License as published by
 *   the Free Software Foundation, Inc., 53 Temple Place Ste 330,
 *   Boston MA 02111-1307, USA; either version 2 of the License, or
 *   (at your option) any later version; incorporated herein by reference.
 *
 * ----------------------------------------------------------------------- */

/*
 * raid6/sse1.c
 *
 * SSE-1/MMXEXT implementation of RAID-6 syndrome functions
 *
 * This is really an MMX implementation, but it requires SSE-1 or
 * AMD MMXEXT for prefetch support and a few other features.  The
 * support for nontemporal memory accesses is enough to make this
 * worthwhile as a separate implementation.
 */

#if defined(__i386__) && !defined(__arch_um__)

#include <linux/raid/pq.h>
#include "x86.h"

/* Defined in raid6/mmx.c */
extern const struct raid6_mmx_constants {
    u64 x1d;
} raid6_mmx_constants;

static int raid6_have_sse1_or_mmxext(void)
{
    /* Not really boot_cpu but "all_cpus" */
    return boot_cpu_has(X86_FEATURE_MMX) &&
        (boot_cpu_has(X86_FEATURE_XMM) ||
         boot_cpu_has(X86_FEATURE_MMXEXT));
}

/*
 * Plain SSE1 implementation
 */
static void raid6_sse11_gen_syndrome(int disks, size_t bytes, void **ptrs)
{
    u8 **dptr = (u8 **)ptrs;
    u8 *p, *q;
    int d, z, z0;

    z0 = disks - 3;     /* Highest data disk */
    p = dptr[z0+1];     /* XOR parity */
    q = dptr[z0+2];     /* RS syndrome */

    kernel_fpu_begin();

    asm volatile("movq %0,%%mm0" : : "m" (raid6_mmx_constants.x1d));
    asm volatile("pxor %mm5,%mm5"); /* Zero temp */

    for ( d = 0 ; d < bytes ; d += 8 ) {
        asm volatile("prefetchnta %0" : : "m" (dptr[z0][d]));
        asm volatile("movq %0,%%mm2" : : "m" (dptr[z0][d])); /* P[0] */
        asm volatile("prefetchnta %0" : : "m" (dptr[z0-1][d]));
        asm volatile("movq %mm2,%mm4"); /* Q[0] */
        asm volatile("movq %0,%%mm6" : : "m" (dptr[z0-1][d]));
        for ( z = z0-2 ; z >= 0 ; z-- ) {
            asm volatile("prefetchnta %0" : : "m" (dptr[z][d]));
            asm volatile("pcmpgtb %mm4,%mm5");
            asm volatile("paddb %mm4,%mm4");
            asm volatile("pand %mm0,%mm5");
            asm volatile("pxor %mm5,%mm4");
            asm volatile("pxor %mm5,%mm5");
            asm volatile("pxor %mm6,%mm2");
            asm volatile("pxor %mm6,%mm4");
            asm volatile("movq %0,%%mm6" : : "m" (dptr[z][d]));
        }
        asm volatile("pcmpgtb %mm4,%mm5");
        asm volatile("paddb %mm4,%mm4");
        asm volatile("pand %mm0,%mm5");
        asm volatile("pxor %mm5,%mm4");
        asm volatile("pxor %mm5,%mm5");
        asm volatile("pxor %mm6,%mm2");
        asm volatile("pxor %mm6,%mm4");

        asm volatile("movntq %%mm2,%0" : "=m" (p[d]));
        asm volatile("movntq %%mm4,%0" : "=m" (q[d]));
    }

    asm volatile("sfence" : : : "memory");
    kernel_fpu_end();
}

const struct raid6_calls raid6_sse1x1 = {
    raid6_sse11_gen_syndrome,
    raid6_have_sse1_or_mmxext,
    "sse1x1",
    1           /* Has cache hints */
};

/*
 * Unrolled-by-2 SSE1 implementation
 */
static void raid6_sse12_gen_syndrome(int disks, size_t bytes, void **ptrs)
{
    u8 **dptr = (u8 **)ptrs;
    u8 *p, *q;
    int d, z, z0;

    z0 = disks - 3;     /* Highest data disk */
    p = dptr[z0+1];     /* XOR parity */
    q = dptr[z0+2];     /* RS syndrome */

    kernel_fpu_begin();

    asm volatile("movq %0,%%mm0" : : "m" (raid6_mmx_constants.x1d));
    asm volatile("pxor %mm5,%mm5"); /* Zero temp */
    asm volatile("pxor %mm7,%mm7"); /* Zero temp */

    /* We uniformly assume a single prefetch covers at least 16 bytes */
    for ( d = 0 ; d < bytes ; d += 16 ) {
        asm volatile("prefetchnta %0" : : "m" (dptr[z0][d]));
        asm volatile("movq %0,%%mm2" : : "m" (dptr[z0][d])); /* P[0] */
        asm volatile("movq %0,%%mm3" : : "m" (dptr[z0][d+8])); /* P[1] */
        asm volatile("movq %mm2,%mm4"); /* Q[0] */
        asm volatile("movq %mm3,%mm6"); /* Q[1] */
        for ( z = z0-1 ; z >= 0 ; z-- ) {
            asm volatile("prefetchnta %0" : : "m" (dptr[z][d]));
            asm volatile("pcmpgtb %mm4,%mm5");
            asm volatile("pcmpgtb %mm6,%mm7");
            asm volatile("paddb %mm4,%mm4");
            asm volatile("paddb %mm6,%mm6");
            asm volatile("pand %mm0,%mm5");
            asm volatile("pand %mm0,%mm7");
            asm volatile("pxor %mm5,%mm4");
            asm volatile("pxor %mm7,%mm6");
            asm volatile("movq %0,%%mm5" : : "m" (dptr[z][d]));
            asm volatile("movq %0,%%mm7" : : "m" (dptr[z][d+8]));
            asm volatile("pxor %mm5,%mm2");
            asm volatile("pxor %mm7,%mm3");
            asm volatile("pxor %mm5,%mm4");
            asm volatile("pxor %mm7,%mm6");
            asm volatile("pxor %mm5,%mm5");
            asm volatile("pxor %mm7,%mm7");
        }
        asm volatile("movntq %%mm2,%0" : "=m" (p[d]));
        asm volatile("movntq %%mm3,%0" : "=m" (p[d+8]));
        asm volatile("movntq %%mm4,%0" : "=m" (q[d]));
        asm volatile("movntq %%mm6,%0" : "=m" (q[d+8]));
    }

    asm volatile("sfence" : :: "memory");
    kernel_fpu_end();
}

const struct raid6_calls raid6_sse1x2 = {
    raid6_sse12_gen_syndrome,
    raid6_have_sse1_or_mmxext,
    "sse1x2",
    1           /* Has cache hints */
};

#endif