Pull platform-drivers into test branch

[deliverable/linux.git] / arch / sh / mm / cache-sh4.c

/*
 * arch/sh/mm/cache-sh4.c
 *
 * Copyright (C) 1999, 2000, 2002  Niibe Yutaka
 * Copyright (C) 2001 - 2006  Paul Mundt
 * Copyright (C) 2003  Richard Curnow
 *
 * This file is subject to the terms and conditions of the GNU General Public
 * License.  See the file "COPYING" in the main directory of this archive
 * for more details.
 */
#include <linux/init.h>
#include <linux/mm.h>
#include <linux/io.h>
#include <linux/mutex.h>
#include <asm/mmu_context.h>
#include <asm/cacheflush.h>

/*
 * The maximum number of pages we support up to when doing ranged dcache
 * flushing. Anything exceeding this will simply flush the dcache in its
 * entirety.
 */
#define MAX_DCACHE_PAGES        64      /* XXX: Tune for ways */

static void __flush_dcache_segment_1way(unsigned long start,
                                        unsigned long extent);
static void __flush_dcache_segment_2way(unsigned long start,
                                        unsigned long extent);
static void __flush_dcache_segment_4way(unsigned long start,
                                        unsigned long extent);

static void __flush_cache_4096(unsigned long addr, unsigned long phys,
                               unsigned long exec_offset);

/*
 * This is initialised here to ensure that it is not placed in the BSS.  If
 * that were to happen, note that cache_init gets called before the BSS is
 * cleared, so this would get nulled out which would be hopeless.
 */
static void (*__flush_dcache_segment_fn)(unsigned long, unsigned long) =
        (void (*)(unsigned long, unsigned long))0xdeadbeef;

static void compute_alias(struct cache_info *c)
{
        c->alias_mask = ((c->sets - 1) << c->entry_shift) & ~(PAGE_SIZE - 1);
        c->n_aliases = (c->alias_mask >> PAGE_SHIFT) + 1;
}

static void __init emit_cache_params(void)
{
        printk("PVR=%08x CVR=%08x PRR=%08x\n",
                ctrl_inl(CCN_PVR),
                ctrl_inl(CCN_CVR),
                ctrl_inl(CCN_PRR));
        printk("I-cache : n_ways=%d n_sets=%d way_incr=%d\n",
                cpu_data->icache.ways,
                cpu_data->icache.sets,
                cpu_data->icache.way_incr);
        printk("I-cache : entry_mask=0x%08x alias_mask=0x%08x n_aliases=%d\n",
                cpu_data->icache.entry_mask,
                cpu_data->icache.alias_mask,
                cpu_data->icache.n_aliases);
        printk("D-cache : n_ways=%d n_sets=%d way_incr=%d\n",
                cpu_data->dcache.ways,
                cpu_data->dcache.sets,
                cpu_data->dcache.way_incr);
        printk("D-cache : entry_mask=0x%08x alias_mask=0x%08x n_aliases=%d\n",
                cpu_data->dcache.entry_mask,
                cpu_data->dcache.alias_mask,
                cpu_data->dcache.n_aliases);

        if (!__flush_dcache_segment_fn)
                panic("unknown number of cache ways\n");
}

/*
 * SH-4 has virtually indexed and physically tagged cache.
 */

/* Worst case assumed to be 64k cache, direct-mapped i.e. 4 synonym bits. */
#define MAX_P3_MUTEXES 16

struct mutex p3map_mutex[MAX_P3_MUTEXES];

void __init p3_cache_init(void)
{
        int i;

        compute_alias(&cpu_data->icache);
        compute_alias(&cpu_data->dcache);

        switch (cpu_data->dcache.ways) {
        case 1:
                __flush_dcache_segment_fn = __flush_dcache_segment_1way;
                break;
        case 2:
                __flush_dcache_segment_fn = __flush_dcache_segment_2way;
                break;
        case 4:
                __flush_dcache_segment_fn = __flush_dcache_segment_4way;
                break;
        default:
                __flush_dcache_segment_fn = NULL;
                break;
        }

        emit_cache_params();

        if (ioremap_page_range(P3SEG, P3SEG + (PAGE_SIZE * 4), 0, PAGE_KERNEL))
                panic("%s failed.", __FUNCTION__);

        for (i = 0; i < cpu_data->dcache.n_aliases; i++)
                mutex_init(&p3map_mutex[i]);
}

/*
 * Write back the dirty D-caches, but not invalidate them.
 *
 * START: Virtual Address (U0, P1, or P3)
 * SIZE: Size of the region.
 */
void __flush_wback_region(void *start, int size)
{
        unsigned long v;
        unsigned long begin, end;

        begin = (unsigned long)start & ~(L1_CACHE_BYTES-1);
        end = ((unsigned long)start + size + L1_CACHE_BYTES-1)
                & ~(L1_CACHE_BYTES-1);
        for (v = begin; v < end; v+=L1_CACHE_BYTES) {
                asm volatile("ocbwb     %0"
                             : /* no output */
                             : "m" (__m(v)));
        }
}

/*
 * Write back the dirty D-caches and invalidate them.
 *
 * START: Virtual Address (U0, P1, or P3)
 * SIZE: Size of the region.
 */
void __flush_purge_region(void *start, int size)
{
        unsigned long v;
        unsigned long begin, end;

        begin = (unsigned long)start & ~(L1_CACHE_BYTES-1);
        end = ((unsigned long)start + size + L1_CACHE_BYTES-1)
                & ~(L1_CACHE_BYTES-1);
        for (v = begin; v < end; v+=L1_CACHE_BYTES) {
                asm volatile("ocbp      %0"
                             : /* no output */
                             : "m" (__m(v)));
        }
}

/*
 * No write back please
 */
void __flush_invalidate_region(void *start, int size)
{
        unsigned long v;
        unsigned long begin, end;

        begin = (unsigned long)start & ~(L1_CACHE_BYTES-1);
        end = ((unsigned long)start + size + L1_CACHE_BYTES-1)
                & ~(L1_CACHE_BYTES-1);
        for (v = begin; v < end; v+=L1_CACHE_BYTES) {
                asm volatile("ocbi      %0"
                             : /* no output */
                             : "m" (__m(v)));
        }
}

/*
 * Write back the range of D-cache, and purge the I-cache.
 *
 * Called from kernel/module.c:sys_init_module and routine for a.out format.
 */
void flush_icache_range(unsigned long start, unsigned long end)
{
        flush_cache_all();
}

/*
 * Write back the D-cache and purge the I-cache for signal trampoline.
 * .. which happens to be the same behavior as flush_icache_range().
 * So, we simply flush out a line.
 */
void flush_cache_sigtramp(unsigned long addr)
{
        unsigned long v, index;
        unsigned long flags;
        int i;

        v = addr & ~(L1_CACHE_BYTES-1);
        asm volatile("ocbwb     %0"
                     : /* no output */
                     : "m" (__m(v)));

        index = CACHE_IC_ADDRESS_ARRAY | (v & cpu_data->icache.entry_mask);

        local_irq_save(flags);
        jump_to_P2();

        for (i = 0; i < cpu_data->icache.ways;
             i++, index += cpu_data->icache.way_incr)
                ctrl_outl(0, index);    /* Clear out Valid-bit */

        back_to_P1();
        wmb();
        local_irq_restore(flags);
}

static inline void flush_cache_4096(unsigned long start,
                                    unsigned long phys)
{
        unsigned long flags, exec_offset = 0;

        /*
         * All types of SH-4 require PC to be in P2 to operate on the I-cache.
         * Some types of SH-4 require PC to be in P2 to operate on the D-cache.
         */
        if ((cpu_data->flags & CPU_HAS_P2_FLUSH_BUG) ||
            (start < CACHE_OC_ADDRESS_ARRAY))
                exec_offset = 0x20000000;

        local_irq_save(flags);
        __flush_cache_4096(start | SH_CACHE_ASSOC,
                           P1SEGADDR(phys), exec_offset);
        local_irq_restore(flags);
}

/*
 * Write back & invalidate the D-cache of the page.
 * (To avoid "alias" issues)
 */
void flush_dcache_page(struct page *page)
{
        if (test_bit(PG_mapped, &page->flags)) {
                unsigned long phys = PHYSADDR(page_address(page));
                unsigned long addr = CACHE_OC_ADDRESS_ARRAY;
                int i, n;

                /* Loop all the D-cache */
                n = cpu_data->dcache.n_aliases;
                for (i = 0; i < n; i++, addr += 4096)
                        flush_cache_4096(addr, phys);
        }

        wmb();
}

/* TODO: Selective icache invalidation through IC address array.. */
static inline void flush_icache_all(void)
{
        unsigned long flags, ccr;

        local_irq_save(flags);
        jump_to_P2();

        /* Flush I-cache */
        ccr = ctrl_inl(CCR);
        ccr |= CCR_CACHE_ICI;
        ctrl_outl(ccr, CCR);

        /*
         * back_to_P1() will take care of the barrier for us, don't add
         * another one!
         */

        back_to_P1();
        local_irq_restore(flags);
}

void flush_dcache_all(void)
{
        (*__flush_dcache_segment_fn)(0UL, cpu_data->dcache.way_size);
        wmb();
}

void flush_cache_all(void)
{
        flush_dcache_all();
        flush_icache_all();
}

static void __flush_cache_mm(struct mm_struct *mm, unsigned long start,
                             unsigned long end)
{
        unsigned long d = 0, p = start & PAGE_MASK;
        unsigned long alias_mask = cpu_data->dcache.alias_mask;
        unsigned long n_aliases = cpu_data->dcache.n_aliases;
        unsigned long select_bit;
        unsigned long all_aliases_mask;
        unsigned long addr_offset;
        pgd_t *dir;
        pmd_t *pmd;
        pud_t *pud;
        pte_t *pte;
        int i;

        dir = pgd_offset(mm, p);
        pud = pud_offset(dir, p);
        pmd = pmd_offset(pud, p);
        end = PAGE_ALIGN(end);

        all_aliases_mask = (1 << n_aliases) - 1;

        do {
                if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd))) {
                        p &= PMD_MASK;
                        p += PMD_SIZE;
                        pmd++;

                        continue;
                }

                pte = pte_offset_kernel(pmd, p);

                do {
                        unsigned long phys;
                        pte_t entry = *pte;

                        if (!(pte_val(entry) & _PAGE_PRESENT)) {
                                pte++;
                                p += PAGE_SIZE;
                                continue;
                        }

                        phys = pte_val(entry) & PTE_PHYS_MASK;

                        if ((p ^ phys) & alias_mask) {
                                d |= 1 << ((p & alias_mask) >> PAGE_SHIFT);
                                d |= 1 << ((phys & alias_mask) >> PAGE_SHIFT);

                                if (d == all_aliases_mask)
                                        goto loop_exit;
                        }

                        pte++;
                        p += PAGE_SIZE;
                } while (p < end && ((unsigned long)pte & ~PAGE_MASK));
                pmd++;
        } while (p < end);

loop_exit:
        addr_offset = 0;
        select_bit = 1;

        for (i = 0; i < n_aliases; i++) {
                if (d & select_bit) {
                        (*__flush_dcache_segment_fn)(addr_offset, PAGE_SIZE);
                        wmb();
                }

                select_bit <<= 1;
                addr_offset += PAGE_SIZE;
        }
}

/*
 * Note : (RPC) since the caches are physically tagged, the only point
 * of flush_cache_mm for SH-4 is to get rid of aliases from the
 * D-cache.  The assumption elsewhere, e.g. flush_cache_range, is that
 * lines can stay resident so long as the virtual address they were
 * accessed with (hence cache set) is in accord with the physical
 * address (i.e. tag).  It's no different here.  So I reckon we don't
 * need to flush the I-cache, since aliases don't matter for that.  We
 * should try that.
 *
 * Caller takes mm->mmap_sem.
 */
void flush_cache_mm(struct mm_struct *mm)
{
        /*
         * If cache is only 4k-per-way, there are never any 'aliases'.  Since
         * the cache is physically tagged, the data can just be left in there.
         */
        if (cpu_data->dcache.n_aliases == 0)
                return;

        /*
         * Don't bother groveling around the dcache for the VMA ranges
         * if there are too many PTEs to make it worthwhile.
         */
        if (mm->nr_ptes >= MAX_DCACHE_PAGES)
                flush_dcache_all();
        else {
                struct vm_area_struct *vma;

                /*
                 * In this case there are reasonably sized ranges to flush,
                 * iterate through the VMA list and take care of any aliases.
                 */
                for (vma = mm->mmap; vma; vma = vma->vm_next)
                        __flush_cache_mm(mm, vma->vm_start, vma->vm_end);
        }

        /* Only touch the icache if one of the VMAs has VM_EXEC set. */
        if (mm->exec_vm)
                flush_icache_all();
}

/*
 * Write back and invalidate I/D-caches for the page.
 *
 * ADDR: Virtual Address (U0 address)
 * PFN: Physical page number
 */
void flush_cache_page(struct vm_area_struct *vma, unsigned long address,
                      unsigned long pfn)
{
        unsigned long phys = pfn << PAGE_SHIFT;
        unsigned int alias_mask;

        alias_mask = cpu_data->dcache.alias_mask;

        /* We only need to flush D-cache when we have alias */
        if ((address^phys) & alias_mask) {
                /* Loop 4K of the D-cache */
                flush_cache_4096(
                        CACHE_OC_ADDRESS_ARRAY | (address & alias_mask),
                        phys);
                /* Loop another 4K of the D-cache */
                flush_cache_4096(
                        CACHE_OC_ADDRESS_ARRAY | (phys & alias_mask),
                        phys);
        }

        alias_mask = cpu_data->icache.alias_mask;
        if (vma->vm_flags & VM_EXEC) {
                /*
                 * Evict entries from the portion of the cache from which code
                 * may have been executed at this address (virtual).  There's
                 * no need to evict from the portion corresponding to the
                 * physical address as for the D-cache, because we know the
                 * kernel has never executed the code through its identity
                 * translation.
                 */
                flush_cache_4096(
                        CACHE_IC_ADDRESS_ARRAY | (address & alias_mask),
                        phys);
        }
}

/*
 * Write back and invalidate D-caches.
 *
 * START, END: Virtual Address (U0 address)
 *
 * NOTE: We need to flush the _physical_ page entry.
 * Flushing the cache lines for U0 only isn't enough.
 * We need to flush for P1 too, which may contain aliases.
 */
void flush_cache_range(struct vm_area_struct *vma, unsigned long start,
                       unsigned long end)
{
        /*
         * If cache is only 4k-per-way, there are never any 'aliases'.  Since
         * the cache is physically tagged, the data can just be left in there.
         */
        if (cpu_data->dcache.n_aliases == 0)
                return;

        /*
         * Don't bother with the lookup and alias check if we have a
         * wide range to cover, just blow away the dcache in its
         * entirety instead. -- PFM.
         */
        if (((end - start) >> PAGE_SHIFT) >= MAX_DCACHE_PAGES)
                flush_dcache_all();
        else
                __flush_cache_mm(vma->vm_mm, start, end);

        if (vma->vm_flags & VM_EXEC) {
                /*
                 * TODO: Is this required???  Need to look at how I-cache
                 * coherency is assured when new programs are loaded to see if
                 * this matters.
                 */
                flush_icache_all();
        }
}

/*
 * flush_icache_user_range
 * @vma: VMA of the process
 * @page: page
 * @addr: U0 address
 * @len: length of the range (< page size)
 */
void flush_icache_user_range(struct vm_area_struct *vma,
                             struct page *page, unsigned long addr, int len)
{
        flush_cache_page(vma, addr, page_to_pfn(page));
        mb();
}

/**
 * __flush_cache_4096
 *
 * @addr:  address in memory mapped cache array
 * @phys:  P1 address to flush (has to match tags if addr has 'A' bit
 *         set i.e. associative write)
 * @exec_offset: set to 0x20000000 if flush has to be executed from P2
 *               region else 0x0
 *
 * The offset into the cache array implied by 'addr' selects the
 * 'colour' of the virtual address range that will be flushed.  The
 * operation (purge/write-back) is selected by the lower 2 bits of
 * 'phys'.
 */
static void __flush_cache_4096(unsigned long addr, unsigned long phys,
                               unsigned long exec_offset)
{
        int way_count;
        unsigned long base_addr = addr;
        struct cache_info *dcache;
        unsigned long way_incr;
        unsigned long a, ea, p;
        unsigned long temp_pc;

        dcache = &cpu_data->dcache;
        /* Write this way for better assembly. */
        way_count = dcache->ways;
        way_incr = dcache->way_incr;

        /*
         * Apply exec_offset (i.e. branch to P2 if required.).
         *
         * FIXME:
         *
         *      If I write "=r" for the (temp_pc), it puts this in r6 hence
         *      trashing exec_offset before it's been added on - why?  Hence
         *      "=&r" as a 'workaround'
         */
        asm volatile("mov.l 1f, %0\n\t"
                     "add   %1, %0\n\t"
                     "jmp   @%0\n\t"
                     "nop\n\t"
                     ".balign 4\n\t"
                     "1:  .long 2f\n\t"
                     "2:\n" : "=&r" (temp_pc) : "r" (exec_offset));

        /*
         * We know there will be >=1 iteration, so write as do-while to avoid
         * pointless nead-of-loop check for 0 iterations.
         */
        do {
                ea = base_addr + PAGE_SIZE;
                a = base_addr;
                p = phys;

                do {
                        *(volatile unsigned long *)a = p;
                        /*
                         * Next line: intentionally not p+32, saves an add, p
                         * will do since only the cache tag bits need to
                         * match.
                         */
                        *(volatile unsigned long *)(a+32) = p;
                        a += 64;
                        p += 64;
                } while (a < ea);

                base_addr += way_incr;
        } while (--way_count != 0);
}

/*
 * Break the 1, 2 and 4 way variants of this out into separate functions to
 * avoid nearly all the overhead of having the conditional stuff in the function
 * bodies (+ the 1 and 2 way cases avoid saving any registers too).
 */
static void __flush_dcache_segment_1way(unsigned long start,
                                        unsigned long extent_per_way)
{
        unsigned long orig_sr, sr_with_bl;
        unsigned long base_addr;
        unsigned long way_incr, linesz, way_size;
        struct cache_info *dcache;
        register unsigned long a0, a0e;

        asm volatile("stc sr, %0" : "=r" (orig_sr));
        sr_with_bl = orig_sr | (1<<28);
        base_addr = ((unsigned long)&empty_zero_page[0]);

        /*
         * The previous code aligned base_addr to 16k, i.e. the way_size of all
         * existing SH-4 D-caches.  Whilst I don't see a need to have this
         * aligned to any better than the cache line size (which it will be
         * anyway by construction), let's align it to at least the way_size of
         * any existing or conceivable SH-4 D-cache.  -- RPC
         */
        base_addr = ((base_addr >> 16) << 16);
        base_addr |= start;

        dcache = &cpu_data->dcache;
        linesz = dcache->linesz;
        way_incr = dcache->way_incr;
        way_size = dcache->way_size;

        a0 = base_addr;
        a0e = base_addr + extent_per_way;
        do {
                asm volatile("ldc %0, sr" : : "r" (sr_with_bl));
                asm volatile("movca.l r0, @%0\n\t"
                             "ocbi @%0" : : "r" (a0));
                a0 += linesz;
                asm volatile("movca.l r0, @%0\n\t"
                             "ocbi @%0" : : "r" (a0));
                a0 += linesz;
                asm volatile("movca.l r0, @%0\n\t"
                             "ocbi @%0" : : "r" (a0));
                a0 += linesz;
                asm volatile("movca.l r0, @%0\n\t"
                             "ocbi @%0" : : "r" (a0));
                asm volatile("ldc %0, sr" : : "r" (orig_sr));
                a0 += linesz;
        } while (a0 < a0e);
}

static void __flush_dcache_segment_2way(unsigned long start,
                                        unsigned long extent_per_way)
{
        unsigned long orig_sr, sr_with_bl;
        unsigned long base_addr;
        unsigned long way_incr, linesz, way_size;
        struct cache_info *dcache;
        register unsigned long a0, a1, a0e;

        asm volatile("stc sr, %0" : "=r" (orig_sr));
        sr_with_bl = orig_sr | (1<<28);
        base_addr = ((unsigned long)&empty_zero_page[0]);

        /* See comment under 1-way above */
        base_addr = ((base_addr >> 16) << 16);
        base_addr |= start;

        dcache = &cpu_data->dcache;
        linesz = dcache->linesz;
        way_incr = dcache->way_incr;
        way_size = dcache->way_size;

        a0 = base_addr;
        a1 = a0 + way_incr;
        a0e = base_addr + extent_per_way;
        do {
                asm volatile("ldc %0, sr" : : "r" (sr_with_bl));
                asm volatile("movca.l r0, @%0\n\t"
                             "movca.l r0, @%1\n\t"
                             "ocbi @%0\n\t"
                             "ocbi @%1" : :
                             "r" (a0), "r" (a1));
                a0 += linesz;
                a1 += linesz;
                asm volatile("movca.l r0, @%0\n\t"
                             "movca.l r0, @%1\n\t"
                             "ocbi @%0\n\t"
                             "ocbi @%1" : :
                             "r" (a0), "r" (a1));
                a0 += linesz;
                a1 += linesz;
                asm volatile("movca.l r0, @%0\n\t"
                             "movca.l r0, @%1\n\t"
                             "ocbi @%0\n\t"
                             "ocbi @%1" : :
                             "r" (a0), "r" (a1));
                a0 += linesz;
                a1 += linesz;
                asm volatile("movca.l r0, @%0\n\t"
                             "movca.l r0, @%1\n\t"
                             "ocbi @%0\n\t"
                             "ocbi @%1" : :
                             "r" (a0), "r" (a1));
                asm volatile("ldc %0, sr" : : "r" (orig_sr));
                a0 += linesz;
                a1 += linesz;
        } while (a0 < a0e);
}

static void __flush_dcache_segment_4way(unsigned long start,
                                        unsigned long extent_per_way)
{
        unsigned long orig_sr, sr_with_bl;
        unsigned long base_addr;
        unsigned long way_incr, linesz, way_size;
        struct cache_info *dcache;
        register unsigned long a0, a1, a2, a3, a0e;

        asm volatile("stc sr, %0" : "=r" (orig_sr));
        sr_with_bl = orig_sr | (1<<28);
        base_addr = ((unsigned long)&empty_zero_page[0]);

        /* See comment under 1-way above */
        base_addr = ((base_addr >> 16) << 16);
        base_addr |= start;

        dcache = &cpu_data->dcache;
        linesz = dcache->linesz;
        way_incr = dcache->way_incr;
        way_size = dcache->way_size;

        a0 = base_addr;
        a1 = a0 + way_incr;
        a2 = a1 + way_incr;
        a3 = a2 + way_incr;
        a0e = base_addr + extent_per_way;
        do {
                asm volatile("ldc %0, sr" : : "r" (sr_with_bl));
                asm volatile("movca.l r0, @%0\n\t"
                             "movca.l r0, @%1\n\t"
                             "movca.l r0, @%2\n\t"
                             "movca.l r0, @%3\n\t"
                             "ocbi @%0\n\t"
                             "ocbi @%1\n\t"
                             "ocbi @%2\n\t"
                             "ocbi @%3\n\t" : :
                             "r" (a0), "r" (a1), "r" (a2), "r" (a3));
                a0 += linesz;
                a1 += linesz;
                a2 += linesz;
                a3 += linesz;
                asm volatile("movca.l r0, @%0\n\t"
                             "movca.l r0, @%1\n\t"
                             "movca.l r0, @%2\n\t"
                             "movca.l r0, @%3\n\t"
                             "ocbi @%0\n\t"
                             "ocbi @%1\n\t"
                             "ocbi @%2\n\t"
                             "ocbi @%3\n\t" : :
                             "r" (a0), "r" (a1), "r" (a2), "r" (a3));
                a0 += linesz;
                a1 += linesz;
                a2 += linesz;
                a3 += linesz;
                asm volatile("movca.l r0, @%0\n\t"
                             "movca.l r0, @%1\n\t"
                             "movca.l r0, @%2\n\t"
                             "movca.l r0, @%3\n\t"
                             "ocbi @%0\n\t"
                             "ocbi @%1\n\t"
                             "ocbi @%2\n\t"
                             "ocbi @%3\n\t" : :
                             "r" (a0), "r" (a1), "r" (a2), "r" (a3));
                a0 += linesz;
                a1 += linesz;
                a2 += linesz;
                a3 += linesz;
                asm volatile("movca.l r0, @%0\n\t"
                             "movca.l r0, @%1\n\t"
                             "movca.l r0, @%2\n\t"
                             "movca.l r0, @%3\n\t"
                             "ocbi @%0\n\t"
                             "ocbi @%1\n\t"
                             "ocbi @%2\n\t"
                             "ocbi @%3\n\t" : :
                             "r" (a0), "r" (a1), "r" (a2), "r" (a3));
                asm volatile("ldc %0, sr" : : "r" (orig_sr));
                a0 += linesz;
                a1 += linesz;
                a2 += linesz;
                a3 += linesz;
        } while (a0 < a0e);
}