cache-inv-icache.c

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/* Invalidate icache when dcache doesn't need invalidation as it's in
 * write-through mode
 *
 * Copyright (C) 2010 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells ([email protected])
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public Licence
 * as published by the Free Software Foundation; either version
 * 2 of the Licence, or (at your option) any later version.
 */
#include <linux/module.h>
#include <linux/mm.h>
#include <asm/cacheflush.h>
#include <asm/smp.h>
#include "cache-smp.h"

static void flush_icache_page_range(unsigned long start, unsigned long end)
{
    unsigned long addr, size, off;
    struct page *page;
    pgd_t *pgd;
    pud_t *pud;
    pmd_t *pmd;
    pte_t *ppte, pte;

    /* work out how much of the page to flush */
    off = start & ~PAGE_MASK;
    size = end - start;

    /* get the physical address the page is mapped to from the page
     * tables */
    pgd = pgd_offset(current->mm, start);
    if (!pgd || !pgd_val(*pgd))
        return;

    pud = pud_offset(pgd, start);
    if (!pud || !pud_val(*pud))
        return;

    pmd = pmd_offset(pud, start);
    if (!pmd || !pmd_val(*pmd))
        return;

    ppte = pte_offset_map(pmd, start);
    if (!ppte)
        return;
    pte = *ppte;
    pte_unmap(ppte);

    if (pte_none(pte))
        return;

    page = pte_page(pte);
    if (!page)
        return;

    addr = page_to_phys(page);

    /* invalidate the icache coverage on that region */
    mn10300_local_icache_inv_range2(addr + off, size);
    smp_cache_call(SMP_ICACHE_INV_RANGE, start, end);
}

void flush_icache_range(unsigned long start, unsigned long end)
{
    unsigned long start_page, end_page;
    unsigned long flags;

    flags = smp_lock_cache();

    if (end > 0x80000000UL) {
        /* addresses above 0xa0000000 do not go through the cache */
        if (end > 0xa0000000UL) {
            end = 0xa0000000UL;
            if (start >= end)
                goto done;
        }

        /* kernel addresses between 0x80000000 and 0x9fffffff do not
         * require page tables, so we just map such addresses
         * directly */
        start_page = (start >= 0x80000000UL) ? start : 0x80000000UL;
        mn10300_icache_inv_range(start_page, end);
        smp_cache_call(SMP_ICACHE_INV_RANGE, start, end);
        if (start_page == start)
            goto done;
        end = start_page;
    }

    start_page = start & PAGE_MASK;
    end_page = (end - 1) & PAGE_MASK;

    if (start_page == end_page) {
        /* the first and last bytes are on the same page */
        flush_icache_page_range(start, end);
    } else if (start_page + 1 == end_page) {
        /* split over two virtually contiguous pages */
        flush_icache_page_range(start, end_page);
        flush_icache_page_range(end_page, end);
    } else {
        /* more than 2 pages; just flush the entire cache */
        mn10300_local_icache_inv();
        smp_cache_call(SMP_ICACHE_INV, 0, 0);
    }

done:
    smp_unlock_cache(flags);
}
EXPORT_SYMBOL(flush_icache_range);