highmem_32.c

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#include <linux/highmem.h>
#include <linux/module.h>
#include <linux/swap.h> /* for totalram_pages */

void *kmap(struct page *page)
{
    might_sleep();
    if (!PageHighMem(page))
        return page_address(page);
    return kmap_high(page);
}
EXPORT_SYMBOL(kmap);

void kunmap(struct page *page)
{
    if (in_interrupt())
        BUG();
    if (!PageHighMem(page))
        return;
    kunmap_high(page);
}
EXPORT_SYMBOL(kunmap);

/*
 * kmap_atomic/kunmap_atomic is significantly faster than kmap/kunmap because
 * no global lock is needed and because the kmap code must perform a global TLB
 * invalidation when the kmap pool wraps.
 *
 * However when holding an atomic kmap it is not legal to sleep, so atomic
 * kmaps are appropriate for short, tight code paths only.
 */
void *kmap_atomic_prot(struct page *page, pgprot_t prot)
{
    unsigned long vaddr;
    int idx, type;

    /* even !CONFIG_PREEMPT needs this, for in_atomic in do_page_fault */
    pagefault_disable();

    if (!PageHighMem(page))
        return page_address(page);

    type = kmap_atomic_idx_push();
    idx = type + KM_TYPE_NR*smp_processor_id();
    vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
    BUG_ON(!pte_none(*(kmap_pte-idx)));
    set_pte(kmap_pte-idx, mk_pte(page, prot));
    arch_flush_lazy_mmu_mode();

    return (void *)vaddr;
}
EXPORT_SYMBOL(kmap_atomic_prot);

void *kmap_atomic(struct page *page)
{
    return kmap_atomic_prot(page, kmap_prot);
}
EXPORT_SYMBOL(kmap_atomic);

/*
 * This is the same as kmap_atomic() but can map memory that doesn't
 * have a struct page associated with it.
 */
void *kmap_atomic_pfn(unsigned long pfn)
{
    return kmap_atomic_prot_pfn(pfn, kmap_prot);
}
EXPORT_SYMBOL_GPL(kmap_atomic_pfn);

void __kunmap_atomic(void *kvaddr)
{
    unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK;

    if (vaddr >= __fix_to_virt(FIX_KMAP_END) &&
        vaddr <= __fix_to_virt(FIX_KMAP_BEGIN)) {
        int idx, type;

        type = kmap_atomic_idx();
        idx = type + KM_TYPE_NR * smp_processor_id();

#ifdef CONFIG_DEBUG_HIGHMEM
        WARN_ON_ONCE(vaddr != __fix_to_virt(FIX_KMAP_BEGIN + idx));
#endif
        /*
         * Force other mappings to Oops if they'll try to access this
         * pte without first remap it.  Keeping stale mappings around
         * is a bad idea also, in case the page changes cacheability
         * attributes or becomes a protected page in a hypervisor.
         */
        kpte_clear_flush(kmap_pte-idx, vaddr);
        kmap_atomic_idx_pop();
        arch_flush_lazy_mmu_mode();
    }
#ifdef CONFIG_DEBUG_HIGHMEM
    else {
        BUG_ON(vaddr < PAGE_OFFSET);
        BUG_ON(vaddr >= (unsigned long)high_memory);
    }
#endif

    pagefault_enable();
}
EXPORT_SYMBOL(__kunmap_atomic);

struct page *kmap_atomic_to_page(void *ptr)
{
    unsigned long idx, vaddr = (unsigned long)ptr;
    pte_t *pte;

    if (vaddr < FIXADDR_START)
        return virt_to_page(ptr);

    idx = virt_to_fix(vaddr);
    pte = kmap_pte - (idx - FIX_KMAP_BEGIN);
    return pte_page(*pte);
}
EXPORT_SYMBOL(kmap_atomic_to_page);

void __init set_highmem_pages_init(void)
{
    struct zone *zone;
    int nid;

    for_each_zone(zone) {
        unsigned long zone_start_pfn, zone_end_pfn;

        if (!is_highmem(zone))
            continue;

        zone_start_pfn = zone->zone_start_pfn;
        zone_end_pfn = zone_start_pfn + zone->spanned_pages;

        nid = zone_to_nid(zone);
        printk(KERN_INFO "Initializing %s for node %d (%08lx:%08lx)\n",
                zone->name, nid, zone_start_pfn, zone_end_pfn);

        add_highpages_with_active_regions(nid, zone_start_pfn,
                 zone_end_pfn);
    }
    totalram_pages += totalhigh_pages;
}