Subversion Repositories or1k_soc_on_altera_embedded_dev_kit

/*

 *  highmem.c: virtual kernel memory mappings for high memory

 *

 *  Provides kernel-static versions of atomic kmap functions originally

 *  found as inlines in include/asm-sparc/highmem.h.  These became

 *  needed as kmap_atomic() and kunmap_atomic() started getting

 *  called from within modules.

 *  -- Tomas Szepe <szepe@pinerecords.com>, September 2002

 *

 *  But kmap_atomic() and kunmap_atomic() cannot be inlined in

 *  modules because they are loaded with btfixup-ped functions.

 */

/*

 * The use of kmap_atomic/kunmap_atomic is discouraged - kmap/kunmap

 * gives a more generic (and caching) interface. But kmap_atomic can

 * be used in IRQ contexts, so in some (very limited) cases we need it.

 *

 * XXX This is an old text. Actually, it's good to use atomic kmaps,

 * provided you remember that they are atomic and not try to sleep

 * with a kmap taken, much like a spinlock. Non-atomic kmaps are

 * shared by CPUs, and so precious, and establishing them requires IPI.

 * Atomic kmaps are lightweight and we may have NCPUS more of them.

 */

#include <linux/mm.h>

#include <linux/highmem.h>

#include <asm/pgalloc.h>

#include <asm/cacheflush.h>

#include <asm/tlbflush.h>

#include <asm/fixmap.h>

void *kmap_atomic(struct page *page, enum km_type type)

{

        unsigned long idx;

        unsigned long vaddr;

        /* even !CONFIG_PREEMPT needs this, for in_atomic in do_page_fault */

        pagefault_disable();

        if (!PageHighMem(page))

                return page_address(page);

        idx = type + KM_TYPE_NR*smp_processor_id();

        vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);

/* XXX Fix - Anton */

#if 0

        __flush_cache_one(vaddr);

#else

        flush_cache_all();

#endif

#ifdef CONFIG_DEBUG_HIGHMEM

        BUG_ON(!pte_none(*(kmap_pte-idx)));

#endif

        set_pte(kmap_pte-idx, mk_pte(page, kmap_prot));

/* XXX Fix - Anton */

#if 0

        __flush_tlb_one(vaddr);

#else

        flush_tlb_all();

#endif

        return (void*) vaddr;

}

void kunmap_atomic(void *kvaddr, enum km_type type)

{

#ifdef CONFIG_DEBUG_HIGHMEM

        unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK;

        unsigned long idx = type + KM_TYPE_NR*smp_processor_id();

        if (vaddr < FIXADDR_START) { // FIXME

                pagefault_enable();

                return;

        }

        BUG_ON(vaddr != __fix_to_virt(FIX_KMAP_BEGIN+idx));

/* XXX Fix - Anton */

#if 0

        __flush_cache_one(vaddr);

#else

        flush_cache_all();

#endif

        /*

         * force other mappings to Oops if they'll try to access

         * this pte without first remap it

         */

        pte_clear(&init_mm, vaddr, kmap_pte-idx);

/* XXX Fix - Anton */

#if 0

        __flush_tlb_one(vaddr);

#else

        flush_tlb_all();

#endif

#endif

        pagefault_enable();

}

/* We may be fed a pagetable here by ptep_to_xxx and others. */

struct page *kmap_atomic_to_page(void *ptr)

{

        unsigned long idx, vaddr = (unsigned long)ptr;

        pte_t *pte;

        if (vaddr < SRMMU_NOCACHE_VADDR)

                return virt_to_page(ptr);

        if (vaddr < PKMAP_BASE)

                return pfn_to_page(__nocache_pa(vaddr) >> PAGE_SHIFT);

        BUG_ON(vaddr < FIXADDR_START);

        BUG_ON(vaddr > FIXADDR_TOP);

        idx = virt_to_fix(vaddr);

        pte = kmap_pte - (idx - FIX_KMAP_BEGIN);

        return pte_page(*pte);

}