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cache.c

/*
 * arch/xtensa/mm/cache.c
 *
 * 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.
 *
 * Copyright (C) 2001-2006 Tensilica Inc.
 *
 * Chris Zankel   <chris@zankel.net>
 * Joe Taylor
 * Marc Gauthier
 *
 */

#include <linux/init.h>
#include <linux/signal.h>
#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/string.h>
#include <linux/types.h>
#include <linux/ptrace.h>
#include <linux/bootmem.h>
#include <linux/swap.h>
#include <linux/pagemap.h>

#include <asm/pgtable.h>
#include <asm/bootparam.h>
#include <asm/mmu_context.h>
#include <asm/tlb.h>
#include <asm/tlbflush.h>
#include <asm/page.h>
#include <asm/pgalloc.h>
#include <asm/pgtable.h>

//#define printd(x...) printk(x)
#define printd(x...) do { } while(0)

/* 
 * Note:
 * The kernel provides one architecture bit PG_arch_1 in the page flags that 
 * can be used for cache coherency.
 *
 * I$-D$ coherency.
 *
 * The Xtensa architecture doesn't keep the instruction cache coherent with
 * the data cache. We use the architecture bit to indicate if the caches
 * are coherent. The kernel clears this bit whenever a page is added to the
 * page cache. At that time, the caches might not be in sync. We, therefore,
 * define this flag as 'clean' if set.
 *
 * D-cache aliasing.
 *
 * With cache aliasing, we have to always flush the cache when pages are
 * unmapped (see tlb_start_vma(). So, we use this flag to indicate a dirty
 * page.
 * 
 *
 *
 */

#if (DCACHE_WAY_SIZE > PAGE_SIZE) && XCHAL_DCACHE_IS_WRITEBACK

/*
 * Any time the kernel writes to a user page cache page, or it is about to
 * read from a page cache page this routine is called.
 *
 */

void flush_dcache_page(struct page *page)
{
      struct address_space *mapping = page_mapping(page);

      /*
       * If we have a mapping but the page is not mapped to user-space
       * yet, we simply mark this page dirty and defer flushing the 
       * caches until update_mmu().
       */

      if (mapping && !mapping_mapped(mapping)) {
            if (!test_bit(PG_arch_1, &page->flags))
                  set_bit(PG_arch_1, &page->flags);
            return;

      } else {

            unsigned long phys = page_to_phys(page);
            unsigned long temp = page->index << PAGE_SHIFT;
            unsigned long alias = !(DCACHE_ALIAS_EQ(temp, phys));
            unsigned long virt;

            /* 
             * Flush the page in kernel space and user space.
             * Note that we can omit that step if aliasing is not
             * an issue, but we do have to synchronize I$ and D$
             * if we have a mapping.
             */

            if (!alias && !mapping)
                  return;

            __flush_invalidate_dcache_page((long)page_address(page));

            virt = TLBTEMP_BASE_1 + (temp & DCACHE_ALIAS_MASK);

            if (alias)
                  __flush_invalidate_dcache_page_alias(virt, phys);

            if (mapping)
                  __invalidate_icache_page_alias(virt, phys);
      }

      /* There shouldn't be an entry in the cache for this page anymore. */
}


/*
 * For now, flush the whole cache. FIXME??
 */

void flush_cache_range(struct vm_area_struct* vma, 
                   unsigned long start, unsigned long end)
{
      __flush_invalidate_dcache_all();
      __invalidate_icache_all();
}

/* 
 * Remove any entry in the cache for this page. 
 *
 * Note that this function is only called for user pages, so use the
 * alias versions of the cache flush functions.
 */

void flush_cache_page(struct vm_area_struct* vma, unsigned long address,
                  unsigned long pfn)
{
      /* Note that we have to use the 'alias' address to avoid multi-hit */

      unsigned long phys = page_to_phys(pfn_to_page(pfn));
      unsigned long virt = TLBTEMP_BASE_1 + (address & DCACHE_ALIAS_MASK);

      __flush_invalidate_dcache_page_alias(virt, phys);
      __invalidate_icache_page_alias(virt, phys);
}

#endif

void
update_mmu_cache(struct vm_area_struct * vma, unsigned long addr, pte_t pte)
{
      unsigned long pfn = pte_pfn(pte);
      struct page *page;

      if (!pfn_valid(pfn))
            return;

      page = pfn_to_page(pfn);

      /* Invalidate old entry in TLBs */

      invalidate_itlb_mapping(addr);
      invalidate_dtlb_mapping(addr);

#if (DCACHE_WAY_SIZE > PAGE_SIZE) && XCHAL_DCACHE_IS_WRITEBACK

      if (!PageReserved(page) && test_bit(PG_arch_1, &page->flags)) {

            unsigned long vaddr = TLBTEMP_BASE_1 + (addr & DCACHE_ALIAS_MASK);
            unsigned long paddr = (unsigned long) page_address(page);
            unsigned long phys = page_to_phys(page);

            __flush_invalidate_dcache_page(paddr);

            __flush_invalidate_dcache_page_alias(vaddr, phys);
            __invalidate_icache_page_alias(vaddr, phys);

            clear_bit(PG_arch_1, &page->flags);
      }
#else
      if (!PageReserved(page) && !test_bit(PG_arch_1, &page->flags)
          && (vma->vm_flags & VM_EXEC) != 0) {
            unsigned long vaddr = addr & PAGE_MASK;
            __flush_dcache_page(vaddr);
            __invalidate_icache_page(vaddr);
            set_bit(PG_arch_1, &page->flags);
      }
#endif
}

/*
 * access_process_vm() has called get_user_pages(), which has done a
 * flush_dcache_page() on the page.
 */

#if (DCACHE_WAY_SIZE > PAGE_SIZE) && XCHAL_DCACHE_IS_WRITEBACK

void copy_to_user_page(struct vm_area_struct *vma, struct page *page, 
            unsigned long vaddr, void *dst, const void *src,
            unsigned long len)
{
      unsigned long phys = page_to_phys(page);
      unsigned long alias = !(DCACHE_ALIAS_EQ(vaddr, phys));

      /* Flush and invalidate user page if aliased. */

      if (alias) {
            unsigned long temp = TLBTEMP_BASE_1 + (vaddr & DCACHE_ALIAS_MASK);
            __flush_invalidate_dcache_page_alias(temp, phys);
      }

      /* Copy data */
      
      memcpy(dst, src, len);

      /*
       * Flush and invalidate kernel page if aliased and synchronize 
       * data and instruction caches for executable pages. 
       */

      if (alias) {
            unsigned long temp = TLBTEMP_BASE_1 + (vaddr & DCACHE_ALIAS_MASK);

            __flush_invalidate_dcache_range((unsigned long) dst, len);
            if ((vma->vm_flags & VM_EXEC) != 0) {
                  __invalidate_icache_page_alias(temp, phys);
            }

      } else if ((vma->vm_flags & VM_EXEC) != 0) {
            __flush_dcache_range((unsigned long)dst,len);
            __invalidate_icache_range((unsigned long) dst, len);
      }
}

extern void copy_from_user_page(struct vm_area_struct *vma, struct page *page,
            unsigned long vaddr, void *dst, const void *src,
            unsigned long len)
{
      unsigned long phys = page_to_phys(page);
      unsigned long alias = !(DCACHE_ALIAS_EQ(vaddr, phys));

      /*
       * Flush user page if aliased. 
       * (Note: a simply flush would be sufficient) 
       */

      if (alias) {
            unsigned long temp = TLBTEMP_BASE_1 + (vaddr & DCACHE_ALIAS_MASK);
            __flush_invalidate_dcache_page_alias(temp, phys);
      }

      memcpy(dst, src, len);
}

#endif

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