release/src-rt-6.x.4708/linux/linux-2.6.36/arch/sparc/mm/highmem.c

   1 /*
   2  *  highmem.c: virtual kernel memory mappings for high memory
   3  *
   4  *  Provides kernel-static versions of atomic kmap functions originally
   5  *  found as inlines in include/asm-sparc/highmem.h.  These became
   6  *  needed as kmap_atomic() and kunmap_atomic() started getting
   7  *  called from within modules.
   8  *  -- Tomas Szepe <szepe@pinerecords.com>, September 2002
   9  *
  10  *  But kmap_atomic() and kunmap_atomic() cannot be inlined in
  11  *  modules because they are loaded with btfixup-ped functions.
  12  */
  13
  14 #include <linux/mm.h>
  15 #include <linux/highmem.h>
  16 #include <asm/pgalloc.h>
  17 #include <asm/cacheflush.h>
  18 #include <asm/tlbflush.h>
  19 #include <asm/fixmap.h>
  20
  21 void *kmap_atomic(struct page *page, enum km_type type)
  22 {
  23         unsigned long idx;
  24         unsigned long vaddr;
  25
  26         /* even !CONFIG_PREEMPT needs this, for in_atomic in do_page_fault */
  27         pagefault_disable();
  28         if (!PageHighMem(page))
  29                 return page_address(page);
  30
  31         debug_kmap_atomic(type);
  32         idx = type + KM_TYPE_NR*smp_processor_id();
  33         vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
  34
  35         flush_cache_all();
  36
  37 #ifdef CONFIG_DEBUG_HIGHMEM
  38         BUG_ON(!pte_none(*(kmap_pte-idx)));
  39 #endif
  40         set_pte(kmap_pte-idx, mk_pte(page, kmap_prot));
  41         flush_tlb_all();
  42
  43         return (void*) vaddr;
  44 }
  45 EXPORT_SYMBOL(kmap_atomic);
  46
  47 void kunmap_atomic_notypecheck(void *kvaddr, enum km_type type)
  48 {
  49 #ifdef CONFIG_DEBUG_HIGHMEM
  50         unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK;
  51         unsigned long idx = type + KM_TYPE_NR*smp_processor_id();
  52
  53         if (vaddr < FIXADDR_START) {
  54                 pagefault_enable();
  55                 return;
  56         }
  57
  58         BUG_ON(vaddr != __fix_to_virt(FIX_KMAP_BEGIN+idx));
  59
  60         flush_cache_all();
  61
  62         /*
  63          * force other mappings to Oops if they'll try to access
  64          * this pte without first remap it
  65          */
  66         pte_clear(&init_mm, vaddr, kmap_pte-idx);
  67         flush_tlb_all();
  68 #endif
  69
  70         pagefault_enable();
  71 }
  72 EXPORT_SYMBOL(kunmap_atomic_notypecheck);
  73
  74 /* We may be fed a pagetable here by ptep_to_xxx and others. */
  75 struct page *kmap_atomic_to_page(void *ptr)
  76 {
  77         unsigned long idx, vaddr = (unsigned long)ptr;
  78         pte_t *pte;
  79
  80         if (vaddr < SRMMU_NOCACHE_VADDR)
  81                 return virt_to_page(ptr);
  82         if (vaddr < PKMAP_BASE)
  83                 return pfn_to_page(__nocache_pa(vaddr) >> PAGE_SHIFT);
  84         BUG_ON(vaddr < FIXADDR_START);
  85         BUG_ON(vaddr > FIXADDR_TOP);
  86
  87         idx = virt_to_fix(vaddr);
  88         pte = kmap_pte - (idx - FIX_KMAP_BEGIN);
  89         return pte_page(*pte);
  90 }