Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 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 | /* |
| 15 | * The use of kmap_atomic/kunmap_atomic is discouraged - kmap/kunmap |
| 16 | * gives a more generic (and caching) interface. But kmap_atomic can |
| 17 | * be used in IRQ contexts, so in some (very limited) cases we need it. |
| 18 | * |
| 19 | * XXX This is an old text. Actually, it's good to use atomic kmaps, |
| 20 | * provided you remember that they are atomic and not try to sleep |
| 21 | * with a kmap taken, much like a spinlock. Non-atomic kmaps are |
| 22 | * shared by CPUs, and so precious, and establishing them requires IPI. |
| 23 | * Atomic kmaps are lightweight and we may have NCPUS more of them. |
| 24 | */ |
| 25 | #include <linux/mm.h> |
| 26 | #include <linux/highmem.h> |
| 27 | #include <asm/pgalloc.h> |
| 28 | #include <asm/cacheflush.h> |
| 29 | #include <asm/tlbflush.h> |
| 30 | #include <asm/fixmap.h> |
| 31 | |
| 32 | void *kmap_atomic(struct page *page, enum km_type type) |
| 33 | { |
| 34 | unsigned long idx; |
| 35 | unsigned long vaddr; |
| 36 | |
| 37 | /* even !CONFIG_PREEMPT needs this, for in_atomic in do_page_fault */ |
Peter Zijlstra | a866374 | 2006-12-06 20:32:20 -0800 | [diff] [blame^] | 38 | pagefault_disable(); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 39 | if (!PageHighMem(page)) |
| 40 | return page_address(page); |
| 41 | |
| 42 | idx = type + KM_TYPE_NR*smp_processor_id(); |
| 43 | vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx); |
| 44 | |
| 45 | /* XXX Fix - Anton */ |
| 46 | #if 0 |
| 47 | __flush_cache_one(vaddr); |
| 48 | #else |
| 49 | flush_cache_all(); |
| 50 | #endif |
| 51 | |
| 52 | #ifdef CONFIG_DEBUG_HIGHMEM |
| 53 | BUG_ON(!pte_none(*(kmap_pte-idx))); |
| 54 | #endif |
| 55 | set_pte(kmap_pte-idx, mk_pte(page, kmap_prot)); |
| 56 | /* XXX Fix - Anton */ |
| 57 | #if 0 |
| 58 | __flush_tlb_one(vaddr); |
| 59 | #else |
| 60 | flush_tlb_all(); |
| 61 | #endif |
| 62 | |
| 63 | return (void*) vaddr; |
| 64 | } |
| 65 | |
| 66 | void kunmap_atomic(void *kvaddr, enum km_type type) |
| 67 | { |
| 68 | #ifdef CONFIG_DEBUG_HIGHMEM |
| 69 | unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK; |
| 70 | unsigned long idx = type + KM_TYPE_NR*smp_processor_id(); |
| 71 | |
| 72 | if (vaddr < FIXADDR_START) { // FIXME |
Peter Zijlstra | a866374 | 2006-12-06 20:32:20 -0800 | [diff] [blame^] | 73 | pagefault_enable(); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 74 | return; |
| 75 | } |
| 76 | |
| 77 | BUG_ON(vaddr != __fix_to_virt(FIX_KMAP_BEGIN+idx)); |
| 78 | |
| 79 | /* XXX Fix - Anton */ |
| 80 | #if 0 |
| 81 | __flush_cache_one(vaddr); |
| 82 | #else |
| 83 | flush_cache_all(); |
| 84 | #endif |
| 85 | |
| 86 | /* |
| 87 | * force other mappings to Oops if they'll try to access |
| 88 | * this pte without first remap it |
| 89 | */ |
| 90 | pte_clear(&init_mm, vaddr, kmap_pte-idx); |
| 91 | /* XXX Fix - Anton */ |
| 92 | #if 0 |
| 93 | __flush_tlb_one(vaddr); |
| 94 | #else |
| 95 | flush_tlb_all(); |
| 96 | #endif |
| 97 | #endif |
| 98 | |
Peter Zijlstra | a866374 | 2006-12-06 20:32:20 -0800 | [diff] [blame^] | 99 | pagefault_enable(); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 100 | } |
| 101 | |
| 102 | /* We may be fed a pagetable here by ptep_to_xxx and others. */ |
| 103 | struct page *kmap_atomic_to_page(void *ptr) |
| 104 | { |
| 105 | unsigned long idx, vaddr = (unsigned long)ptr; |
| 106 | pte_t *pte; |
| 107 | |
| 108 | if (vaddr < SRMMU_NOCACHE_VADDR) |
| 109 | return virt_to_page(ptr); |
| 110 | if (vaddr < PKMAP_BASE) |
| 111 | return pfn_to_page(__nocache_pa(vaddr) >> PAGE_SHIFT); |
| 112 | BUG_ON(vaddr < FIXADDR_START); |
| 113 | BUG_ON(vaddr > FIXADDR_TOP); |
| 114 | |
| 115 | idx = virt_to_fix(vaddr); |
| 116 | pte = kmap_pte - (idx - FIX_KMAP_BEGIN); |
| 117 | return pte_page(*pte); |
| 118 | } |