| Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame^] | 1 | // SPDX-License-Identifier: GPL-2.0 |
| 2 | #include <linux/compiler.h> |
| 3 | #include <linux/init.h> |
| 4 | #include <linux/export.h> |
| 5 | #include <linux/highmem.h> |
| 6 | #include <linux/sched.h> |
| 7 | #include <linux/smp.h> |
| 8 | #include <asm/fixmap.h> |
| 9 | #include <asm/tlbflush.h> |
| 10 | |
| 11 | static pte_t *kmap_pte; |
| 12 | |
| 13 | unsigned long highstart_pfn, highend_pfn; |
| 14 | |
| 15 | void *kmap(struct page *page) |
| 16 | { |
| 17 | void *addr; |
| 18 | |
| 19 | might_sleep(); |
| 20 | if (!PageHighMem(page)) |
| 21 | return page_address(page); |
| 22 | addr = kmap_high(page); |
| 23 | flush_tlb_one((unsigned long)addr); |
| 24 | |
| 25 | return addr; |
| 26 | } |
| 27 | EXPORT_SYMBOL(kmap); |
| 28 | |
| 29 | void kunmap(struct page *page) |
| 30 | { |
| 31 | BUG_ON(in_interrupt()); |
| 32 | if (!PageHighMem(page)) |
| 33 | return; |
| 34 | kunmap_high(page); |
| 35 | } |
| 36 | EXPORT_SYMBOL(kunmap); |
| 37 | |
| 38 | /* |
| 39 | * kmap_atomic/kunmap_atomic is significantly faster than kmap/kunmap because |
| 40 | * no global lock is needed and because the kmap code must perform a global TLB |
| 41 | * invalidation when the kmap pool wraps. |
| 42 | * |
| 43 | * However when holding an atomic kmap is is not legal to sleep, so atomic |
| 44 | * kmaps are appropriate for short, tight code paths only. |
| 45 | */ |
| 46 | |
| 47 | void *kmap_atomic(struct page *page) |
| 48 | { |
| 49 | unsigned long vaddr; |
| 50 | int idx, type; |
| 51 | |
| 52 | preempt_disable(); |
| 53 | pagefault_disable(); |
| 54 | if (!PageHighMem(page)) |
| 55 | return page_address(page); |
| 56 | |
| 57 | type = kmap_atomic_idx_push(); |
| 58 | idx = type + KM_TYPE_NR*smp_processor_id(); |
| 59 | vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx); |
| 60 | #ifdef CONFIG_DEBUG_HIGHMEM |
| 61 | BUG_ON(!pte_none(*(kmap_pte - idx))); |
| 62 | #endif |
| 63 | set_pte(kmap_pte-idx, mk_pte(page, PAGE_KERNEL)); |
| 64 | local_flush_tlb_one((unsigned long)vaddr); |
| 65 | |
| 66 | return (void*) vaddr; |
| 67 | } |
| 68 | EXPORT_SYMBOL(kmap_atomic); |
| 69 | |
| 70 | void __kunmap_atomic(void *kvaddr) |
| 71 | { |
| 72 | unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK; |
| 73 | int type __maybe_unused; |
| 74 | |
| 75 | if (vaddr < FIXADDR_START) { // FIXME |
| 76 | pagefault_enable(); |
| 77 | preempt_enable(); |
| 78 | return; |
| 79 | } |
| 80 | |
| 81 | type = kmap_atomic_idx(); |
| 82 | #ifdef CONFIG_DEBUG_HIGHMEM |
| 83 | { |
| 84 | int idx = type + KM_TYPE_NR * smp_processor_id(); |
| 85 | |
| 86 | BUG_ON(vaddr != __fix_to_virt(FIX_KMAP_BEGIN + idx)); |
| 87 | |
| 88 | /* |
| 89 | * force other mappings to Oops if they'll try to access |
| 90 | * this pte without first remap it |
| 91 | */ |
| 92 | pte_clear(&init_mm, vaddr, kmap_pte-idx); |
| 93 | local_flush_tlb_one(vaddr); |
| 94 | } |
| 95 | #endif |
| 96 | kmap_atomic_idx_pop(); |
| 97 | pagefault_enable(); |
| 98 | preempt_enable(); |
| 99 | } |
| 100 | EXPORT_SYMBOL(__kunmap_atomic); |
| 101 | |
| 102 | /* |
| 103 | * This is the same as kmap_atomic() but can map memory that doesn't |
| 104 | * have a struct page associated with it. |
| 105 | */ |
| 106 | void *kmap_atomic_pfn(unsigned long pfn) |
| 107 | { |
| 108 | unsigned long vaddr; |
| 109 | int idx, type; |
| 110 | |
| 111 | preempt_disable(); |
| 112 | pagefault_disable(); |
| 113 | |
| 114 | type = kmap_atomic_idx_push(); |
| 115 | idx = type + KM_TYPE_NR*smp_processor_id(); |
| 116 | vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx); |
| 117 | set_pte(kmap_pte-idx, pfn_pte(pfn, PAGE_KERNEL)); |
| 118 | flush_tlb_one(vaddr); |
| 119 | |
| 120 | return (void*) vaddr; |
| 121 | } |
| 122 | |
| 123 | void __init kmap_init(void) |
| 124 | { |
| 125 | unsigned long kmap_vstart; |
| 126 | |
| 127 | /* cache the first kmap pte */ |
| 128 | kmap_vstart = __fix_to_virt(FIX_KMAP_BEGIN); |
| 129 | kmap_pte = kmap_get_fixmap_pte(kmap_vstart); |
| 130 | } |