| Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 1 | // SPDX-License-Identifier: GPL-2.0 |
| 2 | /* |
| 3 | * highmem.c: virtual kernel memory mappings for high memory |
| 4 | * |
| 5 | * Provides kernel-static versions of atomic kmap functions originally |
| 6 | * found as inlines in include/asm-sparc/highmem.h. These became |
| 7 | * needed as kmap_atomic() and kunmap_atomic() started getting |
| 8 | * called from within modules. |
| 9 | * -- Tomas Szepe <szepe@pinerecords.com>, September 2002 |
| 10 | * |
| 11 | * But kmap_atomic() and kunmap_atomic() cannot be inlined in |
| 12 | * modules because they are loaded with btfixup-ped functions. |
| 13 | */ |
| 14 | |
| 15 | /* |
| 16 | * The use of kmap_atomic/kunmap_atomic is discouraged - kmap/kunmap |
| 17 | * gives a more generic (and caching) interface. But kmap_atomic can |
| 18 | * be used in IRQ contexts, so in some (very limited) cases we need it. |
| 19 | * |
| 20 | * XXX This is an old text. Actually, it's good to use atomic kmaps, |
| 21 | * provided you remember that they are atomic and not try to sleep |
| 22 | * with a kmap taken, much like a spinlock. Non-atomic kmaps are |
| 23 | * shared by CPUs, and so precious, and establishing them requires IPI. |
| 24 | * Atomic kmaps are lightweight and we may have NCPUS more of them. |
| 25 | */ |
| 26 | #include <linux/highmem.h> |
| 27 | #include <linux/export.h> |
| 28 | #include <linux/mm.h> |
| 29 | |
| 30 | #include <asm/cacheflush.h> |
| 31 | #include <asm/tlbflush.h> |
| 32 | #include <asm/pgalloc.h> |
| 33 | #include <asm/vaddrs.h> |
| 34 | |
| 35 | pgprot_t kmap_prot; |
| 36 | |
| 37 | static pte_t *kmap_pte; |
| 38 | |
| 39 | void __init kmap_init(void) |
| 40 | { |
| 41 | unsigned long address; |
| 42 | pmd_t *dir; |
| 43 | |
| 44 | address = __fix_to_virt(FIX_KMAP_BEGIN); |
| 45 | dir = pmd_offset(pgd_offset_k(address), address); |
| 46 | |
| 47 | /* cache the first kmap pte */ |
| 48 | kmap_pte = pte_offset_kernel(dir, address); |
| 49 | kmap_prot = __pgprot(SRMMU_ET_PTE | SRMMU_PRIV | SRMMU_CACHE); |
| 50 | } |
| 51 | |
| 52 | void *kmap_atomic(struct page *page) |
| 53 | { |
| 54 | unsigned long vaddr; |
| 55 | long idx, type; |
| 56 | |
| 57 | preempt_disable(); |
| 58 | pagefault_disable(); |
| 59 | if (!PageHighMem(page)) |
| 60 | return page_address(page); |
| 61 | |
| 62 | type = kmap_atomic_idx_push(); |
| 63 | idx = type + KM_TYPE_NR*smp_processor_id(); |
| 64 | vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx); |
| 65 | |
| 66 | /* XXX Fix - Anton */ |
| 67 | #if 0 |
| 68 | __flush_cache_one(vaddr); |
| 69 | #else |
| 70 | flush_cache_all(); |
| 71 | #endif |
| 72 | |
| 73 | #ifdef CONFIG_DEBUG_HIGHMEM |
| 74 | BUG_ON(!pte_none(*(kmap_pte-idx))); |
| 75 | #endif |
| 76 | set_pte(kmap_pte-idx, mk_pte(page, kmap_prot)); |
| 77 | /* XXX Fix - Anton */ |
| 78 | #if 0 |
| 79 | __flush_tlb_one(vaddr); |
| 80 | #else |
| 81 | flush_tlb_all(); |
| 82 | #endif |
| 83 | |
| 84 | return (void*) vaddr; |
| 85 | } |
| 86 | EXPORT_SYMBOL(kmap_atomic); |
| 87 | |
| 88 | void __kunmap_atomic(void *kvaddr) |
| 89 | { |
| 90 | unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK; |
| 91 | int type; |
| 92 | |
| 93 | if (vaddr < FIXADDR_START) { // FIXME |
| 94 | pagefault_enable(); |
| 95 | preempt_enable(); |
| 96 | return; |
| 97 | } |
| 98 | |
| 99 | type = kmap_atomic_idx(); |
| 100 | |
| 101 | #ifdef CONFIG_DEBUG_HIGHMEM |
| 102 | { |
| 103 | unsigned long idx; |
| 104 | |
| 105 | idx = type + KM_TYPE_NR * smp_processor_id(); |
| 106 | BUG_ON(vaddr != __fix_to_virt(FIX_KMAP_BEGIN+idx)); |
| 107 | |
| 108 | /* XXX Fix - Anton */ |
| 109 | #if 0 |
| 110 | __flush_cache_one(vaddr); |
| 111 | #else |
| 112 | flush_cache_all(); |
| 113 | #endif |
| 114 | |
| 115 | /* |
| 116 | * force other mappings to Oops if they'll try to access |
| 117 | * this pte without first remap it |
| 118 | */ |
| 119 | pte_clear(&init_mm, vaddr, kmap_pte-idx); |
| 120 | /* XXX Fix - Anton */ |
| 121 | #if 0 |
| 122 | __flush_tlb_one(vaddr); |
| 123 | #else |
| 124 | flush_tlb_all(); |
| 125 | #endif |
| 126 | } |
| 127 | #endif |
| 128 | |
| 129 | kmap_atomic_idx_pop(); |
| 130 | pagefault_enable(); |
| 131 | preempt_enable(); |
| 132 | } |
| 133 | EXPORT_SYMBOL(__kunmap_atomic); |