1 // SPDX-License-Identifier: GPL-2.0 1 // SPDX-License-Identifier: GPL-2.0 2 // Copyright (C) 2018 Hangzhou C-SKY Microsyst !! 2 /* 3 !! 3 * highmem.c: virtual kernel memory mappings for high memory 4 #include <linux/module.h> !! 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 */ 5 #include <linux/highmem.h> 26 #include <linux/highmem.h> 6 #include <linux/smp.h> !! 27 #include <linux/export.h> 7 #include <linux/memblock.h> !! 28 #include <linux/mm.h> 8 #include <asm/fixmap.h> !! 29 9 #include <asm/tlbflush.h> << 10 #include <asm/cacheflush.h> 30 #include <asm/cacheflush.h> >> 31 #include <asm/tlbflush.h> >> 32 #include <asm/pgalloc.h> >> 33 #include <asm/vaddrs.h> 11 34 12 unsigned long highstart_pfn, highend_pfn; !! 35 pgprot_t kmap_prot; 13 36 14 void kmap_flush_tlb(unsigned long addr) !! 37 static pte_t *kmap_pte; >> 38 >> 39 void __init kmap_init(void) 15 { 40 { 16 flush_tlb_one(addr); !! 41 unsigned long address; >> 42 p4d_t *p4d; >> 43 pud_t *pud; >> 44 pmd_t *dir; >> 45 >> 46 address = __fix_to_virt(FIX_KMAP_BEGIN); >> 47 p4d = p4d_offset(pgd_offset_k(address), address); >> 48 pud = pud_offset(p4d, address); >> 49 dir = pmd_offset(pud, address); >> 50 >> 51 /* cache the first kmap pte */ >> 52 kmap_pte = pte_offset_kernel(dir, address); >> 53 kmap_prot = __pgprot(SRMMU_ET_PTE | SRMMU_PRIV | SRMMU_CACHE); 17 } 54 } 18 EXPORT_SYMBOL(kmap_flush_tlb); << 19 55 20 void __init kmap_init(void) !! 56 void *kmap_atomic(struct page *page) 21 { 57 { 22 unsigned long vaddr; 58 unsigned long vaddr; 23 pgd_t *pgd; !! 59 long idx, type; 24 pmd_t *pmd; !! 60 25 pud_t *pud; !! 61 preempt_disable(); 26 pte_t *pte; !! 62 pagefault_disable(); >> 63 if (!PageHighMem(page)) >> 64 return page_address(page); >> 65 >> 66 type = kmap_atomic_idx_push(); >> 67 idx = type + KM_TYPE_NR*smp_processor_id(); >> 68 vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx); >> 69 >> 70 /* XXX Fix - Anton */ >> 71 #if 0 >> 72 __flush_cache_one(vaddr); >> 73 #else >> 74 flush_cache_all(); >> 75 #endif >> 76 >> 77 #ifdef CONFIG_DEBUG_HIGHMEM >> 78 BUG_ON(!pte_none(*(kmap_pte-idx))); >> 79 #endif >> 80 set_pte(kmap_pte-idx, mk_pte(page, kmap_prot)); >> 81 /* XXX Fix - Anton */ >> 82 #if 0 >> 83 __flush_tlb_one(vaddr); >> 84 #else >> 85 flush_tlb_all(); >> 86 #endif 27 87 28 vaddr = PKMAP_BASE; !! 88 return (void*) vaddr; 29 fixrange_init(vaddr, vaddr + PAGE_SIZE !! 89 } >> 90 EXPORT_SYMBOL(kmap_atomic); >> 91 >> 92 void __kunmap_atomic(void *kvaddr) >> 93 { >> 94 unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK; >> 95 int type; 30 96 31 pgd = swapper_pg_dir + pgd_index(vaddr !! 97 if (vaddr < FIXADDR_START) { // FIXME 32 pud = (pud_t *)pgd; !! 98 pagefault_enable(); 33 pmd = pmd_offset(pud, vaddr); !! 99 preempt_enable(); 34 pte = pte_offset_kernel(pmd, vaddr); !! 100 return; 35 pkmap_page_table = pte; !! 101 } >> 102 >> 103 type = kmap_atomic_idx(); >> 104 >> 105 #ifdef CONFIG_DEBUG_HIGHMEM >> 106 { >> 107 unsigned long idx; >> 108 >> 109 idx = type + KM_TYPE_NR * smp_processor_id(); >> 110 BUG_ON(vaddr != __fix_to_virt(FIX_KMAP_BEGIN+idx)); >> 111 >> 112 /* XXX Fix - Anton */ >> 113 #if 0 >> 114 __flush_cache_one(vaddr); >> 115 #else >> 116 flush_cache_all(); >> 117 #endif >> 118 >> 119 /* >> 120 * force other mappings to Oops if they'll try to access >> 121 * this pte without first remap it >> 122 */ >> 123 pte_clear(&init_mm, vaddr, kmap_pte-idx); >> 124 /* XXX Fix - Anton */ >> 125 #if 0 >> 126 __flush_tlb_one(vaddr); >> 127 #else >> 128 flush_tlb_all(); >> 129 #endif >> 130 } >> 131 #endif >> 132 >> 133 kmap_atomic_idx_pop(); >> 134 pagefault_enable(); >> 135 preempt_enable(); 36 } 136 } >> 137 EXPORT_SYMBOL(__kunmap_atomic); 37 138
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