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 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);
17 } 50 }
18 EXPORT_SYMBOL(kmap_flush_tlb); <<
19 51
20 void __init kmap_init(void) !! 52 void *kmap_atomic(struct page *page)
21 { 53 {
22 unsigned long vaddr; 54 unsigned long vaddr;
23 pgd_t *pgd; !! 55 long idx, type;
24 pmd_t *pmd; !! 56
25 pud_t *pud; !! 57 preempt_disable();
26 pte_t *pte; !! 58 pagefault_disable();
27 !! 59 if (!PageHighMem(page))
28 vaddr = PKMAP_BASE; !! 60 return page_address(page);
29 fixrange_init(vaddr, vaddr + PAGE_SIZE !! 61
30 !! 62 type = kmap_atomic_idx_push();
31 pgd = swapper_pg_dir + pgd_index(vaddr !! 63 idx = type + KM_TYPE_NR*smp_processor_id();
32 pud = (pud_t *)pgd; !! 64 vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
33 pmd = pmd_offset(pud, vaddr); !! 65
34 pte = pte_offset_kernel(pmd, vaddr); !! 66 /* XXX Fix - Anton */
35 pkmap_page_table = pte; !! 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();
36 } 132 }
>> 133 EXPORT_SYMBOL(__kunmap_atomic);
37 134
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