1 // SPDX-License-Identifier: GPL-2.0 !! 1 /*
2 // Copyright (C) 2018 Hangzhou C-SKY Microsyst !! 2 * highmem.c: virtual kernel memory mappings for high memory
3 !! 3 *
4 #include <linux/module.h> !! 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>
5 #include <linux/highmem.h> 26 #include <linux/highmem.h>
6 #include <linux/smp.h> !! 27 #include <asm/pgalloc.h>
7 #include <linux/memblock.h> <<
8 #include <asm/fixmap.h> <<
9 #include <asm/tlbflush.h> <<
10 #include <asm/cacheflush.h> 28 #include <asm/cacheflush.h>
>> 29 #include <asm/tlbflush.h>
>> 30 #include <asm/fixmap.h>
11 31
12 unsigned long highstart_pfn, highend_pfn; !! 32 void *kmap_atomic(struct page *page, enum km_type type)
>> 33 {
>> 34 unsigned long idx;
>> 35 unsigned long vaddr;
13 36
14 void kmap_flush_tlb(unsigned long addr) !! 37 /* even !CONFIG_PREEMPT needs this, for in_atomic in do_page_fault */
>> 38 pagefault_disable();
>> 39 if (!PageHighMem(page))
>> 40 return page_address(page);
>> 41
>> 42 debug_kmap_atomic(type);
>> 43 idx = type + KM_TYPE_NR*smp_processor_id();
>> 44 vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
>> 45
>> 46 /* XXX Fix - Anton */
>> 47 #if 0
>> 48 __flush_cache_one(vaddr);
>> 49 #else
>> 50 flush_cache_all();
>> 51 #endif
>> 52
>> 53 #ifdef CONFIG_DEBUG_HIGHMEM
>> 54 BUG_ON(!pte_none(*(kmap_pte-idx)));
>> 55 #endif
>> 56 set_pte(kmap_pte-idx, mk_pte(page, kmap_prot));
>> 57 /* XXX Fix - Anton */
>> 58 #if 0
>> 59 __flush_tlb_one(vaddr);
>> 60 #else
>> 61 flush_tlb_all();
>> 62 #endif
>> 63
>> 64 return (void*) vaddr;
>> 65 }
>> 66 EXPORT_SYMBOL(kmap_atomic);
>> 67
>> 68 void kunmap_atomic(void *kvaddr, enum km_type type)
15 { 69 {
16 flush_tlb_one(addr); !! 70 #ifdef CONFIG_DEBUG_HIGHMEM
>> 71 unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK;
>> 72 unsigned long idx = type + KM_TYPE_NR*smp_processor_id();
>> 73
>> 74 if (vaddr < FIXADDR_START) { // FIXME
>> 75 pagefault_enable();
>> 76 return;
>> 77 }
>> 78
>> 79 BUG_ON(vaddr != __fix_to_virt(FIX_KMAP_BEGIN+idx));
>> 80
>> 81 /* XXX Fix - Anton */
>> 82 #if 0
>> 83 __flush_cache_one(vaddr);
>> 84 #else
>> 85 flush_cache_all();
>> 86 #endif
>> 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 /* XXX Fix - Anton */
>> 94 #if 0
>> 95 __flush_tlb_one(vaddr);
>> 96 #else
>> 97 flush_tlb_all();
>> 98 #endif
>> 99 #endif
>> 100
>> 101 pagefault_enable();
17 } 102 }
18 EXPORT_SYMBOL(kmap_flush_tlb); !! 103 EXPORT_SYMBOL(kunmap_atomic);
19 104
20 void __init kmap_init(void) !! 105 /* We may be fed a pagetable here by ptep_to_xxx and others. */
>> 106 struct page *kmap_atomic_to_page(void *ptr)
21 { 107 {
22 unsigned long vaddr; !! 108 unsigned long idx, vaddr = (unsigned long)ptr;
23 pgd_t *pgd; <<
24 pmd_t *pmd; <<
25 pud_t *pud; <<
26 pte_t *pte; 109 pte_t *pte;
27 110
28 vaddr = PKMAP_BASE; !! 111 if (vaddr < SRMMU_NOCACHE_VADDR)
29 fixrange_init(vaddr, vaddr + PAGE_SIZE !! 112 return virt_to_page(ptr);
30 !! 113 if (vaddr < PKMAP_BASE)
31 pgd = swapper_pg_dir + pgd_index(vaddr !! 114 return pfn_to_page(__nocache_pa(vaddr) >> PAGE_SHIFT);
32 pud = (pud_t *)pgd; !! 115 BUG_ON(vaddr < FIXADDR_START);
33 pmd = pmd_offset(pud, vaddr); !! 116 BUG_ON(vaddr > FIXADDR_TOP);
34 pte = pte_offset_kernel(pmd, vaddr); !! 117
35 pkmap_page_table = pte; !! 118 idx = virt_to_fix(vaddr);
>> 119 pte = kmap_pte - (idx - FIX_KMAP_BEGIN);
>> 120 return pte_page(*pte);
36 } 121 }
37 122
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