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/vaddrs.h>
11 33
12 unsigned long highstart_pfn, highend_pfn; !! 34 static pte_t *kmap_pte;
13 35
14 void kmap_flush_tlb(unsigned long addr) !! 36 void __init kmap_init(void)
15 { 37 {
16 flush_tlb_one(addr); !! 38 unsigned long address = __fix_to_virt(FIX_KMAP_BEGIN);
>> 39
>> 40 /* cache the first kmap pte */
>> 41 kmap_pte = virt_to_kpte(address);
17 } 42 }
18 EXPORT_SYMBOL(kmap_flush_tlb); <<
19 43
20 void __init kmap_init(void) !! 44 void *kmap_atomic_high_prot(struct page *page, pgprot_t prot)
21 { 45 {
22 unsigned long vaddr; 46 unsigned long vaddr;
23 pgd_t *pgd; !! 47 long idx, type;
24 pmd_t *pmd; !! 48
25 pud_t *pud; !! 49 type = kmap_atomic_idx_push();
26 pte_t *pte; !! 50 idx = type + KM_TYPE_NR*smp_processor_id();
27 !! 51 vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
28 vaddr = PKMAP_BASE; !! 52
29 fixrange_init(vaddr, vaddr + PAGE_SIZE !! 53 /* XXX Fix - Anton */
30 !! 54 #if 0
31 pgd = swapper_pg_dir + pgd_index(vaddr !! 55 __flush_cache_one(vaddr);
32 pud = (pud_t *)pgd; !! 56 #else
33 pmd = pmd_offset(pud, vaddr); !! 57 flush_cache_all();
34 pte = pte_offset_kernel(pmd, vaddr); !! 58 #endif
35 pkmap_page_table = pte; !! 59
>> 60 #ifdef CONFIG_DEBUG_HIGHMEM
>> 61 BUG_ON(!pte_none(*(kmap_pte-idx)));
>> 62 #endif
>> 63 set_pte(kmap_pte-idx, mk_pte(page, prot));
>> 64 /* XXX Fix - Anton */
>> 65 #if 0
>> 66 __flush_tlb_one(vaddr);
>> 67 #else
>> 68 flush_tlb_all();
>> 69 #endif
>> 70
>> 71 return (void*) vaddr;
>> 72 }
>> 73 EXPORT_SYMBOL(kmap_atomic_high_prot);
>> 74
>> 75 void kunmap_atomic_high(void *kvaddr)
>> 76 {
>> 77 unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK;
>> 78 int type;
>> 79
>> 80 if (vaddr < FIXADDR_START)
>> 81 return;
>> 82
>> 83 type = kmap_atomic_idx();
>> 84
>> 85 #ifdef CONFIG_DEBUG_HIGHMEM
>> 86 {
>> 87 unsigned long idx;
>> 88
>> 89 idx = type + KM_TYPE_NR * smp_processor_id();
>> 90 BUG_ON(vaddr != __fix_to_virt(FIX_KMAP_BEGIN+idx));
>> 91
>> 92 /* XXX Fix - Anton */
>> 93 #if 0
>> 94 __flush_cache_one(vaddr);
>> 95 #else
>> 96 flush_cache_all();
>> 97 #endif
>> 98
>> 99 /*
>> 100 * force other mappings to Oops if they'll try to access
>> 101 * this pte without first remap it
>> 102 */
>> 103 pte_clear(&init_mm, vaddr, kmap_pte-idx);
>> 104 /* XXX Fix - Anton */
>> 105 #if 0
>> 106 __flush_tlb_one(vaddr);
>> 107 #else
>> 108 flush_tlb_all();
>> 109 #endif
>> 110 }
>> 111 #endif
>> 112
>> 113 kmap_atomic_idx_pop();
36 } 114 }
>> 115 EXPORT_SYMBOL(kunmap_atomic_high);
37 116
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