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