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1/*
2 * highmem.c: virtual kernel memory mappings for high memory
3 *
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>
26#include <linux/highmem.h>
27#include <asm/pgalloc.h>
28#include <asm/cacheflush.h>
29#include <asm/tlbflush.h>
30#include <asm/fixmap.h>
31
32void *__kmap_atomic(struct page *page)
33{
34 unsigned long vaddr;
35 long idx, type;
36
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 type = kmap_atomic_idx_push();
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}
66EXPORT_SYMBOL(__kmap_atomic);
67
68void __kunmap_atomic(void *kvaddr)
69{
70 unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK;
71 int type;
72
73 if (vaddr < FIXADDR_START) { // FIXME
74 pagefault_enable();
75 return;
76 }
77
78 type = kmap_atomic_idx();
79
80#ifdef CONFIG_DEBUG_HIGHMEM
81 {
82 unsigned long idx;
83
84 idx = type + KM_TYPE_NR * smp_processor_id();
85 BUG_ON(vaddr != __fix_to_virt(FIX_KMAP_BEGIN+idx));
86
87 /* XXX Fix - Anton */
88#if 0
89 __flush_cache_one(vaddr);
90#else
91 flush_cache_all();
92#endif
93
94 /*
95 * force other mappings to Oops if they'll try to access
96 * this pte without first remap it
97 */
98 pte_clear(&init_mm, vaddr, kmap_pte-idx);
99 /* XXX Fix - Anton */
100#if 0
101 __flush_tlb_one(vaddr);
102#else
103 flush_tlb_all();
104#endif
105 }
106#endif
107
108 kmap_atomic_idx_pop();
109 pagefault_enable();
110}
111EXPORT_SYMBOL(__kunmap_atomic);
112
113/* We may be fed a pagetable here by ptep_to_xxx and others. */
114struct page *kmap_atomic_to_page(void *ptr)
115{
116 unsigned long idx, vaddr = (unsigned long)ptr;
117 pte_t *pte;
118
119 if (vaddr < SRMMU_NOCACHE_VADDR)
120 return virt_to_page(ptr);
121 if (vaddr < PKMAP_BASE)
122 return pfn_to_page(__nocache_pa(vaddr) >> PAGE_SHIFT);
123 BUG_ON(vaddr < FIXADDR_START);
124 BUG_ON(vaddr > FIXADDR_TOP);
125
126 idx = virt_to_fix(vaddr);
127 pte = kmap_pte - (idx - FIX_KMAP_BEGIN);
128 return pte_page(*pte);
129}
1// SPDX-License-Identifier: GPL-2.0
2/*
3 * highmem.c: virtual kernel memory mappings for high memory
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 */
26#include <linux/highmem.h>
27#include <linux/export.h>
28#include <linux/mm.h>
29
30#include <asm/cacheflush.h>
31#include <asm/tlbflush.h>
32#include <asm/vaddrs.h>
33
34static pte_t *kmap_pte;
35
36void __init kmap_init(void)
37{
38 unsigned long address = __fix_to_virt(FIX_KMAP_BEGIN);
39
40 /* cache the first kmap pte */
41 kmap_pte = virt_to_kpte(address);
42}
43
44void *kmap_atomic_high_prot(struct page *page, pgprot_t prot)
45{
46 unsigned long vaddr;
47 long idx, type;
48
49 type = kmap_atomic_idx_push();
50 idx = type + KM_TYPE_NR*smp_processor_id();
51 vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
52
53/* XXX Fix - Anton */
54#if 0
55 __flush_cache_one(vaddr);
56#else
57 flush_cache_all();
58#endif
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}
73EXPORT_SYMBOL(kmap_atomic_high_prot);
74
75void 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();
114}
115EXPORT_SYMBOL(kunmap_atomic_high);