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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/pgalloc.h>
33#include <asm/vaddrs.h>
34
35pgprot_t kmap_prot;
36
37static pte_t *kmap_pte;
38
39void __init kmap_init(void)
40{
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);
50}
51
52void *kmap_atomic(struct page *page)
53{
54 unsigned long vaddr;
55 long idx, type;
56
57 preempt_disable();
58 pagefault_disable();
59 if (!PageHighMem(page))
60 return page_address(page);
61
62 type = kmap_atomic_idx_push();
63 idx = type + KM_TYPE_NR*smp_processor_id();
64 vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
65
66/* XXX Fix - Anton */
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}
86EXPORT_SYMBOL(kmap_atomic);
87
88void __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();
132}
133EXPORT_SYMBOL(__kunmap_atomic);
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);