1*4882a593Smuzhiyun // SPDX-License-Identifier: GPL-2.0
2*4882a593Smuzhiyun /*
3*4882a593Smuzhiyun * highmem.c: virtual kernel memory mappings for high memory
4*4882a593Smuzhiyun *
5*4882a593Smuzhiyun * Provides kernel-static versions of atomic kmap functions originally
6*4882a593Smuzhiyun * found as inlines in include/asm-sparc/highmem.h. These became
7*4882a593Smuzhiyun * needed as kmap_atomic() and kunmap_atomic() started getting
8*4882a593Smuzhiyun * called from within modules.
9*4882a593Smuzhiyun * -- Tomas Szepe <szepe@pinerecords.com>, September 2002
10*4882a593Smuzhiyun *
11*4882a593Smuzhiyun * But kmap_atomic() and kunmap_atomic() cannot be inlined in
12*4882a593Smuzhiyun * modules because they are loaded with btfixup-ped functions.
13*4882a593Smuzhiyun */
14*4882a593Smuzhiyun
15*4882a593Smuzhiyun /*
16*4882a593Smuzhiyun * The use of kmap_atomic/kunmap_atomic is discouraged - kmap/kunmap
17*4882a593Smuzhiyun * gives a more generic (and caching) interface. But kmap_atomic can
18*4882a593Smuzhiyun * be used in IRQ contexts, so in some (very limited) cases we need it.
19*4882a593Smuzhiyun *
20*4882a593Smuzhiyun * XXX This is an old text. Actually, it's good to use atomic kmaps,
21*4882a593Smuzhiyun * provided you remember that they are atomic and not try to sleep
22*4882a593Smuzhiyun * with a kmap taken, much like a spinlock. Non-atomic kmaps are
23*4882a593Smuzhiyun * shared by CPUs, and so precious, and establishing them requires IPI.
24*4882a593Smuzhiyun * Atomic kmaps are lightweight and we may have NCPUS more of them.
25*4882a593Smuzhiyun */
26*4882a593Smuzhiyun #include <linux/highmem.h>
27*4882a593Smuzhiyun #include <linux/export.h>
28*4882a593Smuzhiyun #include <linux/mm.h>
29*4882a593Smuzhiyun
30*4882a593Smuzhiyun #include <asm/cacheflush.h>
31*4882a593Smuzhiyun #include <asm/tlbflush.h>
32*4882a593Smuzhiyun #include <asm/vaddrs.h>
33*4882a593Smuzhiyun
34*4882a593Smuzhiyun static pte_t *kmap_pte;
35*4882a593Smuzhiyun
kmap_init(void)36*4882a593Smuzhiyun void __init kmap_init(void)
37*4882a593Smuzhiyun {
38*4882a593Smuzhiyun unsigned long address = __fix_to_virt(FIX_KMAP_BEGIN);
39*4882a593Smuzhiyun
40*4882a593Smuzhiyun /* cache the first kmap pte */
41*4882a593Smuzhiyun kmap_pte = virt_to_kpte(address);
42*4882a593Smuzhiyun }
43*4882a593Smuzhiyun
kmap_atomic_high_prot(struct page * page,pgprot_t prot)44*4882a593Smuzhiyun void *kmap_atomic_high_prot(struct page *page, pgprot_t prot)
45*4882a593Smuzhiyun {
46*4882a593Smuzhiyun unsigned long vaddr;
47*4882a593Smuzhiyun long idx, type;
48*4882a593Smuzhiyun
49*4882a593Smuzhiyun type = kmap_atomic_idx_push();
50*4882a593Smuzhiyun idx = type + KM_TYPE_NR*smp_processor_id();
51*4882a593Smuzhiyun vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
52*4882a593Smuzhiyun
53*4882a593Smuzhiyun /* XXX Fix - Anton */
54*4882a593Smuzhiyun #if 0
55*4882a593Smuzhiyun __flush_cache_one(vaddr);
56*4882a593Smuzhiyun #else
57*4882a593Smuzhiyun flush_cache_all();
58*4882a593Smuzhiyun #endif
59*4882a593Smuzhiyun
60*4882a593Smuzhiyun #ifdef CONFIG_DEBUG_HIGHMEM
61*4882a593Smuzhiyun BUG_ON(!pte_none(*(kmap_pte-idx)));
62*4882a593Smuzhiyun #endif
63*4882a593Smuzhiyun set_pte(kmap_pte-idx, mk_pte(page, prot));
64*4882a593Smuzhiyun /* XXX Fix - Anton */
65*4882a593Smuzhiyun #if 0
66*4882a593Smuzhiyun __flush_tlb_one(vaddr);
67*4882a593Smuzhiyun #else
68*4882a593Smuzhiyun flush_tlb_all();
69*4882a593Smuzhiyun #endif
70*4882a593Smuzhiyun
71*4882a593Smuzhiyun return (void*) vaddr;
72*4882a593Smuzhiyun }
73*4882a593Smuzhiyun EXPORT_SYMBOL(kmap_atomic_high_prot);
74*4882a593Smuzhiyun
kunmap_atomic_high(void * kvaddr)75*4882a593Smuzhiyun void kunmap_atomic_high(void *kvaddr)
76*4882a593Smuzhiyun {
77*4882a593Smuzhiyun unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK;
78*4882a593Smuzhiyun int type;
79*4882a593Smuzhiyun
80*4882a593Smuzhiyun if (vaddr < FIXADDR_START)
81*4882a593Smuzhiyun return;
82*4882a593Smuzhiyun
83*4882a593Smuzhiyun type = kmap_atomic_idx();
84*4882a593Smuzhiyun
85*4882a593Smuzhiyun #ifdef CONFIG_DEBUG_HIGHMEM
86*4882a593Smuzhiyun {
87*4882a593Smuzhiyun unsigned long idx;
88*4882a593Smuzhiyun
89*4882a593Smuzhiyun idx = type + KM_TYPE_NR * smp_processor_id();
90*4882a593Smuzhiyun BUG_ON(vaddr != __fix_to_virt(FIX_KMAP_BEGIN+idx));
91*4882a593Smuzhiyun
92*4882a593Smuzhiyun /* XXX Fix - Anton */
93*4882a593Smuzhiyun #if 0
94*4882a593Smuzhiyun __flush_cache_one(vaddr);
95*4882a593Smuzhiyun #else
96*4882a593Smuzhiyun flush_cache_all();
97*4882a593Smuzhiyun #endif
98*4882a593Smuzhiyun
99*4882a593Smuzhiyun /*
100*4882a593Smuzhiyun * force other mappings to Oops if they'll try to access
101*4882a593Smuzhiyun * this pte without first remap it
102*4882a593Smuzhiyun */
103*4882a593Smuzhiyun pte_clear(&init_mm, vaddr, kmap_pte-idx);
104*4882a593Smuzhiyun /* XXX Fix - Anton */
105*4882a593Smuzhiyun #if 0
106*4882a593Smuzhiyun __flush_tlb_one(vaddr);
107*4882a593Smuzhiyun #else
108*4882a593Smuzhiyun flush_tlb_all();
109*4882a593Smuzhiyun #endif
110*4882a593Smuzhiyun }
111*4882a593Smuzhiyun #endif
112*4882a593Smuzhiyun
113*4882a593Smuzhiyun kmap_atomic_idx_pop();
114*4882a593Smuzhiyun }
115*4882a593Smuzhiyun EXPORT_SYMBOL(kunmap_atomic_high);
116