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 * PowerPC version, stolen from the i386 version.
6*4882a593Smuzhiyun *
7*4882a593Smuzhiyun * Used in CONFIG_HIGHMEM systems for memory pages which
8*4882a593Smuzhiyun * are not addressable by direct kernel virtual addresses.
9*4882a593Smuzhiyun *
10*4882a593Smuzhiyun * Copyright (C) 1999 Gerhard Wichert, Siemens AG
11*4882a593Smuzhiyun * Gerhard.Wichert@pdb.siemens.de
12*4882a593Smuzhiyun *
13*4882a593Smuzhiyun *
14*4882a593Smuzhiyun * Redesigned the x86 32-bit VM architecture to deal with
15*4882a593Smuzhiyun * up to 16 Terrabyte physical memory. With current x86 CPUs
16*4882a593Smuzhiyun * we now support up to 64 Gigabytes physical RAM.
17*4882a593Smuzhiyun *
18*4882a593Smuzhiyun * Copyright (C) 1999 Ingo Molnar <mingo@redhat.com>
19*4882a593Smuzhiyun *
20*4882a593Smuzhiyun * Reworked for PowerPC by various contributors. Moved from
21*4882a593Smuzhiyun * highmem.h by Benjamin Herrenschmidt (c) 2009 IBM Corp.
22*4882a593Smuzhiyun */
23*4882a593Smuzhiyun
24*4882a593Smuzhiyun #include <linux/export.h>
25*4882a593Smuzhiyun #include <linux/highmem.h>
26*4882a593Smuzhiyun
27*4882a593Smuzhiyun /*
28*4882a593Smuzhiyun * The use of kmap_atomic/kunmap_atomic is discouraged - kmap/kunmap
29*4882a593Smuzhiyun * gives a more generic (and caching) interface. But kmap_atomic can
30*4882a593Smuzhiyun * be used in IRQ contexts, so in some (very limited) cases we need
31*4882a593Smuzhiyun * it.
32*4882a593Smuzhiyun */
33*4882a593Smuzhiyun #include <asm/tlbflush.h>
34*4882a593Smuzhiyun
kmap_atomic_high_prot(struct page * page,pgprot_t prot)35*4882a593Smuzhiyun void *kmap_atomic_high_prot(struct page *page, pgprot_t prot)
36*4882a593Smuzhiyun {
37*4882a593Smuzhiyun
38*4882a593Smuzhiyun unsigned long vaddr;
39*4882a593Smuzhiyun int idx, type;
40*4882a593Smuzhiyun
41*4882a593Smuzhiyun type = kmap_atomic_idx_push();
42*4882a593Smuzhiyun idx = type + KM_TYPE_NR*smp_processor_id();
43*4882a593Smuzhiyun vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
44*4882a593Smuzhiyun #ifdef CONFIG_DEBUG_HIGHMEM
45*4882a593Smuzhiyun BUG_ON(!pte_none(*(kmap_pte-idx)));
46*4882a593Smuzhiyun #endif
47*4882a593Smuzhiyun set_pte_at(&init_mm, vaddr, kmap_pte-idx, mk_pte(page, prot));
48*4882a593Smuzhiyun local_flush_tlb_page(NULL, vaddr);
49*4882a593Smuzhiyun
50*4882a593Smuzhiyun return (void *) vaddr;
51*4882a593Smuzhiyun }
52*4882a593Smuzhiyun EXPORT_SYMBOL(kmap_atomic_high_prot);
53*4882a593Smuzhiyun
kunmap_atomic_high(void * kvaddr)54*4882a593Smuzhiyun void kunmap_atomic_high(void *kvaddr)
55*4882a593Smuzhiyun {
56*4882a593Smuzhiyun unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK;
57*4882a593Smuzhiyun int type;
58*4882a593Smuzhiyun unsigned int idx;
59*4882a593Smuzhiyun
60*4882a593Smuzhiyun if (vaddr < __fix_to_virt(FIX_KMAP_END))
61*4882a593Smuzhiyun return;
62*4882a593Smuzhiyun
63*4882a593Smuzhiyun type = kmap_atomic_idx();
64*4882a593Smuzhiyun
65*4882a593Smuzhiyun idx = type + KM_TYPE_NR * smp_processor_id();
66*4882a593Smuzhiyun #ifdef CONFIG_DEBUG_HIGHMEM
67*4882a593Smuzhiyun BUG_ON(vaddr != __fix_to_virt(FIX_KMAP_BEGIN + idx));
68*4882a593Smuzhiyun #endif
69*4882a593Smuzhiyun /*
70*4882a593Smuzhiyun * force other mappings to Oops if they'll try to access
71*4882a593Smuzhiyun * this pte without first remap it
72*4882a593Smuzhiyun */
73*4882a593Smuzhiyun pte_clear(&init_mm, vaddr, kmap_pte-idx);
74*4882a593Smuzhiyun local_flush_tlb_page(NULL, vaddr);
75*4882a593Smuzhiyun
76*4882a593Smuzhiyun kmap_atomic_idx_pop();
77*4882a593Smuzhiyun }
78*4882a593Smuzhiyun EXPORT_SYMBOL(kunmap_atomic_high);
79