1/*
  2 * fixmap.h: compile-time virtual memory allocation
  3 *
  4 * This file is subject to the terms and conditions of the GNU General Public
  5 * License.  See the file "COPYING" in the main directory of this archive
  6 * for more details.
  7 *
  8 * Copyright (C) 1998 Ingo Molnar
  9 *
 10 * Support of BIGMEM added by Gerhard Wichert, Siemens AG, July 1999
 11 */
 12
 13#ifndef _ASM_FIXMAP_H
 14#define _ASM_FIXMAP_H
 15
 16#include <linux/kernel.h>
 17#include <linux/threads.h>
 18#include <asm/page.h>
 19#ifdef CONFIG_HIGHMEM
 20#include <asm/kmap_types.h>
 21#endif
 22
 23/*
 24 * Here we define all the compile-time 'special' virtual
 25 * addresses. The point is to have a constant address at
 26 * compile time, but to set the physical address only
 27 * in the boot process. We allocate these special  addresses
 28 * from the end of P3 backwards.
 29 * Also this lets us do fail-safe vmalloc(), we
 30 * can guarantee that these special addresses and
 31 * vmalloc()-ed addresses never overlap.
 32 *
 33 * these 'compile-time allocated' memory buffers are
 34 * fixed-size 4k pages. (or larger if used with an increment
 35 * highger than 1) use fixmap_set(idx,phys) to associate
 36 * physical memory with fixmap indices.
 37 *
 38 * TLB entries of such buffers will not be flushed across
 39 * task switches.
 40 */
 41
 42/*
 43 * on UP currently we will have no trace of the fixmap mechanizm,
 44 * no page table allocations, etc. This might change in the
 45 * future, say framebuffers for the console driver(s) could be
 46 * fix-mapped?
 47 */
 48enum fixed_addresses {
 49	/*
 50	 * The FIX_CMAP entries are used by kmap_coherent() to get virtual
 51	 * addresses which are of a known color, and so their values are
 52	 * important. __fix_to_virt(FIX_CMAP_END - n) must give an address
 53	 * which is the same color as a page (n<<PAGE_SHIFT).
 54	 */
 55#define FIX_N_COLOURS 8
 56	FIX_CMAP_BEGIN,
 57	FIX_CMAP_END = FIX_CMAP_BEGIN + (FIX_N_COLOURS * NR_CPUS) - 1,
 58
 59#ifdef CONFIG_HIGHMEM
 60	FIX_KMAP_BEGIN,	/* reserved pte's for temporary kernel mappings */
 61	FIX_KMAP_END = FIX_KMAP_BEGIN + (KM_TYPE_NR * NR_CPUS) - 1,
 62#endif
 63
 64#ifdef CONFIG_IOREMAP_FIXED
 65	/*
 66	 * FIX_IOREMAP entries are useful for mapping physical address
 67	 * space before ioremap() is useable, e.g. really early in boot
 68	 * before kmalloc() is working.
 69	 */
 70#define FIX_N_IOREMAPS	32
 71	FIX_IOREMAP_BEGIN,
 72	FIX_IOREMAP_END = FIX_IOREMAP_BEGIN + FIX_N_IOREMAPS - 1,
 73#endif
 74
 75	__end_of_fixed_addresses
 76};
 77
 78extern void __set_fixmap(enum fixed_addresses idx,
 79			 unsigned long phys, pgprot_t flags);
 80extern void __clear_fixmap(enum fixed_addresses idx, pgprot_t flags);
 81
 82#define set_fixmap(idx, phys) \
 83		__set_fixmap(idx, phys, PAGE_KERNEL)
 84/*
 85 * Some hardware wants to get fixmapped without caching.
 86 */
 87#define set_fixmap_nocache(idx, phys) \
 88		__set_fixmap(idx, phys, PAGE_KERNEL_NOCACHE)
 89/*
 90 * used by vmalloc.c.
 91 *
 92 * Leave one empty page between vmalloc'ed areas and
 93 * the start of the fixmap, and leave one page empty
 94 * at the top of mem..
 95 */
 96#ifdef CONFIG_SUPERH32
 97#define FIXADDR_TOP	(P4SEG - PAGE_SIZE)
 98#else
 99#define FIXADDR_TOP	((unsigned long)(-PAGE_SIZE))
100#endif
101#define FIXADDR_SIZE	(__end_of_fixed_addresses << PAGE_SHIFT)
102#define FIXADDR_START	(FIXADDR_TOP - FIXADDR_SIZE)
103
104#define __fix_to_virt(x)	(FIXADDR_TOP - ((x) << PAGE_SHIFT))
105#define __virt_to_fix(x)	((FIXADDR_TOP - ((x)&PAGE_MASK)) >> PAGE_SHIFT)
106
107extern void __this_fixmap_does_not_exist(void);
108
109/*
110 * 'index to address' translation. If anyone tries to use the idx
111 * directly without tranlation, we catch the bug with a NULL-deference
112 * kernel oops. Illegal ranges of incoming indices are caught too.
113 */
114static inline unsigned long fix_to_virt(const unsigned int idx)
115{
116	/*
117	 * this branch gets completely eliminated after inlining,
118	 * except when someone tries to use fixaddr indices in an
119	 * illegal way. (such as mixing up address types or using
120	 * out-of-range indices).
121	 *
122	 * If it doesn't get removed, the linker will complain
123	 * loudly with a reasonably clear error message..
124	 */
125	if (idx >= __end_of_fixed_addresses)
126		__this_fixmap_does_not_exist();
127
128        return __fix_to_virt(idx);
129}
130
131static inline unsigned long virt_to_fix(const unsigned long vaddr)
132{
133	BUG_ON(vaddr >= FIXADDR_TOP || vaddr < FIXADDR_START);
134	return __virt_to_fix(vaddr);
135}
136#endif

 1/* SPDX-License-Identifier: GPL-2.0
 
 2 *
 3 * fixmap.h: compile-time virtual memory allocation
 
 
 4 *
 5 * Copyright (C) 1998 Ingo Molnar
 6 *
 7 * Support of BIGMEM added by Gerhard Wichert, Siemens AG, July 1999
 8 */
 9
10#ifndef _ASM_FIXMAP_H
11#define _ASM_FIXMAP_H
12
13#include <linux/kernel.h>
14#include <linux/threads.h>
15#include <asm/page.h>
 
 
 
16
17/*
18 * Here we define all the compile-time 'special' virtual
19 * addresses. The point is to have a constant address at
20 * compile time, but to set the physical address only
21 * in the boot process. We allocate these special  addresses
22 * from the end of P3 backwards.
23 * Also this lets us do fail-safe vmalloc(), we
24 * can guarantee that these special addresses and
25 * vmalloc()-ed addresses never overlap.
26 *
27 * these 'compile-time allocated' memory buffers are
28 * fixed-size 4k pages. (or larger if used with an increment
29 * highger than 1) use fixmap_set(idx,phys) to associate
30 * physical memory with fixmap indices.
31 *
32 * TLB entries of such buffers will not be flushed across
33 * task switches.
34 */
35
36/*
37 * on UP currently we will have no trace of the fixmap mechanizm,
38 * no page table allocations, etc. This might change in the
39 * future, say framebuffers for the console driver(s) could be
40 * fix-mapped?
41 */
42enum fixed_addresses {
43	/*
44	 * The FIX_CMAP entries are used by kmap_coherent() to get virtual
45	 * addresses which are of a known color, and so their values are
46	 * important. __fix_to_virt(FIX_CMAP_END - n) must give an address
47	 * which is the same color as a page (n<<PAGE_SHIFT).
48	 */
49#define FIX_N_COLOURS 8
50	FIX_CMAP_BEGIN,
51	FIX_CMAP_END = FIX_CMAP_BEGIN + (FIX_N_COLOURS * NR_CPUS) - 1,
52
 
 
 
 
 
53#ifdef CONFIG_IOREMAP_FIXED
54	/*
55	 * FIX_IOREMAP entries are useful for mapping physical address
56	 * space before ioremap() is useable, e.g. really early in boot
57	 * before kmalloc() is working.
58	 */
59#define FIX_N_IOREMAPS	32
60	FIX_IOREMAP_BEGIN,
61	FIX_IOREMAP_END = FIX_IOREMAP_BEGIN + FIX_N_IOREMAPS - 1,
62#endif
63
64	__end_of_fixed_addresses
65};
66
67extern void __set_fixmap(enum fixed_addresses idx,
68			 unsigned long phys, pgprot_t flags);
69extern void __clear_fixmap(enum fixed_addresses idx, pgprot_t flags);
70
 
 
 
 
 
 
 
71/*
72 * used by vmalloc.c.
73 *
74 * Leave one empty page between vmalloc'ed areas and
75 * the start of the fixmap, and leave one page empty
76 * at the top of mem..
77 */
 
78#define FIXADDR_TOP	(P4SEG - PAGE_SIZE)
 
 
 
79#define FIXADDR_SIZE	(__end_of_fixed_addresses << PAGE_SHIFT)
80#define FIXADDR_START	(FIXADDR_TOP - FIXADDR_SIZE)
81
82#define FIXMAP_PAGE_NOCACHE PAGE_KERNEL_NOCACHE
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
83
84#include <asm-generic/fixmap.h>
 
85
 
 
 
 
 
86#endif