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 #ifdef CONFIG_HIGHMEM
17 #include <asm/kmap_types.h>
18 #endif
19
20 /*
21 * Here we define all the compile-time 'special' virtual
22 * addresses. The point is to have a constant address at
23 * compile time, but to set the physical address only
24 * in the boot process. We allocate these special addresses
25 * from the end of P3 backwards.
26 * Also this lets us do fail-safe vmalloc(), we
27 * can guarantee that these special addresses and
28 * vmalloc()-ed addresses never overlap.
29 *
30 * these 'compile-time allocated' memory buffers are
31 * fixed-size 4k pages. (or larger if used with an increment
32 * highger than 1) use fixmap_set(idx,phys) to associate
33 * physical memory with fixmap indices.
34 *
35 * TLB entries of such buffers will not be flushed across
36 * task switches.
37 */
38
39 /*
40 * on UP currently we will have no trace of the fixmap mechanizm,
41 * no page table allocations, etc. This might change in the
42 * future, say framebuffers for the console driver(s) could be
43 * fix-mapped?
44 */
45 enum fixed_addresses {
46 /*
47 * The FIX_CMAP entries are used by kmap_coherent() to get virtual
48 * addresses which are of a known color, and so their values are
49 * important. __fix_to_virt(FIX_CMAP_END - n) must give an address
50 * which is the same color as a page (n<<PAGE_SHIFT).
51 */
52 #define FIX_N_COLOURS 8
53 FIX_CMAP_BEGIN,
54 FIX_CMAP_END = FIX_CMAP_BEGIN + (FIX_N_COLOURS * NR_CPUS) - 1,
55
56 #ifdef CONFIG_HIGHMEM
57 FIX_KMAP_BEGIN, /* reserved pte's for temporary kernel mappings */
58 FIX_KMAP_END = FIX_KMAP_BEGIN + (KM_TYPE_NR * NR_CPUS) - 1,
59 #endif
60
61 #ifdef CONFIG_IOREMAP_FIXED
62 /*
63 * FIX_IOREMAP entries are useful for mapping physical address
64 * space before ioremap() is useable, e.g. really early in boot
65 * before kmalloc() is working.
66 */
67 #define FIX_N_IOREMAPS 32
68 FIX_IOREMAP_BEGIN,
69 FIX_IOREMAP_END = FIX_IOREMAP_BEGIN + FIX_N_IOREMAPS - 1,
70 #endif
71
72 __end_of_fixed_addresses
73 };
74
75 extern void __set_fixmap(enum fixed_addresses idx,
76 unsigned long phys, pgprot_t flags);
77 extern void __clear_fixmap(enum fixed_addresses idx, pgprot_t flags);
78
79 /*
80 * used by vmalloc.c.
81 *
82 * Leave one empty page between vmalloc'ed areas and
83 * the start of the fixmap, and leave one page empty
84 * at the top of mem..
85 */
86 #ifdef CONFIG_SUPERH32
87 #define FIXADDR_TOP (P4SEG - PAGE_SIZE)
88 #else
89 #define FIXADDR_TOP ((unsigned long)(-PAGE_SIZE))
90 #endif
91 #define FIXADDR_SIZE (__end_of_fixed_addresses << PAGE_SHIFT)
92 #define FIXADDR_START (FIXADDR_TOP - FIXADDR_SIZE)
93
94 #define FIXMAP_PAGE_NOCACHE PAGE_KERNEL_NOCACHE
95
96 #include <asm-generic/fixmap.h>
97
98 #endif