2 * fixmap.h: compile-time virtual memory allocation
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
8 * Copyright (C) 1998 Ingo Molnar
10 * Support of BIGMEM added by Gerhard Wichert, Siemens AG, July 1999
18 #include <linux/threads.h>
19 #include <asm/kmap_types.h>
23 * Here we define all the compile-time 'special' virtual
24 * addresses. The point is to have a constant address at
25 * compile time, but to set the physical address only
26 * in the boot process. We allocate these special addresses
27 * from the end of virtual memory (0xfffff000) backwards.
28 * Also this lets us do fail-safe vmalloc(), we
29 * can guarantee that these special addresses and
30 * vmalloc()-ed addresses never overlap.
32 * these 'compile-time allocated' memory buffers are
33 * fixed-size 4k pages. (or larger if used with an increment
34 * highger than 1) use fixmap_set(idx,phys) to associate
35 * physical memory with fixmap indices.
37 * TLB entries of such buffers will not be flushed across
42 * on UP currently we will have no trace of the fixmap mechanizm,
43 * no page table allocations, etc. This might change in the
44 * future, say framebuffers for the console driver(s) could be
47 enum fixed_addresses {
48 #define FIX_N_COLOURS 8
50 #ifdef CONFIG_MIPS_MT_SMTC
51 FIX_CMAP_END = FIX_CMAP_BEGIN + (FIX_N_COLOURS * NR_CPUS),
53 FIX_CMAP_END = FIX_CMAP_BEGIN + FIX_N_COLOURS,
56 /* reserved pte's for temporary kernel mappings */
57 FIX_KMAP_BEGIN = FIX_CMAP_END + 1,
58 FIX_KMAP_END = FIX_KMAP_BEGIN+(KM_TYPE_NR*NR_CPUS)-1,
60 __end_of_fixed_addresses
66 * Leave one empty page between vmalloc'ed areas and
67 * the start of the fixmap, and leave one page empty
70 #if defined(CONFIG_CPU_TX39XX) || defined(CONFIG_CPU_TX49XX)
71 #define FIXADDR_TOP ((unsigned long)(long)(int)(0xff000000 - 0x20000))
73 #define FIXADDR_TOP ((unsigned long)(long)(int)0xfffe0000)
75 #define FIXADDR_SIZE (__end_of_fixed_addresses << PAGE_SHIFT)
76 #define FIXADDR_START (FIXADDR_TOP - FIXADDR_SIZE)
78 #define __fix_to_virt(x) (FIXADDR_TOP - ((x) << PAGE_SHIFT))
79 #define __virt_to_fix(x) ((FIXADDR_TOP - ((x)&PAGE_MASK)) >> PAGE_SHIFT)
81 extern void __this_fixmap_does_not_exist(void);
84 * 'index to address' translation. If anyone tries to use the idx
85 * directly without tranlation, we catch the bug with a NULL-deference
86 * kernel oops. Illegal ranges of incoming indices are caught too.
88 static inline unsigned long fix_to_virt(const unsigned int idx)
91 * this branch gets completely eliminated after inlining,
92 * except when someone tries to use fixaddr indices in an
93 * illegal way. (such as mixing up address types or using
94 * out-of-range indices).
96 * If it doesn't get removed, the linker will complain
97 * loudly with a reasonably clear error message..
99 if (idx >= __end_of_fixed_addresses)
100 __this_fixmap_does_not_exist();
102 return __fix_to_virt(idx);
105 static inline unsigned long virt_to_fix(const unsigned long vaddr)
107 BUG_ON(vaddr >= FIXADDR_TOP || vaddr < FIXADDR_START);
108 return __virt_to_fix(vaddr);
112 * Called from pgtable_init()
114 extern void fixrange_init(unsigned long start, unsigned long end,