1 #ifndef __UM_FIXMAP_H
2 #define __UM_FIXMAP_H
3
4 #include <asm/processor.h>
5 #include <asm/system.h>
6 #include <asm/kmap_types.h>
7 #include <asm/archparam.h>
8 #include <asm/page.h>
9 #include <linux/threads.h>
10
11 /*
12 * Here we define all the compile-time 'special' virtual
13 * addresses. The point is to have a constant address at
14 * compile time, but to set the physical address only
15 * in the boot process. We allocate these special addresses
16 * from the end of virtual memory (0xfffff000) backwards.
17 * Also this lets us do fail-safe vmalloc(), we
18 * can guarantee that these special addresses and
19 * vmalloc()-ed addresses never overlap.
20 *
21 * these 'compile-time allocated' memory buffers are
22 * fixed-size 4k pages. (or larger if used with an increment
23 * highger than 1) use fixmap_set(idx,phys) to associate
24 * physical memory with fixmap indices.
25 *
26 * TLB entries of such buffers will not be flushed across
27 * task switches.
28 */
29
30 /*
31 * on UP currently we will have no trace of the fixmap mechanizm,
32 * no page table allocations, etc. This might change in the
33 * future, say framebuffers for the console driver(s) could be
34 * fix-mapped?
35 */
36 enum fixed_addresses {
37 #ifdef CONFIG_HIGHMEM
38 FIX_KMAP_BEGIN, /* reserved pte's for temporary kernel mappings */
39 FIX_KMAP_END = FIX_KMAP_BEGIN+(KM_TYPE_NR*NR_CPUS)-1,
40 #endif
41 __end_of_fixed_addresses
42 };
43
44 extern void __set_fixmap (enum fixed_addresses idx,
45 unsigned long phys, pgprot_t flags);
46
47 #define set_fixmap(idx, phys) \
48 __set_fixmap(idx, phys, PAGE_KERNEL)
49 /*
50 * Some hardware wants to get fixmapped without caching.
51 */
52 #define set_fixmap_nocache(idx, phys) \
53 __set_fixmap(idx, phys, PAGE_KERNEL_NOCACHE)
54 /*
55 * used by vmalloc.c.
56 *
57 * Leave one empty page between vmalloc'ed areas and
58 * the start of the fixmap, and leave one page empty
59 * at the top of mem..
60 */
61
62 #define FIXADDR_TOP (TASK_SIZE - 2 * PAGE_SIZE)
63 #define FIXADDR_SIZE (__end_of_fixed_addresses << PAGE_SHIFT)
64 #define FIXADDR_START (FIXADDR_TOP - FIXADDR_SIZE)
65
66 #define __fix_to_virt(x) (FIXADDR_TOP - ((x) << PAGE_SHIFT))
67 #define __virt_to_fix(x) ((FIXADDR_TOP - ((x)&PAGE_MASK)) >> PAGE_SHIFT)
68
69 extern void __this_fixmap_does_not_exist(void);
70
71 /*
72 * 'index to address' translation. If anyone tries to use the idx
73 * directly without tranlation, we catch the bug with a NULL-deference
74 * kernel oops. Illegal ranges of incoming indices are caught too.
75 */
fix_to_virt(const unsigned int idx)76 static inline unsigned long fix_to_virt(const unsigned int idx)
77 {
78 /*
79 * this branch gets completely eliminated after inlining,
80 * except when someone tries to use fixaddr indices in an
81 * illegal way. (such as mixing up address types or using
82 * out-of-range indices).
83 *
84 * If it doesn't get removed, the linker will complain
85 * loudly with a reasonably clear error message..
86 */
87 if (idx >= __end_of_fixed_addresses)
88 __this_fixmap_does_not_exist();
89
90 return __fix_to_virt(idx);
91 }
92
virt_to_fix(const unsigned long vaddr)93 static inline unsigned long virt_to_fix(const unsigned long vaddr)
94 {
95 BUG_ON(vaddr >= FIXADDR_TOP || vaddr < FIXADDR_START);
96 return __virt_to_fix(vaddr);
97 }
98
99 #endif
100