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