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 */ 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 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