1 /* 2 * fixmap.h: compile-time virtual memory allocation 3 * 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 6 * for more details. 7 * 8 * Copyright (C) 1998 Ingo Molnar 9 * 10 * Copyright 2008 Freescale Semiconductor Inc. 11 * Port to powerpc added by Kumar Gala 12 */ 13 14 #ifndef _ASM_FIXMAP_H 15 #define _ASM_FIXMAP_H 16 17 #ifndef __ASSEMBLY__ 18 #include <linux/kernel.h> 19 #include <asm/page.h> 20 #ifdef CONFIG_HIGHMEM 21 #include <linux/threads.h> 22 #include <asm/kmap_types.h> 23 #endif 24 25 #define FIXADDR_TOP ((unsigned long)(-PAGE_SIZE)) 26 27 /* 28 * Here we define all the compile-time 'special' virtual 29 * addresses. The point is to have a constant address at 30 * compile time, but to set the physical address only 31 * in the boot process. We allocate these special addresses 32 * from the end of virtual memory (0xfffff000) backwards. 33 * Also this lets us do fail-safe vmalloc(), we 34 * can guarantee that these special addresses and 35 * vmalloc()-ed addresses never overlap. 36 * 37 * these 'compile-time allocated' memory buffers are 38 * fixed-size 4k pages. (or larger if used with an increment 39 * highger than 1) use fixmap_set(idx,phys) to associate 40 * physical memory with fixmap indices. 41 * 42 * TLB entries of such buffers will not be flushed across 43 * task switches. 44 */ 45 enum fixed_addresses { 46 FIX_HOLE, 47 #ifdef CONFIG_HIGHMEM 48 FIX_KMAP_BEGIN, /* reserved pte's for temporary kernel mappings */ 49 FIX_KMAP_END = FIX_KMAP_BEGIN+(KM_TYPE_NR*NR_CPUS)-1, 50 #endif 51 /* FIX_PCIE_MCFG, */ 52 __end_of_fixed_addresses 53 }; 54 55 extern void __set_fixmap (enum fixed_addresses idx, 56 phys_addr_t phys, pgprot_t flags); 57 58 #define set_fixmap(idx, phys) \ 59 __set_fixmap(idx, phys, PAGE_KERNEL) 60 /* 61 * Some hardware wants to get fixmapped without caching. 62 */ 63 #define set_fixmap_nocache(idx, phys) \ 64 __set_fixmap(idx, phys, PAGE_KERNEL_NCG) 65 66 #define clear_fixmap(idx) \ 67 __set_fixmap(idx, 0, __pgprot(0)) 68 69 #define __FIXADDR_SIZE (__end_of_fixed_addresses << PAGE_SHIFT) 70 #define FIXADDR_START (FIXADDR_TOP - __FIXADDR_SIZE) 71 72 #define __fix_to_virt(x) (FIXADDR_TOP - ((x) << PAGE_SHIFT)) 73 #define __virt_to_fix(x) ((FIXADDR_TOP - ((x)&PAGE_MASK)) >> PAGE_SHIFT) 74 75 extern void __this_fixmap_does_not_exist(void); 76 77 /* 78 * 'index to address' translation. If anyone tries to use the idx 79 * directly without tranlation, we catch the bug with a NULL-deference 80 * kernel oops. Illegal ranges of incoming indices are caught too. 81 */ 82 static __always_inline unsigned long fix_to_virt(const unsigned int idx) 83 { 84 /* 85 * this branch gets completely eliminated after inlining, 86 * except when someone tries to use fixaddr indices in an 87 * illegal way. (such as mixing up address types or using 88 * out-of-range indices). 89 * 90 * If it doesn't get removed, the linker will complain 91 * loudly with a reasonably clear error message.. 92 */ 93 if (idx >= __end_of_fixed_addresses) 94 __this_fixmap_does_not_exist(); 95 96 return __fix_to_virt(idx); 97 } 98 99 static inline unsigned long virt_to_fix(const unsigned long vaddr) 100 { 101 BUG_ON(vaddr >= FIXADDR_TOP || vaddr < FIXADDR_START); 102 return __virt_to_fix(vaddr); 103 } 104 105 #endif /* !__ASSEMBLY__ */ 106 #endif 107