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 * Support of BIGMEM added by Gerhard Wichert, Siemens AG, July 1999 11 */ 12 13 #ifndef _ASM_FIXMAP_H 14 #define _ASM_FIXMAP_H 15 16 #include <asm/pgtable.h> 17 #ifdef CONFIG_HIGHMEM 18 #include <linux/threads.h> 19 #include <asm/kmap_types.h> 20 #endif 21 22 /* 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 start of the consistent memory region upwards. 28 * Also this lets us do fail-safe vmalloc(), we 29 * can guarantee that these special addresses and 30 * vmalloc()-ed addresses never overlap. 31 * 32 * these 'compile-time allocated' memory buffers are 33 * fixed-size 4k pages. (or larger if used with an increment 34 * higher than 1) use fixmap_set(idx,phys) to associate 35 * physical memory with fixmap indices. 36 */ 37 enum fixed_addresses { 38 #ifdef CONFIG_HIGHMEM 39 /* reserved pte's for temporary kernel mappings */ 40 FIX_KMAP_BEGIN, 41 FIX_KMAP_END = FIX_KMAP_BEGIN + 42 (KM_TYPE_NR * NR_CPUS * DCACHE_N_COLORS) - 1, 43 #endif 44 __end_of_fixed_addresses 45 }; 46 47 #define FIXADDR_TOP (VMALLOC_START - PAGE_SIZE) 48 #define FIXADDR_SIZE (__end_of_fixed_addresses << PAGE_SHIFT) 49 #define FIXADDR_START ((FIXADDR_TOP - FIXADDR_SIZE) & PMD_MASK) 50 51 #define __fix_to_virt(x) (FIXADDR_START + ((x) << PAGE_SHIFT)) 52 #define __virt_to_fix(x) (((x) - FIXADDR_START) >> PAGE_SHIFT) 53 54 #ifndef __ASSEMBLY__ 55 /* 56 * 'index to address' translation. If anyone tries to use the idx 57 * directly without translation, we catch the bug with a NULL-deference 58 * kernel oops. Illegal ranges of incoming indices are caught too. 59 */ 60 static __always_inline unsigned long fix_to_virt(const unsigned int idx) 61 { 62 /* Check if this memory layout is broken because fixmap overlaps page 63 * table. 64 */ 65 BUILD_BUG_ON(FIXADDR_START < 66 XCHAL_PAGE_TABLE_VADDR + XCHAL_PAGE_TABLE_SIZE); 67 BUILD_BUG_ON(idx >= __end_of_fixed_addresses); 68 return __fix_to_virt(idx); 69 } 70 71 static inline unsigned long virt_to_fix(const unsigned long vaddr) 72 { 73 BUG_ON(vaddr >= FIXADDR_TOP || vaddr < FIXADDR_START); 74 return __virt_to_fix(vaddr); 75 } 76 77 #endif 78 79 #define kmap_get_fixmap_pte(vaddr) \ 80 pte_offset_kernel( \ 81 pmd_offset(pud_offset(pgd_offset_k(vaddr), (vaddr)), (vaddr)), \ 82 (vaddr) \ 83 ) 84 85 #endif 86