/* * fixmap.h: compile-time virtual memory allocation * * This file is subject to the terms and conditions of the GNU General Public * License. See the file "COPYING" in the main directory of this archive * for more details. * * Copyright (C) 1998 Ingo Molnar * * Support of BIGMEM added by Gerhard Wichert, Siemens AG, July 1999 */ #ifndef _ASM_FIXMAP_H #define _ASM_FIXMAP_H #include <asm/pgtable.h> #ifdef [31mCONFIG_HIGHMEM[0m #include <linux/threads.h> #include <asm/kmap_types.h> #endif /* * Here we define all the compile-time 'special' virtual * addresses. The point is to have a constant address at * compile time, but to set the physical address only * in the boot process. We allocate these special addresses * from the start of the consistent memory region upwards. * Also this lets us do fail-safe vmalloc(), we * can guarantee that these special addresses and * vmalloc()-ed addresses never overlap. * * these 'compile-time allocated' memory buffers are * fixed-size 4k pages. (or larger if used with an increment * higher than 1) use fixmap_set(idx,phys) to associate * physical memory with fixmap indices. */ enum fixed_addresses { #ifdef [31mCONFIG_HIGHMEM[0m /* reserved pte's for temporary kernel mappings */ FIX_KMAP_BEGIN, FIX_KMAP_END = FIX_KMAP_BEGIN + (KM_TYPE_NR * NR_CPUS * DCACHE_N_COLORS) - 1, #endif __end_of_fixed_addresses }; #define FIXADDR_TOP (VMALLOC_START - PAGE_SIZE) #define FIXADDR_SIZE (__end_of_fixed_addresses << PAGE_SHIFT) #define FIXADDR_START ((FIXADDR_TOP - FIXADDR_SIZE) & PMD_MASK) #define __fix_to_virt(x) (FIXADDR_START + ((x) << PAGE_SHIFT)) #define __virt_to_fix(x) (((x) - FIXADDR_START) >> PAGE_SHIFT) #ifndef __ASSEMBLY__ /* * 'index to address' translation. If anyone tries to use the idx * directly without translation, we catch the bug with a NULL-deference * kernel oops. Illegal ranges of incoming indices are caught too. */ static __always_inline unsigned long fix_to_virt(const unsigned int idx) { /* Check if this memory layout is broken because fixmap overlaps page * table. */ BUILD_BUG_ON(FIXADDR_START < XCHAL_PAGE_TABLE_VADDR + XCHAL_PAGE_TABLE_SIZE); BUILD_BUG_ON(idx >= __end_of_fixed_addresses); return __fix_to_virt(idx); } static inline unsigned long virt_to_fix(const unsigned long vaddr) { BUG_ON(vaddr >= FIXADDR_TOP || vaddr < FIXADDR_START); return __virt_to_fix(vaddr); } #endif #define kmap_get_fixmap_pte(vaddr) \ pte_offset_kernel( \ pmd_offset(pud_offset(pgd_offset_k(vaddr), (vaddr)), (vaddr)), \ (vaddr) \ ) #endif |