/* * 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 <linux/config.h> #include <linux/kernel.h> #include <asm/page.h> #ifdef CONFIG_HIGHMEM #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 top of unused virtual memory (0xfd000000 - 1 page) backwards. * 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 * highger than 1) use fixmap_set(idx,phys) to associate * physical memory with fixmap indices. * * TLB entries of such buffers will not be flushed across * task switches. */ /* * on UP currently we will have no trace of the fixmap mechanism, * no page table allocations, etc. This might change in the * future, say framebuffers for the console driver(s) could be * fix-mapped? */ enum fixed_addresses { FIX_HOLE, #ifdef CONFIG_HIGHMEM FIX_KMAP_BEGIN, FIX_KMAP_END = FIX_KMAP_BEGIN+(KM_TYPE_NR*NR_CPUS)-1, #endif __end_of_fixed_addresses }; extern void __set_fixmap (enum fixed_addresses idx, unsigned long phys, pgprot_t flags); #define set_fixmap(idx, phys) \ __set_fixmap(idx, phys, PAGE_KERNEL) /* * Some hardware wants to get fixmapped without caching. */ #define set_fixmap_nocache(idx, phys) \ __set_fixmap(idx, phys, PAGE_KERNEL_NOCACHE) /* * used by vmalloc.c. * * Leave one empty page between IO pages at 0xfd000000 and * the start of the fixmap. */ #define FIXADDR_TOP (0xfcfff000UL) #define FIXADDR_SIZE ((__end_of_fixed_addresses) << PAGE_SHIFT) #define FIXADDR_START (FIXADDR_TOP - FIXADDR_SIZE) #define __fix_to_virt(x) (FIXADDR_TOP - ((x) << PAGE_SHIFT)) #define __virt_to_fix(x) ((FIXADDR_TOP - ((x)&PAGE_MASK)) >> PAGE_SHIFT) extern void __this_fixmap_does_not_exist(void); /* * 'index to address' translation. If anyone tries to use the idx * directly without tranlation, we catch the bug with a NULL-deference * kernel oops. Illegal ranges of incoming indices are caught too. */ static inline unsigned long fix_to_virt(const unsigned int idx) { /* * this branch gets completely eliminated after inlining, * except when someone tries to use fixaddr indices in an * illegal way. (such as mixing up address types or using * out-of-range indices). * * If it doesn't get removed, the linker will complain * loudly with a reasonably clear error message.. */ if (idx >= __end_of_fixed_addresses) __this_fixmap_does_not_exist(); 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