| /* |
| * 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 end of virtual memory (0xfffff000) 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 mechanizm, |
| * 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 { |
| #ifdef CONFIG_HIGHMEM |
| FIX_KMAP_BEGIN, /* reserved pte's for temporary kernel mappings */ |
| 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 vmalloc'ed areas and |
| * the start of the fixmap, and leave one page empty |
| * at the top of mem.. |
| */ |
| #define FIXADDR_TOP (P4SEG - PAGE_SIZE) |
| #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 |