/* * 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/page.h>#include <spaces.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 {#define FIX_N_COLOURS 8	FIX_CMAP_BEGIN,#ifdef CONFIG_MIPS_MT_SMTC	FIX_CMAP_END = FIX_CMAP_BEGIN + (FIX_N_COLOURS * NR_CPUS * 2),#else	FIX_CMAP_END = FIX_CMAP_BEGIN + (FIX_N_COLOURS * 2),#endif#ifdef CONFIG_HIGHMEM	/* reserved pte's for temporary kernel mappings */	FIX_KMAP_BEGIN = FIX_CMAP_END + 1,	FIX_KMAP_END = FIX_KMAP_BEGIN+(KM_TYPE_NR*NR_CPUS)-1,#endif	__end_of_fixed_addresses}; /* * 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_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);} #define kmap_get_fixmap_pte(vaddr)					\	pte_offset_kernel(pmd_offset(pud_offset(pgd_offset_k(vaddr), (vaddr)), (vaddr)), (vaddr)) /* * Called from pgtable_init() */extern void fixrange_init(unsigned long start, unsigned long end,	pgd_t *pgd_base);  #endif