/* SPDX-License-Identifier: GPL-2.0 * * fixmap.h: compile-time virtual memory allocation * * 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/kernel.h>#include <linux/threads.h>#include <asm/page.h> /* * 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 P3 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 {	/*	 * The FIX_CMAP entries are used by kmap_coherent() to get virtual	 * addresses which are of a known color, and so their values are	 * important. __fix_to_virt(FIX_CMAP_END - n) must give an address	 * which is the same color as a page (n<<PAGE_SHIFT).	 */#define FIX_N_COLOURS 8	FIX_CMAP_BEGIN,	FIX_CMAP_END = FIX_CMAP_BEGIN + (FIX_N_COLOURS * NR_CPUS) - 1, #ifdef CONFIG_IOREMAP_FIXED	/*	 * FIX_IOREMAP entries are useful for mapping physical address	 * space before ioremap() is useable, e.g. really early in boot	 * before kmalloc() is working.	 */#define FIX_N_IOREMAPS	32	FIX_IOREMAP_BEGIN,	FIX_IOREMAP_END = FIX_IOREMAP_BEGIN + FIX_N_IOREMAPS - 1,#endif 	__end_of_fixed_addresses}; extern void __set_fixmap(enum fixed_addresses idx,			 unsigned long phys, pgprot_t flags);extern void __clear_fixmap(enum fixed_addresses idx, pgprot_t flags); /* * 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 FIXMAP_PAGE_NOCACHE PAGE_KERNEL_NOCACHE #include <asm-generic/fixmap.h> #endif