1 /* SPDX-License-Identifier: GPL-2.0 2 * 3 * fixmap.h: compile-time virtual memory allocation 4 * 5 * Copyright (C) 1998 Ingo Molnar 6 * 7 * Support of BIGMEM added by Gerhard Wichert, Siemens AG, July 1999 8 */ 9 10 #ifndef _ASM_FIXMAP_H 11 #define _ASM_FIXMAP_H 12 13 #include <linux/kernel.h> 14 #include <linux/threads.h> 15 #include <asm/page.h> 16 17 /* 18 * Here we define all the compile-time 'special' virtual 19 * addresses. The point is to have a constant address at 20 * compile time, but to set the physical address only 21 * in the boot process. We allocate these special addresses 22 * from the end of P3 backwards. 23 * Also this lets us do fail-safe vmalloc(), we 24 * can guarantee that these special addresses and 25 * vmalloc()-ed addresses never overlap. 26 * 27 * these 'compile-time allocated' memory buffers are 28 * fixed-size 4k pages. (or larger if used with an increment 29 * highger than 1) use fixmap_set(idx,phys) to associate 30 * physical memory with fixmap indices. 31 * 32 * TLB entries of such buffers will not be flushed across 33 * task switches. 34 */ 35 36 /* 37 * on UP currently we will have no trace of the fixmap mechanizm, 38 * no page table allocations, etc. This might change in the 39 * future, say framebuffers for the console driver(s) could be 40 * fix-mapped? 41 */ 42 enum fixed_addresses { 43 /* 44 * The FIX_CMAP entries are used by kmap_coherent() to get virtual 45 * addresses which are of a known color, and so their values are 46 * important. __fix_to_virt(FIX_CMAP_END - n) must give an address 47 * which is the same color as a page (n<<PAGE_SHIFT). 48 */ 49 #define FIX_N_COLOURS 8 50 FIX_CMAP_BEGIN, 51 FIX_CMAP_END = FIX_CMAP_BEGIN + (FIX_N_COLOURS * NR_CPUS) - 1, 52 53 #ifdef CONFIG_IOREMAP_FIXED 54 /* 55 * FIX_IOREMAP entries are useful for mapping physical address 56 * space before ioremap() is useable, e.g. really early in boot 57 * before kmalloc() is working. 58 */ 59 #define FIX_N_IOREMAPS 32 60 FIX_IOREMAP_BEGIN, 61 FIX_IOREMAP_END = FIX_IOREMAP_BEGIN + FIX_N_IOREMAPS - 1, 62 #endif 63 64 __end_of_fixed_addresses 65 }; 66 67 extern void __set_fixmap(enum fixed_addresses idx, 68 unsigned long phys, pgprot_t flags); 69 extern void __clear_fixmap(enum fixed_addresses idx, pgprot_t flags); 70 71 /* 72 * used by vmalloc.c. 73 * 74 * Leave one empty page between vmalloc'ed areas and 75 * the start of the fixmap, and leave one page empty 76 * at the top of mem.. 77 */ 78 #define FIXADDR_TOP (P4SEG - PAGE_SIZE) 79 #define FIXADDR_SIZE (__end_of_fixed_addresses << PAGE_SHIFT) 80 #define FIXADDR_START (FIXADDR_TOP - FIXADDR_SIZE) 81 82 #define FIXMAP_PAGE_NOCACHE PAGE_KERNEL_NOCACHE 83 84 #include <asm-generic/fixmap.h> 85 86 #endif 87