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 #ifdef CONFIG_HIGHMEM 17 #include <asm/kmap_types.h> 18 #endif 19 20 /* 21 * Here we define all the compile-time 'special' virtual 22 * addresses. The point is to have a constant address at 23 * compile time, but to set the physical address only 24 * in the boot process. We allocate these special addresses 25 * from the end of P3 backwards. 26 * Also this lets us do fail-safe vmalloc(), we 27 * can guarantee that these special addresses and 28 * vmalloc()-ed addresses never overlap. 29 * 30 * these 'compile-time allocated' memory buffers are 31 * fixed-size 4k pages. (or larger if used with an increment 32 * highger than 1) use fixmap_set(idx,phys) to associate 33 * physical memory with fixmap indices. 34 * 35 * TLB entries of such buffers will not be flushed across 36 * task switches. 37 */ 38 39 /* 40 * on UP currently we will have no trace of the fixmap mechanizm, 41 * no page table allocations, etc. This might change in the 42 * future, say framebuffers for the console driver(s) could be 43 * fix-mapped? 44 */ 45 enum fixed_addresses { 46 /* 47 * The FIX_CMAP entries are used by kmap_coherent() to get virtual 48 * addresses which are of a known color, and so their values are 49 * important. __fix_to_virt(FIX_CMAP_END - n) must give an address 50 * which is the same color as a page (n<<PAGE_SHIFT). 51 */ 52 #define FIX_N_COLOURS 8 53 FIX_CMAP_BEGIN, 54 FIX_CMAP_END = FIX_CMAP_BEGIN + (FIX_N_COLOURS * NR_CPUS) - 1, 55 56 #ifdef CONFIG_HIGHMEM 57 FIX_KMAP_BEGIN, /* reserved pte's for temporary kernel mappings */ 58 FIX_KMAP_END = FIX_KMAP_BEGIN + (KM_TYPE_NR * NR_CPUS) - 1, 59 #endif 60 61 #ifdef CONFIG_IOREMAP_FIXED 62 /* 63 * FIX_IOREMAP entries are useful for mapping physical address 64 * space before ioremap() is useable, e.g. really early in boot 65 * before kmalloc() is working. 66 */ 67 #define FIX_N_IOREMAPS 32 68 FIX_IOREMAP_BEGIN, 69 FIX_IOREMAP_END = FIX_IOREMAP_BEGIN + FIX_N_IOREMAPS - 1, 70 #endif 71 72 __end_of_fixed_addresses 73 }; 74 75 extern void __set_fixmap(enum fixed_addresses idx, 76 unsigned long phys, pgprot_t flags); 77 extern void __clear_fixmap(enum fixed_addresses idx, pgprot_t flags); 78 79 /* 80 * used by vmalloc.c. 81 * 82 * Leave one empty page between vmalloc'ed areas and 83 * the start of the fixmap, and leave one page empty 84 * at the top of mem.. 85 */ 86 #define FIXADDR_TOP (P4SEG - PAGE_SIZE) 87 #define FIXADDR_SIZE (__end_of_fixed_addresses << PAGE_SHIFT) 88 #define FIXADDR_START (FIXADDR_TOP - FIXADDR_SIZE) 89 90 #define FIXMAP_PAGE_NOCACHE PAGE_KERNEL_NOCACHE 91 92 #include <asm-generic/fixmap.h> 93 94 #endif 95