2 * fixmap.h: compile-time virtual memory allocation
4 * This file is subject to the terms and conditions of the GNU General Public
5 * License. See the file "COPYING" in the main directory of this archive
8 * Copyright (C) 1998 Ingo Molnar
14 #include <linux/kernel.h>
15 #include <asm/apicdef.h>
17 #include <asm/vsyscall.h>
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.
26 * These 'compile-time allocated' memory buffers are
27 * fixed-size 4k pages (or larger if used with an increment
28 * higher than 1). Use set_fixmap(idx,phys) to associate
29 * physical memory with fixmap indices.
31 * TLB entries of such buffers will not be flushed across
35 enum fixed_addresses {
37 VSYSCALL_FIRST_PAGE = VSYSCALL_LAST_PAGE
38 + ((VSYSCALL_END-VSYSCALL_START) >> PAGE_SHIFT) - 1,
41 FIX_EARLYCON_MEM_BASE,
43 FIX_APIC_BASE, /* local (CPU) APIC) -- required for SMP or not */
45 FIX_IO_APIC_BASE_END = FIX_IO_APIC_BASE_0 + MAX_IO_APICS - 1,
46 FIX_EFI_IO_MAP_LAST_PAGE,
47 FIX_EFI_IO_MAP_FIRST_PAGE = FIX_EFI_IO_MAP_LAST_PAGE
48 + MAX_EFI_IO_PAGES - 1,
49 #ifdef CONFIG_PROVIDE_OHCI1394_DMA_INIT
52 __end_of_fixed_addresses
55 extern void __set_fixmap(enum fixed_addresses idx,
56 unsigned long phys, pgprot_t flags);
58 #define set_fixmap(idx, phys) \
59 __set_fixmap(idx, phys, PAGE_KERNEL)
61 * Some hardware wants to get fixmapped without caching.
63 #define set_fixmap_nocache(idx, phys) \
64 __set_fixmap(idx, phys, PAGE_KERNEL_NOCACHE)
66 #define FIXADDR_TOP (VSYSCALL_END-PAGE_SIZE)
67 #define FIXADDR_SIZE (__end_of_fixed_addresses << PAGE_SHIFT)
68 #define FIXADDR_START (FIXADDR_TOP - FIXADDR_SIZE)
70 /* Only covers 32bit vsyscalls currently. Need another set for 64bit. */
71 #define FIXADDR_USER_START ((unsigned long)VSYSCALL32_VSYSCALL)
72 #define FIXADDR_USER_END (FIXADDR_USER_START + PAGE_SIZE)
74 #define __fix_to_virt(x) (FIXADDR_TOP - ((x) << PAGE_SHIFT))
76 extern void __this_fixmap_does_not_exist(void);
79 * 'index to address' translation. If anyone tries to use the idx
80 * directly without translation, we catch the bug with a NULL-deference
81 * kernel oops. Illegal ranges of incoming indices are caught too.
83 static __always_inline unsigned long fix_to_virt(const unsigned int idx)
86 * this branch gets completely eliminated after inlining,
87 * except when someone tries to use fixaddr indices in an
88 * illegal way. (such as mixing up address types or using
89 * out-of-range indices).
91 * If it doesn't get removed, the linker will complain
92 * loudly with a reasonably clear error message..
94 if (idx >= __end_of_fixed_addresses)
95 __this_fixmap_does_not_exist();
97 return __fix_to_virt(idx);