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>
16 #include <xen/gnttab.h>
18 #include <asm/vsyscall.h>
19 #include <asm/vsyscall32.h>
23 * Here we define all the compile-time 'special' virtual
24 * addresses. The point is to have a constant address at
25 * compile time, but to set the physical address only
26 * in the boot process.
28 * these 'compile-time allocated' memory buffers are
29 * fixed-size 4k pages. (or larger if used with an increment
30 * highger than 1) use fixmap_set(idx,phys) to associate
31 * physical memory with fixmap indices.
33 * TLB entries of such buffers will not be flushed across
37 enum fixed_addresses {
39 VSYSCALL_FIRST_PAGE = VSYSCALL_LAST_PAGE + ((VSYSCALL_END-VSYSCALL_START) >> PAGE_SHIFT) - 1,
42 #ifdef CONFIG_X86_LOCAL_APIC
43 FIX_APIC_BASE, /* local (CPU) APIC) -- required for SMP or not */
45 #ifdef CONFIG_X86_IO_APIC
47 FIX_IO_APIC_BASE_END = FIX_IO_APIC_BASE_0 + MAX_IO_APICS-1,
51 FIX_ACPI_END = FIX_ACPI_BEGIN + FIX_ACPI_PAGES - 1,
54 #define NR_FIX_ISAMAPS 256
56 FIX_ISAMAP_BEGIN = FIX_ISAMAP_END + NR_FIX_ISAMAPS - 1,
57 __end_of_permanent_fixed_addresses,
58 /* temporary boot-time mappings, used before ioremap() is functional */
59 #define NR_FIX_BTMAPS 16
60 FIX_BTMAP_END = __end_of_permanent_fixed_addresses,
61 FIX_BTMAP_BEGIN = FIX_BTMAP_END + NR_FIX_BTMAPS - 1,
62 __end_of_fixed_addresses
65 extern void __set_fixmap (enum fixed_addresses idx,
66 unsigned long phys, pgprot_t flags);
68 #define set_fixmap(idx, phys) \
69 __set_fixmap(idx, phys, PAGE_KERNEL)
71 * Some hardware wants to get fixmapped without caching.
73 #define set_fixmap_nocache(idx, phys) \
74 __set_fixmap(idx, phys, PAGE_KERNEL_NOCACHE)
76 #define clear_fixmap(idx) \
77 __set_fixmap(idx, 0, __pgprot(0))
79 #define FIXADDR_TOP (VSYSCALL_END-PAGE_SIZE)
80 #define FIXADDR_SIZE (__end_of_fixed_addresses << PAGE_SHIFT)
81 #define FIXADDR_START (FIXADDR_TOP - FIXADDR_SIZE)
83 /* Only covers 32bit vsyscalls currently. Need another set for 64bit. */
84 #define FIXADDR_USER_START ((unsigned long)VSYSCALL32_VSYSCALL)
85 #define FIXADDR_USER_END (FIXADDR_USER_START + PAGE_SIZE)
87 #define __fix_to_virt(x) (FIXADDR_TOP - ((x) << PAGE_SHIFT))
89 extern void __this_fixmap_does_not_exist(void);
92 * 'index to address' translation. If anyone tries to use the idx
93 * directly without translation, we catch the bug with a NULL-deference
94 * kernel oops. Illegal ranges of incoming indices are caught too.
96 static __always_inline unsigned long fix_to_virt(const unsigned int idx)
99 * this branch gets completely eliminated after inlining,
100 * except when someone tries to use fixaddr indices in an
101 * illegal way. (such as mixing up address types or using
102 * out-of-range indices).
104 * If it doesn't get removed, the linker will complain
105 * loudly with a reasonably clear error message..
107 if (idx >= __end_of_fixed_addresses)
108 __this_fixmap_does_not_exist();
110 return __fix_to_virt(idx);