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Masami reported: > Since the fixmap pages are assigned higher address to lower, > text_poke() has to use it with inverted order (FIX_TEXT_POKE1 > to FIX_TEXT_POKE0). I prefer to just invert the order of the fixmap declaration. It's simpler and more straightforward. Backward fixmaps seems to be used by both x86 32 and 64. It's really rare but a nasty bug, because it only hurts when instructions to patch are crossing a page boundary. If this happens, the fixmap write accesses will spill on the following fixmap, which may very well crash the system. And this does not crash the system, it could leave illegal instructions in place. Thanks Masami for finding this. It seems to have crept into the 2.6.30-rc series, so this calls for a -stable inclusion. Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca> Acked-by: Masami Hiramatsu <mhiramat@redhat.com> Cc: <stable@kernel.org> LKML-Reference: <20090701213722.GH19926@Krystal> Signed-off-by: Ingo Molnar <mingo@elte.hu>
209 lines
6.1 KiB
C
209 lines
6.1 KiB
C
/*
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* fixmap.h: compile-time virtual memory allocation
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*
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* This file is subject to the terms and conditions of the GNU General Public
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* License. See the file "COPYING" in the main directory of this archive
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* for more details.
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*
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* Copyright (C) 1998 Ingo Molnar
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*
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* Support of BIGMEM added by Gerhard Wichert, Siemens AG, July 1999
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* x86_32 and x86_64 integration by Gustavo F. Padovan, February 2009
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*/
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#ifndef _ASM_X86_FIXMAP_H
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#define _ASM_X86_FIXMAP_H
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#ifndef __ASSEMBLY__
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#include <linux/kernel.h>
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#include <asm/acpi.h>
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#include <asm/apicdef.h>
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#include <asm/page.h>
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#ifdef CONFIG_X86_32
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#include <linux/threads.h>
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#include <asm/kmap_types.h>
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#else
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#include <asm/vsyscall.h>
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#endif
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/*
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* We can't declare FIXADDR_TOP as variable for x86_64 because vsyscall
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* uses fixmaps that relies on FIXADDR_TOP for proper address calculation.
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* Because of this, FIXADDR_TOP x86 integration was left as later work.
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*/
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#ifdef CONFIG_X86_32
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/* used by vmalloc.c, vsyscall.lds.S.
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*
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* Leave one empty page between vmalloc'ed areas and
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* the start of the fixmap.
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*/
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extern unsigned long __FIXADDR_TOP;
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#define FIXADDR_TOP ((unsigned long)__FIXADDR_TOP)
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#define FIXADDR_USER_START __fix_to_virt(FIX_VDSO)
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#define FIXADDR_USER_END __fix_to_virt(FIX_VDSO - 1)
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#else
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#define FIXADDR_TOP (VSYSCALL_END-PAGE_SIZE)
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/* Only covers 32bit vsyscalls currently. Need another set for 64bit. */
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#define FIXADDR_USER_START ((unsigned long)VSYSCALL32_VSYSCALL)
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#define FIXADDR_USER_END (FIXADDR_USER_START + PAGE_SIZE)
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#endif
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/*
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* Here we define all the compile-time 'special' virtual
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* addresses. The point is to have a constant address at
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* compile time, but to set the physical address only
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* in the boot process.
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* for x86_32: We allocate these special addresses
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* from the end of virtual memory (0xfffff000) backwards.
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* Also this lets us do fail-safe vmalloc(), we
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* can guarantee that these special addresses and
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* vmalloc()-ed addresses never overlap.
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*
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* These 'compile-time allocated' memory buffers are
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* fixed-size 4k pages (or larger if used with an increment
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* higher than 1). Use set_fixmap(idx,phys) to associate
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* physical memory with fixmap indices.
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*
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* TLB entries of such buffers will not be flushed across
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* task switches.
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*/
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enum fixed_addresses {
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#ifdef CONFIG_X86_32
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FIX_HOLE,
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FIX_VDSO,
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#else
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VSYSCALL_LAST_PAGE,
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VSYSCALL_FIRST_PAGE = VSYSCALL_LAST_PAGE
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+ ((VSYSCALL_END-VSYSCALL_START) >> PAGE_SHIFT) - 1,
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VSYSCALL_HPET,
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#endif
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FIX_DBGP_BASE,
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FIX_EARLYCON_MEM_BASE,
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#ifdef CONFIG_X86_LOCAL_APIC
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FIX_APIC_BASE, /* local (CPU) APIC) -- required for SMP or not */
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#endif
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#ifdef CONFIG_X86_IO_APIC
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FIX_IO_APIC_BASE_0,
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FIX_IO_APIC_BASE_END = FIX_IO_APIC_BASE_0 + MAX_IO_APICS - 1,
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#endif
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#ifdef CONFIG_X86_VISWS_APIC
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FIX_CO_CPU, /* Cobalt timer */
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FIX_CO_APIC, /* Cobalt APIC Redirection Table */
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FIX_LI_PCIA, /* Lithium PCI Bridge A */
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FIX_LI_PCIB, /* Lithium PCI Bridge B */
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#endif
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#ifdef CONFIG_X86_F00F_BUG
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FIX_F00F_IDT, /* Virtual mapping for IDT */
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#endif
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#ifdef CONFIG_X86_CYCLONE_TIMER
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FIX_CYCLONE_TIMER, /*cyclone timer register*/
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#endif
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#ifdef CONFIG_X86_32
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FIX_KMAP_BEGIN, /* reserved pte's for temporary kernel mappings */
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FIX_KMAP_END = FIX_KMAP_BEGIN+(KM_TYPE_NR*NR_CPUS)-1,
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#ifdef CONFIG_PCI_MMCONFIG
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FIX_PCIE_MCFG,
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#endif
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#endif
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#ifdef CONFIG_PARAVIRT
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FIX_PARAVIRT_BOOTMAP,
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#endif
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FIX_TEXT_POKE1, /* reserve 2 pages for text_poke() */
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FIX_TEXT_POKE0, /* first page is last, because allocation is backward */
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__end_of_permanent_fixed_addresses,
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/*
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* 256 temporary boot-time mappings, used by early_ioremap(),
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* before ioremap() is functional.
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*
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* We round it up to the next 256 pages boundary so that we
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* can have a single pgd entry and a single pte table:
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*/
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#define NR_FIX_BTMAPS 64
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#define FIX_BTMAPS_SLOTS 4
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FIX_BTMAP_END = __end_of_permanent_fixed_addresses + 256 -
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(__end_of_permanent_fixed_addresses & 255),
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FIX_BTMAP_BEGIN = FIX_BTMAP_END + NR_FIX_BTMAPS*FIX_BTMAPS_SLOTS - 1,
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#ifdef CONFIG_PROVIDE_OHCI1394_DMA_INIT
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FIX_OHCI1394_BASE,
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#endif
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#ifdef CONFIG_X86_32
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FIX_WP_TEST,
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#endif
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__end_of_fixed_addresses
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};
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extern void reserve_top_address(unsigned long reserve);
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#define FIXADDR_SIZE (__end_of_permanent_fixed_addresses << PAGE_SHIFT)
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#define FIXADDR_BOOT_SIZE (__end_of_fixed_addresses << PAGE_SHIFT)
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#define FIXADDR_START (FIXADDR_TOP - FIXADDR_SIZE)
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#define FIXADDR_BOOT_START (FIXADDR_TOP - FIXADDR_BOOT_SIZE)
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extern int fixmaps_set;
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extern pte_t *kmap_pte;
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extern pgprot_t kmap_prot;
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extern pte_t *pkmap_page_table;
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void __native_set_fixmap(enum fixed_addresses idx, pte_t pte);
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void native_set_fixmap(enum fixed_addresses idx,
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phys_addr_t phys, pgprot_t flags);
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#ifndef CONFIG_PARAVIRT
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static inline void __set_fixmap(enum fixed_addresses idx,
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phys_addr_t phys, pgprot_t flags)
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{
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native_set_fixmap(idx, phys, flags);
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}
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#endif
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#define set_fixmap(idx, phys) \
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__set_fixmap(idx, phys, PAGE_KERNEL)
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/*
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* Some hardware wants to get fixmapped without caching.
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*/
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#define set_fixmap_nocache(idx, phys) \
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__set_fixmap(idx, phys, PAGE_KERNEL_NOCACHE)
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#define clear_fixmap(idx) \
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__set_fixmap(idx, 0, __pgprot(0))
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#define __fix_to_virt(x) (FIXADDR_TOP - ((x) << PAGE_SHIFT))
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#define __virt_to_fix(x) ((FIXADDR_TOP - ((x)&PAGE_MASK)) >> PAGE_SHIFT)
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extern void __this_fixmap_does_not_exist(void);
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/*
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* 'index to address' translation. If anyone tries to use the idx
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* directly without translation, we catch the bug with a NULL-deference
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* kernel oops. Illegal ranges of incoming indices are caught too.
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*/
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static __always_inline unsigned long fix_to_virt(const unsigned int idx)
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{
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/*
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* this branch gets completely eliminated after inlining,
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* except when someone tries to use fixaddr indices in an
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* illegal way. (such as mixing up address types or using
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* out-of-range indices).
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*
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* If it doesn't get removed, the linker will complain
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* loudly with a reasonably clear error message..
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*/
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if (idx >= __end_of_fixed_addresses)
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__this_fixmap_does_not_exist();
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return __fix_to_virt(idx);
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}
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static inline unsigned long virt_to_fix(const unsigned long vaddr)
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{
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BUG_ON(vaddr >= FIXADDR_TOP || vaddr < FIXADDR_START);
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return __virt_to_fix(vaddr);
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}
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#endif /* !__ASSEMBLY__ */
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#endif /* _ASM_X86_FIXMAP_H */
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