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/*
* highmem.h: virtual kernel memory mappings for high memory
*
* Used in CONFIG_HIGHMEM systems for memory pages which
* are not addressable by direct kernel virtual addresses.
*
* Copyright (C) 1999 Gerhard Wichert, Siemens AG
* Gerhard.Wichert@pdb.siemens.de
*
*
* Redesigned the x86 32-bit VM architecture to deal with
* up to 16 Terabyte physical memory. With current x86 CPUs
* we now support up to 64 Gigabytes physical RAM.
*
* Copyright (C) 1999 Ingo Molnar <mingo@redhat.com>
*/
#ifndef _ASM_HIGHMEM_H
#define _ASM_HIGHMEM_H
#ifdef __KERNEL__
#include <linux/config.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <asm/kmap_types.h>
#include <asm/pgtable.h>
/* undef for production */
#define HIGHMEM_DEBUG 1
/* declarations for highmem.c */
extern unsigned long highstart_pfn, highend_pfn;
extern pte_t *kmap_pte;
extern pgprot_t kmap_prot;
extern pte_t *pkmap_page_table;
extern void kmap_init(void) __init;
/*
* Right now we initialize only a single pte table. It can be extended
* easily, subsequent pte tables have to be allocated in one physical
* chunk of RAM.
*/
#define PKMAP_BASE (0xfe000000UL)
#ifdef CONFIG_X86_PAE
#define LAST_PKMAP 512
#else
#define LAST_PKMAP 1024
#endif
#define LAST_PKMAP_MASK (LAST_PKMAP-1)
#define PKMAP_NR(virt) ((virt-PKMAP_BASE) >> PAGE_SHIFT)
#define PKMAP_ADDR(nr) (PKMAP_BASE + ((nr) << PAGE_SHIFT))
extern void * FASTCALL(kmap_high(struct page *page));
extern void FASTCALL(kunmap_high(struct page *page));
static inline void *kmap(struct page *page)
{
if (in_interrupt())
BUG();
if (page < highmem_start_page)
return page_address(page);
return kmap_high(page);
}
static inline void kunmap(struct page *page)
{
if (in_interrupt())
BUG();
if (page < highmem_start_page)
return;
kunmap_high(page);
}
/*
* The use of kmap_atomic/kunmap_atomic is discouraged - kmap/kunmap
* gives a more generic (and caching) interface. But kmap_atomic can
* be used in IRQ contexts, so in some (very limited) cases we need
* it.
*/
static inline void *kmap_atomic(struct page *page, enum km_type type)
{
enum fixed_addresses idx;
unsigned long vaddr;
if (page < highmem_start_page)
return page_address(page);
idx = type + KM_TYPE_NR*smp_processor_id();
vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
#if HIGHMEM_DEBUG
if (!pte_none(*(kmap_pte-idx)))
BUG();
#endif
set_pte(kmap_pte-idx, mk_pte(page, kmap_prot));
__flush_tlb_one(vaddr);
return (void*) vaddr;
}
static inline void kunmap_atomic(void *kvaddr, enum km_type type)
{
#if HIGHMEM_DEBUG
unsigned long vaddr = (unsigned long) kvaddr;
enum fixed_addresses idx = type + KM_TYPE_NR*smp_processor_id();
if (vaddr < FIXADDR_START) // FIXME
return;
if (vaddr != __fix_to_virt(FIX_KMAP_BEGIN+idx))
BUG();
/*
* force other mappings to Oops if they'll try to access
* this pte without first remap it
*/
pte_clear(kmap_pte-idx);
__flush_tlb_one(vaddr);
#endif
}
#endif /* __KERNEL__ */
#endif /* _ASM_HIGHMEM_H */
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