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/*
* highmem.h: virtual kernel memory mappings for high memory
*
* PowerPC version, stolen from the i386 version.
*
* 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 Terrabyte 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/init.h>
#include <linux/interrupt.h>
#include <asm/kmap_types.h>
#include <asm/tlbflush.h>
#include <asm/page.h>
/* undef for production */
#define HIGHMEM_DEBUG 1
extern pte_t *kmap_pte;
extern pgprot_t kmap_prot;
extern pte_t *pkmap_page_table;
/*
* 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 CONFIG_HIGHMEM_START
#define LAST_PKMAP (1 << PTE_SHIFT)
#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))
#define KMAP_FIX_BEGIN (PKMAP_BASE + 0x00400000UL)
extern void *kmap_high(struct page *page);
extern void kunmap_high(struct page *page);
static inline void *kmap(struct page *page)
{
might_sleep();
if (!PageHighMem(page))
return page_address(page);
return kmap_high(page);
}
static inline void kunmap(struct page *page)
{
BUG_ON(in_interrupt());
if (!PageHighMem(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)
{
unsigned int idx;
unsigned long vaddr;
/* even !CONFIG_PREEMPT needs this, for in_atomic in do_page_fault */
inc_preempt_count();
if (!PageHighMem(page))
return page_address(page);
idx = type + KM_TYPE_NR*smp_processor_id();
vaddr = KMAP_FIX_BEGIN + idx * PAGE_SIZE;
#ifdef HIGHMEM_DEBUG
BUG_ON(!pte_none(*(kmap_pte+idx)));
#endif
set_pte_at(&init_mm, vaddr, kmap_pte+idx, mk_pte(page, kmap_prot));
flush_tlb_page(NULL, vaddr);
return (void*) vaddr;
}
static inline void kunmap_atomic(void *kvaddr, enum km_type type)
{
#ifdef HIGHMEM_DEBUG
unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK;
unsigned int idx = type + KM_TYPE_NR*smp_processor_id();
if (vaddr < KMAP_FIX_BEGIN) { // FIXME
dec_preempt_count();
preempt_check_resched();
return;
}
BUG_ON(vaddr != KMAP_FIX_BEGIN + idx * PAGE_SIZE);
/*
* force other mappings to Oops if they'll try to access
* this pte without first remap it
*/
pte_clear(&init_mm, vaddr, kmap_pte+idx);
flush_tlb_page(NULL, vaddr);
#endif
dec_preempt_count();
preempt_check_resched();
}
static inline struct page *kmap_atomic_to_page(void *ptr)
{
unsigned long idx, vaddr = (unsigned long) ptr;
if (vaddr < KMAP_FIX_BEGIN)
return virt_to_page(ptr);
idx = (vaddr - KMAP_FIX_BEGIN) >> PAGE_SHIFT;
return pte_page(kmap_pte[idx]);
}
#define flush_cache_kmaps() flush_cache_all()
#endif /* __KERNEL__ */
#endif /* _ASM_HIGHMEM_H */
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