138 lines
3.3 KiB
C
138 lines
3.3 KiB
C
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/*
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* highmem.h: virtual kernel memory mappings for high memory
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*
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* PowerPC version, stolen from the i386 version.
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*
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* Used in CONFIG_HIGHMEM systems for memory pages which
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* are not addressable by direct kernel virtual addresses.
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*
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* Copyright (C) 1999 Gerhard Wichert, Siemens AG
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* Gerhard.Wichert@pdb.siemens.de
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*
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*
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* Redesigned the x86 32-bit VM architecture to deal with
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* up to 16 Terrabyte physical memory. With current x86 CPUs
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* we now support up to 64 Gigabytes physical RAM.
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*
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* Copyright (C) 1999 Ingo Molnar <mingo@redhat.com>
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*/
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#ifndef _ASM_HIGHMEM_H
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#define _ASM_HIGHMEM_H
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#ifdef __KERNEL__
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#include <linux/init.h>
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#include <linux/interrupt.h>
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#include <asm/kmap_types.h>
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#include <asm/tlbflush.h>
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#include <asm/page.h>
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/* undef for production */
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#define HIGHMEM_DEBUG 1
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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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/*
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* Right now we initialize only a single pte table. It can be extended
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* easily, subsequent pte tables have to be allocated in one physical
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* chunk of RAM.
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*/
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#define PKMAP_BASE CONFIG_HIGHMEM_START
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#define LAST_PKMAP (1 << PTE_SHIFT)
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#define LAST_PKMAP_MASK (LAST_PKMAP-1)
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#define PKMAP_NR(virt) ((virt-PKMAP_BASE) >> PAGE_SHIFT)
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#define PKMAP_ADDR(nr) (PKMAP_BASE + ((nr) << PAGE_SHIFT))
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#define KMAP_FIX_BEGIN (PKMAP_BASE + 0x00400000UL)
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extern void *kmap_high(struct page *page);
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extern void kunmap_high(struct page *page);
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static inline void *kmap(struct page *page)
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{
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might_sleep();
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if (!PageHighMem(page))
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return page_address(page);
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return kmap_high(page);
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}
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static inline void kunmap(struct page *page)
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{
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BUG_ON(in_interrupt());
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if (!PageHighMem(page))
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return;
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kunmap_high(page);
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}
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/*
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* The use of kmap_atomic/kunmap_atomic is discouraged - kmap/kunmap
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* gives a more generic (and caching) interface. But kmap_atomic can
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* be used in IRQ contexts, so in some (very limited) cases we need
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* it.
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*/
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static inline void *kmap_atomic(struct page *page, enum km_type type)
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{
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unsigned int idx;
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unsigned long vaddr;
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/* even !CONFIG_PREEMPT needs this, for in_atomic in do_page_fault */
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inc_preempt_count();
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if (!PageHighMem(page))
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return page_address(page);
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idx = type + KM_TYPE_NR*smp_processor_id();
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vaddr = KMAP_FIX_BEGIN + idx * PAGE_SIZE;
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#ifdef HIGHMEM_DEBUG
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BUG_ON(!pte_none(*(kmap_pte+idx)));
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#endif
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set_pte_at(&init_mm, vaddr, kmap_pte+idx, mk_pte(page, kmap_prot));
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flush_tlb_page(NULL, vaddr);
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return (void*) vaddr;
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}
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static inline void kunmap_atomic(void *kvaddr, enum km_type type)
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{
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#ifdef HIGHMEM_DEBUG
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unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK;
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unsigned int idx = type + KM_TYPE_NR*smp_processor_id();
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if (vaddr < KMAP_FIX_BEGIN) { // FIXME
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dec_preempt_count();
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preempt_check_resched();
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return;
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}
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BUG_ON(vaddr != KMAP_FIX_BEGIN + idx * PAGE_SIZE);
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/*
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* force other mappings to Oops if they'll try to access
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* this pte without first remap it
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*/
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pte_clear(&init_mm, vaddr, kmap_pte+idx);
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flush_tlb_page(NULL, vaddr);
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#endif
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dec_preempt_count();
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preempt_check_resched();
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}
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static inline struct page *kmap_atomic_to_page(void *ptr)
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{
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unsigned long idx, vaddr = (unsigned long) ptr;
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if (vaddr < KMAP_FIX_BEGIN)
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return virt_to_page(ptr);
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idx = (vaddr - KMAP_FIX_BEGIN) >> PAGE_SHIFT;
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return pte_page(kmap_pte[idx]);
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}
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#define flush_cache_kmaps() flush_cache_all()
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#endif /* __KERNEL__ */
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#endif /* _ASM_HIGHMEM_H */
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