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a866374aec
Introduce pagefault_{disable,enable}() and use these where previously we did
manual preempt increments/decrements to make the pagefault handler do the
atomic thing.
Currently they still rely on the increased preempt count, but do not rely on
the disabled preemption, this might go away in the future.
(NOTE: the extra barrier() in pagefault_disable might fix some holes on
machines which have too many registers for their own good)
[heiko.carstens@de.ibm.com: s390 fix]
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Nick Piggin <npiggin@suse.de>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
136 lines
3.3 KiB
C
136 lines
3.3 KiB
C
/*
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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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pagefault_disable();
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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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pagefault_enable();
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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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pagefault_enable();
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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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