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https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
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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>
121 lines
2.7 KiB
C
121 lines
2.7 KiB
C
#include <linux/module.h>
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#include <linux/highmem.h>
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#include <asm/tlbflush.h>
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void *__kmap(struct page *page)
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{
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void *addr;
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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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addr = kmap_high(page);
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flush_tlb_one((unsigned long)addr);
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return addr;
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}
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void __kunmap(struct page *page)
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{
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if (in_interrupt())
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BUG();
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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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* kmap_atomic/kunmap_atomic is significantly faster than kmap/kunmap because
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* no global lock is needed and because the kmap code must perform a global TLB
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* invalidation when the kmap pool wraps.
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*
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* However when holding an atomic kmap is is not legal to sleep, so atomic
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* kmaps are appropriate for short, tight code paths only.
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*/
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void *__kmap_atomic(struct page *page, enum km_type type)
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{
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enum fixed_addresses 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 = __fix_to_virt(FIX_KMAP_BEGIN + idx);
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#ifdef CONFIG_DEBUG_HIGHMEM
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if (!pte_none(*(kmap_pte-idx)))
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BUG();
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#endif
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set_pte(kmap_pte-idx, mk_pte(page, kmap_prot));
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local_flush_tlb_one((unsigned long)vaddr);
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return (void*) vaddr;
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}
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void __kunmap_atomic(void *kvaddr, enum km_type type)
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{
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#ifdef CONFIG_DEBUG_HIGHMEM
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unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK;
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enum fixed_addresses idx = type + KM_TYPE_NR*smp_processor_id();
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if (vaddr < FIXADDR_START) { // FIXME
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pagefault_enable();
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return;
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}
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if (vaddr != __fix_to_virt(FIX_KMAP_BEGIN+idx))
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BUG();
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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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local_flush_tlb_one(vaddr);
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#endif
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pagefault_enable();
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}
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#ifndef CONFIG_LIMITED_DMA
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/*
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* This is the same as kmap_atomic() but can map memory that doesn't
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* have a struct page associated with it.
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*/
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void *kmap_atomic_pfn(unsigned long pfn, enum km_type type)
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{
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enum fixed_addresses idx;
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unsigned long vaddr;
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pagefault_disable();
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idx = type + KM_TYPE_NR*smp_processor_id();
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vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
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set_pte(kmap_pte-idx, pfn_pte(pfn, kmap_prot));
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flush_tlb_one(vaddr);
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return (void*) vaddr;
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}
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#endif /* CONFIG_LIMITED_DMA */
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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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pte_t *pte;
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if (vaddr < FIXADDR_START)
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return virt_to_page(ptr);
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idx = virt_to_fix(vaddr);
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pte = kmap_pte - (idx - FIX_KMAP_BEGIN);
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return pte_page(*pte);
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}
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EXPORT_SYMBOL(__kmap);
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EXPORT_SYMBOL(__kunmap);
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EXPORT_SYMBOL(__kmap_atomic);
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EXPORT_SYMBOL(__kunmap_atomic);
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EXPORT_SYMBOL(__kmap_atomic_to_page);
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