forked from Minki/linux
db0dc75d64
Signed-off-by: Arun Sharma <asharma@fb.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: linux-kernel@vger.kernel.org Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/1334961696-19580-5-git-send-email-asharma@fb.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
50 lines
934 B
C
50 lines
934 B
C
/*
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* User address space access functions.
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*
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* For licencing details see kernel-base/COPYING
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*/
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#include <linux/highmem.h>
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#include <linux/module.h>
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#include <asm/word-at-a-time.h>
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#include <linux/sched.h>
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/*
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* best effort, GUP based copy_from_user() that is NMI-safe
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*/
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unsigned long
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copy_from_user_nmi(void *to, const void __user *from, unsigned long n)
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{
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unsigned long offset, addr = (unsigned long)from;
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unsigned long size, len = 0;
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struct page *page;
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void *map;
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int ret;
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if (__range_not_ok(from, n, TASK_SIZE) == 0)
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return len;
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do {
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ret = __get_user_pages_fast(addr, 1, 0, &page);
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if (!ret)
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break;
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offset = addr & (PAGE_SIZE - 1);
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size = min(PAGE_SIZE - offset, n - len);
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map = kmap_atomic(page);
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memcpy(to, map+offset, size);
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kunmap_atomic(map);
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put_page(page);
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len += size;
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to += size;
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addr += size;
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} while (len < n);
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return len;
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}
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EXPORT_SYMBOL_GPL(copy_from_user_nmi);
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