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[PATCH] Fix up mmap_kmem

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vma->vm_pgoff is an pfn _offset_ relatif to the begining
of the memory start. The previous code was doing at first:

	vma->vm_pgoff << PAGE_SHIFT

which results into a wrong physical address since some
platforms have a physical mem start that can be different
from 0. After that the previous call __pa() on this
wrong physical address, however __pa() is used to convert
a _virtual_ address into a physical one.

This patch rewrites this convertion. It calculates the
pfn of PAGE_OFFSET which is the pfn of the mem start
then it adds the vma->vm_pgoff to it.

It also uses virt_to_phys() instead of __pa() since the
latter shouldn't be used by drivers.

Signed-off-by: Franck Bui-Huu <fbuihuu@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Franck Bui-Huu 2006-10-12 21:06:33 +02:00 committed by Linus Torvalds
parent a5344a9555
commit 99a10a60ba
1 changed files with 2 additions and 2 deletions
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4
drivers/char/mem.c
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@ -292,8 +292,8 @@ static int mmap_kmem(struct file * file, struct vm_area_struct * vma)
{
unsigned long pfn;
/* Turn a kernel-virtual address into a physical page frame */
pfn = __pa((u64)vma->vm_pgoff << PAGE_SHIFT) >> PAGE_SHIFT;
/* Turn a pfn offset into an absolute pfn */
pfn = PFN_DOWN(virt_to_phys((void *)PAGE_OFFSET)) + vma->vm_pgoff;
/*
* RED-PEN: on some architectures there is more mapped memory