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x86, early_ioremap: fix fencepost error

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The x86 implementation of early_ioremap has an off by one error. If we get
an object which ends on the first byte of a page we undermap by one page and
this causes a crash on boot with the ASUS P5QL whose DMI table happens to fit
this alignment.

The size computation is currently

	last_addr = phys_addr + size - 1;
	npages = (PAGE_ALIGN(last_addr) - phys_addr)

(Consider a request for 1 byte at alignment 0...)

Closes #11693

Debugging work by Ian Campbell/Felix Geyer

Signed-off-by: Alan Cox <alan@rehat.com>
Cc: <stable@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Alan Cox 2008-10-10 10:46:45 +01:00 committed by Ingo Molnar
parent e1e23bb051
commit c613ec1a7f
1 changed files with 1 additions and 1 deletions
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arch/x86/mm/ioremap.c
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@ -614,7 +614,7 @@ void __init *early_ioremap(unsigned long phys_addr, unsigned long size)
*/
offset = phys_addr & ~PAGE_MASK;
phys_addr &= PAGE_MASK;
size = PAGE_ALIGN(last_addr) - phys_addr;
size = PAGE_ALIGN(last_addr + 1) - phys_addr;
/*
* Mappings have to fit in the FIX_BTMAP area.