x86, early_ioremap: fix fencepost error

commit c613ec1a7ff3714da11c7c48a13bab03beb5c376 upstream

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>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/arch/x86/mm/ioremap.c b/arch/x86/mm/ioremap.c
index f96b2e4d5f2b2a777b57a943c9d04067aec1d9da..4f8b47eb9d5f82225e9277e8d512d2cc494f66b8 100644 (file)
--- a/arch/x86/mm/ioremap.c
+++ b/arch/x86/mm/ioremap.c
@@ -438,7 +438,7 @@ 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.