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ARM: 8292/1: mm: fix size rounding-down of arm_add_memory() function

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The current rounding of "size" is wrong:

 - If "start" is sufficiently near the next page boundary, "size"
   is decremented by more than enough and the last page is lost.

 - If "size" is sufficiently small, it is wrapped around and gets
   a bogus value.

Signed-off-by: Masahiro Yamada <yamada.m@jp.panasonic.com>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
Acked-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
This commit is contained in:
Masahiro Yamada 2015-01-20 04:38:25 +01:00 committed by Russell King
parent 2d9ed7406f
commit 909ba297be
1 changed files with 5 additions and 2 deletions
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7
arch/arm/kernel/setup.c
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@ -657,10 +657,13 @@ int __init arm_add_memory(u64 start, u64 size)
/* /*
* Ensure that start/size are aligned to a page boundary. * Ensure that start/size are aligned to a page boundary.
* Size is appropriately rounded down, start is rounded up. * Size is rounded down, start is rounded up.
*/ */
size -= start & ~PAGE_MASK;
aligned_start = PAGE_ALIGN(start); aligned_start = PAGE_ALIGN(start);
if (aligned_start > start + size)
size = 0;
else
size -= aligned_start - start;
#ifndef CONFIG_ARCH_PHYS_ADDR_T_64BIT #ifndef CONFIG_ARCH_PHYS_ADDR_T_64BIT
if (aligned_start > ULONG_MAX) { if (aligned_start > ULONG_MAX) {