ARM: 8292/1: mm: fix size rounding-down of arm_add_memory() function
authorMasahiro Yamada <yamada.m@jp.panasonic.com>
Tue, 20 Jan 2015 03:38:25 +0000 (04:38 +0100)
committerRussell King <rmk+kernel@arm.linux.org.uk>
Wed, 21 Jan 2015 15:52:40 +0000 (15:52 +0000)
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>
arch/arm/kernel/setup.c

index f9c863911038ac7d2cbdb5c3d154edd482df8d8a..d13f185e7bd50a7f91224a9c3e63695525273883 100644 (file)
@@ -657,10 +657,13 @@ int __init arm_add_memory(u64 start, u64 size)
 
        /*
         * 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);
+       if (aligned_start > start + size)
+               size = 0;
+       else
+               size -= aligned_start - start;
 
 #ifndef CONFIG_ARCH_PHYS_ADDR_T_64BIT
        if (aligned_start > ULONG_MAX) {