Commit 54df2db3 authored Mar 29, 2013 by Akinobu Mita Committed by David S. Miller Mar 31, 2013

sparc/srmmu: clear trailing edge of bitmap properly



srmmu_nocache_bitmap is cleared by bit_map_init().  But bit_map_init()
attempts to clear by memset(), so it can't clear the trailing edge of
bitmap properly on big-endian architecture if the number of bits is not
a multiple of BITS_PER_LONG.

Actually, the number of bits in srmmu_nocache_bitmap is not always
a multiple of BITS_PER_LONG.  It is calculated as below:

        bitmap_bits = srmmu_nocache_size >> SRMMU_NOCACHE_BITMAP_SHIFT;

srmmu_nocache_size is decided proportionally by the amount of system RAM
and it is rounded to a multiple of PAGE_SIZE.  SRMMU_NOCACHE_BITMAP_SHIFT
is defined as (PAGE_SHIFT - 4).  So it can only be said that bitmap_bits
is a multiple of 16.

This fixes the problem by using bitmap_clear() instead of memset()
in bit_map_init() and this also uses BITS_TO_LONGS() to calculate correct
size at bitmap allocation time.

Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: sparclinux@vger.kernel.org
Signed-off-by: David S. Miller <davem@davemloft.net>

parent 71196a26

arch/sparc/lib/bitext.c

+1 −5

Original line number	Diff line number	Diff line
		@@ -119,11 +119,7 @@ void bit_map_clear(struct bit_map *t, int offset, int len)

		void bit_map_init(struct bit_map t, unsigned long map, int size)
		{

		if ((size & 07) != 0)
		BUG();
		memset(map, 0, size>>3);

		bitmap_zero(map, size);
		memset(t, 0, sizeof *t);
		spin_lock_init(&t->lock);
		t->map = map;

arch/sparc/mm/srmmu.c

+3 −1

Original line number	Diff line number	Diff line
		@@ -280,7 +280,9 @@ static void __init srmmu_nocache_init(void)
		SRMMU_NOCACHE_ALIGN_MAX, 0UL);
		memset(srmmu_nocache_pool, 0, srmmu_nocache_size);

		srmmu_nocache_bitmap = __alloc_bootmem(bitmap_bits >> 3, SMP_CACHE_BYTES, 0UL);
		srmmu_nocache_bitmap =
		__alloc_bootmem(BITS_TO_LONGS(bitmap_bits) * sizeof(long),
		SMP_CACHE_BYTES, 0UL);
		bit_map_init(&srmmu_nocache_map, srmmu_nocache_bitmap, bitmap_bits);

		srmmu_swapper_pg_dir = __srmmu_get_nocache(SRMMU_PGD_TABLE_SIZE, SRMMU_PGD_TABLE_SIZE);

Admin message