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authorRalf Baechle <ralf@linux-mips.org>2007-09-11 18:05:33 +0100
committerRalf Baechle <ralf@linux-mips.org>2007-09-11 19:03:26 +0100
commitb868868ae0f7272228c95cc760338ffe35bb739d (patch)
tree71ed6189bc2dddd3f79aae0969e41381f905a709 /arch
parent01e9943c79ad4edb2c0b76c99029e34d704223ce (diff)
downloadlinux-linaro-b868868ae0f7272228c95cc760338ffe35bb739d.tar.gz
[MIPS] Fix aliasing bug in copy_user_highpage.
Copy_user_highpage was written assuming it was only being called for breaking COW pages in which case the source page isn't cached as in marked cachable under it kernel virtual address. If it is called anyway the aliasing avoidance strategy implemented by kmap_coherent will fail. Avoid the use of kmap_coherent for pages marked dirty and to avoid another instance of this sort of bug, place a BUG_ON in kmap_coherent. Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Diffstat (limited to 'arch')
-rw-r--r--arch/mips/mm/init.c5
1 files changed, 4 insertions, 1 deletions
diff --git a/arch/mips/mm/init.c b/arch/mips/mm/init.c
index 09d91505b90..5240432e6d1 100644
--- a/arch/mips/mm/init.c
+++ b/arch/mips/mm/init.c
@@ -8,6 +8,7 @@
* Kevin D. Kissell, kevink@mips.com and Carsten Langgaard, carstenl@mips.com
* Copyright (C) 2000 MIPS Technologies, Inc. All rights reserved.
*/
+#include <linux/bug.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/signal.h>
@@ -132,6 +133,8 @@ void *kmap_coherent(struct page *page, unsigned long addr)
pte_t pte;
int tlbidx;
+ BUG_ON(Page_dcache_dirty(page));
+
inc_preempt_count();
idx = (addr >> PAGE_SHIFT) & (FIX_N_COLOURS - 1);
#ifdef CONFIG_MIPS_MT_SMTC
@@ -208,7 +211,7 @@ void copy_user_highpage(struct page *to, struct page *from,
void *vfrom, *vto;
vto = kmap_atomic(to, KM_USER1);
- if (cpu_has_dc_aliases) {
+ if (cpu_has_dc_aliases && !Page_dcache_dirty(from)) {
vfrom = kmap_coherent(from, vaddr);
copy_page(vto, vfrom);
kunmap_coherent();