[MIPS] Fix aliasing bug in copy_user_highpage, take 2.
Turns out b868868ae0f7272228c95cc760338ffe35bb739d wasn't quite right.
When called for a page that isn't marked dirty it would artificially
create an alias instead of doing the obvious thing and access the page
via KSEG0.
The same issue also exists in copy_to_user_page and copy_from_user_page
which was causing the machine to die under rare circumstances for example
when running ps if the BUG_ON() assertion added by the earlier fix was
getting triggered.
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
diff --git a/arch/mips/mm/init.c b/arch/mips/mm/init.c
index 5240432..110ee76 100644
--- a/arch/mips/mm/init.c
+++ b/arch/mips/mm/init.c
@@ -211,7 +211,7 @@
void *vfrom, *vto;
vto = kmap_atomic(to, KM_USER1);
- if (cpu_has_dc_aliases && !Page_dcache_dirty(from)) {
+ if (cpu_has_dc_aliases && page_mapped(from)) {
vfrom = kmap_coherent(from, vaddr);
copy_page(vto, vfrom);
kunmap_coherent();
@@ -234,12 +234,15 @@
struct page *page, unsigned long vaddr, void *dst, const void *src,
unsigned long len)
{
- if (cpu_has_dc_aliases) {
+ if (cpu_has_dc_aliases && page_mapped(page)) {
void *vto = kmap_coherent(page, vaddr) + (vaddr & ~PAGE_MASK);
memcpy(vto, src, len);
kunmap_coherent();
- } else
+ } else {
memcpy(dst, src, len);
+ if (cpu_has_dc_aliases)
+ SetPageDcacheDirty(page);
+ }
if ((vma->vm_flags & VM_EXEC) && !cpu_has_ic_fills_f_dc)
flush_cache_page(vma, vaddr, page_to_pfn(page));
}
@@ -250,13 +253,15 @@
struct page *page, unsigned long vaddr, void *dst, const void *src,
unsigned long len)
{
- if (cpu_has_dc_aliases) {
- void *vfrom =
- kmap_coherent(page, vaddr) + (vaddr & ~PAGE_MASK);
+ if (cpu_has_dc_aliases && page_mapped(page)) {
+ void *vfrom = kmap_coherent(page, vaddr) + (vaddr & ~PAGE_MASK);
memcpy(dst, vfrom, len);
kunmap_coherent();
- } else
+ } else {
memcpy(dst, src, len);
+ if (cpu_has_dc_aliases)
+ SetPageDcacheDirty(page);
+ }
}
EXPORT_SYMBOL(copy_from_user_page);