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authorAtsushi Nemoto <anemo@mba.ocn.ne.jp>2006-12-12 17:14:56 +0000
committerLinus Torvalds <torvalds@woody.osdl.org>2006-12-13 09:27:08 -0800
commitbcd022801ee514e28c32837f0b3ce18c775f1a7b (patch)
tree6230fbec80e9f1c7580efa685ded26f638f81ef0 /arch/mips/mm
parent9de455b20705f36384a711d4a20bcf7ba1ab180b (diff)
[PATCH] MIPS: Fix COW D-cache aliasing on fork
Provide a custom copy_user_highpage() to deal with aliasing issues on MIPS. It uses kmap_coherent() to map an user page for kernel with same color. Rewrite copy_to_user_page() and copy_from_user_page() with the new interfaces to avoid extra cache flushing. The main part of this patch was originally written by Ralf Baechle; Atushi Nemoto did the the debugging. Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp> Signed-off-by: Ralf Baechle <ralf@linux-mips.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'arch/mips/mm')
-rw-r--r--arch/mips/mm/init.c25
1 files changed, 25 insertions, 0 deletions
diff --git a/arch/mips/mm/init.c b/arch/mips/mm/init.c
index ea2d15370bb..30245c09d02 100644
--- a/arch/mips/mm/init.c
+++ b/arch/mips/mm/init.c
@@ -203,6 +203,31 @@ static inline void kunmap_coherent(struct page *page)
preempt_check_resched();
}
+void copy_user_highpage(struct page *to, struct page *from,
+ unsigned long vaddr, struct vm_area_struct *vma)
+{
+ void *vfrom, *vto;
+
+ vto = kmap_atomic(to, KM_USER1);
+ if (cpu_has_dc_aliases) {
+ vfrom = kmap_coherent(from, vaddr);
+ copy_page(vto, vfrom);
+ kunmap_coherent(from);
+ } else {
+ vfrom = kmap_atomic(from, KM_USER0);
+ copy_page(vto, vfrom);
+ kunmap_atomic(vfrom, KM_USER0);
+ }
+ if (((vma->vm_flags & VM_EXEC) && !cpu_has_ic_fills_f_dc) ||
+ pages_do_alias((unsigned long)vto, vaddr & PAGE_MASK))
+ flush_data_cache_page((unsigned long)vto);
+ kunmap_atomic(vto, KM_USER1);
+ /* Make sure this page is cleared on other CPU's too before using it */
+ smp_wmb();
+}
+
+EXPORT_SYMBOL(copy_user_highpage);
+
void copy_to_user_page(struct vm_area_struct *vma,
struct page *page, unsigned long vaddr, void *dst, const void *src,
unsigned long len)