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[PATCH] MIPS: Fix COW D-cache aliasing on fork

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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>
This commit is contained in:
Atsushi Nemoto
2006-12-12 17:14:56 +00:00
committed by Linus Torvalds
parent 9de455b207
commit bcd022801e
2 changed files with 31 additions and 10 deletions
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25
arch/mips/mm/init.c
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@@ -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)