On Tue, 17 Oct 2006 13:15:37 +0400
Dmitriy Monakhov <[email protected]> wrote:
> from mm/memory.c:
> 1434 static inline void cow_user_page(struct page *dst, struct page *src, unsigned long va)
> 1435 {
> 1436 /*
> 1437 * If the source page was a PFN mapping, we don't have
> 1438 * a "struct page" for it. We do a best-effort copy by
> 1439 * just copying from the original user address. If that
> 1440 * fails, we just zero-fill it. Live with it.
> 1441 */
> 1442 if (unlikely(!src)) {
> 1443 void *kaddr = kmap_atomic(dst, KM_USER0);
> 1444 void __user *uaddr = (void __user *)(va & PAGE_MASK);
> 1445
> 1446 /*
> 1447 * This really shouldn't fail, because the page is there
> 1448 * in the page tables. But it might just be unreadable,
> 1449 * in which case we just give up and fill the result with
> 1450 * zeroes.
> 1451 */
> 1452 if (__copy_from_user_inatomic(kaddr, uaddr, PAGE_SIZE))
> 1453 memset(kaddr, 0, PAGE_SIZE);
> 1454 kunmap_atomic(kaddr, KM_USER0);
> #### D-cache have to be flushed here.
> #### It seems it is just forgotten.
>
> 1455 return;
> 1456
> 1457 }
> 1458 copy_user_highpage(dst, src, va);
> #### Ok here. flush_dcache_page() called from this func if arch need it
> 1459 }
>
This page has just been allocated and is private to the caller - there can
be no userspace mappings of it.
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
[Index of Archives]
[Kernel Newbies]
[Netfilter]
[Bugtraq]
[Photo]
[Stuff]
[Gimp]
[Yosemite News]
[MIPS Linux]
[ARM Linux]
[Linux Security]
[Linux RAID]
[Video 4 Linux]
[Linux for the blind]
[Linux Resources]
