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| author | Zachary Amsden <zach@vmware.com> | 2006-10-01 10:29:36 +0400 |
|---|---|---|
| committer | Linus Torvalds <torvalds@g5.osdl.org> | 2006-10-01 11:39:34 +0400 |
| commit | d6d861e3c963b4077c83e078e3e300c4b81f93e7 (patch) | |
| tree | 842071ac905575aa0ea8bedd3a1ac5db29416bcf /include/asm-i386/pgtable-3level.h | |
| parent | 23002d88be309a7c78db69363c9d933a29a3b0bb (diff) | |
| download | linux-d6d861e3c963b4077c83e078e3e300c4b81f93e7.tar.xz | |
[PATCH] paravirt: optimize ptep establish for pae
The ptep_establish macro is only used on user-level PTEs, for P->P mapping
changes. Since these always happen under protection of the pagetable lock,
the strong synchronization of a 64-bit cmpxchg is not needed, in fact, not
even a lock prefix needs to be used. We can simply instead clear the P-bit,
followed by a normal set. The write ordering is still important to avoid the
possibility of the TLB snooping a partially written PTE and getting a bad
mapping installed.
Signed-off-by: Zachary Amsden <zach@vmware.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Jeremy Fitzhardinge <jeremy@xensource.com>
Cc: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'include/asm-i386/pgtable-3level.h')
| -rw-r--r-- | include/asm-i386/pgtable-3level.h | 15 |
1 files changed, 15 insertions, 0 deletions
diff --git a/include/asm-i386/pgtable-3level.h b/include/asm-i386/pgtable-3level.h index 0d899173232e..7c58debdb39e 100644 --- a/include/asm-i386/pgtable-3level.h +++ b/include/asm-i386/pgtable-3level.h @@ -58,6 +58,21 @@ static inline void set_pte(pte_t *ptep, pte_t pte) } #define set_pte_at(mm,addr,ptep,pteval) set_pte(ptep,pteval) +/* + * Since this is only called on user PTEs, and the page fault handler + * must handle the already racy situation of simultaneous page faults, + * we are justified in merely clearing the PTE present bit, followed + * by a set. The ordering here is important. + */ +static inline void set_pte_present(struct mm_struct *mm, unsigned long addr, pte_t *ptep, pte_t pte) +{ + ptep->pte_low = 0; + smp_wmb(); + ptep->pte_high = pte.pte_high; + smp_wmb(); + ptep->pte_low = pte.pte_low; +} + #define __HAVE_ARCH_SET_PTE_ATOMIC #define set_pte_atomic(pteptr,pteval) \ set_64bit((unsigned long long *)(pteptr),pte_val(pteval)) |