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Messages in this thread Complete thread (EXPERIMENTAL)Patch in this message |
On Fri, May 09, 2008 at 12:08:18PM +0200, Ingo Molnar wrote:
* Venki Pallipadi <venkatesh.pallipadi@intel.com> wrote: I've tried doing it slightly differently below, don't know whether
you'll consider it an improvement or not.
Hugh: Thanks for looking into this. Yes. I like your modified patch. Simpler and smaller. i have stuck your original patch into testing and nothing blew up so far. Due to the mm/ bits this is not for the scope of x86.git, but obviously it all looks good and is .26-worthy to me: Acked-by: Ingo Molnar <mingo@elte.hu> Tested-by: Ingo Molnar <mingo@elte.hu> Venki, could you please send a full patch against -git that has everything from Hugh included, with an updated changelog, for Linus/Andrew to ack/apply? Ingo, Split up the patch into two parts as the pci part was unrelated to mprotect problem in a sense. And the second patch for mprotect problem. There is a defect in mprotect, which lets the user to change the page cache type bits by-passing the kernel reserve_memtype and free_memtype wrappers. Fix the problem by not letting mprotect change the PAT bits. Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com> Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Hugh Dickins <hugh@veritas.com> --- include/asm-x86/pgtable.h | 16 +++++++++++++--- mm/mprotect.c | 11 ++++++++++- 2 files changed, 23 insertions(+), 4 deletions(-)Index: linux-2.6/mm/mprotect.c [view this diff only] ===================================================================
--- linux-2.6.orig/mm/mprotect.c 2008-05-09 10:50:28.000000000 -0700
+++ linux-2.6/mm/mprotect.c 2008-05-09 11:01:23.000000000 -0700
@@ -26,6 +26,13 @@
#include <asm/cacheflush.h>
#include <asm/tlbflush.h>
+#ifndef pgprot_modify
+static inline pgprot_t pgprot_modify(pgprot_t oldprot, pgprot_t newprot)
+{
+ return newprot;
+}
+#endif
+
static void change_pte_range(struct mm_struct *mm, pmd_t *pmd,
unsigned long addr, unsigned long end, pgprot_t newprot,
int dirty_accountable)
@@ -192,7 +199,9 @@ success:
* held in write mode.
*/
vma->vm_flags = newflags;
- vma->vm_page_prot = vm_get_page_prot(newflags);
+ vma->vm_page_prot = pgprot_modify(vma->vm_page_prot,
+ vm_get_page_prot(newflags));
+
if (vma_wants_writenotify(vma)) {
vma->vm_page_prot = vm_get_page_prot(newflags & ~VM_SHARED);
dirty_accountable = 1;
Index: linux-2.6/include/asm-x86/pgtable.h
===================================================================
--- linux-2.6.orig/include/asm-x86/pgtable.h 2008-05-09 10:50:28.000000000 -0700
+++ linux-2.6/include/asm-x86/pgtable.h 2008-05-09 11:01:23.000000000 -0700
@@ -57,7 +57,8 @@
#define _KERNPG_TABLE (_PAGE_PRESENT | _PAGE_RW | _PAGE_ACCESSED | \
_PAGE_DIRTY)
-#define _PAGE_CHG_MASK (PTE_MASK | _PAGE_ACCESSED | _PAGE_DIRTY)
+#define _PAGE_CHG_MASK (PTE_MASK |_PAGE_PCD | _PAGE_PWT | \
+ _PAGE_ACCESSED | _PAGE_DIRTY)
#define _PAGE_CACHE_MASK (_PAGE_PCD | _PAGE_PWT)
#define _PAGE_CACHE_WB (0)
@@ -288,12 +289,21 @@ static inline pte_t pte_modify(pte_t pte
* Chop off the NX bit (if present), and add the NX portion of
* the newprot (if present):
*/
- val &= _PAGE_CHG_MASK & ~_PAGE_NX;
- val |= pgprot_val(newprot) & __supported_pte_mask;
+ val &= _PAGE_CHG_MASK;
+ val |= pgprot_val(newprot) & (~_PAGE_CHG_MASK) & __supported_pte_mask;
return __pte(val);
}
+/* mprotect needs to preserve PAT bits when updating vm_page_prot */
+#define pgprot_modify pgprot_modify
+static inline pgprot_t pgprot_modify(pgprot_t oldprot, pgprot_t newprot)
+{
+ pgprotval_t preservebits = pgprot_val(oldprot) & _PAGE_CHG_MASK;
+ pgprotval_t addbits = pgprot_val(newprot);
+ return __pgprot(preservebits | addbits);
+}
+
#define pte_pgprot(x) __pgprot(pte_val(x) & (0xfff | _PAGE_NX))
#define canon_pgprot(p) __pgprot(pgprot_val(p) & __supported_pte_mask)
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