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x86: cpa, strict range check in try_preserve_large_page() 

Right now, we check only the first 4k page for static required protections.
This does not take overlapping regions into account. So we might end up
setting the wrong permissions/protections for other parts of this large page.

This can be optimized further, but correctness is the important part.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Thomas Gleixner 2008-02-09 23:24:09 +01:00
parent b1d95f4e41
commit fac8493960
1 changed files with 15 additions and 2 deletions
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17
arch/x86/mm/pageattr.c
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@ -253,10 +253,10 @@ static int
try_preserve_large_page(pte_t *kpte, unsigned long address,
struct cpa_data *cpa)
{
unsigned long nextpage_addr, numpages, pmask, psize, flags;
unsigned long nextpage_addr, numpages, pmask, psize, flags, addr;
pte_t new_pte, old_pte, *tmp;
pgprot_t old_prot, new_prot;
int do_split = 1;
int i, do_split = 1;
unsigned int level;
spin_lock_irqsave(&pgd_lock, flags);
@ -303,6 +303,19 @@ try_preserve_large_page(pte_t *kpte, unsigned long address,
pgprot_val(new_prot) |= pgprot_val(cpa->mask_set);
new_prot = static_protections(new_prot, address);
/*
* We need to check the full range, whether
* static_protection() requires a different pgprot for one of
* the pages in the range we try to preserve:
*/
addr = address + PAGE_SIZE;
for (i = 1; i < cpa->numpages; i++, addr += PAGE_SIZE) {
pgprot_t chk_prot = static_protections(new_prot, addr);
if (pgprot_val(chk_prot) != pgprot_val(new_prot))
goto out_unlock;
}
/*
* If there are no changes, return. maxpages has been updated
* above: