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x86: CPA fix pagetable split

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Move the readout of the large entry into the spinlock section to
prevent an unlikely but possible race.

Mark the pmd/pud entry present after the split. We preserved the
non present bit in the new split mapping.

Remove the stale gfp_flags double initialization.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Thomas Gleixner 2008-02-04 16:48:08 +01:00 committed by Ingo Molnar
parent 31422c51e0
commit 07cf89c05f
1 changed files with 7 additions and 3 deletions
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10
arch/x86/mm/pageattr.c
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@ -336,7 +336,7 @@ out_unlock:
static int split_large_page(pte_t *kpte, unsigned long address)
{
pgprot_t ref_prot = pte_pgprot(pte_clrhuge(*kpte));
pgprot_t ref_prot;
gfp_t gfp_flags = GFP_KERNEL;
unsigned long flags, addr, pfn;
pte_t *pbase, *tmp;
@ -344,7 +344,6 @@ static int split_large_page(pte_t *kpte, unsigned long address)
unsigned int i, level;
#ifdef CONFIG_DEBUG_PAGEALLOC
gfp_flags = __GFP_HIGH | __GFP_NOFAIL | __GFP_NOWARN;
gfp_flags = GFP_ATOMIC | __GFP_NOWARN;
#endif
base = alloc_pages(gfp_flags, 0);
@ -368,6 +367,7 @@ static int split_large_page(pte_t *kpte, unsigned long address)
#ifdef CONFIG_X86_32
paravirt_alloc_pt(&init_mm, page_to_pfn(base));
#endif
ref_prot = pte_pgprot(pte_clrhuge(*kpte));
/*
* Get the target pfn from the original entry:
@ -377,13 +377,17 @@ static int split_large_page(pte_t *kpte, unsigned long address)
set_pte(&pbase[i], pfn_pte(pfn, ref_prot));
/*
* Install the new, split up pagetable. Important detail here:
* Install the new, split up pagetable. Important details here:
*
* On Intel the NX bit of all levels must be cleared to make a
* page executable. See section 4.13.2 of Intel 64 and IA-32
* Architectures Software Developer's Manual).
*
* Mark the entry present. The current mapping might be
* set to not present, which we preserved above.
*/
ref_prot = pte_pgprot(pte_mkexec(pte_clrhuge(*kpte)));
pgprot_val(ref_prot) |= _PAGE_PRESENT;
__set_pmd_pte(kpte, address, mk_pte(base, ref_prot));
base = NULL;