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Commit 5ebf3f8d authored by Andi Kleen's avatar Andi Kleen Committed by Greg Kroah-Hartman
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x86/speculation/l1tf: Make pmd/pud_mknotpresent() invert 



commit 0768f91530ff46683e0b372df14fd79fe8d156e5 upstream

Some cases in THP like:
  - MADV_FREE
  - mprotect
  - split

mark the PMD non present for temporarily to prevent races. The window for
an L1TF attack in these contexts is very small, but it wants to be fixed
for correctness sake.

Use the proper low level functions for pmd/pud_mknotpresent() to address
this.

Signed-off-by: default avatarAndi Kleen <ak@linux.intel.com>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarDavid Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 4656dfb6

arch/x86/include/asm/pgtable.h

+6 −5
Original line number Diff line number Diff line
@@ -350,11 +350,6 @@ static inline pmd_t pmd_mkwrite(pmd_t pmd) 
	return pmd_set_flags(pmd, _PAGE_RW);

}



static inline pmd_t pmd_mknotpresent(pmd_t pmd)

{

	return pmd_clear_flags(pmd, _PAGE_PRESENT | _PAGE_PROTNONE);

}



#ifdef CONFIG_HAVE_ARCH_SOFT_DIRTY

static inline int pte_soft_dirty(pte_t pte)

{
@@ -418,6 +413,12 @@ static inline pmd_t pfn_pmd(unsigned long page_nr, pgprot_t pgprot) 
	return __pmd(pfn | massage_pgprot(pgprot));

}



static inline pmd_t pmd_mknotpresent(pmd_t pmd)

{

	return pfn_pmd(pmd_pfn(pmd),

		       __pgprot(pmd_flags(pmd) & ~(_PAGE_PRESENT|_PAGE_PROTNONE)));

}



static inline u64 flip_protnone_guard(u64 oldval, u64 val, u64 mask);



static inline pte_t pte_modify(pte_t pte, pgprot_t newprot)