Commit 0768f915 authored by Andi Kleen's avatar Andi Kleen Committed by Thomas Gleixner
Browse files

x86/speculation/l1tf: Make pmd/pud_mknotpresent() invert 



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>
parent f22cc87f

arch/x86/include/asm/pgtable.h

+12 −10
Original line number Diff line number Diff line
@@ -410,11 +410,6 @@ 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);

}



static inline pud_t pud_set_flags(pud_t pud, pudval_t set)

{

	pudval_t v = native_pud_val(pud);
@@ -469,11 +464,6 @@ static inline pud_t pud_mkwrite(pud_t pud) 
	return pud_set_flags(pud, _PAGE_RW);

}



static inline pud_t pud_mknotpresent(pud_t pud)

{

	return pud_clear_flags(pud, _PAGE_PRESENT | _PAGE_PROTNONE);

}



#ifdef CONFIG_HAVE_ARCH_SOFT_DIRTY

static inline int pte_soft_dirty(pte_t pte)

{
@@ -577,6 +567,18 @@ static inline pud_t pfn_pud(unsigned long page_nr, pgprot_t pgprot) 
	return __pud(pfn | check_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 pud_t pud_mknotpresent(pud_t pud)

{

	return pfn_pud(pud_pfn(pud),

	      __pgprot(pud_flags(pud) & ~(_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)

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