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    Subject[PATCH 12/16] x86/mm/pae: Populate the user page-table with user pgd's
    Date
    From: Joerg Roedel <jroedel@suse.de>

    This is the last part of the PAE page-table setup for PAE
    before we can add the CR3 switch to the entry code.

    Signed-off-by: Joerg Roedel <jroedel@suse.de>
    ---
    arch/x86/include/asm/pgtable-3level.h | 3 +++
    arch/x86/mm/pti.c | 7 +++++++
    2 files changed, 10 insertions(+)

    diff --git a/arch/x86/include/asm/pgtable-3level.h b/arch/x86/include/asm/pgtable-3level.h
    index bc4af5453802..910f0b35370e 100644
    --- a/arch/x86/include/asm/pgtable-3level.h
    +++ b/arch/x86/include/asm/pgtable-3level.h
    @@ -98,6 +98,9 @@ static inline void native_set_pmd(pmd_t *pmdp, pmd_t pmd)

    static inline void native_set_pud(pud_t *pudp, pud_t pud)
    {
    +#ifdef CONFIG_PAGE_TABLE_ISOLATION
    + pud.p4d.pgd = pti_set_user_pgd(&pudp->p4d.pgd, pud.p4d.pgd);
    +#endif
    set_64bit((unsigned long long *)(pudp), native_pud_val(pud));
    }

    diff --git a/arch/x86/mm/pti.c b/arch/x86/mm/pti.c
    index 6b6bfd13350e..a561b5625d6c 100644
    --- a/arch/x86/mm/pti.c
    +++ b/arch/x86/mm/pti.c
    @@ -122,6 +122,7 @@ pgd_t __pti_set_user_pgd(pgd_t *pgdp, pgd_t pgd)
    */
    kernel_to_user_pgdp(pgdp)->pgd = pgd.pgd;

    +#ifdef CONFIG_X86_64
    /*
    * If this is normal user memory, make it NX in the kernel
    * pagetables so that, if we somehow screw up and return to
    @@ -134,10 +135,16 @@ pgd_t __pti_set_user_pgd(pgd_t *pgdp, pgd_t pgd)
    * may execute from it
    * - we don't have NX support
    * - we're clearing the PGD (i.e. the new pgd is not present).
    + * - We run on a 32 bit kernel. 2-level paging doesn't support NX at
    + * all and PAE paging does not support it on the PGD level. We can
    + * set it in the PMD level there in the future, but that means we
    + * need to unshare the PMDs between the kernel and the user
    + * page-tables.
    */
    if ((pgd.pgd & (_PAGE_USER|_PAGE_PRESENT)) == (_PAGE_USER|_PAGE_PRESENT) &&
    (__supported_pte_mask & _PAGE_NX))
    pgd.pgd |= _PAGE_NX;
    +#endif

    /* return the copy of the PGD we want the kernel to use: */
    return pgd;
    --
    2.13.6
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