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    Subject[PATCH v23 18/28] mm/mmap: Add shadow stack pages to memory accounting
    Date
    Account shadow stack pages to stack memory.

    Signed-off-by: Yu-cheng Yu <yu-cheng.yu@intel.com>
    Reviewed-by: Kees Cook <keescook@chromium.org>
    ---
    arch/x86/mm/pgtable.c | 7 +++++++
    include/linux/pgtable.h | 11 +++++++++++
    mm/mmap.c | 5 +++++
    3 files changed, 23 insertions(+)

    diff --git a/arch/x86/mm/pgtable.c b/arch/x86/mm/pgtable.c
    index 0f4fbf51a9fc..948d28c29964 100644
    --- a/arch/x86/mm/pgtable.c
    +++ b/arch/x86/mm/pgtable.c
    @@ -895,3 +895,10 @@ int pmd_free_pte_page(pmd_t *pmd, unsigned long addr)

    #endif /* CONFIG_X86_64 */
    #endif /* CONFIG_HAVE_ARCH_HUGE_VMAP */
    +
    +#ifdef CONFIG_ARCH_HAS_SHADOW_STACK
    +bool arch_shadow_stack_mapping(vm_flags_t vm_flags)
    +{
    + return (vm_flags & VM_SHSTK);
    +}
    +#endif
    diff --git a/include/linux/pgtable.h b/include/linux/pgtable.h
    index cbd98484c4f1..487c08df4365 100644
    --- a/include/linux/pgtable.h
    +++ b/include/linux/pgtable.h
    @@ -1470,6 +1470,17 @@ static inline pmd_t arch_maybe_pmd_mkwrite(pmd_t pmd, struct vm_area_struct *vma
    #endif /* CONFIG_ARCH_MAYBE_MKWRITE */
    #endif /* CONFIG_MMU */

    +#ifdef CONFIG_MMU
    +#ifdef CONFIG_ARCH_HAS_SHADOW_STACK
    +bool arch_shadow_stack_mapping(vm_flags_t vm_flags);
    +#else
    +static inline bool arch_shadow_stack_mapping(vm_flags_t vm_flags)
    +{
    + return false;
    +}
    +#endif /* CONFIG_ARCH_HAS_SHADOW_STACK */
    +#endif /* CONFIG_MMU */
    +
    /*
    * Architecture PAGE_KERNEL_* fallbacks
    *
    diff --git a/mm/mmap.c b/mm/mmap.c
    index 3f287599a7a3..2ac67882ace2 100644
    --- a/mm/mmap.c
    +++ b/mm/mmap.c
    @@ -1718,6 +1718,9 @@ static inline int accountable_mapping(struct file *file, vm_flags_t vm_flags)
    if (file && is_file_hugepages(file))
    return 0;

    + if (arch_shadow_stack_mapping(vm_flags))
    + return 1;
    +
    return (vm_flags & (VM_NORESERVE | VM_SHARED | VM_WRITE)) == VM_WRITE;
    }

    @@ -3387,6 +3390,8 @@ void vm_stat_account(struct mm_struct *mm, vm_flags_t flags, long npages)
    mm->stack_vm += npages;
    else if (is_data_mapping(flags))
    mm->data_vm += npages;
    + else if (arch_shadow_stack_mapping(flags))
    + mm->stack_vm += npages;
    }

    static vm_fault_t special_mapping_fault(struct vm_fault *vmf);
    --
    2.21.0
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