On Thu, Apr 15, 2021 at 03:14:07PM -0700, Yu-cheng Yu wrote:
> Account shadow stack pages to stack memory.
>
> Signed-off-by: Yu-cheng Yu <yu-cheng.yu@xxxxxxxxx>
> Cc: Kees Cook <keescook@xxxxxxxxxxxx>
> Cc: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
> ---
> v25:
> - Remove #ifdef CONFIG_ARCH_HAS_SHADOW_STACK for is_shadow_stack_mapping().
> v24:
> - Change arch_shadow_stack_mapping() to is_shadow_stack_mapping().
> - Change VM_SHSTK to VM_SHADOW_STACK.
>
> arch/x86/include/asm/pgtable.h | 3 +++
> arch/x86/mm/pgtable.c | 5 +++++
> include/linux/pgtable.h | 9 +++++++++
> mm/mmap.c | 5 +++++
> 4 files changed, 22 insertions(+)
>
> diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtable.h
> index da5dea417663..7f324edaedfa 100644
> --- a/arch/x86/include/asm/pgtable.h
> +++ b/arch/x86/include/asm/pgtable.h
> @@ -1692,6 +1692,9 @@ static inline bool arch_faults_on_old_pte(void)
> #define maybe_mkwrite maybe_mkwrite
> extern pte_t maybe_mkwrite(pte_t pte, struct vm_area_struct *vma);
>
> +#define is_shadow_stack_mapping is_shadow_stack_mapping
> +extern bool is_shadow_stack_mapping(vm_flags_t vm_flags);
> +
> #endif /* __ASSEMBLY__ */
>
> #endif /* _ASM_X86_PGTABLE_H */
> diff --git a/arch/x86/mm/pgtable.c b/arch/x86/mm/pgtable.c
> index e778dbbef3d8..69c0ef583c55 100644
> --- a/arch/x86/mm/pgtable.c
> +++ b/arch/x86/mm/pgtable.c
> @@ -897,3 +897,8 @@ int pmd_free_pte_page(pmd_t *pmd, unsigned long addr)
>
> #endif /* CONFIG_X86_64 */
> #endif /* CONFIG_HAVE_ARCH_HUGE_VMAP */
> +
> +bool is_shadow_stack_mapping(vm_flags_t vm_flags)
> +{
> + return (vm_flags & VM_SHADOW_STACK);
Nit: parentheses are redundant.
> +}
> diff --git a/include/linux/pgtable.h b/include/linux/pgtable.h
> index 5e772392a379..45b601fa1a1c 100644
> --- a/include/linux/pgtable.h
> +++ b/include/linux/pgtable.h
> @@ -1446,6 +1446,15 @@ static inline bool arch_has_pfn_modify_check(void)
> }
> #endif /* !_HAVE_ARCH_PFN_MODIFY_ALLOWED */
>
> +#ifdef CONFIG_MMU
> +#ifndef is_shadow_stack_mapping
> +static inline bool is_shadow_stack_mapping(vm_flags_t vm_flags)
> +{
> + return false;
> +}
> +#endif
> +#endif /* CONFIG_MMU */
What the purpose #ifdef CONFIG_MMU? Looks redundant.
Otherwise:
Reviewed-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
> +
> /*
> * Architecture PAGE_KERNEL_* fallbacks
> *
> diff --git a/mm/mmap.c b/mm/mmap.c
> index 3f287599a7a3..d77fb39b6ab5 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 (is_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 (is_shadow_stack_mapping(flags))
> + mm->stack_vm += npages;
> }
>
> static vm_fault_t special_mapping_fault(struct vm_fault *vmf);
> --
> 2.21.0
>
>
--
Kirill A. Shutemov
