Messages in this thread | | | Subject | Re: [PATCH v23 18/28] mm/mmap: Add shadow stack pages to memory accounting | From | "Yu, Yu-cheng" <> | Date | Fri, 26 Mar 2021 08:46:30 -0700 |
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On 3/22/2021 3:57 AM, Kirill A. Shutemov wrote: > On Tue, Mar 16, 2021 at 08:10:44AM -0700, Yu-cheng Yu wrote: >> 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; >> + > > What's wrong with testing (vm_flags & VM_SHSTK) here? VM_SHSTK is 0 on > non-x86. > >> 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; > > Ditto. >
The thought was, here all testings are done with helpers, e.g. is_data_mapping(), so creating a helper for shadow stack is more inline with the existing code. Or, maybe we can call it is_shadow_stack_mapping()? And, since we have a helper, use it in accountable_mapping() as well. Or do you have other suggestions?
Thanks, Yu-cheng
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