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Shutemov" To: "Yu, Yu-cheng" Cc: x86@kernel.org, "H. Peter Anvin" , Thomas Gleixner , Ingo Molnar , linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-mm@kvack.org, linux-arch@vger.kernel.org, linux-api@vger.kernel.org, Arnd Bergmann , Andy Lutomirski , Balbir Singh , Borislav Petkov , Cyrill Gorcunov , Dave Hansen , Eugene Syromiatnikov , Florian Weimer , "H.J. Lu" , Jann Horn , Jonathan Corbet , Kees Cook , Mike Kravetz , Nadav Amit , Oleg Nesterov , Pavel Machek , Peter Zijlstra , Randy Dunlap , "Ravi V. Shankar" , Vedvyas Shanbhogue , Dave Martin , Weijiang Yang , Pengfei Xu , Haitao Huang Subject: Re: [PATCH v23 18/28] mm/mmap: Add shadow stack pages to memory accounting Message-ID: <20210329101040.sra6aqvgjbmy72bj@box> References: <20210316151054.5405-1-yu-cheng.yu@intel.com> <20210316151054.5405-19-yu-cheng.yu@intel.com> <20210322105729.24rt4nwc3blipxsr@box> <4b926140-66ac-f538-df94-8213b8a2ab86@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4b926140-66ac-f538-df94-8213b8a2ab86@intel.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Mar 26, 2021 at 08:46:30AM -0700, Yu, Yu-cheng wrote: > 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 > > > Reviewed-by: Kees Cook > > > --- > > > 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? is_shadow_stack_mapping() sounds reasonable. My point is that we already have ifdef around #define VM_SHSTK. No need in duplicating it for helper. -- Kirill A. Shutemov