From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pl0-f72.google.com (mail-pl0-f72.google.com [209.85.160.72]) by kanga.kvack.org (Postfix) with ESMTP id DE5256B026E for ; Thu, 7 Jun 2018 10:40:43 -0400 (EDT) Received: by mail-pl0-f72.google.com with SMTP id a5-v6so5475197plp.8 for ; Thu, 07 Jun 2018 07:40:43 -0700 (PDT) Received: from mga18.intel.com (mga18.intel.com. [134.134.136.126]) by mx.google.com with ESMTPS id b60-v6si54342625plc.270.2018.06.07.07.40.42 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 07 Jun 2018 07:40:42 -0700 (PDT) From: Yu-cheng Yu Subject: [PATCH 6/9] x86/mm: Introduce ptep_set_wrprotect_flush and related functions Date: Thu, 7 Jun 2018 07:37:02 -0700 Message-Id: <20180607143705.3531-7-yu-cheng.yu@intel.com> In-Reply-To: <20180607143705.3531-1-yu-cheng.yu@intel.com> References: <20180607143705.3531-1-yu-cheng.yu@intel.com> Sender: owner-linux-mm@kvack.org List-ID: To: linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-mm@kvack.org, linux-arch@vger.kernel.org, x86@kernel.org, "H. Peter Anvin" , Thomas Gleixner , Ingo Molnar , "H.J. Lu" , Vedvyas Shanbhogue , "Ravi V. Shankar" , Dave Hansen , Andy Lutomirski , Jonathan Corbet , Oleg Nesterov , Arnd Bergmann , Mike Kravetz Cc: Yu-cheng Yu The function ptep_set_wrprotect()/huge_ptep_set_wrprotect() is used by copy_page_range()/copy_hugetlb_page_range() to copy PTEs. On x86, when the shadow stack is enabled, only a shadow stack PTE has the read-only and _PAGE_DIRTY_HW combination. Upon making a dirty PTE read-only, we move its _PAGE_DIRTY_HW to _PAGE_DIRTY_SW. When ptep_set_wrprotect() moves _PAGE_DIRTY_HW to _PAGE_DIRTY_SW, if the PTE is writable and the mm is shared, another task could race to set _PAGE_DIRTY_HW again. Introduce ptep_set_wrprotect_flush(), pmdp_set_wrprotect_flush(), and huge_ptep_set_wrprotect_flush() to make sure this does not happen. Signed-off-by: Yu-cheng Yu --- arch/x86/include/asm/pgtable.h | 56 +++++++++++++++++++++++++++++++++++------- include/asm-generic/pgtable.h | 26 ++++++++++++++++++++ 2 files changed, 73 insertions(+), 9 deletions(-) diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtable.h index 0996f8a6979a..1053b940b35c 100644 --- a/arch/x86/include/asm/pgtable.h +++ b/arch/x86/include/asm/pgtable.h @@ -1148,11 +1148,27 @@ static inline pte_t ptep_get_and_clear_full(struct mm_struct *mm, return pte; } -#define __HAVE_ARCH_PTEP_SET_WRPROTECT -static inline void ptep_set_wrprotect(struct mm_struct *mm, - unsigned long addr, pte_t *ptep) -{ - clear_bit(_PAGE_BIT_RW, (unsigned long *)&ptep->pte); +#define __HAVE_ARCH_PTEP_SET_WRPROTECT_FLUSH +extern pte_t ptep_clear_flush(struct vm_area_struct *vma, + unsigned long address, + pte_t *ptep); +static inline void ptep_set_wrprotect_flush(struct vm_area_struct *vma, + unsigned long addr, pte_t *ptep) +{ + bool rw; + + rw = test_and_clear_bit(_PAGE_BIT_RW, (unsigned long *)&ptep->pte); + if (IS_ENABLED(CONFIG_X86_INTEL_SHADOW_STACK_USER)) { + struct mm_struct *mm = vma->vm_mm; + pte_t pte; + + if (rw && (atomic_read(&mm->mm_users) > 1)) + pte = ptep_clear_flush(vma, addr, ptep); + else + pte = *ptep; + pte = pte_move_flags(pte, _PAGE_DIRTY_HW, _PAGE_DIRTY_SW); + set_pte_at(mm, addr, ptep, pte); + } } #define flush_tlb_fix_spurious_fault(vma, address) do { } while (0) @@ -1198,11 +1214,33 @@ static inline pud_t pudp_huge_get_and_clear(struct mm_struct *mm, return native_pudp_get_and_clear(pudp); } -#define __HAVE_ARCH_PMDP_SET_WRPROTECT -static inline void pmdp_set_wrprotect(struct mm_struct *mm, - unsigned long addr, pmd_t *pmdp) +#define __HAVE_ARCH_HUGE_PTEP_SET_WRPROTECT_FLUSH +static inline void huge_ptep_set_wrprotect_flush(struct vm_area_struct *vma, + unsigned long addr, pte_t *ptep) { - clear_bit(_PAGE_BIT_RW, (unsigned long *)pmdp); + ptep_set_wrprotect_flush(vma, addr, ptep); +} + +#define __HAVE_ARCH_PMDP_SET_WRPROTECT_FLUSH +extern pmd_t pmdp_huge_clear_flush(struct vm_area_struct *vma, + unsigned long address, + pmd_t *pmdp); +static inline void pmdp_set_wrprotect_flush(struct vm_area_struct *vma, + unsigned long addr, pmd_t *pmdp) +{ bool rw; + + rw = test_and_clear_bit(_PAGE_BIT_RW, (unsigned long *)&pmdp); + if (IS_ENABLED(CONFIG_X86_INTEL_SHADOW_STACK_USER)) { + struct mm_struct *mm = vma->vm_mm; + pmd_t pmd; + + if (rw && (atomic_read(&mm->mm_users) > 1)) + pmd = pmdp_huge_clear_flush(vma, addr, pmdp); + else + pmd = *pmdp; + pmd = pmd_move_flags(pmd, _PAGE_DIRTY_HW, _PAGE_DIRTY_SW); + set_pmd_at(mm, addr, pmdp, pmd); + } } #define pud_write pud_write diff --git a/include/asm-generic/pgtable.h b/include/asm-generic/pgtable.h index 3f6f998509f0..9bcfdfc045bb 100644 --- a/include/asm-generic/pgtable.h +++ b/include/asm-generic/pgtable.h @@ -121,6 +121,15 @@ static inline int pmdp_clear_flush_young(struct vm_area_struct *vma, #endif /* CONFIG_TRANSPARENT_HUGEPAGE */ #endif +#ifndef __HAVE_ARCH_HUGE_PTEP_SET_WRPROTECT_FLUSH +static inline void huge_ptep_set_wrorptect_flush(struct vm_area_struct *vma, + unsigned long addr, + pte_t *ptep) +{ + huge_ptep_set_wrprotect(vma->vm_mm, addr, ptep); +} +#endif + #ifndef __HAVE_ARCH_PTEP_GET_AND_CLEAR static inline pte_t ptep_get_and_clear(struct mm_struct *mm, unsigned long address, @@ -226,6 +235,15 @@ static inline void ptep_set_wrprotect(struct mm_struct *mm, unsigned long addres } #endif +#ifndef __HAVE_ARCH_PTEP_SET_WRPROTECT_FLUSH +static inline void ptep_set_wrprotect_flush(struct vm_area_struct *vma, + unsigned long address, + pte_t *ptep) +{ + ptep_set_wrprotect(vma->vm_mm, address, ptep); +} +#endif + #ifndef pte_savedwrite #define pte_savedwrite pte_write #endif @@ -266,6 +284,14 @@ static inline void pmdp_set_wrprotect(struct mm_struct *mm, } #endif /* CONFIG_TRANSPARENT_HUGEPAGE */ #endif +#ifndef __HAVE_ARCH_PMDP_SET_WRPROTECT_FLUSH +static inline void pmdp_set_wrprotect_flush(struct vm_area_struct *vma, + unsigned long address, + pmd_t *pmdp) +{ + pmdp_set_wrprotect(vma->vm_mm, address, pmdp); +} +#endif #ifndef __HAVE_ARCH_PUDP_SET_WRPROTECT #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD static inline void pudp_set_wrprotect(struct mm_struct *mm, -- 2.15.1