From: Yu-cheng Yu <yu-cheng.yu@intel.com>
To: x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>,
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 <arnd@arndb.de>,
Andy Lutomirski <luto@amacapital.net>,
Balbir Singh <bsingharora@gmail.com>,
Cyrill Gorcunov <gorcunov@gmail.com>,
Dave Hansen <dave.hansen@linux.intel.com>,
Florian Weimer <fweimer@redhat.com>,
"H.J. Lu" <hjl.tools@gmail.com>, Jann Horn <jannh@google.com>,
Jonathan Corbet <corbet@lwn.net>,
Kees Cook <keescook@chromiun.org>,
Mike Kravetz <mike.kravetz@oracle.com>,
Nadav Amit <nadav.amit@gmail.com>,
Oleg Nesterov <oleg@redhat.com>, Pavel Machek <pavel@ucw.cz>,
Peter Zijlstra <peterz@infradead.org>,
"Ravi V. Shankar" <ravi.v.shankar@intel.com>,
Vedvyas Shanbhogue <vedvyas.shanbhogue@intel.com>
Cc: Yu-cheng Yu <yu-cheng.yu@intel.com>
Subject: [RFC PATCH v3 12/24] x86/mm: Modify ptep_set_wrprotect and pmdp_set_wrprotect for _PAGE_DIRTY_SW
Date: Thu, 30 Aug 2018 07:38:52 -0700 [thread overview]
Message-ID: <20180830143904.3168-13-yu-cheng.yu@intel.com> (raw)
In-Reply-To: <20180830143904.3168-1-yu-cheng.yu@intel.com>
When Shadow Stack is enabled, the read-only and PAGE_DIRTY_HW PTE
setting is reserved only for the Shadow Stack. To track dirty of
non-Shadow Stack read-only PTEs, we use PAGE_DIRTY_SW.
Update ptep_set_wrprotect() and pmdp_set_wrprotect().
Signed-off-by: Yu-cheng Yu <yu-cheng.yu@intel.com>
---
arch/x86/include/asm/pgtable.h | 42 ++++++++++++++++++++++++++++++++++
1 file changed, 42 insertions(+)
diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtable.h
index 4d50de77ea96..556ef258eeff 100644
--- a/arch/x86/include/asm/pgtable.h
+++ b/arch/x86/include/asm/pgtable.h
@@ -1203,7 +1203,28 @@ static inline pte_t ptep_get_and_clear_full(struct mm_struct *mm,
static inline void ptep_set_wrprotect(struct mm_struct *mm,
unsigned long addr, pte_t *ptep)
{
+ pte_t pte;
+
clear_bit(_PAGE_BIT_RW, (unsigned long *)&ptep->pte);
+ pte = *ptep;
+
+ /*
+ * Some processors can start a write, but ending up seeing
+ * a read-only PTE by the time they get to the Dirty bit.
+ * In this case, they will set the Dirty bit, leaving a
+ * read-only, Dirty PTE which looks like a Shadow Stack PTE.
+ *
+ * However, this behavior has been improved and will not occur
+ * on processors supporting Shadow Stacks. Without this
+ * guarantee, a transition to a non-present PTE and flush the
+ * TLB would be needed.
+ *
+ * When change a writable PTE to read-only and if the PTE has
+ * _PAGE_DIRTY_HW set, we move that bit to _PAGE_DIRTY_SW so
+ * that the PTE is not a valid Shadow Stack PTE.
+ */
+ 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)
@@ -1266,7 +1287,28 @@ static inline pud_t pudp_huge_get_and_clear(struct mm_struct *mm,
static inline void pmdp_set_wrprotect(struct mm_struct *mm,
unsigned long addr, pmd_t *pmdp)
{
+ pmd_t pmd;
+
clear_bit(_PAGE_BIT_RW, (unsigned long *)pmdp);
+ pmd = *pmdp;
+
+ /*
+ * Some processors can start a write, but ending up seeing
+ * a read-only PTE by the time they get to the Dirty bit.
+ * In this case, they will set the Dirty bit, leaving a
+ * read-only, Dirty PTE which looks like a Shadow Stack PTE.
+ *
+ * However, this behavior has been improved and will not occur
+ * on processors supporting Shadow Stacks. Without this
+ * guarantee, a transition to a non-present PTE and flush the
+ * TLB would be needed.
+ *
+ * When change a writable PTE to read-only and if the PTE has
+ * _PAGE_DIRTY_HW set, we move that bit to _PAGE_DIRTY_SW so
+ * that the PTE is not a valid Shadow Stack PTE.
+ */
+ pmd = pmd_move_flags(pmd, _PAGE_DIRTY_HW, _PAGE_DIRTY_SW);
+ set_pmd_at(mm, addr, pmdp, pmd);
}
#define pud_write pud_write
--
2.17.1
next prev parent reply other threads:[~2018-08-30 14:47 UTC|newest]
Thread overview: 73+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-08-30 14:38 [RFC PATCH v3 00/24] Control Flow Enforcement: Shadow Stack Yu-cheng Yu
2018-08-30 14:38 ` [RFC PATCH v3 01/24] x86/cpufeatures: Add CPUIDs for Control-flow Enforcement Technology (CET) Yu-cheng Yu
2018-08-30 14:38 ` [RFC PATCH v3 02/24] x86/fpu/xstate: Change some names to separate XSAVES system and user states Yu-cheng Yu
2018-08-30 14:38 ` [RFC PATCH v3 03/24] x86/fpu/xstate: Enable XSAVES system states Yu-cheng Yu
2018-08-30 14:38 ` [RFC PATCH v3 04/24] x86/fpu/xstate: Add XSAVES system states for shadow stack Yu-cheng Yu
2018-08-30 14:38 ` [RFC PATCH v3 05/24] Documentation/x86: Add CET description Yu-cheng Yu
2018-08-30 20:39 ` Pavel Machek
2018-08-30 22:49 ` Yu-cheng Yu
2018-09-14 21:17 ` Yu-cheng Yu
2018-09-03 2:56 ` Randy Dunlap
2018-08-30 14:38 ` [RFC PATCH v3 06/24] x86/cet: Control protection exception handler Yu-cheng Yu
2018-08-31 15:01 ` Jann Horn
2018-08-31 16:20 ` Yu-cheng Yu
2018-08-30 14:38 ` [RFC PATCH v3 07/24] x86/cet/shstk: Add Kconfig option for user-mode shadow stack Yu-cheng Yu
2018-08-30 14:38 ` [RFC PATCH v3 08/24] mm: Introduce VM_SHSTK for shadow stack memory Yu-cheng Yu
2018-08-30 14:38 ` [RFC PATCH v3 09/24] x86/mm: Change _PAGE_DIRTY to _PAGE_DIRTY_HW Yu-cheng Yu
2018-08-30 14:38 ` [RFC PATCH v3 10/24] x86/mm: Introduce _PAGE_DIRTY_SW Yu-cheng Yu
2018-08-30 14:38 ` [RFC PATCH v3 11/24] drm/i915/gvt: Update _PAGE_DIRTY to _PAGE_DIRTY_BITS Yu-cheng Yu
2018-08-30 14:38 ` Yu-cheng Yu [this message]
2018-08-30 15:49 ` [RFC PATCH v3 12/24] x86/mm: Modify ptep_set_wrprotect and pmdp_set_wrprotect for _PAGE_DIRTY_SW Jann Horn
2018-08-30 16:02 ` Yu-cheng Yu
2018-08-30 16:08 ` Dave Hansen
2018-08-30 16:23 ` Jann Horn
2018-08-30 17:19 ` Dave Hansen
2018-08-30 17:26 ` Yu-cheng Yu
2018-08-30 17:33 ` Dave Hansen
2018-08-30 17:54 ` Yu-cheng Yu
2018-08-30 17:59 ` Jann Horn
2018-08-30 20:21 ` Yu-cheng Yu
2018-08-30 20:44 ` Jann Horn
2018-08-30 20:52 ` Yu-cheng Yu
2018-08-30 21:01 ` Jann Horn
2018-08-30 21:47 ` Jann Horn
2018-08-31 9:53 ` Peter Zijlstra
2018-08-31 14:33 ` Yu-cheng Yu
2018-08-31 14:47 ` Dave Hansen
2018-08-31 15:48 ` Yu-cheng Yu
2018-08-31 15:58 ` Dave Hansen
2018-08-31 16:29 ` Peter Zijlstra
2018-09-14 20:39 ` Yu-cheng Yu
2018-09-14 20:46 ` Dave Hansen
2018-09-14 21:08 ` Yu-cheng Yu
2018-09-14 21:33 ` Dave Hansen
2018-08-31 1:23 ` Andy Lutomirski
2018-08-30 17:34 ` Andy Lutomirski
2018-08-30 18:55 ` Dave Hansen
2018-08-31 17:46 ` Andy Lutomirski
2018-08-31 17:52 ` Dave Hansen
2018-08-30 19:59 ` Randy Dunlap
2018-08-30 20:23 ` Yu-cheng Yu
2018-08-31 16:29 ` Dave Hansen
2018-08-30 14:38 ` [RFC PATCH v3 13/24] x86/mm: Shadow stack page fault error checking Yu-cheng Yu
2018-08-30 14:38 ` [RFC PATCH v3 14/24] mm: Handle shadow stack page fault Yu-cheng Yu
2018-08-30 14:38 ` [RFC PATCH v3 15/24] mm: Handle THP/HugeTLB " Yu-cheng Yu
2018-08-30 14:38 ` [RFC PATCH v3 16/24] mm: Update can_follow_write_pte/pmd for shadow stack Yu-cheng Yu
2018-08-30 14:38 ` [RFC PATCH v3 17/24] mm: Introduce do_mmap_locked() Yu-cheng Yu
2018-08-30 14:38 ` [RFC PATCH v3 18/24] x86/cet/shstk: User-mode shadow stack support Yu-cheng Yu
2018-08-30 16:10 ` Jann Horn
2018-08-30 16:20 ` Yu-cheng Yu
2018-08-30 14:38 ` [RFC PATCH v3 19/24] x86/cet/shstk: Introduce WRUSS instruction Yu-cheng Yu
2018-08-30 15:39 ` Jann Horn
2018-08-30 15:55 ` Andy Lutomirski
2018-08-30 16:22 ` Yu-cheng Yu
2018-08-31 21:49 ` Yu-cheng Yu
2018-08-31 22:16 ` Andy Lutomirski
2018-09-14 20:46 ` Yu-cheng Yu
2018-08-30 14:39 ` [RFC PATCH v3 20/24] x86/cet/shstk: Signal handling for shadow stack Yu-cheng Yu
2018-08-30 14:39 ` [RFC PATCH v3 21/24] x86/cet/shstk: ELF header parsing of Shadow Stack Yu-cheng Yu
2018-08-30 14:39 ` [RFC PATCH v3 22/24] x86/cet/shstk: Handle thread shadow stack Yu-cheng Yu
2018-08-30 14:39 ` [RFC PATCH v3 23/24] x86/cet/shstk: Add arch_prctl functions for Shadow Stack Yu-cheng Yu
2018-08-30 14:39 ` [RFC PATCH v3 24/24] x86/cet/shstk: Add Shadow Stack instructions to opcode map Yu-cheng Yu
2018-09-02 8:13 ` [RFC PATCH v3 00/24] Control Flow Enforcement: Shadow Stack Balbir Singh
2018-09-04 14:47 ` Yu-cheng Yu
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