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[192.55.52.93]) by mx.google.com with ESMTPS id o12-v6si32492543plg.114.2018.11.19.13.54.22 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 19 Nov 2018 13:54:22 -0800 (PST) Received-SPF: pass (google.com: domain of yu-cheng.yu@intel.com designates 192.55.52.93 as permitted sender) client-ip=192.55.52.93; Authentication-Results: mx.google.com; spf=pass (google.com: domain of yu-cheng.yu@intel.com designates 192.55.52.93 as permitted sender) smtp.mailfrom=yu-cheng.yu@intel.com; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=intel.com X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga008.jf.intel.com ([10.7.209.65]) by fmsmga102.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 19 Nov 2018 13:54:22 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.56,254,1539673200"; d="scan'208";a="93319866" Received: from yyu32-desk1.sc.intel.com ([143.183.136.147]) by orsmga008.jf.intel.com with ESMTP; 19 Nov 2018 13:54:21 -0800 From: Yu-cheng Yu To: 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 , 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 Cc: Yu-cheng Yu Subject: [RFC PATCH v6 11/26] x86/mm: Introduce _PAGE_DIRTY_SW Date: Mon, 19 Nov 2018 13:47:54 -0800 Message-Id: <20181119214809.6086-12-yu-cheng.yu@intel.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20181119214809.6086-1-yu-cheng.yu@intel.com> References: <20181119214809.6086-1-yu-cheng.yu@intel.com> X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: X-Virus-Scanned: ClamAV using ClamSMTP A RO and dirty PTE exists in the following cases: (a) A page is modified and then shared with a fork()'ed child; (b) A R/O page that has been COW'ed; (c) A SHSTK page. The processor does not read the dirty bit for (a) and (b), but checks the dirty bit for (c). To prevent the use of non-SHSTK memory as SHSTK, we introduce a spare bit of the 64-bit PTE as _PAGE_BIT_DIRTY_SW and use that for (a) and (b). This results to the following possible PTE settings: Modified PTE: (R/W + DIRTY_HW) Modified and shared PTE: (R/O + DIRTY_SW) R/O PTE COW'ed: (R/O + DIRTY_SW) SHSTK PTE: (R/O + DIRTY_HW) SHSTK PTE COW'ed: (R/O + DIRTY_HW) SHSTK PTE shared: (R/O + DIRTY_SW) Note that _PAGE_BIT_DRITY_SW is only used in R/O PTEs but not R/W PTEs. When this patch is applied, there are six free bits left in the 64-bit PTE. There is no more free bit in the 32-bit PTE (except for PAE) and shadow stack is not implemented for the 32-bit kernel. Signed-off-by: Yu-cheng Yu --- arch/x86/include/asm/pgtable.h | 129 ++++++++++++++++++++++----- arch/x86/include/asm/pgtable_types.h | 21 ++++- 2 files changed, 128 insertions(+), 22 deletions(-) diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtable.h index be71584bbd9a..db4b9d22d2f7 100644 --- a/arch/x86/include/asm/pgtable.h +++ b/arch/x86/include/asm/pgtable.h @@ -118,9 +118,9 @@ extern pmdval_t early_pmd_flags; * The following only work if pte_present() is true. * Undefined behaviour if not.. */ -static inline int pte_dirty(pte_t pte) +static inline bool pte_dirty(pte_t pte) { - return pte_flags(pte) & _PAGE_DIRTY; + return pte_flags(pte) & _PAGE_DIRTY_BITS; } @@ -142,9 +142,9 @@ static inline int pte_young(pte_t pte) return pte_flags(pte) & _PAGE_ACCESSED; } -static inline int pmd_dirty(pmd_t pmd) +static inline bool pmd_dirty(pmd_t pmd) { - return pmd_flags(pmd) & _PAGE_DIRTY; + return pmd_flags(pmd) & _PAGE_DIRTY_BITS; } static inline int pmd_young(pmd_t pmd) @@ -152,9 +152,9 @@ static inline int pmd_young(pmd_t pmd) return pmd_flags(pmd) & _PAGE_ACCESSED; } -static inline int pud_dirty(pud_t pud) +static inline bool pud_dirty(pud_t pud) { - return pud_flags(pud) & _PAGE_DIRTY; + return pud_flags(pud) & _PAGE_DIRTY_BITS; } static inline int pud_young(pud_t pud) @@ -293,9 +293,23 @@ static inline pte_t pte_clear_flags(pte_t pte, pteval_t clear) return native_make_pte(v & ~clear); } +#if defined(CONFIG_X86_INTEL_SHADOW_STACK_USER) +static inline pte_t pte_move_flags(pte_t pte, pteval_t from, pteval_t to) +{ + if (pte_flags(pte) & from) + pte = pte_set_flags(pte_clear_flags(pte, from), to); + return pte; +} +#else +static inline pte_t pte_move_flags(pte_t pte, pteval_t from, pteval_t to) +{ + return pte; +} +#endif + static inline pte_t pte_mkclean(pte_t pte) { - return pte_clear_flags(pte, _PAGE_DIRTY); + return pte_clear_flags(pte, _PAGE_DIRTY_BITS); } static inline pte_t pte_mkold(pte_t pte) @@ -305,6 +319,7 @@ static inline pte_t pte_mkold(pte_t pte) static inline pte_t pte_wrprotect(pte_t pte) { + pte = pte_move_flags(pte, _PAGE_DIRTY_HW, _PAGE_DIRTY_SW); return pte_clear_flags(pte, _PAGE_RW); } @@ -315,9 +330,24 @@ static inline pte_t pte_mkexec(pte_t pte) static inline pte_t pte_mkdirty(pte_t pte) { + pteval_t dirty = (!IS_ENABLED(CONFIG_X86_INTEL_SHADOW_STACK_USER) || + pte_write(pte)) ? _PAGE_DIRTY_HW:_PAGE_DIRTY_SW; + return pte_set_flags(pte, dirty | _PAGE_SOFT_DIRTY); +} + +#ifdef CONFIG_ARCH_HAS_SHSTK +static inline pte_t pte_mkdirty_shstk(pte_t pte) +{ + pte = pte_clear_flags(pte, _PAGE_DIRTY_SW); return pte_set_flags(pte, _PAGE_DIRTY_HW | _PAGE_SOFT_DIRTY); } +static inline bool pte_dirty_hw(pte_t pte) +{ + return pte_flags(pte) & _PAGE_DIRTY_HW; +} +#endif + static inline pte_t pte_mkyoung(pte_t pte) { return pte_set_flags(pte, _PAGE_ACCESSED); @@ -325,6 +355,7 @@ static inline pte_t pte_mkyoung(pte_t pte) static inline pte_t pte_mkwrite(pte_t pte) { + pte = pte_move_flags(pte, _PAGE_DIRTY_SW, _PAGE_DIRTY_HW); return pte_set_flags(pte, _PAGE_RW); } @@ -372,6 +403,20 @@ static inline pmd_t pmd_clear_flags(pmd_t pmd, pmdval_t clear) return native_make_pmd(v & ~clear); } +#if defined(CONFIG_X86_INTEL_SHADOW_STACK_USER) +static inline pmd_t pmd_move_flags(pmd_t pmd, pmdval_t from, pmdval_t to) +{ + if (pmd_flags(pmd) & from) + pmd = pmd_set_flags(pmd_clear_flags(pmd, from), to); + return pmd; +} +#else +static inline pmd_t pmd_move_flags(pmd_t pmd, pmdval_t from, pmdval_t to) +{ + return pmd; +} +#endif + static inline pmd_t pmd_mkold(pmd_t pmd) { return pmd_clear_flags(pmd, _PAGE_ACCESSED); @@ -379,19 +424,36 @@ static inline pmd_t pmd_mkold(pmd_t pmd) static inline pmd_t pmd_mkclean(pmd_t pmd) { - return pmd_clear_flags(pmd, _PAGE_DIRTY); + return pmd_clear_flags(pmd, _PAGE_DIRTY_BITS); } static inline pmd_t pmd_wrprotect(pmd_t pmd) { + pmd = pmd_move_flags(pmd, _PAGE_DIRTY_HW, _PAGE_DIRTY_SW); return pmd_clear_flags(pmd, _PAGE_RW); } static inline pmd_t pmd_mkdirty(pmd_t pmd) { + pmdval_t dirty = (!IS_ENABLED(CONFIG_X86_INTEL_SHADOW_STACK_USER) || + (pmd_flags(pmd) & _PAGE_RW)) ? + _PAGE_DIRTY_HW:_PAGE_DIRTY_SW; + return pmd_set_flags(pmd, dirty | _PAGE_SOFT_DIRTY); +} + +#ifdef CONFIG_ARCH_HAS_SHSTK +static inline pmd_t pmd_mkdirty_shstk(pmd_t pmd) +{ + pmd = pmd_clear_flags(pmd, _PAGE_DIRTY_SW); return pmd_set_flags(pmd, _PAGE_DIRTY_HW | _PAGE_SOFT_DIRTY); } +static inline bool pmd_dirty_hw(pmd_t pmd) +{ + return pmd_flags(pmd) & _PAGE_DIRTY_HW; +} +#endif + static inline pmd_t pmd_mkdevmap(pmd_t pmd) { return pmd_set_flags(pmd, _PAGE_DEVMAP); @@ -409,6 +471,7 @@ static inline pmd_t pmd_mkyoung(pmd_t pmd) static inline pmd_t pmd_mkwrite(pmd_t pmd) { + pmd = pmd_move_flags(pmd, _PAGE_DIRTY_SW, _PAGE_DIRTY_HW); return pmd_set_flags(pmd, _PAGE_RW); } @@ -426,6 +489,20 @@ static inline pud_t pud_clear_flags(pud_t pud, pudval_t clear) return native_make_pud(v & ~clear); } +#if defined(CONFIG_X86_INTEL_SHADOW_STACK_USER) +static inline pud_t pud_move_flags(pud_t pud, pudval_t from, pudval_t to) +{ + if (pud_flags(pud) & from) + pud = pud_set_flags(pud_clear_flags(pud, from), to); + return pud; +} +#else +static inline pud_t pud_move_flags(pud_t pud, pudval_t from, pudval_t to) +{ + return pud; +} +#endif + static inline pud_t pud_mkold(pud_t pud) { return pud_clear_flags(pud, _PAGE_ACCESSED); @@ -433,17 +510,22 @@ static inline pud_t pud_mkold(pud_t pud) static inline pud_t pud_mkclean(pud_t pud) { - return pud_clear_flags(pud, _PAGE_DIRTY); + return pud_clear_flags(pud, _PAGE_DIRTY_BITS); } static inline pud_t pud_wrprotect(pud_t pud) { + pud = pud_move_flags(pud, _PAGE_DIRTY_HW, _PAGE_DIRTY_SW); return pud_clear_flags(pud, _PAGE_RW); } static inline pud_t pud_mkdirty(pud_t pud) { - return pud_set_flags(pud, _PAGE_DIRTY_HW | _PAGE_SOFT_DIRTY); + pudval_t dirty = (!IS_ENABLED(CONFIG_X86_INTEL_SHADOW_STACK_USER) || + (pud_flags(pud) & _PAGE_RW)) ? + _PAGE_DIRTY_HW:_PAGE_DIRTY_SW; + + return pud_set_flags(pud, dirty | _PAGE_SOFT_DIRTY); } static inline pud_t pud_mkdevmap(pud_t pud) @@ -463,6 +545,7 @@ static inline pud_t pud_mkyoung(pud_t pud) static inline pud_t pud_mkwrite(pud_t pud) { + pud = pud_move_flags(pud, _PAGE_DIRTY_SW, _PAGE_DIRTY_HW); return pud_set_flags(pud, _PAGE_RW); } @@ -594,19 +677,12 @@ static inline pte_t pte_modify(pte_t pte, pgprot_t newprot) val &= _PAGE_CHG_MASK; val |= check_pgprot(newprot) & ~_PAGE_CHG_MASK; val = flip_protnone_guard(oldval, val, PTE_PFN_MASK); + if ((pte_write(pte) && !(pgprot_val(newprot) & _PAGE_RW))) + return pte_move_flags(__pte(val), _PAGE_DIRTY_HW, + _PAGE_DIRTY_SW); return __pte(val); } -static inline pmd_t pmd_modify(pmd_t pmd, pgprot_t newprot) -{ - pmdval_t val = pmd_val(pmd), oldval = val; - - val &= _HPAGE_CHG_MASK; - val |= check_pgprot(newprot) & ~_HPAGE_CHG_MASK; - val = flip_protnone_guard(oldval, val, PHYSICAL_PMD_PAGE_MASK); - return __pmd(val); -} - /* mprotect needs to preserve PAT bits when updating vm_page_prot */ #define pgprot_modify pgprot_modify static inline pgprot_t pgprot_modify(pgprot_t oldprot, pgprot_t newprot) @@ -1158,6 +1234,19 @@ static inline int pmd_write(pmd_t pmd) return pmd_flags(pmd) & _PAGE_RW; } +static inline pmd_t pmd_modify(pmd_t pmd, pgprot_t newprot) +{ + pmdval_t val = pmd_val(pmd), oldval = val; + + val &= _HPAGE_CHG_MASK; + val |= check_pgprot(newprot) & ~_HPAGE_CHG_MASK; + val = flip_protnone_guard(oldval, val, PHYSICAL_PMD_PAGE_MASK); + if ((pmd_write(pmd) && !(pgprot_val(newprot) & _PAGE_RW))) + return pmd_move_flags(__pmd(val), _PAGE_DIRTY_HW, + _PAGE_DIRTY_SW); + return __pmd(val); +} + #define __HAVE_ARCH_PMDP_HUGE_GET_AND_CLEAR static inline pmd_t pmdp_huge_get_and_clear(struct mm_struct *mm, unsigned long addr, pmd_t *pmdp) diff --git a/arch/x86/include/asm/pgtable_types.h b/arch/x86/include/asm/pgtable_types.h index 7b6a7f088f53..6a2b42490fb2 100644 --- a/arch/x86/include/asm/pgtable_types.h +++ b/arch/x86/include/asm/pgtable_types.h @@ -23,6 +23,7 @@ #define _PAGE_BIT_SOFTW2 10 /* " */ #define _PAGE_BIT_SOFTW3 11 /* " */ #define _PAGE_BIT_PAT_LARGE 12 /* On 2MB or 1GB pages */ +#define _PAGE_BIT_SOFTW5 57 /* available for programmer */ #define _PAGE_BIT_SOFTW4 58 /* available for programmer */ #define _PAGE_BIT_PKEY_BIT0 59 /* Protection Keys, bit 1/4 */ #define _PAGE_BIT_PKEY_BIT1 60 /* Protection Keys, bit 2/4 */ @@ -34,6 +35,7 @@ #define _PAGE_BIT_CPA_TEST _PAGE_BIT_SOFTW1 #define _PAGE_BIT_SOFT_DIRTY _PAGE_BIT_SOFTW3 /* software dirty tracking */ #define _PAGE_BIT_DEVMAP _PAGE_BIT_SOFTW4 +#define _PAGE_BIT_DIRTY_SW _PAGE_BIT_SOFTW5 /* was written to */ /* If _PAGE_BIT_PRESENT is clear, we use these: */ /* - if the user mapped it with PROT_NONE; pte_present gives true */ @@ -109,6 +111,21 @@ #define _PAGE_DEVMAP (_AT(pteval_t, 0)) #endif +/* + * _PAGE_DIRTY_HW: set by the processor when a page is written. + * _PAGE_DIRTY_SW: a spare bit tracking a written, but now R/O page. + * [R/W + _PAGE_DIRTY_HW] <-> [R/O + _PAGE_DIRTY_SW]. + * _PAGE_SOFT_DIRTY: a spare bit used to track written pages since a time point + * set by the system admin; see Documentation/admin-guide/mm/soft-dirty.rst. + */ +#if defined(CONFIG_X86_INTEL_SHADOW_STACK_USER) +#define _PAGE_DIRTY_SW (_AT(pteval_t, 1) << _PAGE_BIT_DIRTY_SW) +#else +#define _PAGE_DIRTY_SW (_AT(pteval_t, 0)) +#endif + +#define _PAGE_DIRTY_BITS (_PAGE_DIRTY_HW | _PAGE_DIRTY_SW) + #define _PAGE_PROTNONE (_AT(pteval_t, 1) << _PAGE_BIT_PROTNONE) #define _PAGE_TABLE_NOENC (_PAGE_PRESENT | _PAGE_RW | _PAGE_USER |\ @@ -122,9 +139,9 @@ * instance, and is *not* included in this mask since * pte_modify() does modify it. */ -#define _PAGE_CHG_MASK (PTE_PFN_MASK | _PAGE_PCD | _PAGE_PWT | \ +#define _PAGE_CHG_MASK (PTE_PFN_MASK | _PAGE_PCD | _PAGE_PWT | \ _PAGE_SPECIAL | _PAGE_ACCESSED | _PAGE_DIRTY_HW | \ - _PAGE_SOFT_DIRTY | _PAGE_DEVMAP) + _PAGE_DIRTY_SW | _PAGE_SOFT_DIRTY | _PAGE_DEVMAP) #define _HPAGE_CHG_MASK (_PAGE_CHG_MASK | _PAGE_PSE) /*