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From: Yu-cheng Yu <yu-cheng.yu@intel.com>
To: Dave Hansen <dave.hansen@intel.com>,
	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@kernel.org>,
	Balbir Singh <bsingharora@gmail.com>,
	 Borislav Petkov <bp@alien8.de>,
	Cyrill Gorcunov <gorcunov@gmail.com>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	Eugene Syromiatnikov <esyr@redhat.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@chromium.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>,
	Randy Dunlap <rdunlap@infradead.org>,
	"Ravi V. Shankar" <ravi.v.shankar@intel.com>,
	Vedvyas Shanbhogue <vedvyas.shanbhogue@intel.com>,
	 Dave Martin <Dave.Martin@arm.com>,
	x86-patch-review@intel.com
Subject: Re: [RFC PATCH v9 09/27] x86/mm: Introduce _PAGE_DIRTY_SW
Date: Wed, 01 Apr 2020 12:08:16 -0700	[thread overview]
Message-ID: <6f68d7af6a618c087a85d2db6ad40b346e055452.camel@intel.com> (raw)
In-Reply-To: <325d3a25-0016-ea19-c0c9-7958066fc94e@intel.com>

On Wed, 2020-02-26 at 13:35 -0800, Dave Hansen wrote:
> On 2/5/20 10:19 AM, Yu-cheng Yu wrote:
> > When Shadow Stack (SHSTK) is introduced, a R/O and Dirty PTE exists in the
> > following cases:
> > 
> > (a) A modified, copy-on-write (COW) page;
> > (b) A R/O page that has been COW'ed;
> > (c) A SHSTK page.
[...]

> > diff --git a/arch/x86/include/asm/pgtable_types.h b/arch/x86/include/asm/pgtable_types.h
> > index e647e3c75578..826823df917f 100644
> > --- a/arch/x86/include/asm/pgtable_types.h
> > +++ b/arch/x86/include/asm/pgtable_types.h
> > @@ -23,7 +23,8 @@
> >  #define _PAGE_BIT_SOFTW2	10	/* " */
> >  #define _PAGE_BIT_SOFTW3	11	/* " */
> >  #define _PAGE_BIT_PAT_LARGE	12	/* On 2MB or 1GB pages */
> > -#define _PAGE_BIT_SOFTW4	58	/* available for programmer */
> > +#define _PAGE_BIT_SOFTW4	57	/* available for programmer */
> > +#define _PAGE_BIT_SOFTW5	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 */
> >  #define _PAGE_BIT_PKEY_BIT2	61	/* Protection Keys, bit 3/4 */
> > @@ -35,6 +36,12 @@
> >  #define _PAGE_BIT_SOFT_DIRTY	_PAGE_BIT_SOFTW3 /* software dirty tracking */
> >  #define _PAGE_BIT_DEVMAP	_PAGE_BIT_SOFTW4
> >  
> > +/*
> > + * This bit indicates a copy-on-write page, and is different from
> > + * _PAGE_BIT_SOFT_DIRTY, which tracks which pages a task writes to.
> > + */
> > +#define _PAGE_BIT_DIRTY_SW	_PAGE_BIT_SOFTW5 /* was written to */
> 
> Does it *only* indicate a copy-on-write (or copy-on-access) page?  If
> so, haven't we misnamed it?

It indicates either a copy-on-write page or a read-only page that has been
cow'ed.  What about _PAGE_BIT_COW?

Yu-cheng




  reply	other threads:[~2020-04-01 19:08 UTC|newest]

Thread overview: 107+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-05 18:19 [RFC PATCH v9 00/27] Control-flow Enforcement: Shadow Stack Yu-cheng Yu
2020-02-05 18:19 ` [RFC PATCH v9 01/27] Documentation/x86: Add CET description Yu-cheng Yu
2020-02-06  0:16   ` Randy Dunlap
2020-02-06 20:17     ` Yu-cheng Yu
2020-02-25 20:02   ` Kees Cook
2020-02-28 15:55     ` Yu-cheng Yu
2020-02-26 17:57   ` Dave Hansen
2020-03-09 17:00     ` Yu-cheng Yu
2020-03-09 17:21       ` Dave Hansen
2020-03-09 19:27         ` Yu-cheng Yu
2020-03-09 19:35           ` Dave Hansen
2020-03-09 19:50             ` H.J. Lu
2020-03-09 20:16               ` Andy Lutomirski
2020-03-09 20:54                 ` H.J. Lu
2020-03-09 20:59                   ` Dave Hansen
2020-03-09 21:12                     ` H.J. Lu
2020-03-09 22:02                       ` Andy Lutomirski
2020-03-09 22:19                       ` Dave Hansen
2020-03-09 23:11                         ` H.J. Lu
2020-03-09 23:20                           ` Dave Hansen
2020-03-09 23:51                             ` H.J. Lu
2020-03-09 23:59                               ` Andy Lutomirski
2020-03-10  0:08                                 ` H.J. Lu
2020-03-10  1:21                                   ` Andy Lutomirski
2020-03-10  2:13                                     ` H.J. Lu
2020-02-05 18:19 ` [RFC PATCH v9 02/27] x86/cpufeatures: Add CET CPU feature flags for Control-flow Enforcement Technology (CET) Yu-cheng Yu
2020-02-25 20:02   ` Kees Cook
2020-02-05 18:19 ` [RFC PATCH v9 03/27] x86/fpu/xstate: Introduce CET MSR XSAVES supervisor states Yu-cheng Yu
2020-02-25 20:04   ` Kees Cook
2020-02-05 18:19 ` [RFC PATCH v9 04/27] x86/cet: Add control-protection fault handler Yu-cheng Yu
2020-02-25 20:06   ` Kees Cook
2020-02-26 17:10   ` Dave Hansen
2020-03-05 20:44     ` Yu-cheng Yu
2020-02-05 18:19 ` [RFC PATCH v9 05/27] x86/cet/shstk: Add Kconfig option for user-mode Shadow Stack protection Yu-cheng Yu
2020-02-25 20:07   ` Kees Cook
2020-02-26 17:03   ` Dave Hansen
2020-02-26 19:57     ` Pavel Machek
2020-03-05 20:38     ` Yu-cheng Yu
2020-02-26 18:05   ` Dave Hansen
2020-02-27  1:02     ` H.J. Lu
2020-02-27  1:16       ` Dave Hansen
2020-02-27  2:11         ` H.J. Lu
2020-02-27  3:57           ` Andy Lutomirski
2020-02-27 18:03             ` Dave Hansen
2020-03-06 18:37     ` Yu-cheng Yu
2020-03-06 19:02       ` Dave Hansen
2020-03-06 21:16         ` Yu-cheng Yu
2020-02-05 18:19 ` [RFC PATCH v9 06/27] mm: Introduce VM_SHSTK for Shadow Stack memory Yu-cheng Yu
2020-02-25 20:07   ` Kees Cook
2020-02-26 18:07   ` Dave Hansen
2020-02-05 18:19 ` [RFC PATCH v9 07/27] Add guard pages around a Shadow Stack Yu-cheng Yu
2020-02-25 20:11   ` Kees Cook
2020-02-26 18:17   ` Dave Hansen
2020-02-05 18:19 ` [RFC PATCH v9 08/27] x86/mm: Change _PAGE_DIRTY to _PAGE_DIRTY_HW Yu-cheng Yu
2020-02-25 20:12   ` Kees Cook
2020-02-26 18:20   ` Dave Hansen
2020-02-05 18:19 ` [RFC PATCH v9 09/27] x86/mm: Introduce _PAGE_DIRTY_SW Yu-cheng Yu
2020-02-25 20:12   ` Kees Cook
2020-02-26 21:35   ` Dave Hansen
2020-04-01 19:08     ` Yu-cheng Yu [this message]
2020-04-01 19:22       ` Dave Hansen
2020-02-05 18:19 ` [RFC PATCH v9 10/27] x86/mm: Update pte_modify, pmd_modify, and _PAGE_CHG_MASK for _PAGE_DIRTY_SW Yu-cheng Yu
2020-02-26 22:02   ` Dave Hansen
2020-02-05 18:19 ` [RFC PATCH v9 11/27] drm/i915/gvt: Change _PAGE_DIRTY to _PAGE_DIRTY_BITS Yu-cheng Yu
2020-02-25 20:13   ` Kees Cook
2020-02-26 22:04   ` Dave Hansen
2020-04-03 15:42     ` Yu-cheng Yu
2020-02-05 18:19 ` [RFC PATCH v9 12/27] x86/mm: Modify ptep_set_wrprotect and pmdp_set_wrprotect for _PAGE_DIRTY_SW Yu-cheng Yu
2020-02-25 20:14   ` Kees Cook
2020-02-26 22:20   ` Dave Hansen
2020-02-05 18:19 ` [RFC PATCH v9 13/27] x86/mm: Shadow Stack page fault error checking Yu-cheng Yu
2020-02-25 20:16   ` Kees Cook
2020-02-26 22:47   ` Dave Hansen
2020-02-05 18:19 ` [RFC PATCH v9 14/27] mm: Handle Shadow Stack page fault Yu-cheng Yu
2020-02-25 20:20   ` Kees Cook
2020-03-05 18:30     ` Yu-cheng Yu
2020-02-27  0:08   ` Dave Hansen
2020-04-07 18:14     ` Yu-cheng Yu
2020-04-07 22:21       ` Dave Hansen
2020-04-08 18:18         ` Yu-cheng Yu
2020-02-05 18:19 ` [RFC PATCH v9 15/27] mm: Handle THP/HugeTLB " Yu-cheng Yu
2020-02-25 20:59   ` Kees Cook
2020-03-13 22:00     ` Yu-cheng Yu
2020-02-05 18:19 ` [RFC PATCH v9 16/27] mm: Update can_follow_write_pte() for Shadow Stack Yu-cheng Yu
2020-02-27  0:34   ` Dave Hansen
2020-02-05 18:19 ` [RFC PATCH v9 17/27] x86/cet/shstk: User-mode Shadow Stack support Yu-cheng Yu
2020-02-25 21:07   ` Kees Cook
2020-02-27  0:55   ` Dave Hansen
2020-02-05 18:19 ` [RFC PATCH v9 18/27] x86/cet/shstk: Introduce WRUSS instruction Yu-cheng Yu
2020-02-25 21:10   ` Kees Cook
2020-03-05 18:39     ` Yu-cheng Yu
2020-02-05 18:19 ` [RFC PATCH v9 19/27] x86/cet/shstk: Handle signals for Shadow Stack Yu-cheng Yu
2020-02-25 21:17   ` Kees Cook
2020-02-05 18:19 ` [RFC PATCH v9 20/27] ELF: UAPI and Kconfig additions for ELF program properties Yu-cheng Yu
2020-02-05 18:19 ` [RFC PATCH v9 21/27] binfmt_elf: Define GNU_PROPERTY_X86_FEATURE_1_AND Yu-cheng Yu
2020-02-25 21:18   ` Kees Cook
2020-02-05 18:19 ` [RFC PATCH v9 22/27] ELF: Add ELF program property parsing support Yu-cheng Yu
2020-02-25 21:20   ` Kees Cook
2020-02-05 18:19 ` [RFC PATCH v9 23/27] ELF: Introduce arch_setup_elf_property() Yu-cheng Yu
2020-02-05 18:19 ` [RFC PATCH v9 24/27] x86/cet/shstk: ELF header parsing for Shadow Stack Yu-cheng Yu
2020-02-25 21:22   ` Kees Cook
2020-02-05 18:19 ` [RFC PATCH v9 25/27] x86/cet/shstk: Handle thread " Yu-cheng Yu
2020-02-25 21:29   ` Kees Cook
2020-03-25 21:51     ` Yu-cheng Yu
2020-02-05 18:19 ` [RFC PATCH v9 26/27] mm/mmap: Add Shadow Stack pages to memory accounting Yu-cheng Yu
2020-02-05 18:19 ` [RFC PATCH v9 27/27] x86/cet/shstk: Add arch_prctl functions for Shadow Stack Yu-cheng Yu
2020-02-25 21:31 ` [RFC PATCH v9 00/27] Control-flow Enforcement: " Kees Cook

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