From: Matthew Wilcox <willy@infradead.org>
To: Dave Hansen <dave.hansen@intel.com>
Cc: Andy Lutomirski <luto@amacapital.net>,
Yu-cheng Yu <yu-cheng.yu@intel.com>, X86 ML <x86@kernel.org>,
"H. Peter Anvin" <hpa@zytor.com>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>,
LKML <linux-kernel@vger.kernel.org>,
"open list:DOCUMENTATION" <linux-doc@vger.kernel.org>,
Linux-MM <linux-mm@kvack.org>,
linux-arch <linux-arch@vger.kernel.org>,
Linux API <linux-api@vger.kernel.org>,
Arnd Bergmann <arnd@arndb.de>,
Balbir Singh <bsingharora@gmail.com>,
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>,
"Shanbhogue, Vedvyas" <vedvyas.shanbhogue@intel.com>
Subject: Re: [PATCH v5 04/27] x86/fpu/xstate: Add XSAVES system states for shadow stack
Date: Fri, 9 Nov 2018 09:17:40 -0800 [thread overview]
Message-ID: <20181109171740.GT3074@bombadil.infradead.org> (raw)
In-Reply-To: <6cd2ae51-2d2a-9c68-df7c-45b49e0a813f@intel.com>
On Fri, Nov 09, 2018 at 09:13:32AM -0800, Dave Hansen wrote:
> On 11/8/18 4:32 PM, Matthew Wilcox wrote:
> >> Now, looking at Yu-cheng's specific example, it doesn't matter. We've
> >> got 64-bit types and natural 64-bit alignment. Without __packed, we
> >> need to look out for natural alignment screwing us up. With __packed,
> >> it just does what it *looks* like it does.
> > The question is whether Yu-cheng's struct is ever embedded in another
> > struct. And if so, what does the hardware do?
>
> It's not really.
>
> +struct cet_user_state {
> + u64 u_cet; /* user control flow settings */
> + u64 user_ssp; /* user shadow stack pointer */
> +} __packed;
>
> This ends up embedded in 'struct fpu'. The hardware tells us what the
> sum of all the sizes of all the state components are, and also tells us
> the offsets inside the larger buffer.
>
> We double-check that the structure sizes exactly match the sizes that
> the hardware tells us that the buffer pieces are via XCHECK_SZ().
>
> But, later versions of the hardware have instructions that don't have
> static offsets for the state components (when the XSAVES/XSAVEC
> instructions are used). So, for those, the structure embedding isn't
> used at *all* since some state might not be present.
But *when present*, this structure is always aligned on an 8-byte
boundary, right?
next prev parent reply other threads:[~2018-11-09 17:17 UTC|newest]
Thread overview: 80+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-10-11 15:14 [PATCH v5 00/27] Control Flow Enforcement: Shadow Stack Yu-cheng Yu
2018-10-11 15:14 ` [PATCH v5 01/27] x86/cpufeatures: Add CPUIDs for Control Flow Enforcement Technology (CET) Yu-cheng Yu
2018-10-11 16:43 ` Borislav Petkov
2018-10-11 16:45 ` Yu-cheng Yu
2018-10-11 15:14 ` [PATCH v5 02/27] x86/fpu/xstate: Change names to separate XSAVES system and user states Yu-cheng Yu
2018-10-15 17:03 ` Borislav Petkov
2018-10-11 15:14 ` [PATCH v5 03/27] x86/fpu/xstate: Introduce XSAVES system states Yu-cheng Yu
2018-10-17 10:41 ` Borislav Petkov
2018-10-17 22:39 ` Randy Dunlap
2018-10-17 22:58 ` Borislav Petkov
2018-10-17 23:17 ` Randy Dunlap
2018-10-18 9:26 ` Borislav Petkov
2018-10-18 9:31 ` Pavel Machek
2018-10-18 12:10 ` Borislav Petkov
2018-10-18 18:33 ` Randy Dunlap
2018-10-18 9:24 ` Pavel Machek
2018-10-11 15:15 ` [PATCH v5 04/27] x86/fpu/xstate: Add XSAVES system states for shadow stack Yu-cheng Yu
2018-11-08 18:40 ` Borislav Petkov
2018-11-08 20:40 ` Yu-cheng Yu
2018-11-08 23:52 ` Borislav Petkov
2018-11-11 11:31 ` Pavel Machek
2018-11-11 11:31 ` Pavel Machek
2018-11-11 14:59 ` Andy Lutomirski
2018-11-11 19:02 ` Pavel Machek
2018-11-08 20:46 ` Andy Lutomirski
2018-11-08 21:01 ` Yu-cheng Yu
2018-11-08 21:22 ` Andy Lutomirski
2018-11-08 21:31 ` Cyrill Gorcunov
2018-11-08 22:01 ` Andy Lutomirski
2018-11-08 22:18 ` Cyrill Gorcunov
2018-11-08 21:48 ` Dave Hansen
2018-11-08 22:00 ` Matthew Wilcox
2018-11-08 23:35 ` Dave Hansen
2018-11-09 0:32 ` Matthew Wilcox
2018-11-09 0:45 ` Andy Lutomirski
2018-11-09 17:13 ` Dave Hansen
2018-11-09 17:17 ` Matthew Wilcox [this message]
2018-11-09 17:20 ` Dave Hansen
2018-11-09 17:28 ` Dave Hansen
2018-11-11 11:31 ` Pavel Machek
2018-10-11 15:15 ` [PATCH v5 05/27] Documentation/x86: Add CET description Yu-cheng Yu
2018-11-13 18:43 ` Borislav Petkov
2018-11-13 21:02 ` Yu-cheng Yu
2018-10-11 15:15 ` [PATCH v5 06/27] x86/cet: Control protection exception handler Yu-cheng Yu
2018-11-14 18:44 ` Borislav Petkov
2018-11-14 20:19 ` Yu-cheng Yu
2018-11-14 20:28 ` Borislav Petkov
2018-10-11 15:15 ` [PATCH v5 07/27] mm/mmap: Create a guard area between VMAs Yu-cheng Yu
2018-10-11 20:39 ` Jann Horn
2018-10-11 20:49 ` Yu-cheng Yu
2018-10-11 20:55 ` Andy Lutomirski
2018-10-12 21:49 ` Yu-cheng Yu
2018-10-12 13:17 ` Matthew Wilcox
2018-10-11 20:49 ` Dave Hansen
2018-10-12 10:24 ` Florian Weimer
2018-10-11 15:15 ` [PATCH v5 08/27] x86/cet/shstk: Add Kconfig option for user-mode shadow stack Yu-cheng Yu
2018-10-11 15:15 ` [PATCH v5 09/27] mm: Introduce VM_SHSTK for shadow stack memory Yu-cheng Yu
2018-10-11 15:15 ` [PATCH v5 10/27] mm/mmap: Prevent Shadow Stack VMA merges Yu-cheng Yu
2018-10-11 15:15 ` [PATCH v5 11/27] x86/mm: Change _PAGE_DIRTY to _PAGE_DIRTY_HW Yu-cheng Yu
2018-10-11 15:15 ` [PATCH v5 12/27] x86/mm: Introduce _PAGE_DIRTY_SW Yu-cheng Yu
2018-10-11 15:15 ` [PATCH v5 13/27] drm/i915/gvt: Update _PAGE_DIRTY to _PAGE_DIRTY_BITS Yu-cheng Yu
2018-10-11 15:15 ` [PATCH v5 14/27] x86/mm: Modify ptep_set_wrprotect and pmdp_set_wrprotect for _PAGE_DIRTY_SW Yu-cheng Yu
2018-10-11 15:15 ` [PATCH v5 15/27] x86/mm: Shadow stack page fault error checking Yu-cheng Yu
2018-10-11 15:15 ` [PATCH v5 16/27] mm: Handle shadow stack page fault Yu-cheng Yu
2018-10-11 15:15 ` [PATCH v5 17/27] mm: Handle THP/HugeTLB " Yu-cheng Yu
2018-10-11 15:15 ` [PATCH v5 18/27] mm: Update can_follow_write_pte/pmd for shadow stack Yu-cheng Yu
2018-10-11 15:15 ` [PATCH v5 19/27] mm: Introduce do_mmap_locked() Yu-cheng Yu
2018-10-11 15:15 ` [PATCH v5 20/27] x86/cet/shstk: User-mode shadow stack support Yu-cheng Yu
2018-10-11 15:15 ` [PATCH v5 21/27] x86/cet/shstk: Introduce WRUSS instruction Yu-cheng Yu
2018-11-06 18:43 ` Dave Hansen
2018-11-06 18:55 ` Andy Lutomirski
2018-11-06 20:21 ` Yu-cheng Yu
2018-10-11 15:15 ` [PATCH v5 22/27] x86/cet/shstk: Signal handling for shadow stack Yu-cheng Yu
2018-10-11 15:15 ` [PATCH v5 23/27] x86/cet/shstk: ELF header parsing of Shadow Stack Yu-cheng Yu
2018-10-11 15:15 ` [PATCH v5 24/27] x86/cet/shstk: Handle thread shadow stack Yu-cheng Yu
2018-10-11 15:15 ` [PATCH v5 25/27] mm/mmap: Add Shadow stack pages to memory accounting Yu-cheng Yu
2018-10-11 15:15 ` [PATCH v5 26/27] x86/cet/shstk: Add arch_prctl functions for Shadow Stack Yu-cheng Yu
2018-10-11 15:15 ` [PATCH v5 27/27] x86/cet/shstk: Add Shadow Stack instructions to opcode map Yu-cheng Yu
2018-10-11 19:21 ` [PATCH v5 00/27] Control Flow Enforcement: Shadow Stack Dave Hansen
2018-10-11 19:29 ` Yu-cheng Yu
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