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From: Dave Hansen <dave.hansen@intel.com>
To: "Yu, Yu-cheng" <yu-cheng.yu@intel.com>,
	Andy Lutomirski <luto@kernel.org>
Cc: 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>,
	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>,
	Weijiang Yang <weijiang.yang@intel.com>
Subject: Re: [PATCH v11 25/25] x86/cet/shstk: Add arch_prctl functions for shadow stack
Date: Tue, 25 Aug 2020 12:19:39 -0700	[thread overview]
Message-ID: <086c73d8-9b06-f074-e315-9964eb666db9@intel.com> (raw)
In-Reply-To: <2d253891-9393-44d0-35e0-4b9a2da23cec@intel.com>

On 8/25/20 11:43 AM, Yu, Yu-cheng wrote:
>>> arch_prctl(ARCH_X86_CET_MMAP_SHSTK, u64 *args)
>>>      Allocate a new shadow stack.
>>>
>>>      The parameter 'args' is a pointer to a user buffer.
>>>
>>>      *args = desired size
>>>      *(args + 1) = MAP_32BIT or MAP_POPULATE
>>>
>>>      On returning, *args is the allocated shadow stack address.
>>
>> This is hideous.  Would this be better as a new syscall?
> 
> Could you point out why this is hideous, so that I can modify the
> arch_prctl?

Passing values in memory is hideous when we don't have to.  A syscall
would let you have separate arguments for size and flags and would also
let you have a nice return value instead of needing to do that in memory
too.

> I think this is more arch-specific.  Even if it becomes a new syscall,
> we still need to pass the same parameters.

Right, but without the copying in and out of memory.

  reply	other threads:[~2020-08-25 19:19 UTC|newest]

Thread overview: 89+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-08-25  0:25 [PATCH v11 00/25] Control-flow Enforcement: Shadow Stack Yu-cheng Yu
2020-08-25  0:25 ` [PATCH v11 01/25] Documentation/x86: Add CET description Yu-cheng Yu
2020-08-25  0:25 ` [PATCH v11 02/25] x86/cpufeatures: Add CET CPU feature flags for Control-flow Enforcement Technology (CET) Yu-cheng Yu
2020-08-25  0:25 ` [PATCH v11 03/25] x86/fpu/xstate: Introduce CET MSR XSAVES supervisor states Yu-cheng Yu
2020-08-25  0:25 ` [PATCH v11 04/25] x86/cet: Add control-protection fault handler Yu-cheng Yu
2020-08-25  0:25 ` [PATCH v11 05/25] x86/cet/shstk: Add Kconfig option for user-mode Shadow Stack Yu-cheng Yu
2020-08-25  0:25 ` [PATCH v11 06/25] x86/mm: Change _PAGE_DIRTY to _PAGE_DIRTY_HW Yu-cheng Yu
2020-08-25  0:25 ` [PATCH v11 07/25] x86/mm: Remove _PAGE_DIRTY_HW from kernel RO pages Yu-cheng Yu
2020-08-25  0:25 ` [PATCH v11 08/25] x86/mm: Introduce _PAGE_COW Yu-cheng Yu
2020-08-25  0:25 ` [PATCH v11 09/25] drm/i915/gvt: Change _PAGE_DIRTY to _PAGE_DIRTY_BITS Yu-cheng Yu
2020-08-25  0:25 ` [PATCH v11 10/25] x86/mm: Update pte_modify for _PAGE_COW Yu-cheng Yu
2020-08-25  0:25 ` [PATCH v11 11/25] x86/mm: Update ptep_set_wrprotect() and pmdp_set_wrprotect() for transition from _PAGE_DIRTY_HW to _PAGE_COW Yu-cheng Yu
2020-08-25  0:25 ` [PATCH v11 12/25] mm: Introduce VM_SHSTK for shadow stack memory Yu-cheng Yu
2020-08-25  0:25 ` [PATCH v11 13/25] x86/mm: Shadow Stack page fault error checking Yu-cheng Yu
2020-08-25  0:25 ` [PATCH v11 14/25] x86/mm: Update maybe_mkwrite() for shadow stack Yu-cheng Yu
2020-08-25  0:25 ` [PATCH v11 15/25] mm: Fixup places that call pte_mkwrite() directly Yu-cheng Yu
2020-08-25  0:25 ` [PATCH v11 16/25] mm: Add guard pages around a shadow stack Yu-cheng Yu
2020-08-25  0:25 ` [PATCH v11 17/25] mm/mmap: Add shadow stack pages to memory accounting Yu-cheng Yu
2020-08-25  0:25 ` [PATCH v11 18/25] mm: Update can_follow_write_pte() for shadow stack Yu-cheng Yu
2020-08-25  0:25 ` [PATCH v11 19/25] mm: Re-introduce do_mmap_pgoff() Yu-cheng Yu
2020-08-25  0:25 ` [PATCH v11 20/25] x86/cet/shstk: User-mode shadow stack support Yu-cheng Yu
2020-08-25  0:25 ` [PATCH v11 21/25] x86/cet/shstk: Handle signals for shadow stack Yu-cheng Yu
2020-08-25  0:25 ` [PATCH v11 22/25] binfmt_elf: Define GNU_PROPERTY_X86_FEATURE_1_AND properties Yu-cheng Yu
2020-08-25  0:25 ` [PATCH v11 23/25] ELF: Introduce arch_setup_elf_property() Yu-cheng Yu
2020-08-25  0:25 ` [PATCH v11 24/25] x86/cet/shstk: Handle thread shadow stack Yu-cheng Yu
2020-08-25  0:25 ` [PATCH v11 25/25] x86/cet/shstk: Add arch_prctl functions for " Yu-cheng Yu
2020-08-25  0:36   ` Andy Lutomirski
2020-08-25 18:43     ` Yu, Yu-cheng
2020-08-25 19:19       ` Dave Hansen [this message]
2020-08-25 21:04         ` Yu, Yu-cheng
2020-08-25 23:20           ` Dave Hansen
2020-08-25 23:34             ` Yu, Yu-cheng
2020-08-26 16:46               ` Dave Martin
2020-08-26 16:51                 ` Florian Weimer
2020-08-26 17:04                   ` Andy Lutomirski
2020-08-26 18:49                     ` Yu, Yu-cheng
2020-08-26 19:43                       ` H.J. Lu
2020-08-26 19:57                       ` Dave Hansen
2020-08-27 13:26                         ` H.J. Lu
2020-09-01 10:28                           ` Dave Martin
2020-09-01 17:23                             ` Yu, Yu-cheng
2020-09-01 17:45                               ` Andy Lutomirski
2020-09-01 18:11                                 ` Dave Hansen
2020-09-02 13:58                                   ` Dave Martin
     [not found]                                   ` <46dffdfd-92f8-0f05-6164-945f217b0958@intel.com>
2020-09-08 17:57                                     ` Dave Hansen
2020-09-08 18:25                                       ` Yu, Yu-cheng
2020-09-09 22:08                                         ` Yu, Yu-cheng
2020-09-09 22:59                                           ` Dave Hansen
2020-09-09 23:07                                             ` Yu, Yu-cheng
2020-09-09 23:11                                               ` Dave Hansen
2020-09-09 23:25                                                 ` Yu, Yu-cheng
2020-09-09 23:29                                                   ` Dave Hansen
2020-09-09 23:45                                                     ` Yu, Yu-cheng
2020-09-11 22:59                                                     ` Yu-cheng Yu
2020-09-14 14:50                                                       ` [NEEDS-REVIEW] " Dave Hansen
2020-09-14 18:31                                                         ` Andy Lutomirski
2020-09-14 20:44                                                           ` Yu, Yu-cheng
2020-09-14 21:14                                                           ` Dave Hansen
2020-09-16 13:52                                                             ` Andy Lutomirski
2020-09-16 19:25                                                               ` Yu, Yu-cheng
2021-09-14  1:33                                                           ` [NEEDS-REVIEW] " Edgecombe, Rick P
2021-09-14  9:53                                                             ` Borislav Petkov
2021-09-20 16:48                                                             ` Andy Lutomirski
2021-09-23 23:32                                                               ` Edgecombe, Rick P
     [not found]                                                         ` <bf2ab309-f8c4-83da-1c0a-5684e5bc5c82@intel.com>
2020-09-15 19:08                                                           ` Yu-cheng Yu
2020-09-15 19:24                                                             ` Dave Hansen
2020-09-15 20:16                                                               ` Yu, Yu-cheng
2020-08-26 17:08                   ` Dave Martin
2020-08-27 13:18                     ` Florian Weimer
2020-08-27 13:28                       ` H.J. Lu
2020-08-27 13:36                         ` Florian Weimer
2020-08-27 14:07                           ` H.J. Lu
2020-08-27 14:08                             ` H.J. Lu
2020-09-01 17:49                               ` Yu, Yu-cheng
2020-09-01 17:50                                 ` Florian Weimer
2020-09-01 17:58                                   ` Yu, Yu-cheng
2020-09-01 18:17                                     ` Florian Weimer
2020-09-01 18:19                                       ` H.J. Lu
2020-09-01 18:24                                       ` Yu, Yu-cheng
2020-08-27 18:13                           ` Yu, Yu-cheng
2020-08-27 18:56                             ` Andy Lutomirski
2020-08-27 19:33                               ` Yu, Yu-cheng
2020-08-27 19:37                               ` H.J. Lu
2020-08-28  1:35                                 ` Andy Lutomirski
2020-08-28  1:44                                   ` H.J. Lu
2020-08-28  6:23                                     ` Florian Weimer
2020-08-28 11:37                                       ` H.J. Lu
2020-08-28 17:39                                         ` Andy Lutomirski
2020-08-28 17:45                                           ` H.J. Lu

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