From: "Yu, Yu-cheng" <yu-cheng.yu@intel.com>
To: Dave Hansen <dave.hansen@intel.com>, Andy Lutomirski <luto@kernel.org>
Cc: Jann Horn <jannh@google.com>,
the arch/x86 maintainers <x86@kernel.org>,
"H. Peter Anvin" <hpa@zytor.com>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>,
kernel list <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>, 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 6/9] x86/cet: Add PTRACE interface for CET
Date: Thu, 3 Sep 2020 10:59:14 -0700 [thread overview]
Message-ID: <2a58982b-8a69-1280-86ec-d0b70ede4453@intel.com> (raw)
In-Reply-To: <8fcde9bb-284f-f089-96d3-702f501a6258@intel.com>
On 9/3/2020 9:42 AM, Dave Hansen wrote:
> On 9/3/20 9:32 AM, Andy Lutomirski wrote:
>>> Taking the config register out of the init state is illogical, as is
>>> writing to SSP while the config register is in its init state.
>> What's so special about the INIT state? It's optimized by XSAVES, but
>> it's just a number, right? So taking the register out of the INIT
>> state is kind of like saying "gdb wanted to set xmm0 to (0,0,0,1), but
>> it was in the INIT state to begin with", right?
>
> Yeah, that's a good point. The init state shouldn't be special, as the
> hardware is within its right to choose not to use the init optimization
> at any time.
>
Then, I would suggest changing get_xsave_addr() to return non-null for
the INIT state case. For the other two cases, it still returns NULL.
But this also requires any write to INIT states to set xstate_bv bits
properly. This would be a pitfall for any code addition later on.
Looking at this another way. Would it be better for the debugger to get
an error and then to set the MSR directly first (vs. changing the XSAVES
INIT state first)?
next prev parent reply other threads:[~2020-09-03 17:59 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-25 0:26 [PATCH v11 0/9] Control-flow Enforcement: Indirect Branch Tracking, PTRACE Yu-cheng Yu
2020-08-25 0:26 ` [PATCH v11 1/9] x86/cet/ibt: Add Kconfig option for user-mode Indirect Branch Tracking Yu-cheng Yu
2020-08-25 0:26 ` [PATCH v11 2/9] x86/cet/ibt: User-mode Indirect Branch Tracking support Yu-cheng Yu
2020-08-25 0:26 ` [PATCH v11 3/9] x86/cet/ibt: Handle signals for Indirect Branch Tracking Yu-cheng Yu
2020-08-25 0:26 ` [PATCH v11 4/9] x86/cet/ibt: ELF header parsing " Yu-cheng Yu
2020-08-25 0:26 ` [PATCH v11 5/9] x86/cet/ibt: Update arch_prctl functions " Yu-cheng Yu
2020-08-25 0:26 ` [PATCH v11 6/9] x86/cet: Add PTRACE interface for CET Yu-cheng Yu
2020-09-02 20:03 ` Jann Horn
2020-09-02 22:13 ` Yu, Yu-cheng
2020-09-02 23:50 ` Andy Lutomirski
2020-09-03 2:53 ` Yu, Yu-cheng
2020-09-03 4:35 ` Andy Lutomirski
2020-09-03 14:26 ` Dave Hansen
2020-09-03 14:54 ` Andy Lutomirski
2020-09-03 16:09 ` Yu, Yu-cheng
2020-09-03 16:11 ` Dave Hansen
2020-09-03 16:15 ` Andy Lutomirski
2020-09-03 16:25 ` Dave Hansen
2020-09-03 16:32 ` Andy Lutomirski
2020-09-03 16:42 ` Dave Hansen
2020-09-03 17:59 ` Yu, Yu-cheng [this message]
2020-09-03 16:21 ` Yu, Yu-cheng
2020-09-03 16:25 ` Andy Lutomirski
2020-09-03 0:33 ` Jann Horn
2020-09-03 2:53 ` Yu, Yu-cheng
2020-08-25 0:26 ` [PATCH v11 7/9] x86/vdso/32: Add ENDBR32 to __kernel_vsyscall entry point Yu-cheng Yu
2020-08-25 0:26 ` [PATCH v11 8/9] x86/vdso: Insert endbr32/endbr64 to vDSO Yu-cheng Yu
2020-08-25 0:33 ` Andy Lutomirski
2020-08-25 16:13 ` Yu, Yu-cheng
2020-08-25 0:26 ` [PATCH v11 9/9] x86: Disallow vsyscall emulation when CET is enabled Yu-cheng Yu
2020-08-25 0:32 ` Andy Lutomirski
2020-08-25 9:14 ` Florian Weimer
2020-08-25 15:08 ` Yu, Yu-cheng
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