From: Peter Zijlstra <peterz@infradead.org>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: Andy Lutomirski <luto@kernel.org>,
Lai Jiangshan <jiangshanlai@gmail.com>,
LKML <linux-kernel@vger.kernel.org>,
Lai Jiangshan <laijs@linux.alibaba.com>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
X86 ML <x86@kernel.org>, "H. Peter Anvin" <hpa@zytor.com>,
Alexandre Chartre <alexandre.chartre@oracle.com>,
"Gustavo A. R. Silva" <gustavoars@kernel.org>,
"Chang S. Bae" <chang.seok.bae@intel.com>,
Sasha Levin <sashal@kernel.org>
Subject: Re: [PATCH 1/2] x86/hw_breakpoint: Prevent data breakpoints on __per_cpu_offset
Date: Fri, 5 Feb 2021 13:46:55 +0100 [thread overview]
Message-ID: <YB0+P3LiduCpWctO@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <877dnmagb1.fsf@nanos.tec.linutronix.de>
On Fri, Feb 05, 2021 at 12:45:54PM +0100, Thomas Gleixner wrote:
> On Thu, Feb 04 2021 at 16:11, Andy Lutomirski wrote:
> > On Thu, Feb 4, 2021 at 6:26 AM Lai Jiangshan <jiangshanlai@gmail.com> wrote:
> >> When FSGSBASE is enabled, paranoid_entry() fetches the per-CPU
> >> GSBASE value via __per_cpu_offset or pcpu_unit_offsets.
> >>
> >> When data breakpoint is set on __per_cpu_offset[cpu] (read-write
> >> operation), the specific cpu will be stuck in the infinite #DB loop.
> >> RCU will try to send NMI to the specific cpu, but it is not working
> >> either since NMI also relies on paranoid_entry().
> >
> > Should we consider having a .percpu..noinstr section and having
> > objtool enforce this?
>
> I think so.
I'll put it on the TODO list somewhere ...
next prev parent reply other threads:[~2021-02-06 0:22 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-04 15:27 [PATCH 1/2] x86/hw_breakpoint: Prevent data breakpoints on __per_cpu_offset Lai Jiangshan
2021-02-04 15:27 ` [PATCH 2/2] x86/hw_breakpoint: Prevent data breakpoints on cpu_dr7 Lai Jiangshan
2021-02-05 19:15 ` [tip: x86/urgent] x86/debug: " tip-bot2 for Lai Jiangshan
2021-02-05 0:11 ` [PATCH 1/2] x86/hw_breakpoint: Prevent data breakpoints on __per_cpu_offset Andy Lutomirski
2021-02-05 11:45 ` Thomas Gleixner
2021-02-05 12:46 ` Peter Zijlstra [this message]
2021-02-05 19:15 ` [tip: x86/urgent] x86/debug: " tip-bot2 for Lai Jiangshan
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=YB0+P3LiduCpWctO@hirez.programming.kicks-ass.net \
--to=peterz@infradead.org \
--cc=alexandre.chartre@oracle.com \
--cc=bp@alien8.de \
--cc=chang.seok.bae@intel.com \
--cc=gustavoars@kernel.org \
--cc=hpa@zytor.com \
--cc=jiangshanlai@gmail.com \
--cc=laijs@linux.alibaba.com \
--cc=linux-kernel@vger.kernel.org \
--cc=luto@kernel.org \
--cc=mingo@redhat.com \
--cc=sashal@kernel.org \
--cc=tglx@linutronix.de \
--cc=x86@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox