From: Thomas Gleixner <tglx@linutronix.de>
To: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Jiri Kosina <jikos@kernel.org>,
Tom Lendacky <thomas.lendacky@amd.com>,
Ingo Molnar <mingo@redhat.com>,
Peter Zijlstra <peterz@infradead.org>,
Josh Poimboeuf <jpoimboe@redhat.com>,
Andrea Arcangeli <aarcange@redhat.com>,
David Woodhouse <dwmw@amazon.co.uk>,
Andi Kleen <ak@linux.intel.com>,
Dave Hansen <dave.hansen@intel.com>,
Casey Schaufler <casey.schaufler@intel.com>,
Asit Mallick <asit.k.mallick@intel.com>,
Arjan van de Ven <arjan@linux.intel.com>,
Jon Masters <jcm@redhat.com>,
linux-kernel@vger.kernel.org, x86@kernel.org
Subject: Re: [Patch v3 07/13] x86/process Add arch_set_dumpable
Date: Fri, 19 Oct 2018 21:12:48 +0200 (CEST) [thread overview]
Message-ID: <alpine.DEB.2.21.1810192100130.1651@nanos.tec.linutronix.de> (raw)
In-Reply-To: <c8bb3ea2-d060-5cad-1544-ae5ff5f8fd3b@linux.intel.com>
On Thu, 18 Oct 2018, Tim Chen wrote:
> On 10/18/2018 06:28 AM, Thomas Gleixner wrote:
> >
> > So now the obvious question. set_dumpable() operates on tsk->mm. i.e. it's
> > a process wide operation. But arch_set_dumpable() operates on the task
> > itself. What about the other tasks of that process?
>
> I missed this part.
>
> Fixing this is tricky as I don't see an easy way to
> reverse map mm back to all tasks that use the same mm
> to update their STIBP flags.
task is known and handed in to the function. So why do you want to reverse
map mm?
for_each_thread(task, ...) is what you want. The only thing to verify is
whether you can lock the tasks sighand lock there. And then it's enough to
set/clear the TIF bit and let it take effect at the next context switch.
Thanks,
tglx
next prev parent reply other threads:[~2018-10-19 19:13 UTC|newest]
Thread overview: 47+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-10-17 17:59 [Patch v3 00/13] Provide process property based options to enable Spectre v2 userspace-userspace protection Tim Chen
2018-10-17 17:59 ` [Patch v3 01/13] x86/speculation: Clean up spectre_v2_parse_cmdline Tim Chen
2018-10-18 12:43 ` Thomas Gleixner
2018-10-17 17:59 ` [Patch v3 02/13] x86/speculation: Remove unnecessary ret variable in cpu_show_common Tim Chen
2018-10-18 12:46 ` Thomas Gleixner
2018-10-17 17:59 ` [Patch v3 03/13] x86/speculation: Add static key for Enhanced IBRS Tim Chen
2018-10-18 12:50 ` Thomas Gleixner
2018-10-26 16:58 ` Waiman Long
2018-10-26 18:15 ` Tim Chen
2018-10-28 9:32 ` Thomas Gleixner
2018-10-17 17:59 ` [Patch v3 04/13] x86/speculation: Disable STIBP when enhanced IBRS is in use Tim Chen
2018-10-18 12:58 ` Thomas Gleixner
2018-10-26 17:00 ` Waiman Long
2018-10-26 18:18 ` Tim Chen
2018-10-26 18:29 ` Tim Chen
2018-10-17 17:59 ` [Patch v3 05/13] x86/smt: Create cpu_smt_enabled static key for SMT specific code Tim Chen
2018-10-18 13:03 ` Thomas Gleixner
2018-10-19 7:51 ` Peter Zijlstra
2018-10-17 17:59 ` [Patch v3 06/13] mm: Pass task instead of task->mm as argument to set_dumpable Tim Chen
2018-10-18 13:22 ` Thomas Gleixner
2018-10-19 20:02 ` Peter Zijlstra
2018-10-17 17:59 ` [Patch v3 07/13] x86/process Add arch_set_dumpable Tim Chen
2018-10-18 13:28 ` Thomas Gleixner
2018-10-18 18:46 ` Tim Chen
2018-10-19 19:12 ` Thomas Gleixner [this message]
2018-10-19 20:16 ` Thomas Gleixner
2018-10-22 23:55 ` Tim Chen
2018-10-17 17:59 ` [Patch v3 08/13] x86/speculation: Rename SSBD update functions Tim Chen
2018-10-18 13:37 ` Thomas Gleixner
2018-10-17 17:59 ` [Patch v3 09/13] x86/speculation: Reorganize SPEC_CTRL MSR update Tim Chen
2018-10-18 13:47 ` Thomas Gleixner
2018-10-26 17:21 ` Waiman Long
2018-10-26 18:25 ` Tim Chen
2018-10-17 17:59 ` [Patch v3 10/13] x86/speculation: Add per thread STIBP flag Tim Chen
2018-10-18 13:53 ` Thomas Gleixner
2018-10-17 17:59 ` [Patch v3 11/13] x86/speculation: Add Spectre v2 lite app to app protection mode Tim Chen
2018-10-18 15:12 ` Thomas Gleixner
2018-10-17 17:59 ` [Patch v3 12/13] x86/speculation: Protect non-dumpable processes against Spectre v2 attack Tim Chen
2018-10-18 15:17 ` Thomas Gleixner
2018-10-26 17:46 ` Waiman Long
2018-10-26 18:10 ` Tim Chen
2018-10-17 17:59 ` [Patch v3 13/13] x86/speculation: Create PRCTL interface to restrict indirect branch speculation Tim Chen
2018-10-17 19:12 ` Randy Dunlap
2018-10-18 15:31 ` Thomas Gleixner
2018-10-19 7:57 ` [Patch v3 00/13] Provide process property based options to enable Spectre v2 userspace-userspace protection Peter Zijlstra
2018-10-19 16:43 ` Tim Chen
2018-10-19 18:38 ` Peter Zijlstra
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=alpine.DEB.2.21.1810192100130.1651@nanos.tec.linutronix.de \
--to=tglx@linutronix.de \
--cc=aarcange@redhat.com \
--cc=ak@linux.intel.com \
--cc=arjan@linux.intel.com \
--cc=asit.k.mallick@intel.com \
--cc=casey.schaufler@intel.com \
--cc=dave.hansen@intel.com \
--cc=dwmw@amazon.co.uk \
--cc=jcm@redhat.com \
--cc=jikos@kernel.org \
--cc=jpoimboe@redhat.com \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@redhat.com \
--cc=peterz@infradead.org \
--cc=thomas.lendacky@amd.com \
--cc=tim.c.chen@linux.intel.com \
--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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.