From: Dave Hansen <dave.hansen@intel.com>
To: Andy Lutomirski <luto@amacapital.net>
Cc: Andy Lutomirski <luto@kernel.org>,
"Christopherson, Sean J" <sean.j.christopherson@intel.com>,
Jann Horn <jannh@google.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
Rich Felker <dalias@libc.org>,
Dave Hansen <dave.hansen@linux.intel.com>,
Jethro Beekman <jethro@fortanix.com>,
Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>,
Florian Weimer <fweimer@redhat.com>,
Linux API <linux-api@vger.kernel.org>, X86 ML <x86@kernel.org>,
linux-arch <linux-arch@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
nhorman@redhat.com, npmccallum@redhat.com, "Ayoun,
Serge" <serge.ayoun@intel.com>,
shay.katz-zamir@intel.com, linux-sgx@vger.kernel.org,
Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
Carlos O'Donell <carlos@redhat.com>,
adhemerval.zanella@linaro.org
Subject: Re: RFC: userspace exception fixups
Date: Tue, 6 Nov 2018 13:00:49 -0800 [thread overview]
Message-ID: <209cf4a5-eda9-2495-539f-fed22252cf02@intel.com> (raw)
In-Reply-To: <1C426267-492F-4AE7-8BE8-C7FE278531F9@amacapital.net>
On 11/6/18 12:12 PM, Andy Lutomirski wrote:
> True, but what if we have a nasty enclave that writes to memory just
> below SP *before* decrementing SP?
Yeah, that would be unfortunate. If an enclave did this (roughly):
1. EENTER
2. Hardware sets eenter_hwframe->sp = %sp
3. Enclave runs... wants to do out-call
4. Enclave sets up parameters:
memcpy(&eenter_hwframe->sp[-offset], arg1, size);
...
5. Enclave sets eenter_hwframe->sp -= offset
If we got a signal between 4 and 5, we'd clobber the copy of 'arg1' that
was on the stack. The enclave could easily fix this by moving ->sp first.
But, this is one of those "fun" parts of the ABI that I think we need to
talk about. If we do this, we also basically require that the code
which handles asynchronous exits must *not* write to the stack. That's
not hard because it's typically just a single ERESUME instruction, but
it *is* a requirement.
It means fun stuff like that you absolutely can't just async-exit to C code.
next prev parent reply other threads:[~2018-11-06 21:00 UTC|newest]
Thread overview: 91+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-01 17:53 RFC: userspace exception fixups Andy Lutomirski
2018-11-01 18:09 ` Florian Weimer
2018-11-01 18:30 ` Rich Felker
2018-11-01 19:00 ` Jarkko Sakkinen
2018-11-01 18:27 ` Rich Felker
2018-11-01 18:33 ` Jann Horn
2018-11-01 18:52 ` Rich Felker
2018-11-01 19:10 ` Linus Torvalds
2018-11-01 19:31 ` Rich Felker
2018-11-01 21:24 ` Linus Torvalds
2018-11-01 23:22 ` Andy Lutomirski
2018-11-02 16:30 ` Sean Christopherson
2018-11-02 16:37 ` Jethro Beekman
2018-11-02 16:52 ` Sean Christopherson
2018-11-02 16:56 ` Jethro Beekman
2018-11-02 17:01 ` Andy Lutomirski
2018-11-02 17:05 ` Jethro Beekman
2018-11-02 17:16 ` Andy Lutomirski
2018-11-02 17:32 ` Rich Felker
2018-11-02 17:12 ` Sean Christopherson
2018-11-02 22:42 ` Jarkko Sakkinen
2018-11-02 16:56 ` Dave Hansen
2018-11-02 17:06 ` Sean Christopherson
2018-11-02 17:13 ` Dave Hansen
2018-11-02 17:33 ` Sean Christopherson
2018-11-02 17:48 ` Andy Lutomirski
2018-11-02 18:27 ` Sean Christopherson
2018-11-02 19:02 ` Jann Horn
2018-11-02 22:04 ` Sean Christopherson
2018-11-02 23:27 ` Jann Horn
2018-11-02 23:32 ` Andy Lutomirski
2018-11-02 23:36 ` Jann Horn
2018-11-06 15:37 ` Sean Christopherson
2018-11-06 16:57 ` Andy Lutomirski
2018-11-06 17:03 ` Dave Hansen
2018-11-06 17:19 ` Sean Christopherson
2018-11-06 18:20 ` Andy Lutomirski
2018-11-06 18:41 ` Dave Hansen
2018-11-06 19:02 ` Andy Lutomirski
2018-11-06 19:22 ` Dave Hansen
2018-11-06 20:12 ` Andy Lutomirski
2018-11-06 21:00 ` Dave Hansen [this message]
2018-11-06 21:07 ` Andy Lutomirski
2018-11-06 21:41 ` Andy Lutomirski
2018-11-06 21:59 ` Sean Christopherson
2018-11-06 23:00 ` Andy Lutomirski
2018-11-06 23:35 ` Sean Christopherson
2018-11-06 23:39 ` Andy Lutomirski
2018-11-07 0:02 ` Sean Christopherson
2018-11-07 1:17 ` Andy Lutomirski
2018-11-07 6:47 ` Jethro Beekman
2018-11-07 15:34 ` Sean Christopherson
2018-11-07 19:01 ` Sean Christopherson
2018-11-07 20:56 ` Dave Hansen
2018-11-08 15:04 ` Jarkko Sakkinen
2018-11-08 19:54 ` Sean Christopherson
2018-11-08 20:05 ` Andy Lutomirski
2018-11-08 20:10 ` Dave Hansen
2018-11-08 21:16 ` Sean Christopherson
2018-11-08 21:50 ` Dave Hansen
2018-11-08 22:04 ` Sean Christopherson
2018-11-09 7:12 ` Christoph Hellwig
2018-11-06 23:17 ` Rich Felker
2018-11-06 23:26 ` Sean Christopherson
2018-11-07 21:27 ` Rich Felker
2018-11-07 21:33 ` Andy Lutomirski
2018-11-07 21:40 ` Sean Christopherson
2018-11-08 15:11 ` Jarkko Sakkinen
2018-11-06 17:00 ` Dave Hansen
2018-11-02 22:37 ` Jarkko Sakkinen
2018-11-01 19:06 ` Linus Torvalds
2018-11-02 22:07 ` Jarkko Sakkinen
2018-11-18 7:15 ` Jarkko Sakkinen
2018-11-18 7:18 ` Jarkko Sakkinen
2018-11-18 13:02 ` Jarkko Sakkinen
2018-11-19 5:17 ` Jethro Beekman
2018-11-19 14:05 ` Jarkko Sakkinen
2018-11-19 14:59 ` Jarkko Sakkinen
2018-11-19 15:29 ` Andy Lutomirski
2018-11-19 16:02 ` Jarkko Sakkinen
2018-11-19 17:00 ` Andy Lutomirski
2018-11-20 10:11 ` Jarkko Sakkinen
2018-11-20 15:19 ` Andy Lutomirski
2018-11-20 22:55 ` Jarkko Sakkinen
2018-11-21 5:17 ` Jethro Beekman
2018-11-21 15:17 ` Jarkko Sakkinen
2018-11-24 17:07 ` Jarkko Sakkinen
2018-11-26 14:35 ` Sean Christopherson
2018-11-26 22:06 ` Jarkko Sakkinen
2018-11-20 18:09 ` Sean Christopherson
2018-11-20 22:46 ` Jarkko Sakkinen
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=209cf4a5-eda9-2495-539f-fed22252cf02@intel.com \
--to=dave.hansen@intel.com \
--cc=adhemerval.zanella@linaro.org \
--cc=andriy.shevchenko@linux.intel.com \
--cc=bp@alien8.de \
--cc=carlos@redhat.com \
--cc=dalias@libc.org \
--cc=dave.hansen@linux.intel.com \
--cc=fweimer@redhat.com \
--cc=jannh@google.com \
--cc=jarkko.sakkinen@linux.intel.com \
--cc=jethro@fortanix.com \
--cc=linux-api@vger.kernel.org \
--cc=linux-arch@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-sgx@vger.kernel.org \
--cc=luto@amacapital.net \
--cc=luto@kernel.org \
--cc=mingo@redhat.com \
--cc=nhorman@redhat.com \
--cc=npmccallum@redhat.com \
--cc=peterz@infradead.org \
--cc=sean.j.christopherson@intel.com \
--cc=serge.ayoun@intel.com \
--cc=shay.katz-zamir@intel.com \
--cc=tglx@linutronix.de \
--cc=torvalds@linux-foundation.org \
--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;
as well as URLs for NNTP newsgroup(s).