From: "H.J. Lu" <hjl.tools@gmail.com>
To: Florian Weimer <fweimer@redhat.com>
Cc: gnu-gabi@sourceware.org,
IA32 System V Application Binary Interface
<ia32-abi@googlegroups.com>,
"x86-64-abi@googlegroups.com" <x86-64-abi@googlegroups.com>,
"Shanbhogue, Vedvyas" <vedvyas.shanbhogue@intel.com>
Subject: Re: RFC: Update x86 psABI to support shadow stac
Date: Sun, 01 Jan 2017 00:00:00 -0000 [thread overview]
Message-ID: <CAMe9rOpoEMgRrTy5G1jsO4A7aAtEvYx3nizwZz8haVXFceogOA@mail.gmail.com> (raw)
In-Reply-To: <53356291-bb6d-3a69-3dc7-4a1f011942bd@redhat.com>
On Thu, Jun 22, 2017 at 6:10 AM, Florian Weimer <fweimer@redhat.com> wrote:
> On 06/22/2017 03:01 PM, H.J. Lu wrote:
>> On Thu, Jun 22, 2017 at 5:51 AM, Florian Weimer <fweimer@redhat.com> wrote:
>>> On 06/21/2017 05:25 PM, H.J. Lu wrote:
>>>> GNU_PROPERTY_X86_FEATURE_1_SHSTK is set on output only if it is set on
>>>> all relocatable inputs, which means that the C library must be compiled
>>>> with SHSTK-enabled compiler.
>>>
>>> I don't think this is sufficiently detailed for an ABI specification.
>>> It needs to say what an SHSTK-enabled compiler does.
>>
>> Compilers just need to make return address popped from shadow
>> stack match return address popped from normal stack.
>
> Nothing else? Would a writable GOT still be fine?
Writable GOT is OK.
> The responsibilities for compliance are split between caller and callee,
> which can live in different shared objects. I think it would be prudent
> to formulate the requirement in such a way that compliance can be
> checked by looking at one DSO in isolation.
What do you mean by it?
> Is there a requirement that the return address is popped from the same
> stack location where it was pushed by the call instruction? Or could
> you return with an elevated stack pointer if you copied the address first?
Stack location isn't checked. Only the popped return address is checked.
Vedvyas can confirm it.
--
H.J.
next prev parent reply other threads:[~2017-06-22 18:45 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-01-01 0:00 H.J. Lu
2017-01-01 0:00 ` Florian Weimer
2017-01-01 0:00 ` H.J. Lu
2017-01-01 0:00 ` Florian Weimer
2017-01-01 0:00 ` H.J. Lu [this message]
2017-01-01 0:00 ` Florian Weimer
2017-01-01 0:00 ` H.J. Lu
2017-01-01 0:00 ` Florian Weimer
2017-01-01 0:00 ` H.J. Lu
2017-01-01 0:00 ` Florian Weimer
2017-01-01 0:00 ` H.J. Lu
2017-01-01 0:00 ` Shanbhogue, Vedvyas
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=CAMe9rOpoEMgRrTy5G1jsO4A7aAtEvYx3nizwZz8haVXFceogOA@mail.gmail.com \
--to=hjl.tools@gmail.com \
--cc=fweimer@redhat.com \
--cc=gnu-gabi@sourceware.org \
--cc=ia32-abi@googlegroups.com \
--cc=vedvyas.shanbhogue@intel.com \
--cc=x86-64-abi@googlegroups.com \
/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 read-only IMAP folder(s) and NNTP newsgroup(s).