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: <CAMe9rOoTRi=f5q0yULKZXp7i8O-V7i7kvNEFKD6NJt-JbHT1Ow@mail.gmail.com> (raw)
In-Reply-To: <2cf0aaad-7c15-6040-2e5b-5e92ffaf011e@redhat.com>
On Fri, Jul 28, 2017 at 7:59 AM, Florian Weimer <fweimer@redhat.com> wrote:
> On 07/27/2017 06:21 PM, H.J. Lu wrote:
>> On Thu, Jul 27, 2017 at 8:44 AM, Florian Weimer <fweimer@redhat.com> wrote:
>>> On 06/28/2017 01:21 PM, H.J. Lu wrote:
>>>> On Wed, Jun 28, 2017 at 2:58 AM, Florian Weimer <fweimer@redhat.com> wrote:
>>>>> On 06/22/2017 08:44 PM, H.J. Lu wrote:
>>>>>>> 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?
>>>>>
>>>>> I suggest to word the ABI requirement in such a way that it is possible
>>>>> to verify if a shared object complies with it isolation, independent of
>>>>> how its functions are called.
>>>>>
>>>>
>>>> 99% of existing binaries are compatible with shadow stack.
>>>
>>> I find that surprising, or does this number to refer to x86-64 binaries
>>> only?
>>
>> CET is x86 specific. You can take a look at the current CET changes for
>> GCC at
>>
>> https://github.com/hjl-tools/gcc/tree/hjl/cet/reorg16
>
> So i386 is supported? Then I find your claim about 99% compatibility
Yes, i386 is supported.
> surprising because LLVM uses this instruction sequence
>
> calll .L0$pb
> .L0$pb:
> popl %ebx
> .Ltmp0:
> addl $_GLOBAL_OFFSET_TABLE_+(.Ltmp0-.L0$pb), %ebx
>
> to set %ebx to the GOT pointer.
>
This is called "call 0" and it won't push on shadow stack. CET
document will be updated to reflect it.
--
H.J.
next prev parent reply other threads:[~2017-07-28 20:54 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
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 [this message]
2017-01-01 0:00 ` Shanbhogue, Vedvyas
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