SafeStack proposal in GCC

[Joel Sherrill]

On 5/9/2016 2:45 PM, Ian Lance Taylor wrote:
> On Mon, May 9, 2016 at 12:41 PM, Joel Sherrill
> <joel.sherrill@oarcorp.com> wrote:
>>
>> On 5/9/2016 2:25 PM, Ian Lance Taylor wrote:
>>>
>>> On Fri, May 6, 2016 at 10:42 PM, Rich Felker <dalias@libc.org> wrote:
>>>>
>>>>
>>>> The *context APIs are deprecated and I'm not sure they're worth
>>>> supporting with this. It would be a good excuse to get people to stop
>>>> using them.
>>>
>>>
>>> The gccgo library uses them, because there is no working alternative.
>>
>>
>> FWIW when this transition occurred, that's when the RTEMS port broke.
>> We don't have these methods.
>
> Yes, that was unfortunate, but it was a significant increase in efficiency.
>
>> It would be an interesting exercise to see if they could be
>> implemented in terms of our internal thread context management
>> APIs but no one has ever looked into it deeply.
>
> They are short functions, and easy to implement.  They don't need to
> use any thread context management, they just manipulate registers.
> The catch is that, because they manipulate registers, they are
> inherently machine-specific.

I suppose we could reuse implementations from *BSD for a subset
of targets. Those would likely be the targets folks care about
anyway.

Hmm... would those make sense to add to newlib? I am thinking
they are similar to setjmp/longjmp and shouldn't need supervisor
mode access.
  
> Ian
>