Re: [PATCH resend] MIPS: Allow FPU emulator to use non-stack area.

From: Andy Lutomirski
Date: Tue Oct 07 2014 - 15:28:45 EST


On Tue, Oct 7, 2014 at 12:21 PM, Rich Felker <dalias@xxxxxxxx> wrote:
> On Tue, Oct 07, 2014 at 12:16:59PM -0700, Leonid Yegoshin wrote:
>> On 10/07/2014 12:09 PM, Rich Felker wrote:
>> >I agree completely here. We should not break things (or, as it
>> >seems, leave them broken) for common usage cases that affect
>> >everyone just to coddle proprietary vendor-specific instructions.
>> >The latter just should not be used in delay slots unless the chip
>> >vendor also promises to provide fpu branch in hardware. Rich
>> And what do you propose - remove a current in-stack emulation and
>> you still think it doesn't break a status-quo?
>
> The in-stack trampoline support could be left but used only for
> emulating instructions the kernel doesn't know. This would make all
> normal binaries immediately usable with non-executable stack, and
> would avoid the only potential source of regressions. Ultimately I
> think the "xol" stuff should be removed, but that could be a long term
> goal.

Does anything break if the xol stuff is disabled for PT_GNU_STACK tasks?

>
> Rich



--
Andy Lutomirski
AMA Capital Management, LLC
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