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Re: [PATCH resend] MIPS: Allow FPU emulator to use non-stack area.
- From: Andy Lutomirski <luto at amacapital dot net>
- To: Rich Felker <dalias at libc dot org>
- Cc: Leonid Yegoshin <Leonid dot Yegoshin at imgtec dot com>, Matthew Fortune <Matthew dot Fortune at imgtec dot com>, David Daney <david dot s dot daney at gmail dot com>, David Daney <ddaney at caviumnetworks dot com>, David Daney <ddaney dot cavm at gmail dot com>, "libc-alpha at sourceware dot org" <libc-alpha at sourceware dot org>, "linux-kernel at vger dot kernel dot org" <linux-kernel at vger dot kernel dot org>, "linux-mips at linux-mips dot org" <linux-mips at linux-mips dot org>, David Daney <david dot daney at cavium dot com>
- Date: Tue, 7 Oct 2014 12:28:18 -0700
- Subject: Re: [PATCH resend] MIPS: Allow FPU emulator to use non-stack area.
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On Tue, Oct 7, 2014 at 12:21 PM, Rich Felker <dalias@libc.org> 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