Re: [PATCH 07/56] microblaze_v2: Signal support

Michal Simek
2008-05-06T09:40:51Z

I hope that conclusion is remove #if 0 from signal.c code.

M

> You're right. (I think I've been staring at this too much today... :)
>
> Steve
>
>> -----Original Message-----
>> From: John Williams [mailto:john.williams@petalogix.com]
>> Sent: Monday, May 05, 2008 5:26 PM
>> To: Stephen Neuendorffer
>> Cc: monstr@seznam.cz; linux-kernel@vger.kernel.org; arnd@arndb.de;
> linux-arch@vger.kernel.org; John
>> Linn; matthew@wil.cx; will.newton@gmail.com; drepper@redhat.com;
> microblaze-uclinux@itee.uq.edu.au;
>> grant.likely@secretlab.ca; Michal Simek
>> Subject: RE: [PATCH 07/56] microblaze_v2: Signal support
>>
>> On Mon, 2008-05-05 at 17:13 -0700, Stephen Neuendorffer wrote:
>>> I'm somewhat ignorant about what this code is attempting to do, but
> with
>>> some quick poking around (m68knommu, blackfin) seems to suggest that
>>> other architectures don't do this, while others (v850) have almost
>>> exactly the same code (although they are somewhat smarter and are
>>> careful not to flush the whole cache).
>>>
>>> At the very least, it seems like there is some work in this area
> needed.
>> flush_cache_sigtramp should just invalidate 8 bytes up from the base
>> address of the trampoline. This is just the region on the process
> stack
>> where we insert a kind of call-back back. Writing the opcodes goes
> via
>> the dcache, and so there's a vanishingly small possibility that the
> CPU
>> will get a false hit on on an icache fetch when the code is executed.
>>
>> That was what Michal's patch had when I scanned it yesterday. It
>> certainly won't/shouldn't be invalidating the entire cache.
>>
>> Cheers,
>>
>> John
>>
>>
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