From: Jurij Smakov <jurij@xxxxxxxxx>
Date: Sat, 22 Oct 2011 10:43:39 +0100
> On Sat, Oct 22, 2011 at 05:05:05AM -0400, David Miller wrote:
>> From: Jurij Smakov <jurij@xxxxxxxxx>
>> Date: Sat, 22 Oct 2011 10:00:24 +0100
>>
>> > Is something conceptually wrong with just doing this:
>> >
>> > asm volatile ("save; flush; restore");
>> >
>> > It fixes the problem for freebsd (will test on linux later today), and
>> > does not rely on compiler doing (or not doing) the "right"
>> > optimization.
>>
>> I would not do a "naked" save here, please just use the construct
>> I showed you with the %o7 register clobber.
>
> Yes, I missed that save is not allocating any memory, which is
> wrong. What I actually had in mind was this:
>
> asm volatile ("save %sp, -96, %sp; flushw; restore");
Only works on 32-bit, will crash on 64-bit.
Just let the compiler do it for you, please... the compiler absolutely cannot
optimize away a function that uses a volatile asm statement. And it absolutely
cannot make a function that clobbers %o7 a leaf function.
Please just use the approach I suggested, it covers all cases and is in fact
future proof.
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