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Date: Mon, 26 Sep 2011 13:43:47 +0200
From: Jan Kiszka <jan.kiszka@siemens.com>
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Subject: Re: [Qemu-devel] [PATCH v2] tcg: Remove stack protection from
	helper functions
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To: Peter Maydell <peter.maydell@linaro.org>
Cc: Blue Swirl <blauwirbel@gmail.com>, Laurent Desnogues <laurent.desnogues@gmail.com>, Anthony Liguori <aliguori@us.ibm.com>, Mulyadi Santosa <mulyadi.santosa@gmail.com>, qemu-devel <qemu-devel@nongnu.org>

On 2011-09-26 13:33, Peter Maydell wrote:
> On 26 September 2011 11:51, Jan Kiszka <jan.kiszka@siemens.com> wrote:
>> This increases the overhead of frequently executed helpers. We need to
>> move rule past QEMU_CFLAGS assignment to ensure that the required simple
>> assignment picks up all bits. The signal workaround is moved just for
>> the sake of consistency.
> 
>> +# NOTE: Must be after the last QEMU_CFLAGS assignment
>> +op_helper.o user-exec.o: QEMU_CFLAGS := $(subst -fstack-protector-all,,$(QEMU_CFLAGS)) $(HELPER_CFLAGS)
> 
> Why also user-exec.o ? 

That's a good question. It doesn't look like it's deserving this.

> Why not the other source files with helpers in?

Name them and I add them.

> This doesn't seem very consistent. Maybe the right answer is to have
> some of the offending helper functions inline instead? 

I can't imagine that this could be a short- or even mid-term answer.
Inlining is a huge work.

> (Or to not
> have -fstack-protector-all globally?)

Opt-in instead of opt-out, that might be some approach, though I bet the
out-out set still bets the opt-in crowed by some orders of magnitude.

Jan

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