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From: Florian Weimer <fweimer@redhat.com>
To: Stefan Liebler <stli@linux.ibm.com>
Cc: GNU C Library <libc-alpha@sourceware.org>
Subject: Re: [PATCH] S390: Remove not needed stack frame in syscall function.
References: <0e66f775-9669-ff29-e605-195b79382b3e@linux.ibm.com>
Date: Tue, 22 Oct 2019 10:25:00 -0000
In-Reply-To: <0e66f775-9669-ff29-e605-195b79382b3e@linux.ibm.com> (Stefan
	Liebler's message of "Tue, 22 Oct 2019 10:00:04 +0200")
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* Stefan Liebler:

> As an svc invocation does not clobber any user space registers
> despite of the return value r2 and it does not need a special
> stack frame. This patch gets rid of the extra frame.
> We just have to save and restore r6 and r7 as those are
> preserved across function calls.

Looks okay to me.  Would it be possible to save r6 and r7 in
caller-saved registers not clobbered by the system call?  That might
provide another small benefit.

Thanks,
Florian