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Re: [PATCH] S390: Remove not needed stack frame in syscall function.
- From: Florian Weimer <fweimer at redhat dot com>
- To: Stefan Liebler <stli at linux dot ibm dot com>
- Cc: GNU C Library <libc-alpha at sourceware dot org>
- Date: Tue, 22 Oct 2019 12:25:46 +0200
- Subject: Re: [PATCH] S390: Remove not needed stack frame in syscall function.
- References: <0e66f775-9669-ff29-e605-195b79382b3e@linux.ibm.com>
* 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