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From: Heiko Carstens <hca@linux.ibm.com>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: Ilya Leoshkevich <iii@linux.ibm.com>,
	Ingo Molnar <mingo@redhat.com>,
	linux-kernel@vger.kernel.org, Sven Schnelle <svens@linux.ibm.com>,
	Vasily Gorbik <gor@linux.ibm.com>,
	linux-s390@vger.kernel.org
Subject: Re: [PATCH 1/2] ftrace: Introduce ftrace_need_init_nop()
Date: Sat, 31 Jul 2021 08:47:35 +0200	[thread overview]
Message-ID: <YQTyB5eeC0FvDm06@osiris> (raw)
In-Reply-To: <20210730220741.4da6fdf6@oasis.local.home>

On Fri, Jul 30, 2021 at 10:07:41PM -0400, Steven Rostedt wrote:
> On Wed, 28 Jul 2021 23:25:45 +0200
> Ilya Leoshkevich <iii@linux.ibm.com> wrote:
> 
> > Implementing live patching on s390 requires each function's prologue to
> > contain a very special kind of nop, which gcc and clang don't generate.
> > However, the current code assumes that if CC_USING_NOP_MCOUNT is
> > defined, then whatever the compiler generates is good enough.
> > 
> > Move the CC_USING_NOP_MCOUNT check into the new ftrace_need_init_nop()
> > macro, that the architectures can override.
> > 
> > An alternative solution is to disable using -mnop-mcount in the
> > Makefile, however, this makes the build logic (even) more complicated
> > and forces the arch-specific code to deal with the useless __fentry__
> > symbol.
> > 
> > Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
> 
> I'm fine with this patch, and also you taking it in via the s390 tree.
> 
> Reviewed-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

Thanks a lot!

  reply	other threads:[~2021-07-31  6:48 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-28 21:25 [PATCH 0/2] s390/ftrace: implement hotpatching Ilya Leoshkevich
2021-07-28 21:25 ` [PATCH 1/2] ftrace: Introduce ftrace_need_init_nop() Ilya Leoshkevich
2021-07-31  2:07   ` Steven Rostedt
2021-07-31  6:47     ` Heiko Carstens [this message]
2021-07-28 21:25 ` [PATCH 2/2] s390/ftrace: implement hotpatching Ilya Leoshkevich
2021-07-31  6:47 ` [PATCH 0/2] " Heiko Carstens

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