From: Steven Rostedt <rostedt@goodmis.org>
To: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: LKML <linux-kernel@vger.kernel.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
"H. Peter Anvin" <hpa@zytor.com>, Jiri Kosina <jikos@kernel.org>,
Miroslav Benes <mbenes@suse.cz>, Petr Mladek <pmladek@suse.com>,
Joe Lawrence <joe.lawrence@redhat.com>,
live-patching@vger.kernel.org, x86@kernel.org,
Borislav Petkov <bp@alien8.de>
Subject: Re: [RFC][PATCH] ftrace/x86: Remove mcount support
Date: Thu, 9 May 2019 22:30:51 -0400 [thread overview]
Message-ID: <20190509223051.710a8f4e@gandalf.local.home> (raw)
In-Reply-To: <20190509201430.2eabpqjv2kw7dwnv@treble>
On Thu, 9 May 2019 15:14:30 -0500
Josh Poimboeuf <jpoimboe@redhat.com> wrote:
> > Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
> > ---
> > arch/x86/include/asm/ftrace.h | 8 +++----
> > arch/x86/include/asm/livepatch.h | 3 ---
> > arch/x86/kernel/ftrace_32.S | 36 +++++---------------------------
> > arch/x86/kernel/ftrace_64.S | 28 +------------------------
> > 4 files changed, 9 insertions(+), 66 deletions(-)
>
> I was wondering why you didn't do s/mcount/fentry/ everywhere, but I
> guess it's because mcount is still used by other arches, so it still has
> a generic meaning tree-wide, right?
Yes, fentry works nicely when you have a single instruction that pushes
the return address on the stack and then jumps to another location.
It's much trickier to implement with link registers. There's a few
different implementations for other archs, but mcount happens to be the
one supported by most.
>
> Anyway it's nice to finally see this cruft disappear.
>
> Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Thanks!
-- Steve
next prev parent reply other threads:[~2019-05-10 2:30 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-05-09 19:49 Steven Rostedt
2019-05-09 19:59 ` Peter Zijlstra
2019-05-09 20:03 ` Jiri Kosina
2019-05-09 20:12 ` Linus Torvalds
2019-05-10 2:28 ` Steven Rostedt
2019-05-10 7:30 ` Jiri Kosina
2019-05-09 20:14 ` Josh Poimboeuf
2019-05-10 2:30 ` Steven Rostedt [this message]
2019-05-10 2:37 ` Steven Rostedt
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