From: Borislav Petkov <bp@suse.de>
To: Namhyung Kim <namhyung@kernel.org>, Steven Rostedt <rostedt@goodmis.org>
Cc: Masami Hiramatsu <mhiramat@kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
Ingo Molnar <mingo@kernel.org>,
x86@kernel.org, "H.J. Lu" <hjl.tools@gmail.com>
Subject: Re: [PATCH] ftrace/x86: Fix function graph tracer reset path
Date: Mon, 16 May 2016 21:03:59 +0200 [thread overview]
Message-ID: <20160516190359.GB16265@pd.tnic> (raw)
In-Reply-To: <20160516142453.GB16239@danjae.aot.lge.com>
On Mon, May 16, 2016 at 11:24:53PM +0900, Namhyung Kim wrote:
> > -GLOBAL(ftrace_stub)
> > +/* This is weak to keep gas from relaxing the jumps */
> > +WEAK(ftrace_stub)
> > retq
> > END(ftrace_caller)
You could also force the 5-byte jump. I guess you could also write
simply ".long 0" in there but this way it is more robust if someone
decides to add other stuff between the JMP and the ftrace_stub label.
---
diff --git a/arch/x86/kernel/mcount_64.S b/arch/x86/kernel/mcount_64.S
index ed48a9f465f8..b1db8a584c06 100644
--- a/arch/x86/kernel/mcount_64.S
+++ b/arch/x86/kernel/mcount_64.S
@@ -179,7 +179,9 @@ GLOBAL(ftrace_epilogue)
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
GLOBAL(ftrace_graph_call)
- jmp ftrace_stub
+ .byte 0xe9
+ .long ftrace_stub - 1f
+1:
#endif
GLOBAL(ftrace_stub)
--
Regards/Gruss,
Boris.
SUSE Linux GmbH, GF: Felix Imendörffer, Jane Smithard, Graham Norton, HRB 21284 (AG Nürnberg)
--
next prev parent reply other threads:[~2016-05-16 19:04 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-05-13 13:53 [PATCH] ftrace/x86: Fix function graph tracer reset path Namhyung Kim
2016-05-13 14:06 ` Steven Rostedt
2016-05-15 21:41 ` Matt Fleming
2016-05-15 0:41 ` Masami Hiramatsu
2016-05-15 13:06 ` Namhyung Kim
[not found] ` <20160516175614.53e0ceed3ec0880526fa1799@kernel.org>
2016-05-16 12:32 ` Namhyung Kim
2016-05-16 13:58 ` Steven Rostedt
2016-05-16 14:24 ` Namhyung Kim
2016-05-16 19:03 ` Borislav Petkov [this message]
2016-05-16 19:13 ` Steven Rostedt
2016-05-16 19:19 ` Borislav Petkov
2016-05-16 19:23 ` Steven Rostedt
2016-05-16 19:52 ` Matt Fleming
2016-05-16 22:08 ` Masami Hiramatsu
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