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Re: [v2 PATCH 5/5] tracing, MIPS: Fix set_graph_function of function gra

To: Wu Zhangjin <wuzhangjin@gmail.com>
Subject: Re: [v2 PATCH 5/5] tracing, MIPS: Fix set_graph_function of function graph tracer
From: Sergei Shtylyov <sshtylyov@mvista.com>
Date: Fri, 21 Jan 2011 20:35:41 +0300
Cc: Ralf Baechle <ralf@linux-mips.org>, Steven Rostedt <srostedt@redhat.com>, linux-mips@linux-mips.org
In-reply-to: <1295630970-32044-1-git-send-email-wuzhangjin@gmail.com>
Original-recipient: rfc822;linux-mips@linux-mips.org
References: <1295630970-32044-1-git-send-email-wuzhangjin@gmail.com>
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Hello.

Wu Zhangjin wrote:

trace.func should be set to the recorded ip of the mcount calling site
in the __mcount_loc section to filter the function entries configured
through the tracing/set_graph_function interface, but before, this is
set to the self_ra(the return address of mcount), which has made
set_graph_function not work as expected.

This fixes it via calculating the right recorded ip in the __mcount_loc
section and assign it to trace.func.

Reported-by: Zhiping Zhong <xzhong86@163.com>
Signed-off-by: Wu Zhangjin <wuzhangjin@gmail.com>
---
 arch/mips/kernel/ftrace.c |   11 +++++++++--
 1 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/arch/mips/kernel/ftrace.c b/arch/mips/kernel/ftrace.c
index bc91e4a..be3fa7a 100644
--- a/arch/mips/kernel/ftrace.c
+++ b/arch/mips/kernel/ftrace.c
[...]
@@ -304,7 +304,14 @@ void prepare_ftrace_return(unsigned long *parent_ra_addr, 
unsigned long self_ra,
                return;
        }
- trace.func = self_ra;
+       /*
+        * Get the recorded ip of the current mcount calling site in the
+        * __mcount_loc section, which will be used to filter the function
+        * entries configured through the tracing/set_graph_function interface.
+        */
+
+       insns = (in_kernel_space(self_ra)) ? 2 : MCOUNT_OFFSET_INSNS + 1;

   You're still keeping the parens around the function call. Why? :-)

WBR, Sergei

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