linux-kernel - [RFC PATCH 1/4] ftrace: Make recordmcount.c handle __fentry_

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Date:	Tue, 07 Aug 2012 15:38:46 -0400
From:	Steven Rostedt <rostedt@...dmis.org>
To:	linux-kernel@...r.kernel.org
Cc:	Ingo Molnar <mingo@...e.hu>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Andi Kleen <andi@...stfloor.org>,
	John Reiser <jreiser@...wagon.com>
Subject: [RFC PATCH 1/4] ftrace: Make recordmcount.c handle __fentry__

From: Steven Rostedt <srostedt@...hat.com>

With gcc 4.6.0 the -mfentry feature places the function profiling
call at the start of the function. When this is used, the call is
to __fentry__ and not mcount.

Change recordmcount.c to record both callers to __fentry__ and
mcount.

Cc: John Reiser <jreiser@...wagon.com>
Cc: Andi Kleen <andi@...stfloor.org>
Signed-off-by: Steven Rostedt <rostedt@...dmis.org>
---
 scripts/recordmcount.h |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/scripts/recordmcount.h b/scripts/recordmcount.h
index 54e35c1..9d1421e 100644
--- a/scripts/recordmcount.h
+++ b/scripts/recordmcount.h
@@ -261,11 +261,13 @@ static unsigned get_mcountsym(Elf_Sym const *const sym0,
 		&sym0[Elf_r_sym(relp)];
 	char const *symname = &str0[w(symp->st_name)];
 	char const *mcount = gpfx == '_' ? "_mcount" : "mcount";
+	char const *fentry = "__fentry__";
 
 	if (symname[0] == '.')
 		++symname;  /* ppc64 hack */
 	if (strcmp(mcount, symname) == 0 ||
-	    (altmcount && strcmp(altmcount, symname) == 0))
+	    (altmcount && strcmp(altmcount, symname) == 0) ||
+	    (strcmp(fentry, symname) == 0))
 		mcountsym = Elf_r_sym(relp);
 
 	return mcountsym;
-- 
1.7.10.4



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