linux-kernel - [PATCH 07/19] ftrace/x86_32: Simplify parameter setup for ftrace_regs

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Date:	Fri, 20 Jul 2012 22:19:50 -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>,
	Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	"H. Peter Anvin" <hpa@...or.com>, Uros Bizjak <ubizjak@...il.com>
Subject: [PATCH 07/19] ftrace/x86_32: Simplify parameter setup for ftrace_regs_caller

From: Uros Bizjak <ubizjak@...il.com>

The final position of the stack after saving regs and setting up
the parameters for ftrace_regs_call, is the position of the pt_regs
needed for the 4th parameter. Instead of saving it into a temporary
reg and pushing the reg, simply push the stack pointer.

Link: http://lkml.kernel.org/r/1342702344.12353.16.camel@gandalf.stny.rr.com

Signed-off-by: Uros Bizjak <ubizjak@...il.com>
Signed-off-by: Steven Rostedt <rostedt@...dmis.org>
---
 arch/x86/kernel/entry_32.S |    5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/arch/x86/kernel/entry_32.S b/arch/x86/kernel/entry_32.S
index 46caa56..4dc3017 100644
--- a/arch/x86/kernel/entry_32.S
+++ b/arch/x86/kernel/entry_32.S
@@ -1169,10 +1169,9 @@ ENTRY(ftrace_regs_caller)
 	movl $__KERNEL_CS,13*4(%esp)
 
 	movl 12*4(%esp), %eax	/* Load ip (1st parameter) */
-	movl 0x4(%ebp), %edx	/* Load parent ip (2cd parameter) */
-	lea  (%esp), %ecx
-	pushl %ecx		/* Save pt_regs as 4th parameter */
+	movl 0x4(%ebp), %edx	/* Load parent ip (2nd parameter) */
 	leal function_trace_op, %ecx /* Save ftrace_pos in 3rd parameter */
+	pushl %esp		/* Save pt_regs as 4th parameter */
 
 GLOBAL(ftrace_regs_call)
 	call ftrace_stub
-- 
1.7.10.4



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