linux-kernel - [PATCH v3 5/8] x86/ftrace: Use __pa_symbol instead of _

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Date:	Mon, 05 Nov 2012 11:05:53 -0800
From:	Alexander Duyck <alexander.h.duyck@...el.com>
To:	tglx@...utronix.de, mingo@...hat.com, hpa@...or.com,
	andi@...stfloor.org
Cc:	linux-kernel@...r.kernel.org, x86@...nel.org,
	Steven Rostedt <rostedt@...dmis.org>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Alexander Duyck <alexander.h.duyck@...el.com>
Subject: [PATCH v3 5/8] x86/ftrace: Use __pa_symbol instead of __pa on C
	visible symbols

Instead of using __pa which is meant to be a general function for converting
virtual addresses to physical addresses we can use __pa_symbol which is the
preferred way of decoding kernel text virtual addresses to physical addresses.

In this case we are not directly converting C visible symbols however if we
know that the instruction pointer is somewhere between _text and _etext we
know that we are going to be translating an address form the kernel text
space.

Cc: Steven Rostedt <rostedt@...dmis.org>
Cc: Frederic Weisbecker <fweisbec@...il.com>
Signed-off-by: Alexander Duyck <alexander.h.duyck@...el.com>
---

 arch/x86/kernel/ftrace.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kernel/ftrace.c b/arch/x86/kernel/ftrace.c
index 1d41402..42a392a 100644
--- a/arch/x86/kernel/ftrace.c
+++ b/arch/x86/kernel/ftrace.c
@@ -89,7 +89,7 @@ do_ftrace_mod_code(unsigned long ip, const void *new_code)
 	 * kernel identity mapping to modify code.
 	 */
 	if (within(ip, (unsigned long)_text, (unsigned long)_etext))
-		ip = (unsigned long)__va(__pa(ip));
+		ip = (unsigned long)__va(__pa_symbol(ip));
 
 	return probe_kernel_write((void *)ip, new_code, MCOUNT_INSN_SIZE);
 }
@@ -279,7 +279,7 @@ static int ftrace_write(unsigned long ip, const char *val, int size)
 	 * kernel identity mapping to modify code.
 	 */
 	if (within(ip, (unsigned long)_text, (unsigned long)_etext))
-		ip = (unsigned long)__va(__pa(ip));
+		ip = (unsigned long)__va(__pa_symbol(ip));
 
 	return probe_kernel_write((void *)ip, val, size);
 }

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