linux-kernel - [PATCH 2/6] ftrace: Make ftrace_location

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Message-Id: <1458817445-5855-2-git-send-email-mpe@ellerman.id.au>
Date:	Thu, 24 Mar 2016 22:04:01 +1100
From:	Michael Ellerman <mpe@...erman.id.au>
To:	<linuxppc-dev@...abs.org>
Cc:	bsingharora@...il.com, duwe@....de, <linux-kernel@...r.kernel.org>,
	rostedt@...dmis.org, kamalesh@...ux.vnet.ibm.com, pmladek@...e.com,
	jeyu@...hat.com, jkosina@...e.cz, live-patching@...r.kernel.org,
	mbenes@...e.cz
Subject: [PATCH 2/6] ftrace: Make ftrace_location_range() global

In order to support live patching on powerpc we would like to call
ftrace_location_range(), so make it global.

Signed-off-by: Torsten Duwe <duwe@...e.de>
Signed-off-by: Balbir Singh <bsingharora@...il.com>
Signed-off-by: Michael Ellerman <mpe@...erman.id.au>
---
 include/linux/ftrace.h |  1 +
 kernel/trace/ftrace.c  | 14 +++++++++++++-
 2 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index 6d9df3f7e334..93230e97e897 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -455,6 +455,7 @@ int ftrace_update_record(struct dyn_ftrace *rec, int enable);
 int ftrace_test_record(struct dyn_ftrace *rec, int enable);
 void ftrace_run_stop_machine(int command);
 unsigned long ftrace_location(unsigned long ip);
+unsigned long ftrace_location_range(unsigned long start, unsigned long end);
 unsigned long ftrace_get_addr_new(struct dyn_ftrace *rec);
 unsigned long ftrace_get_addr_curr(struct dyn_ftrace *rec);
 
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 57a6eea84694..f4e6aae6ebe7 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -1533,7 +1533,19 @@ static int ftrace_cmp_recs(const void *a, const void *b)
 	return 0;
 }
 
-static unsigned long ftrace_location_range(unsigned long start, unsigned long end)
+/**
+ * ftrace_location_range - return the first address of a traced location
+ *	if it touches the given ip range
+ * @start: start of range to search.
+ * @end: end of range to search (inclusive). @end points to the last byte
+ *	to check.
+ *
+ * Returns rec->ip if the related ftrace location is a least partly within
+ * the given address range. That is, the first address of the instruction
+ * that is either a NOP or call to the function tracer. It checks the ftrace
+ * internal tables to determine if the address belongs or not.
+ */
+unsigned long ftrace_location_range(unsigned long start, unsigned long end)
 {
 	struct ftrace_page *pg;
 	struct dyn_ftrace *rec;
-- 
2.5.0