linux-kernel - [PATCH] printk: Fix %pB when there's no symbol at the address

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Date:	Mon, 14 Jul 2014 23:38:40 +0900
From:	Namhyung Kim <namhyung@...nel.org>
To:	Ingo Molnar <mingo@...nel.org>
Cc:	Peter Zijlstra <peterz@...radead.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>,
	LKML <linux-kernel@...r.kernel.org>,
	Steven Rostedt <rostedt@...dmis.org>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Josh Poimboeuf <jpoimboe@...hat.com>
Subject: [PATCH] printk: Fix %pB when there's no symbol at the address

The __sprint_symbol() should restore original address when
kallsyms_lookup() failed to find a symbol.  It's reported when
dumpstack shows an address in a dynamically allocated trampoline
for ftrace.

  [ 1314.612287]  [<ffffffff81700312>] dump_stack+0x45/0x56
  [ 1314.612290]  [<ffffffff8125f5b0>] ? meminfo_proc_open+0x30/0x30
  [ 1314.612293]  [<ffffffffa080a494>] kpatch_ftrace_handler+0x14/0xf0 [kpatch]
  [ 1314.612306]  [<ffffffffa00160c4>] 0xffffffffa00160c3

You can see a difference in the hex address - c4 and c3.  Fix it.

Reported-by: Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>
Cc: Steven Rostedt <rostedt@...dmis.org>
Cc: Frederic Weisbecker <fweisbec@...il.com>
Cc: Josh Poimboeuf <jpoimboe@...hat.com>
Signed-off-by: Namhyung Kim <namhyung@...nel.org>
---
 kernel/kallsyms.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/kallsyms.c b/kernel/kallsyms.c
index cb0cf37dac3a..ae5167087845 100644
--- a/kernel/kallsyms.c
+++ b/kernel/kallsyms.c
@@ -364,7 +364,7 @@ static int __sprint_symbol(char *buffer, unsigned long address,
 	address += symbol_offset;
 	name = kallsyms_lookup(address, &size, &offset, &modname, buffer);
 	if (!name)
-		return sprintf(buffer, "0x%lx", address);
+		return sprintf(buffer, "0x%lx", address - symbol_offset);
 
 	if (name != buffer)
 		strcpy(buffer, name);
-- 
2.0.0

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