[PATCH] Transparently handle <.symbol> lookup for kprobes

[Srinivasa Ds <srinivasa@in.ibm.com>]

When data symbols are not present in kernel image, user needs to add
dot(".") before function name explicitly, that he wants to probe in kprobe 
module on ppc64.

for ex:-
When data symbols are missing on ppc64,
====================
[root@llm27lp1 ~]# cat /proc/kallsyms | grep do_fork
c00000000006283c T .do_fork
==============================
User needs add "." to "do_fork"

kp.symbol_name = ".do_fork";
============================

This makes kprobe modules unportable. Below patch fixes the problem.


Signed-off-by: Srinivasa Ds <srinivasa@in.ibm.com>
Signed-off-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com>


---
 include/asm-powerpc/kprobes.h |    6 ++++++
 1 file changed, 6 insertions(+)

Index: linux-2.6.21-rc7/include/asm-powerpc/kprobes.h
===================================================================
--- linux-2.6.21-rc7.orig/include/asm-powerpc/kprobes.h
+++ linux-2.6.21-rc7/include/asm-powerpc/kprobes.h
@@ -64,6 +64,12 @@ typedef unsigned int kprobe_opcode_t;
 				addr = *(kprobe_opcode_t **)addr;	\
 		} else if (name[0] != '.')				\
 			addr = *(kprobe_opcode_t **)addr;		\
+	} else {							\
+		char dot_name[KSYM_NAME_LEN+1];				\
+		dot_name[0] = '.';					\
+		dot_name[1] = '\0';					\
+		strncat(dot_name, name, KSYM_NAME_LEN);			\
+		addr = (kprobe_opcode_t *)kallsyms_lookup_name(dot_name); \
 	}								\
 }