[PATCH][kprobe]disallow kprobes on emulate_step function

[Gui,Jian]

Probing on emulate_step function will crash 2.6.18.1 when it is
triggered. This problem is powerpc dependent.

When kprobe is triggered, emulate_step is on its kernel path and
will cause recursive kprobe fault. This patch can disallow
kprobes on emulate_step function.


diff -Nur linux-2.6.18.1/arch/powerpc/lib/sstep.c 
new/arch/powerpc/lib/sstep.c
--- linux-2.6.18.1/arch/powerpc/lib/sstep.c     2006-10-13 
23:34:03.000000000 -0400
+++ new/arch/powerpc/lib/sstep.c        2006-10-31 06:14:44.000000000 
-0500
@@ -9,6 +9,7 @@
   * 2 of the License, or (at your option) any later version.
   */
  #include <linux/kernel.h>
+#include <linux/kprobes.h>
  #include <linux/ptrace.h>
  #include <asm/sstep.h>
  #include <asm/processor.h>
@@ -51,7 +52,7 @@
   * or -1 if the instruction is one that should not be stepped,
   * such as an rfid, or a mtmsrd that would clear MSR_RI.
   */
-int emulate_step(struct pt_regs *regs, unsigned int instr)
+int __kprobes emulate_step(struct pt_regs *regs, unsigned int instr)
  {
         unsigned int opcode, rd;
         unsigned long int imm;