kprobes/x86: Blacklist indirect thunk functions for kprobes

Mark __x86_indirect_thunk_* functions as blacklist for kprobes
because those functions can be called from anywhere in the kernel
including blacklist functions of kprobes.

Signed-off-by: Masami Hiramatsu <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Acked-by: David Woodhouse <[email protected]>
Cc: Andi Kleen <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Ananth N Mavinakayanahalli <[email protected]>
Cc: Arjan van de Ven <[email protected]>
Cc: Greg Kroah-Hartman <[email protected]>
Cc: [email protected]
Link: https://lkml.kernel.org/r/151629209111.10241.5444852823378068683.stgit@devbox

Author: mhiramat

arch/x86/lib/retpoline.S

@@ -25,7 +25,8 @@ ENDPROC(__x86_indirect_thunk_\reg)
  * than one per register with the correct names. So we do it
  * the simple and nasty way...
  */
-#define EXPORT_THUNK(reg) EXPORT_SYMBOL(__x86_indirect_thunk_ ## reg)
+#define __EXPORT_THUNK(sym) _ASM_NOKPROBE(sym); EXPORT_SYMBOL(sym)
+#define EXPORT_THUNK(reg) __EXPORT_THUNK(__x86_indirect_thunk_ ## reg)
 #define GENERATE_THUNK(reg) THUNK reg ; EXPORT_THUNK(reg)
 
 GENERATE_THUNK(_ASM_AX)