kprobes/x86: Blacklist indirect thunk functions for kprobes

commit c1804a236894ecc942da7dc6c5abe209e56cba93 upstream.

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 <mhiramat@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: David Woodhouse <dwmw@amazon.co.uk>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ananth N Mavinakayanahalli <ananth@linux.vnet.ibm.com>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Greg Kroah-Hartman <gregkh@linux-foundation.org>
Link: https://lkml.kernel.org/r/151629209111.10241.5444852823378068683.stgit@devbox
[bwh: Backported to 3.16: exports are still done from C]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/arch/x86/lib/retpoline.S b/arch/x86/lib/retpoline.S
index 5e606465e504f27692019af0e7585c30bc37cff1..20d0e6c89f2e80e239b41eb210d6e6784be51acf 100644 (file)
--- a/arch/x86/lib/retpoline.S
+++ b/arch/x86/lib/retpoline.S
@@ -24,7 +24,9 @@ ENDPROC(__x86_indirect_thunk_\reg)
  * than one per register with the correct names. So we do it
  * the simple and nasty way...
  */
-#define GENERATE_THUNK(reg) THUNK reg
+#define __EXPORT_THUNK(sym) _ASM_NOKPROBE(sym)
+#define EXPORT_THUNK(reg) __EXPORT_THUNK(__x86_indirect_thunk_ ## reg)
+#define GENERATE_THUNK(reg) THUNK reg ; EXPORT_THUNK(reg)
 
 GENERATE_THUNK(_ASM_AX)
 GENERATE_THUNK(_ASM_BX)