x86/asm/traps: Disable tracing and kprobes in fixup_bad_iret and sync_regs

commit 7ddc6a21 upstream.

These functions can be executed on the int3 stack, so kprobes
are dangerous. Tracing is probably a bad idea, too.

Fixes: b645af2d ("x86_64, traps: Rework bad_iret")
Signed-off-by: Andy Lutomirski <luto@amacapital.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Link: http://lkml.kernel.org/r/50e33d26adca60816f3ba968875801652507d0c4.1416870125.git.luto@amacapital.netSigned-off-by: Ingo Molnar <mingo@kernel.org>
[bwh: Backported to 3.10:
 - Use __kprobes instead of NOKPROBE_SYMBOL()
 - Adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>

arch/x86/kernel/traps.c

@@ -369,7 +369,7 @@ dotraplinkage void __kprobes notrace do_int3(struct pt_regs *regs, long error_co
  * for scheduling or signal handling. The actual stack switch is done in
  * entry.S
  */
-asmlinkage __kprobes struct pt_regs *sync_regs(struct pt_regs *eregs)
+asmlinkage notrace __kprobes struct pt_regs *sync_regs(struct pt_regs *eregs)
 {
 	struct pt_regs *regs = eregs;
 	/* Did already sync */
@@ -394,7 +394,7 @@ struct bad_iret_stack {
 	struct pt_regs regs;
 };
 
-asmlinkage __visible
+asmlinkage __visible notrace __kprobes
 struct bad_iret_stack *fixup_bad_iret(struct bad_iret_stack *s)
 {
 	/*