ftrace: Remove FTRACE_UPDATE_MODIFY_CALL_REGS flag

As the decision to what needs to be done (converting a call to the
ftrace_caller to ftrace_caller_regs or to convert from ftrace_caller_regs
to ftrace_caller) can easily be determined from the rec->flags of
FTRACE_FL_REGS and FTRACE_FL_REGS_EN, there's no need to have the
ftrace_check_record() return either a UPDATE_MODIFY_CALL_REGS or a
UPDATE_MODIFY_CALL. Just he latter is enough. This added flag causes
more complexity than is required. Remove it.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

arch/x86/kernel/ftrace.c

@@ -366,7 +366,6 @@ static int add_breakpoints(struct dyn_ftrace *rec, int enable)
 		/* converting nop to call */
 		return add_brk_on_nop(rec);
 
-	case FTRACE_UPDATE_MODIFY_CALL_REGS:
 	case FTRACE_UPDATE_MODIFY_CALL:
 	case FTRACE_UPDATE_MAKE_NOP:
 		/* converting a call to a nop */
@@ -469,7 +468,6 @@ static int add_update(struct dyn_ftrace *rec, int enable)
 	case FTRACE_UPDATE_IGNORE:
 		return 0;
 
-	case FTRACE_UPDATE_MODIFY_CALL_REGS:
 	case FTRACE_UPDATE_MODIFY_CALL:
 	case FTRACE_UPDATE_MAKE_CALL:
 		/* converting nop to call */
@@ -516,7 +514,6 @@ static int finish_update(struct dyn_ftrace *rec, int enable)
 	case FTRACE_UPDATE_IGNORE:
 		return 0;
 
-	case FTRACE_UPDATE_MODIFY_CALL_REGS:
 	case FTRACE_UPDATE_MODIFY_CALL:
 	case FTRACE_UPDATE_MAKE_CALL:
 		/* converting nop to call */

include/linux/ftrace.h

@@ -362,14 +362,12 @@ enum {
  *  IGNORE           - The function is already what we want it to be
  *  MAKE_CALL        - Start tracing the function
  *  MODIFY_CALL      - Stop saving regs for the function
- *  MODIFY_CALL_REGS - Start saving regs for the function
  *  MAKE_NOP         - Stop tracing the function
  */
 enum {
 	FTRACE_UPDATE_IGNORE,
 	FTRACE_UPDATE_MAKE_CALL,
 	FTRACE_UPDATE_MODIFY_CALL,
-	FTRACE_UPDATE_MODIFY_CALL_REGS,
 	FTRACE_UPDATE_MAKE_NOP,
 };
 

kernel/trace/ftrace.c

@@ -1701,18 +1701,14 @@ static int ftrace_check_record(struct dyn_ftrace *rec, int enable, int update)
 		/*
 		 * If this record is being updated from a nop, then
 		 *   return UPDATE_MAKE_CALL.
-		 * Otherwise, if the EN flag is set, then return
-		 *   UPDATE_MODIFY_CALL_REGS to tell the caller to convert
-		 *   from the non-save regs, to a save regs function.
 		 * Otherwise,
 		 *   return UPDATE_MODIFY_CALL to tell the caller to convert
-		 *   from the save regs, to a non-save regs function.
+		 *   from the save regs, to a non-save regs function or
+		 *   vice versa.
 		 */
 		if (flag & FTRACE_FL_ENABLED)
 			return FTRACE_UPDATE_MAKE_CALL;
-		else if (rec->flags & FTRACE_FL_REGS_EN)
-			return FTRACE_UPDATE_MODIFY_CALL_REGS;
-		else
+
 		return FTRACE_UPDATE_MODIFY_CALL;
 	}
 
@@ -1815,7 +1811,6 @@ __ftrace_replace_code(struct dyn_ftrace *rec, int enable)
 	case FTRACE_UPDATE_MAKE_NOP:
 		return ftrace_make_nop(NULL, rec, ftrace_addr);
 
-	case FTRACE_UPDATE_MODIFY_CALL_REGS:
 	case FTRACE_UPDATE_MODIFY_CALL:
 		return ftrace_modify_call(rec, ftrace_old_addr, ftrace_addr);
 	}