ftrace: Have the callbacks receive a struct ftrace_regs instead of pt_regs

In preparation to have arguments of a function passed to callbacks attached
to functions as default, change the default callback prototype to receive a
struct ftrace_regs as the forth parameter instead of a pt_regs.

For callbacks that set the FL_SAVE_REGS flag in their ftrace_ops flags, they
will now need to get the pt_regs via a ftrace_get_regs() helper call. If
this is called by a callback that their ftrace_ops did not have a
FL_SAVE_REGS flag set, it that helper function will return NULL.

This will allow the ftrace_regs to hold enough just to get the parameters
and stack pointer, but without the worry that callbacks may have a pt_regs
that is not completely filled.
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

arch/csky/kernel/probes/ftrace.c

@@ -11,17 +11,19 @@ int arch_check_ftrace_location(struct kprobe *p)
 
 /* Ftrace callback handler for kprobes -- called under preepmt disabed */
 void kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip,
-			   struct ftrace_ops *ops, struct pt_regs *regs)
+			   struct ftrace_ops *ops, struct ftrace_regs *fregs)
 {
 	int bit;
 	bool lr_saver = false;
 	struct kprobe *p;
 	struct kprobe_ctlblk *kcb;
+	struct pt_regs *regs;
 
 	bit = ftrace_test_recursion_trylock(ip, parent_ip);
 	if (bit < 0)
 		return;
 
+	regs = ftrace_get_regs(fregs);
 	preempt_disable_notrace();
 	p = get_kprobe((kprobe_opcode_t *)ip);
 	if (!p) {

arch/nds32/kernel/ftrace.c

@@ -10,7 +10,7 @@ extern void (*ftrace_trace_function)(unsigned long, unsigned long,
 extern void ftrace_graph_caller(void);
 
 noinline void __naked ftrace_stub(unsigned long ip, unsigned long parent_ip,
-				  struct ftrace_ops *op, struct pt_regs *regs)
+				  struct ftrace_ops *op, struct ftrace_regs *fregs)
 {
 	__asm__ ("");  /* avoid to optimize as pure function */
 }
@@ -38,7 +38,7 @@ EXPORT_SYMBOL(_mcount);
 #else /* CONFIG_DYNAMIC_FTRACE */
 
 noinline void __naked ftrace_stub(unsigned long ip, unsigned long parent_ip,
-				  struct ftrace_ops *op, struct pt_regs *regs)
+				  struct ftrace_ops *op, struct ftrace_regs *fregs)
 {
 	__asm__ ("");  /* avoid to optimize as pure function */
 }

arch/parisc/kernel/ftrace.c

@@ -51,7 +51,7 @@ static void __hot prepare_ftrace_return(unsigned long *parent,
 void notrace __hot ftrace_function_trampoline(unsigned long parent,
 				unsigned long self_addr,
 				unsigned long org_sp_gr3,
-				struct pt_regs *regs)
+				struct ftrace_regs *fregs)
 {
 #ifndef CONFIG_DYNAMIC_FTRACE
 	extern ftrace_func_t ftrace_trace_function;
@@ -61,7 +61,7 @@ void notrace __hot ftrace_function_trampoline(unsigned long parent,
 	if (function_trace_op->flags & FTRACE_OPS_FL_ENABLED &&
 	    ftrace_trace_function != ftrace_stub)
 		ftrace_trace_function(self_addr, parent,
-				function_trace_op, regs);
+				function_trace_op, fregs);
 
 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
 	if (dereference_function_descriptor(ftrace_graph_return) !=
@@ -204,9 +204,10 @@ int ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec,
 
 #ifdef CONFIG_KPROBES_ON_FTRACE
 void kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip,
-			   struct ftrace_ops *ops, struct pt_regs *regs)
+			   struct ftrace_ops *ops, struct ftrace_regs *fregs)
 {
 	struct kprobe_ctlblk *kcb;
+	struct pt_regs *regs;
 	struct kprobe *p;
 	int bit;
 
@@ -214,6 +215,7 @@ void kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip,
 	if (bit < 0)
 		return;
 
+	regs = ftrace_get_regs(fregs);
 	preempt_disable_notrace();
 	p = get_kprobe((kprobe_opcode_t *)ip);
 	if (unlikely(!p) || kprobe_disabled(p))

arch/powerpc/kernel/kprobes-ftrace.c

@@ -14,16 +14,18 @@
 
 /* Ftrace callback handler for kprobes */
 void kprobe_ftrace_handler(unsigned long nip, unsigned long parent_nip,
-			   struct ftrace_ops *ops, struct pt_regs *regs)
+			   struct ftrace_ops *ops, struct ftrace_regs *fregs)
 {
 	struct kprobe *p;
 	struct kprobe_ctlblk *kcb;
+	struct pt_regs *regs;
 	int bit;
 
 	bit = ftrace_test_recursion_trylock(nip, parent_nip);
 	if (bit < 0)
 		return;
 
+	regs = ftrace_get_regs(fregs);
 	preempt_disable_notrace();
 	p = get_kprobe((kprobe_opcode_t *)nip);
 	if (unlikely(!p) || kprobe_disabled(p))

arch/s390/kernel/ftrace.c

@@ -198,9 +198,10 @@ int ftrace_disable_ftrace_graph_caller(void)
 
 #ifdef CONFIG_KPROBES_ON_FTRACE
 void kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip,
-		struct ftrace_ops *ops, struct pt_regs *regs)
+		struct ftrace_ops *ops, struct ftrace_regs *fregs)
 {
 	struct kprobe_ctlblk *kcb;
+	struct pt_regs *regs;
 	struct kprobe *p;
 	int bit;
 
@@ -208,6 +209,7 @@ void kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip,
 	if (bit < 0)
 		return;
 
+	regs = ftrace_get_regs(fregs);
 	preempt_disable_notrace();
 	p = get_kprobe((kprobe_opcode_t *)ip);
 	if (unlikely(!p) || kprobe_disabled(p))

arch/x86/kernel/kprobes/ftrace.c

@@ -14,8 +14,9 @@
 
 /* Ftrace callback handler for kprobes -- called under preepmt disabed */
 void kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip,
-			   struct ftrace_ops *ops, struct pt_regs *regs)
+			   struct ftrace_ops *ops, struct ftrace_regs *fregs)
 {
+	struct pt_regs *regs = ftrace_get_regs(fregs);
 	struct kprobe *p;
 	struct kprobe_ctlblk *kcb;
 	int bit;

fs/pstore/ftrace.c

@@ -26,7 +26,7 @@ static u64 pstore_ftrace_stamp;
 static void notrace pstore_ftrace_call(unsigned long ip,
 				       unsigned long parent_ip,
 				       struct ftrace_ops *op,
-				       struct pt_regs *regs)
+				       struct ftrace_regs *fregs)
 {
 	int bit;
 	unsigned long flags;

include/linux/ftrace.h

@@ -90,8 +90,20 @@ ftrace_enable_sysctl(struct ctl_table *table, int write,
 
 struct ftrace_ops;
 
+struct ftrace_regs {
+	struct pt_regs		regs;
+};
+
+static __always_inline struct pt_regs *ftrace_get_regs(struct ftrace_regs *fregs)
+{
+	if (!fregs)
+		return NULL;
+
+	return &fregs->regs;
+}
+
 typedef void (*ftrace_func_t)(unsigned long ip, unsigned long parent_ip,
-			      struct ftrace_ops *op, struct pt_regs *regs);
+			      struct ftrace_ops *op, struct ftrace_regs *fregs);
 
 ftrace_func_t ftrace_ops_get_func(struct ftrace_ops *ops);
 
@@ -259,7 +271,7 @@ int register_ftrace_function(struct ftrace_ops *ops);
 int unregister_ftrace_function(struct ftrace_ops *ops);
 
 extern void ftrace_stub(unsigned long a0, unsigned long a1,
-			struct ftrace_ops *op, struct pt_regs *regs);
+			struct ftrace_ops *op, struct ftrace_regs *fregs);
 
 #else /* !CONFIG_FUNCTION_TRACER */
 /*

include/linux/kprobes.h

@@ -345,7 +345,7 @@ static inline void wait_for_kprobe_optimizer(void) { }
 #endif /* CONFIG_OPTPROBES */
 #ifdef CONFIG_KPROBES_ON_FTRACE
 extern void kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip,
-				  struct ftrace_ops *ops, struct pt_regs *regs);
+				  struct ftrace_ops *ops, struct ftrace_regs *fregs);
 extern int arch_prepare_kprobe_ftrace(struct kprobe *p);
 #endif
 

kernel/livepatch/patch.c

@@ -40,8 +40,9 @@ struct klp_ops *klp_find_ops(void *old_func)
 static void notrace klp_ftrace_handler(unsigned long ip,
 				       unsigned long parent_ip,
 				       struct ftrace_ops *fops,
-				       struct pt_regs *regs)
+				       struct ftrace_regs *fregs)
 {
+	struct pt_regs *regs = ftrace_get_regs(fregs);
 	struct klp_ops *ops;
 	struct klp_func *func;
 	int patch_state;

kernel/trace/ftrace.c

@@ -121,7 +121,7 @@ struct ftrace_ops global_ops;
 
 #if ARCH_SUPPORTS_FTRACE_OPS
 static void ftrace_ops_list_func(unsigned long ip, unsigned long parent_ip,
-				 struct ftrace_ops *op, struct pt_regs *regs);
+				 struct ftrace_ops *op, struct ftrace_regs *fregs);
 #else
 /* See comment below, where ftrace_ops_list_func is defined */
 static void ftrace_ops_no_ops(unsigned long ip, unsigned long parent_ip);
@@ -140,7 +140,7 @@ static inline void ftrace_ops_init(struct ftrace_ops *ops)
 }
 
 static void ftrace_pid_func(unsigned long ip, unsigned long parent_ip,
-			    struct ftrace_ops *op, struct pt_regs *regs)
+			    struct ftrace_ops *op, struct ftrace_regs *fregs)
 {
 	struct trace_array *tr = op->private;
 	int pid;
@@ -154,7 +154,7 @@ static void ftrace_pid_func(unsigned long ip, unsigned long parent_ip,
 			return;
 	}
 
-	op->saved_func(ip, parent_ip, op, regs);
+	op->saved_func(ip, parent_ip, op, fregs);
 }
 
 static void ftrace_sync_ipi(void *data)
@@ -754,7 +754,7 @@ ftrace_profile_alloc(struct ftrace_profile_stat *stat, unsigned long ip)
 
 static void
 function_profile_call(unsigned long ip, unsigned long parent_ip,
-		      struct ftrace_ops *ops, struct pt_regs *regs)
+		      struct ftrace_ops *ops, struct ftrace_regs *fregs)
 {
 	struct ftrace_profile_stat *stat;
 	struct ftrace_profile *rec;
@@ -2143,6 +2143,7 @@ static int ftrace_check_record(struct dyn_ftrace *rec, bool enable, bool update)
 				else
 					rec->flags &= ~FTRACE_FL_TRAMP_EN;
 			}
+
 			if (flag & FTRACE_FL_DIRECT) {
 				/*
 				 * If there's only one user (direct_ops helper)
@@ -2368,8 +2369,9 @@ unsigned long ftrace_find_rec_direct(unsigned long ip)
 }
 
 static void call_direct_funcs(unsigned long ip, unsigned long pip,
-			      struct ftrace_ops *ops, struct pt_regs *regs)
+			      struct ftrace_ops *ops, struct ftrace_regs *fregs)
 {
+	struct pt_regs *regs = ftrace_get_regs(fregs);
 	unsigned long addr;
 
 	addr = ftrace_find_rec_direct(ip);
@@ -4292,7 +4294,7 @@ static int __init ftrace_mod_cmd_init(void)
 core_initcall(ftrace_mod_cmd_init);
 
 static void function_trace_probe_call(unsigned long ip, unsigned long parent_ip,
-				      struct ftrace_ops *op, struct pt_regs *pt_regs)
+				      struct ftrace_ops *op, struct ftrace_regs *fregs)
 {
 	struct ftrace_probe_ops *probe_ops;
 	struct ftrace_func_probe *probe;
@@ -6911,8 +6913,9 @@ void ftrace_reset_array_ops(struct trace_array *tr)
 
 static nokprobe_inline void
 __ftrace_ops_list_func(unsigned long ip, unsigned long parent_ip,
-		       struct ftrace_ops *ignored, struct pt_regs *regs)
+		       struct ftrace_ops *ignored, struct ftrace_regs *fregs)
 {
+	struct pt_regs *regs = ftrace_get_regs(fregs);
 	struct ftrace_ops *op;
 	int bit;
 
@@ -6945,7 +6948,7 @@ __ftrace_ops_list_func(unsigned long ip, unsigned long parent_ip,
 				pr_warn("op=%p %pS\n", op, op);
 				goto out;
 			}
-			op->func(ip, parent_ip, op, regs);
+			op->func(ip, parent_ip, op, fregs);
 		}
 	} while_for_each_ftrace_op(op);
 out:
@@ -6968,9 +6971,9 @@ __ftrace_ops_list_func(unsigned long ip, unsigned long parent_ip,
  */
 #if ARCH_SUPPORTS_FTRACE_OPS
 static void ftrace_ops_list_func(unsigned long ip, unsigned long parent_ip,
-				 struct ftrace_ops *op, struct pt_regs *regs)
+				 struct ftrace_ops *op, struct ftrace_regs *fregs)
 {
-	__ftrace_ops_list_func(ip, parent_ip, NULL, regs);
+	__ftrace_ops_list_func(ip, parent_ip, NULL, fregs);
 }
 NOKPROBE_SYMBOL(ftrace_ops_list_func);
 #else
@@ -6987,7 +6990,7 @@ NOKPROBE_SYMBOL(ftrace_ops_no_ops);
  * this function will be called by the mcount trampoline.
  */
 static void ftrace_ops_assist_func(unsigned long ip, unsigned long parent_ip,
-				   struct ftrace_ops *op, struct pt_regs *regs)
+				   struct ftrace_ops *op, struct ftrace_regs *fregs)
 {
 	int bit;
 
@@ -6998,7 +7001,7 @@ static void ftrace_ops_assist_func(unsigned long ip, unsigned long parent_ip,
 	preempt_disable_notrace();
 
 	if (!(op->flags & FTRACE_OPS_FL_RCU) || rcu_is_watching())
-		op->func(ip, parent_ip, op, regs);
+		op->func(ip, parent_ip, op, fregs);
 
 	preempt_enable_notrace();
 	trace_clear_recursion(bit);

kernel/trace/trace_event_perf.c

@@ -432,7 +432,7 @@ NOKPROBE_SYMBOL(perf_trace_buf_update);
 #ifdef CONFIG_FUNCTION_TRACER
 static void
 perf_ftrace_function_call(unsigned long ip, unsigned long parent_ip,
-			  struct ftrace_ops *ops, struct pt_regs *pt_regs)
+			  struct ftrace_ops *ops,  struct ftrace_regs *fregs)
 {
 	struct ftrace_entry *entry;
 	struct perf_event *event;

kernel/trace/trace_events.c

@@ -3673,7 +3673,7 @@ static struct trace_event_file event_trace_file __initdata;
 
 static void __init
 function_test_events_call(unsigned long ip, unsigned long parent_ip,
-			  struct ftrace_ops *op, struct pt_regs *pt_regs)
+			  struct ftrace_ops *op, struct ftrace_regs *regs)
 {
 	struct trace_buffer *buffer;
 	struct ring_buffer_event *event;

kernel/trace/trace_functions.c

@@ -23,10 +23,10 @@ static void tracing_start_function_trace(struct trace_array *tr);
 static void tracing_stop_function_trace(struct trace_array *tr);
 static void
 function_trace_call(unsigned long ip, unsigned long parent_ip,
-		    struct ftrace_ops *op, struct pt_regs *pt_regs);
+		    struct ftrace_ops *op, struct ftrace_regs *fregs);
 static void
 function_stack_trace_call(unsigned long ip, unsigned long parent_ip,
-			  struct ftrace_ops *op, struct pt_regs *pt_regs);
+			  struct ftrace_ops *op, struct ftrace_regs *fregs);
 static struct tracer_flags func_flags;
 
 /* Our option */
@@ -89,7 +89,6 @@ void ftrace_destroy_function_files(struct trace_array *tr)
 static int function_trace_init(struct trace_array *tr)
 {
 	ftrace_func_t func;
-
 	/*
 	 * Instance trace_arrays get their ops allocated
 	 * at instance creation. Unless it failed
@@ -129,7 +128,7 @@ static void function_trace_start(struct trace_array *tr)
 
 static void
 function_trace_call(unsigned long ip, unsigned long parent_ip,
-		    struct ftrace_ops *op, struct pt_regs *pt_regs)
+		    struct ftrace_ops *op, struct ftrace_regs *fregs)
 {
 	struct trace_array *tr = op->private;
 	struct trace_array_cpu *data;
@@ -178,7 +177,7 @@ function_trace_call(unsigned long ip, unsigned long parent_ip,
 
 static void
 function_stack_trace_call(unsigned long ip, unsigned long parent_ip,
-			  struct ftrace_ops *op, struct pt_regs *pt_regs)
+			  struct ftrace_ops *op, struct ftrace_regs *fregs)
 {
 	struct trace_array *tr = op->private;
 	struct trace_array_cpu *data;

kernel/trace/trace_irqsoff.c

@@ -138,7 +138,7 @@ static int func_prolog_dec(struct trace_array *tr,
  */
 static void
 irqsoff_tracer_call(unsigned long ip, unsigned long parent_ip,
-		    struct ftrace_ops *op, struct pt_regs *pt_regs)
+		    struct ftrace_ops *op, struct ftrace_regs *fregs)
 {
 	struct trace_array *tr = irqsoff_trace;
 	struct trace_array_cpu *data;

kernel/trace/trace_sched_wakeup.c

@@ -212,7 +212,7 @@ static void wakeup_print_header(struct seq_file *s)
  */
 static void
 wakeup_tracer_call(unsigned long ip, unsigned long parent_ip,
-		   struct ftrace_ops *op, struct pt_regs *pt_regs)
+		   struct ftrace_ops *op, struct ftrace_regs *fregs)
 {
 	struct trace_array *tr = wakeup_trace;
 	struct trace_array_cpu *data;

kernel/trace/trace_selftest.c

@@ -107,7 +107,7 @@ static int trace_selftest_test_probe1_cnt;
 static void trace_selftest_test_probe1_func(unsigned long ip,
 					    unsigned long pip,
 					    struct ftrace_ops *op,
-					    struct pt_regs *pt_regs)
+					    struct ftrace_regs *fregs)
 {
 	trace_selftest_test_probe1_cnt++;
 }
@@ -116,7 +116,7 @@ static int trace_selftest_test_probe2_cnt;
 static void trace_selftest_test_probe2_func(unsigned long ip,
 					    unsigned long pip,
 					    struct ftrace_ops *op,
-					    struct pt_regs *pt_regs)
+					    struct ftrace_regs *fregs)
 {
 	trace_selftest_test_probe2_cnt++;
 }
@@ -125,7 +125,7 @@ static int trace_selftest_test_probe3_cnt;
 static void trace_selftest_test_probe3_func(unsigned long ip,
 					    unsigned long pip,
 					    struct ftrace_ops *op,
-					    struct pt_regs *pt_regs)
+					    struct ftrace_regs *fregs)
 {
 	trace_selftest_test_probe3_cnt++;
 }
@@ -134,7 +134,7 @@ static int trace_selftest_test_global_cnt;
 static void trace_selftest_test_global_func(unsigned long ip,
 					    unsigned long pip,
 					    struct ftrace_ops *op,
-					    struct pt_regs *pt_regs)
+					    struct ftrace_regs *fregs)
 {
 	trace_selftest_test_global_cnt++;
 }
@@ -143,7 +143,7 @@ static int trace_selftest_test_dyn_cnt;
 static void trace_selftest_test_dyn_func(unsigned long ip,
 					 unsigned long pip,
 					 struct ftrace_ops *op,
-					 struct pt_regs *pt_regs)
+					 struct ftrace_regs *fregs)
 {
 	trace_selftest_test_dyn_cnt++;
 }
@@ -414,7 +414,7 @@ static int trace_selftest_recursion_cnt;
 static void trace_selftest_test_recursion_func(unsigned long ip,
 					       unsigned long pip,
 					       struct ftrace_ops *op,
-					       struct pt_regs *pt_regs)
+					       struct ftrace_regs *fregs)
 {
 	/*
 	 * This function is registered without the recursion safe flag.
@@ -429,7 +429,7 @@ static void trace_selftest_test_recursion_func(unsigned long ip,
 static void trace_selftest_test_recursion_safe_func(unsigned long ip,
 						    unsigned long pip,
 						    struct ftrace_ops *op,
-						    struct pt_regs *pt_regs)
+						    struct ftrace_regs *fregs)
 {
 	/*
 	 * We said we would provide our own recursion. By calling
@@ -548,9 +548,11 @@ static enum {
 static void trace_selftest_test_regs_func(unsigned long ip,
 					  unsigned long pip,
 					  struct ftrace_ops *op,
-					  struct pt_regs *pt_regs)
+					  struct ftrace_regs *fregs)
 {
-	if (pt_regs)
+	struct pt_regs *regs = ftrace_get_regs(fregs);
+
+	if (regs)
 		trace_selftest_regs_stat = TRACE_SELFTEST_REGS_FOUND;
 	else
 		trace_selftest_regs_stat = TRACE_SELFTEST_REGS_NOT_FOUND;

kernel/trace/trace_stack.c

@@ -290,7 +290,7 @@ static void check_stack(unsigned long ip, unsigned long *stack)
 
 static void
 stack_trace_call(unsigned long ip, unsigned long parent_ip,
-		 struct ftrace_ops *op, struct pt_regs *pt_regs)
+		 struct ftrace_ops *op, struct ftrace_regs *fregs)
 {
 	unsigned long stack;