Merge tag 'trace-v4.21' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace

Pull tracing updates from Steven Rostedt:

 - Rework of the kprobe/uprobe and synthetic events to consolidate all
   the dynamic event code. This will make changes in the future easier.

 - Partial rewrite of the function graph tracing infrastructure. This
   will allow for multiple users of hooking onto functions to get the
   callback (return) of the function. This is the ground work for having
   kprobes and function graph tracer using one code base.

 - Clean up of the histogram code that will facilitate adding more
   features to the histograms in the future.

 - Addition of str_has_prefix() and a few use cases. There currently is
   a similar function strstart() that is used in a few places, but only
   returns a bool and not a length. These instances will be removed in
   the future to use str_has_prefix() instead.

 - A few other various clean ups as well.

* tag 'trace-v4.21' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: (57 commits)
  tracing: Use the return of str_has_prefix() to remove open coded numbers
  tracing: Have the historgram use the result of str_has_prefix() for len of prefix
  tracing: Use str_has_prefix() instead of using fixed sizes
  tracing: Use str_has_prefix() helper for histogram code
  string.h: Add str_has_prefix() helper function
  tracing: Make function ‘ftrace_exports’ static
  tracing: Simplify printf'ing in seq_print_sym
  tracing: Avoid -Wformat-nonliteral warning
  tracing: Merge seq_print_sym_short() and seq_print_sym_offset()
  tracing: Add hist trigger comments for variable-related fields
  tracing: Remove hist trigger synth_var_refs
  tracing: Use hist trigger's var_ref array to destroy var_refs
  tracing: Remove open-coding of hist trigger var_ref management
  tracing: Use var_refs[] for hist trigger reference checking
  tracing: Change strlen to sizeof for hist trigger static strings
  tracing: Remove unnecessary hist trigger struct field
  tracing: Fix ftrace_graph_get_ret_stack() to use task and not current
  seq_buf: Use size_t for len in seq_buf_puts()
  seq_buf: Make seq_buf_puts() null-terminate the buffer
  arm64: Use ftrace_graph_get_ret_stack() instead of curr_ret_stack
  ...

3 files changed, 14 insertions, 9 deletions

diff --git a/arch/sparc/kernel/perf_event.c b/arch/sparc/kernel/perf_event.c
index 47c871394ccb..6de7c684c29f 100644
--- a/arch/sparc/kernel/perf_event.c
+++ b/arch/sparc/kernel/perf_event.c
@@ -1767,9 +1767,11 @@ void perf_callchain_kernel(struct perf_callchain_entry_ctx *entry,
 		perf_callchain_store(entry, pc);
 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
 		if ((pc + 8UL) == (unsigned long) &return_to_handler) {
-			int index = current->curr_ret_stack;
-			if (current->ret_stack && index >= graph) {
-				pc = current->ret_stack[index - graph].ret;
+			struct ftrace_ret_stack *ret_stack;
+			ret_stack = ftrace_graph_get_ret_stack(current,
+							       graph);
+			if (ret_stack) {
+				pc = ret_stack->ret;
 				perf_callchain_store(entry, pc);
 				graph++;
 			}
diff --git a/arch/sparc/kernel/stacktrace.c b/arch/sparc/kernel/stacktrace.c
index be4c14cccc05..dd654e651500 100644
--- a/arch/sparc/kernel/stacktrace.c
+++ b/arch/sparc/kernel/stacktrace.c
@@ -57,9 +57,11 @@ static void __save_stack_trace(struct thread_info *tp,
 			trace->entries[trace->nr_entries++] = pc;
 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
 			if ((pc + 8UL) == (unsigned long) &return_to_handler) {
-				int index = t->curr_ret_stack;
-				if (t->ret_stack && index >= graph) {
-					pc = t->ret_stack[index - graph].ret;
+				struct ftrace_ret_stack *ret_stack;
+				ret_stack = ftrace_graph_get_ret_stack(t,
+								       graph);
+				if (ret_stack) {
+					pc = ret_stack->ret;
 					if (trace->nr_entries <
 					    trace->max_entries)
 						trace->entries[trace->nr_entries++] = pc;
diff --git a/arch/sparc/kernel/traps_64.c b/arch/sparc/kernel/traps_64.c
index aa624ed79db1..0cd02a64a451 100644
--- a/arch/sparc/kernel/traps_64.c
+++ b/arch/sparc/kernel/traps_64.c
@@ -2502,9 +2502,10 @@ void show_stack(struct task_struct *tsk, unsigned long *_ksp)
 		printk(" [%016lx] %pS\n", pc, (void *) pc);
 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
 		if ((pc + 8UL) == (unsigned long) &return_to_handler) {
-			int index = tsk->curr_ret_stack;
-			if (tsk->ret_stack && index >= graph) {
-				pc = tsk->ret_stack[index - graph].ret;
+			struct ftrace_ret_stack *ret_stack;
+			ret_stack = ftrace_graph_get_ret_stack(tsk, graph);
+			if (ret_stack) {
+				pc = ret_stack->ret;
 				printk(" [%016lx] %pS\n", pc, (void *) pc);
 				graph++;
 			}