Commit 495d714a authored Dec 31, 2018 by Linus Torvalds

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
  ...

parents f12e840c 3d739c1f

Documentation/trace/kprobetrace.rst

+3 −0

Original line number	Diff line number	Diff line
		@@ -20,6 +20,9 @@ current_tracer. Instead of that, add probe points via
		/sys/kernel/debug/tracing/kprobe_events, and enable it via
		/sys/kernel/debug/tracing/events/kprobes/<EVENT>/enable.

		You can also use /sys/kernel/debug/tracing/dynamic_events instead of
		kprobe_events. That interface will provide unified access to other
		dynamic events too.

		Synopsis of kprobe_events
		-------------------------

Documentation/trace/uprobetracer.rst

+4 −0

Original line number	Diff line number	Diff line
		@@ -18,6 +18,10 @@ current_tracer. Instead of that, add probe points via
		However unlike kprobe-event tracer, the uprobe event interface expects the
		user to calculate the offset of the probepoint in the object.

		You can also use /sys/kernel/debug/tracing/dynamic_events instead of
		uprobe_events. That interface will provide unified access to other
		dynamic events too.

		Synopsis of uprobe_tracer
		-------------------------
		::

arch/arm64/kernel/ftrace.c

+1 −0

Original line number	Diff line number	Diff line
		@@ -193,6 +193,7 @@ int ftrace_make_nop(struct module mod, struct dyn_ftrace rec,

		void arch_ftrace_update_code(int command)
		{
		command \|= FTRACE_MAY_SLEEP;
		ftrace_modify_all_code(command);
		}

arch/arm64/kernel/perf_callchain.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -168,7 +168,7 @@ void perf_callchain_kernel(struct perf_callchain_entry_ctx *entry,
		frame.fp = regs->regs[29];
		frame.pc = regs->pc;
		#ifdef CONFIG_FUNCTION_GRAPH_TRACER
		frame.graph = current->curr_ret_stack;
		frame.graph = 0;
		#endif

		walk_stackframe(current, &frame, callchain_trace, entry);

arch/arm64/kernel/process.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -461,7 +461,7 @@ unsigned long get_wchan(struct task_struct *p)
		frame.fp = thread_saved_fp(p);
		frame.pc = thread_saved_pc(p);
		#ifdef CONFIG_FUNCTION_GRAPH_TRACER
		frame.graph = p->curr_ret_stack;
		frame.graph = 0;
		#endif
		do {
		if (unwind_frame(p, &frame))

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