Merge branch 'tracing-fixes-for-linus' of... (935cc932) · Commits · 戴 / test

Documentation/trace/ftrace-design.txt

+23 −3

Original line number	Diff line number	Diff line
		function tracer guts
		====================
		By Mike Frysinger

		Introduction
		------------
		@@ -173,14 +174,16 @@ void ftrace_graph_caller(void)

		unsigned long *frompc = &...;
		unsigned long selfpc = <return address> - MCOUNT_INSN_SIZE;
		prepare_ftrace_return(frompc, selfpc);
		/* passing frame pointer up is optional -- see below */
		prepare_ftrace_return(frompc, selfpc, frame_pointer);

		/* restore all state needed by the ABI */
		}
		#endif

		For information on how to implement prepare_ftrace_return(), simply look at
		the x86 version. The only architecture-specific piece in it is the setup of
		For information on how to implement prepare_ftrace_return(), simply look at the
		x86 version (the frame pointer passing is optional; see the next section for
		more information). The only architecture-specific piece in it is the setup of
		the fault recovery table (the asm(...) code). The rest should be the same
		across architectures.

		@@ -205,6 +208,23 @@ void return_to_handler(void)
		#endif


		HAVE_FUNCTION_GRAPH_FP_TEST
		---------------------------

		An arch may pass in a unique value (frame pointer) to both the entering and
		exiting of a function. On exit, the value is compared and if it does not
		match, then it will panic the kernel. This is largely a sanity check for bad
		code generation with gcc. If gcc for your port sanely updates the frame
		pointer under different opitmization levels, then ignore this option.

		However, adding support for it isn't terribly difficult. In your assembly code
		that calls prepare_ftrace_return(), pass the frame pointer as the 3rd argument.
		Then in the C version of that function, do what the x86 port does and pass it
		along to ftrace_push_return_trace() instead of a stub value of 0.

		Similarly, when you call ftrace_return_to_handler(), pass it the frame pointer.


		HAVE_FTRACE_NMI_ENTER
		---------------------

Documentation/trace/ftrace.txt

+1 −1

Original line number	Diff line number	Diff line
		@@ -1625,7 +1625,7 @@ If I am only interested in sys_nanosleep and hrtimer_interrupt:

		# echo sys_nanosleep hrtimer_interrupt \
		> set_ftrace_filter
		# echo ftrace > current_tracer
		# echo function > current_tracer
		# echo 1 > tracing_enabled
		# usleep 1
		# echo 0 > tracing_enabled

kernel/trace/Kconfig

+1 −3

Original line number	Diff line number	Diff line
		@@ -27,9 +27,7 @@ config HAVE_FUNCTION_GRAPH_TRACER
		config HAVE_FUNCTION_GRAPH_FP_TEST
		bool
		help
		An arch may pass in a unique value (frame pointer) to both the
		entering and exiting of a function. On exit, the value is compared
		and if it does not match, then it will panic the kernel.
		See Documentation/trace/ftrace-design.txt

		config HAVE_FUNCTION_TRACE_MCOUNT_TEST
		bool

kernel/trace/ring_buffer.c

+21 −3

Original line number	Diff line number	Diff line
		@@ -464,6 +464,8 @@ struct ring_buffer_iter {
		struct ring_buffer_per_cpu *cpu_buffer;
		unsigned long head;
		struct buffer_page *head_page;
		struct buffer_page *cache_reader_page;
		unsigned long cache_read;
		u64 read_stamp;
		};

		@@ -2716,6 +2718,8 @@ static void rb_iter_reset(struct ring_buffer_iter *iter)
		iter->read_stamp = cpu_buffer->read_stamp;
		else
		iter->read_stamp = iter->head_page->page->time_stamp;
		iter->cache_reader_page = cpu_buffer->reader_page;
		iter->cache_read = cpu_buffer->read;
		}

		/**
		@@ -3060,13 +3064,22 @@ rb_iter_peek(struct ring_buffer_iter iter, u64 ts)
		struct ring_buffer_event *event;
		int nr_loops = 0;

		if (ring_buffer_iter_empty(iter))
		return NULL;

		cpu_buffer = iter->cpu_buffer;
		buffer = cpu_buffer->buffer;

		/*
		* Check if someone performed a consuming read to
		* the buffer. A consuming read invalidates the iterator
		* and we need to reset the iterator in this case.
		*/
		if (unlikely(iter->cache_read != cpu_buffer->read \|\|
		iter->cache_reader_page != cpu_buffer->reader_page))
		rb_iter_reset(iter);

		again:
		if (ring_buffer_iter_empty(iter))
		return NULL;

		/*
		* We repeat when a timestamp is encountered.
		* We can get multiple timestamps by nested interrupts or also
		@@ -3081,6 +3094,11 @@ rb_iter_peek(struct ring_buffer_iter iter, u64 ts)
		if (rb_per_cpu_empty(cpu_buffer))
		return NULL;

		if (iter->head >= local_read(&iter->head_page->page->commit)) {
		rb_inc_iter(iter);
		goto again;
		}

		event = rb_iter_head_event(iter);

		switch (event->type_len) {

kernel/trace/trace.c

+5 −0

Original line number	Diff line number	Diff line
		@@ -951,6 +951,11 @@ void trace_find_cmdline(int pid, char comm[])
		return;
		}

		if (WARN_ON_ONCE(pid < 0)) {
		strcpy(comm, "<XXX>");
		return;
		}

		if (pid > PID_MAX_DEFAULT) {
		strcpy(comm, "<...>");
		return;

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