Commit 0f1f6923 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge tag 'trace-v4.20-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace 

Pull tracing fixes from Steven Rostedt:
 "While rewriting the function graph tracer, I discovered a design flaw
  that was introduced by a patch that tried to fix one bug, but by doing
  so created another bug.

  As both bugs corrupt the output (but they do not crash the kernel), I
  decided to fix the design such that it could have both bugs fixed. The
  original fix, fixed time reporting of the function graph tracer when
  doing a max_depth of one. This was code that can test how much the
  kernel interferes with userspace. But in doing so, it could corrupt
  the time keeping of the function profiler.

  The issue is that the curr_ret_stack variable was being used for two
  different meanings. One was to keep track of the stack pointer on the
  ret_stack (shadow stack used by the function graph tracer), and the
  other use case was the graph call depth. Although, the two may be
  closely related, where they got updated was the issue that lead to the
  two different bugs that required the two use cases to be updated
  differently.

  The big issue with this fix is that it requires changing each
  architecture. The good news is, I was able to remove a lot of code
  that was duplicated within the architectures and place it into a
  single location. Then I could make the fix in one place.

  I pushed this code into linux-next to let it settle over a week, and
  before doing so, I cross compiled all the affected architectures to
  make sure that they built fine.

  In the mean time, I also pulled in a patch that fixes the sched_switch
  previous tasks state output, that was not actually correct"

* tag 'trace-v4.20-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
  sched, trace: Fix prev_state output in sched_switch tracepoint
  function_graph: Have profiler use curr_ret_stack and not depth
  function_graph: Reverse the order of pushing the ret_stack and the callback
  function_graph: Move return callback before update of curr_ret_stack
  function_graph: Use new curr_ret_depth to manage depth instead of curr_ret_stack
  function_graph: Make ftrace_push_return_trace() static
  sparc/function_graph: Simplify with function_graph_enter()
  sh/function_graph: Simplify with function_graph_enter()
  s390/function_graph: Simplify with function_graph_enter()
  riscv/function_graph: Simplify with function_graph_enter()
  powerpc/function_graph: Simplify with function_graph_enter()
  parisc: function_graph: Simplify with function_graph_enter()
  nds32: function_graph: Simplify with function_graph_enter()
  MIPS: function_graph: Simplify with function_graph_enter()
  microblaze: function_graph: Simplify with function_graph_enter()
  arm64: function_graph: Simplify with function_graph_enter()
  ARM: function_graph: Simplify with function_graph_enter()
  x86/function_graph: Simplify with function_graph_enter()
  function_graph: Create function_graph_enter() to consolidate architecture code
parents 570a3743 3054426d

arch/arm/kernel/ftrace.c

+1 −16
Original line number Diff line number Diff line
@@ -183,9 +183,7 @@ void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr, 
			   unsigned long frame_pointer)

{

	unsigned long return_hooker = (unsigned long) &return_to_handler;

	struct ftrace_graph_ent trace;

	unsigned long old;

	int err;



	if (unlikely(atomic_read(&current->tracing_graph_pause)))

		return;
@@ -193,21 +191,8 @@ void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr, 
	old = *parent;

	*parent = return_hooker;



	trace.func = self_addr;

	trace.depth = current->curr_ret_stack + 1;



	/* Only trace if the calling function expects to */

	if (!ftrace_graph_entry(&trace)) {

	if (function_graph_enter(old, self_addr, frame_pointer, NULL))

		*parent = old;

		return;

	}



	err = ftrace_push_return_trace(old, self_addr, &trace.depth,

				       frame_pointer, NULL);

	if (err == -EBUSY) {

		*parent = old;

		return;

	}

}



#ifdef CONFIG_DYNAMIC_FTRACE

arch/arm64/kernel/ftrace.c

+1 −14
Original line number Diff line number Diff line
@@ -216,8 +216,6 @@ void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr, 
{

	unsigned long return_hooker = (unsigned long)&return_to_handler;

	unsigned long old;

	struct ftrace_graph_ent trace;

	int err;



	if (unlikely(atomic_read(&current->tracing_graph_pause)))

		return;
@@ -229,18 +227,7 @@ void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr, 
	 */

	old = *parent;



	trace.func = self_addr;

	trace.depth = current->curr_ret_stack + 1;



	/* Only trace if the calling function expects to */

	if (!ftrace_graph_entry(&trace))

		return;



	err = ftrace_push_return_trace(old, self_addr, &trace.depth,

				       frame_pointer, NULL);

	if (err == -EBUSY)

		return;

	else

	if (!function_graph_enter(old, self_addr, frame_pointer, NULL))

		*parent = return_hooker;

}

arch/microblaze/kernel/ftrace.c

+2 −13
Original line number Diff line number Diff line
@@ -22,8 +22,7 @@ 
void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr)

{

	unsigned long old;

	int faulted, err;

	struct ftrace_graph_ent trace;

	int faulted;

	unsigned long return_hooker = (unsigned long)

				&return_to_handler;
@@ -63,18 +62,8 @@ void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr) 
		return;

	}



	err = ftrace_push_return_trace(old, self_addr, &trace.depth, 0, NULL);

	if (err == -EBUSY) {

	if (function_graph_enter(old, self_addr, 0, NULL))

		*parent = old;

		return;

	}



	trace.func = self_addr;

	/* Only trace if the calling function expects to */

	if (!ftrace_graph_entry(&trace)) {

		current->curr_ret_stack--;

		*parent = old;

	}

}

#endif /* CONFIG_FUNCTION_GRAPH_TRACER */

arch/mips/kernel/ftrace.c

+2 −12
Original line number Diff line number Diff line
@@ -322,7 +322,6 @@ void prepare_ftrace_return(unsigned long *parent_ra_addr, unsigned long self_ra, 
			   unsigned long fp)

{

	unsigned long old_parent_ra;

	struct ftrace_graph_ent trace;

	unsigned long return_hooker = (unsigned long)

	    &return_to_handler;

	int faulted, insns;
@@ -369,12 +368,6 @@ void prepare_ftrace_return(unsigned long *parent_ra_addr, unsigned long self_ra, 
	if (unlikely(faulted))

		goto out;



	if (ftrace_push_return_trace(old_parent_ra, self_ra, &trace.depth, fp,

				     NULL) == -EBUSY) {

		*parent_ra_addr = old_parent_ra;

		return;

	}



	/*

	 * Get the recorded ip of the current mcount calling site in the

	 * __mcount_loc section, which will be used to filter the function
@@ -382,13 +375,10 @@ void prepare_ftrace_return(unsigned long *parent_ra_addr, unsigned long self_ra, 
	 */



	insns = core_kernel_text(self_ra) ? 2 : MCOUNT_OFFSET_INSNS + 1;

	trace.func = self_ra - (MCOUNT_INSN_SIZE * insns);

	self_ra -= (MCOUNT_INSN_SIZE * insns);



	/* Only trace if the calling function expects to */

	if (!ftrace_graph_entry(&trace)) {

		current->curr_ret_stack--;

	if (function_graph_enter(old_parent_ra, self_ra, fp, NULL))

		*parent_ra_addr = old_parent_ra;

	}

	return;

out:

	ftrace_graph_stop();

arch/nds32/kernel/ftrace.c

+2 −16
Original line number Diff line number Diff line
@@ -211,28 +211,14 @@ void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr, 
			   unsigned long frame_pointer)

{

	unsigned long return_hooker = (unsigned long)&return_to_handler;

	struct ftrace_graph_ent trace;

	unsigned long old;

	int err;



	if (unlikely(atomic_read(&current->tracing_graph_pause)))

		return;



	old = *parent;



	trace.func = self_addr;

	trace.depth = current->curr_ret_stack + 1;



	/* Only trace if the calling function expects to */

	if (!ftrace_graph_entry(&trace))

		return;



	err = ftrace_push_return_trace(old, self_addr, &trace.depth,

				       frame_pointer, NULL);



	if (err == -EBUSY)

		return;



	if (!function_graph_enter(old, self_addr, frame_pointer, NULL))

		*parent = return_hooker;

}

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