linux-toradex.git/kernel/trace/trace_functions_graph.c, branch v4.12-rc1

tracing/fgraph: Have wakeup and irqsoff tracers ignore graph functions too

2016-12-09T14:21:35+00:00

Currently both the wakeup and irqsoff traces do not handle set_graph_notrace
well. The ftrace infrastructure will ignore the return paths of all
functions leaving them hanging without an end:

  # echo '*spin*' > set_graph_notrace
  # cat trace
  [...]
          _raw_spin_lock() {
            preempt_count_add() {
            do_raw_spin_lock() {
          update_rq_clock();

Where the '*spin*' functions should have looked like this:

          _raw_spin_lock() {
            preempt_count_add();
            do_raw_spin_lock();
          }
          update_rq_clock();

Instead, have the wakeup and irqsoff tracers ignore the functions that are
set by the set_graph_notrace like the function_graph tracer does. Move
the logic in the function_graph tracer into a header to allow wakeup and
irqsoff tracers to use it as well.

Cc: Namhyung Kim 
Signed-off-by: Steven Rostedt

fgraph: Handle a case where a tracer ignores set_graph_notrace

2016-12-09T14:19:28+00:00

Both the wakeup and irqsoff tracers can use the function graph tracer when
the display-graph option is set. The problem is that they ignore the notrace
file, and record the entry of functions that would be ignored by the
function_graph tracer. This causes the trace->depth to be recorded into the
ring buffer. The set_graph_notrace uses a trick by adding a large negative
number to the trace->depth when a graph function is to be ignored.

On trace output, the graph function uses the depth to record a stack of
functions. But since the depth is negative, it accesses the array with a
negative number and causes an out of bounds access that can cause a kernel
oops or corrupt data.

Have the print functions handle cases where a tracer still records functions
even when they are in set_graph_notrace.

Also add warnings if the depth is below zero before accessing the array.

Note, the function graph logic will still prevent the return of these
functions from being recorded, which means that they will be left hanging
without a return. For example:

   # echo '*spin*' > set_graph_notrace
   # echo 1 > options/display-graph
   # echo wakeup > current_tracer
   # cat trace
   [...]
      _raw_spin_lock() {
        preempt_count_add() {
        do_raw_spin_lock() {
      update_rq_clock();

Where it should look like:

      _raw_spin_lock() {
        preempt_count_add();
        do_raw_spin_lock();
      }
      update_rq_clock();

Cc: stable@vger.kernel.org
Cc: Namhyung Kim 
Fixes: 29ad23b00474 ("ftrace: Add set_graph_notrace filter")
Signed-off-by: Steven Rostedt

tracing: Make __buffer_unlock_commit() always_inline

2016-11-24T01:30:51+00:00

The function __buffer_unlock_commit() is called in a few places outside of
trace.c. But for the most part, it should really be inlined, as it is in the
hot path of the trace_events. For the callers outside of trace.c, create a
new function trace_buffer_unlock_commit_nostack(), as the reason it was used
was to avoid the stack tracing that trace_buffer_unlock_commit() could do.

Link: http://lkml.kernel.org/r/20161121183700.GW26852@two.firstfloor.org

Reported-by: Andi Kleen 
Signed-off-by: Steven Rostedt

Merge tag 'trace-v4.9' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace

2016-10-06T18:48:41+00:00

Pull tracing updates from Steven Rostedt:
 "This release cycle is rather small.  Just a few fixes to tracing.

  The big change is the addition of the hwlat tracer. It not only
  detects SMIs, but also other latency that's caused by the hardware. I
  have detected some latency from large boxes having bus contention"

* tag 'trace-v4.9' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
  tracing: Call traceoff trigger after event is recorded
  ftrace/scripts: Add helper script to bisect function tracing problem functions
  tracing: Have max_latency be defined for HWLAT_TRACER as well
  tracing: Add NMI tracing in hwlat detector
  tracing: Have hwlat trace migrate across tracing_cpumask CPUs
  tracing: Add documentation for hwlat_detector tracer
  tracing: Added hardware latency tracer
  ftrace: Access ret_stack->subtime only in the function profiler
  function_graph: Handle TRACE_BPUTS in print_graph_comment
  tracing/uprobe: Drop isdigit() check in create_trace_uprobe

ftrace: Access ret_stack->subtime only in the function profiler

2016-09-01T16:19:40+00:00

The subtime is used only for function profiler with function graph
tracer enabled.  Move the definition of subtime under
CONFIG_FUNCTION_PROFILER to reduce the memory usage.  Also move the
initialization of subtime into the graph entry callback.

Link: http://lkml.kernel.org/r/20160831025529.24018-1-namhyung@kernel.org

Cc: Ingo Molnar 
Cc: Josh Poimboeuf 
Signed-off-by: Namhyung Kim 
Signed-off-by: Steven Rostedt

function_graph: Handle TRACE_BPUTS in print_graph_comment

2016-09-01T15:19:55+00:00

It missed to handle TRACE_BPUTS so messages recorded by trace_bputs()
will be shown with symbol info unnecessarily.

You can see it with the trace_printk sample code:

  # cd /sys/kernel/tracing/
  # echo sys_sync > set_graph_function
  # echo 1 > options/sym-offset
  # echo function_graph > current_tracer

Note that the sys_sync filter was there to prevent recording other
functions and the sym-offset option was needed since the first message
was called from a module init function so kallsyms doesn't have the
symbol and omitted in the output.

  # cd ~/build/kernel
  # insmod samples/trace_printk/trace-printk.ko

  # cd -
  # head trace

Before:

  # tracer: function_graph
  #
  # CPU  DURATION                  FUNCTION CALLS
  # |     |   |                     |   |   |   |
   1)               |  /* 0xffffffffa0002000: This is a static string that will use trace_bputs */
   1)               |  /* This is a dynamic string that will use trace_puts */
   1)               |  /* trace_printk_irq_work+0x5/0x7b [trace_printk]: (irq) This is a static string that will use trace_bputs */
   1)               |  /* (irq) This is a dynamic string that will use trace_puts */
   1)               |  /* (irq) This is a static string that will use trace_bprintk() */
   1)               |  /* (irq) This is a dynamic string that will use trace_printk */

After:

  # tracer: function_graph
  #
  # CPU  DURATION                  FUNCTION CALLS
  # |     |   |                     |   |   |   |
   1)               |  /* This is a static string that will use trace_bputs */
   1)               |  /* This is a dynamic string that will use trace_puts */
   1)               |  /* (irq) This is a static string that will use trace_bputs */
   1)               |  /* (irq) This is a dynamic string that will use trace_puts */
   1)               |  /* (irq) This is a static string that will use trace_bprintk() */
   1)               |  /* (irq) This is a dynamic string that will use trace_printk */

Link: http://lkml.kernel.org/r/20160901024354.13720-1-namhyung@kernel.org

Signed-off-by: Namhyung Kim 
Signed-off-by: Steven Rostedt

ftrace: Add ftrace_graph_ret_addr() stack unwinding helpers

2016-08-24T10:15:14+00:00

When function graph tracing is enabled for a function, ftrace modifies
the stack by replacing the original return address with the address of a
hook function (return_to_handler).

Stack unwinders need a way to get the original return address.  Add an
arch-independent helper function for that named ftrace_graph_ret_addr().

This adds two variations of the function: one depends on
HAVE_FUNCTION_GRAPH_RET_ADDR_PTR, and the other relies on an index state
variable.

The former is recommended because, in some cases, the latter can cause
problems when the unwinder skips stack frames.  It can get out of sync
with the ret_stack index and wrong addresses can be reported for the
stack trace.

Once all arches have been ported to use
HAVE_FUNCTION_GRAPH_RET_ADDR_PTR, we can get rid of the distinction.

Signed-off-by: Josh Poimboeuf 
Acked-by: Steven Rostedt 
Cc: Andy Lutomirski 
Cc: Andy Lutomirski 
Cc: Borislav Petkov 
Cc: Brian Gerst 
Cc: Byungchul Park 
Cc: Denys Vlasenko 
Cc: Frederic Weisbecker 
Cc: H. Peter Anvin 
Cc: Kees Cook 
Cc: Linus Torvalds 
Cc: Nilay Vaish 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Link: http://lkml.kernel.org/r/36bd90f762fc5e5af3929e3797a68a64906421cf.1471607358.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar

ftrace: Add return address pointer to ftrace_ret_stack

2016-08-24T10:15:14+00:00

Storing this value will help prevent unwinders from getting out of sync
with the function graph tracer ret_stack.  Now instead of needing a
stateful iterator, they can compare the return address pointer to find
the right ret_stack entry.

Note that an array of 50 ftrace_ret_stack structs is allocated for every
task.  So when an arch implements this, it will add either 200 or 400
bytes of memory usage per task (depending on whether it's a 32-bit or
64-bit platform).

Signed-off-by: Josh Poimboeuf 
Acked-by: Steven Rostedt 
Cc: Andy Lutomirski 
Cc: Andy Lutomirski 
Cc: Borislav Petkov 
Cc: Brian Gerst 
Cc: Byungchul Park 
Cc: Denys Vlasenko 
Cc: Frederic Weisbecker 
Cc: H. Peter Anvin 
Cc: Kees Cook 
Cc: Linus Torvalds 
Cc: Nilay Vaish 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Link: http://lkml.kernel.org/r/a95cfcc39e8f26b89a430c56926af0bb217bc0a1.1471607358.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar

ftrace: Only allocate the ret_stack 'fp' field when needed

2016-08-24T10:15:14+00:00

This saves some memory when HAVE_FUNCTION_GRAPH_FP_TEST isn't defined.
On x86_64 with newer versions of gcc which have -mfentry, it saves 400
bytes per task.

Signed-off-by: Josh Poimboeuf 
Acked-by: Steven Rostedt 
Cc: Andy Lutomirski 
Cc: Andy Lutomirski 
Cc: Borislav Petkov 
Cc: Brian Gerst 
Cc: Byungchul Park 
Cc: Denys Vlasenko 
Cc: Frederic Weisbecker 
Cc: H. Peter Anvin 
Cc: Kees Cook 
Cc: Linus Torvalds 
Cc: Nilay Vaish 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Link: http://lkml.kernel.org/r/5c7747d9ea7b5cb47ef0a8ce8a6cea6bf7aa94bf.1471607358.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar

ftrace: Remove CONFIG_HAVE_FUNCTION_GRAPH_FP_TEST from config

2016-08-24T10:15:13+00:00

Make HAVE_FUNCTION_GRAPH_FP_TEST a normal define, independent from
kconfig.  This removes some config file pollution and simplifies the
checking for the fp test.

Suggested-by: Steven Rostedt 
Signed-off-by: Josh Poimboeuf 
Acked-by: Steven Rostedt 
Cc: Andy Lutomirski 
Cc: Andy Lutomirski 
Cc: Borislav Petkov 
Cc: Brian Gerst 
Cc: Byungchul Park 
Cc: Denys Vlasenko 
Cc: Frederic Weisbecker 
Cc: H. Peter Anvin 
Cc: Kees Cook 
Cc: Linus Torvalds 
Cc: Nilay Vaish 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Link: http://lkml.kernel.org/r/2c4e5f05054d6d367f702fd153af7a0109dd5c81.1471607358.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar