linux-stable.git/kernel/trace/trace.h, branch v4.12.2

ftrace: Remove #ifdef from code and add clear_ftrace_function_probes() stub

2017-05-18T01:53:32+00:00

No need to add ugly #ifdefs in the code. Having a standard stub file is much
prettier.

Signed-off-by: Steven Rostedt (VMware)

ftrace/instances: Clear function triggers when removing instances

2017-05-18T01:52:22+00:00

If instance directories are deleted while there are registered function
triggers:

  # cd /sys/kernel/debug/tracing/instances
  # mkdir test
  # echo "schedule:enable_event:sched:sched_switch" > test/set_ftrace_filter
  # rmdir test
  Unable to handle kernel paging request for data at address 0x00000008
  Unable to handle kernel paging request for data at address 0x00000008
  Faulting instruction address: 0xc0000000021edde8
  Oops: Kernel access of bad area, sig: 11 [#1]
  SMP NR_CPUS=2048
  NUMA
  pSeries
  Modules linked in: iptable_mangle ipt_MASQUERADE nf_nat_masquerade_ipv4 iptable_nat nf_nat_ipv4 nf_nat nf_conntrack_ipv4 nf_defrag_ipv4 xt_conntrack nf_conntrack ipt_REJECT nf_reject_ipv4 xt_tcpudp tun bridge stp llc kvm iptable_filter fuse binfmt_misc pseries_rng rng_core vmx_crypto ib_iser rdma_cm iw_cm ib_cm ib_core libiscsi scsi_transport_iscsi ip_tables x_tables autofs4 btrfs raid10 raid456 async_raid6_recov async_memcpy async_pq async_xor async_tx xor raid6_pq libcrc32c multipath virtio_net virtio_blk virtio_pci crc32c_vpmsum virtio_ring virtio
  CPU: 8 PID: 8694 Comm: rmdir Not tainted 4.11.0-nnr+ #113
  task: c0000000bab52800 task.stack: c0000000baba0000
  NIP: c0000000021edde8 LR: c0000000021f0590 CTR: c000000002119620
  REGS: c0000000baba3870 TRAP: 0300   Not tainted  (4.11.0-nnr+)
  MSR: 8000000000009033 
    CR: 22002422  XER: 20000000
  CFAR: 00007fffabb725a8 DAR: 0000000000000008 DSISR: 40000000 SOFTE: 0
  GPR00: c00000000220f750 c0000000baba3af0 c000000003157e00 0000000000000000
  GPR04: 0000000000000040 00000000000000eb 0000000000000040 0000000000000000
  GPR08: 0000000000000000 0000000000000113 0000000000000000 c00000000305db98
  GPR12: c000000002119620 c00000000fd42c00 0000000000000000 0000000000000000
  GPR16: 0000000000000000 0000000000000000 0000000000000000 0000000000000000
  GPR20: 0000000000000000 0000000000000000 c0000000bab52e90 0000000000000000
  GPR24: 0000000000000000 00000000000000eb 0000000000000040 c0000000baba3bb0
  GPR28: c00000009cb06eb0 c0000000bab52800 c00000009cb06eb0 c0000000baba3bb0
  NIP [c0000000021edde8] ring_buffer_lock_reserve+0x8/0x4e0
  LR [c0000000021f0590] trace_event_buffer_lock_reserve+0xe0/0x1a0
  Call Trace:
  [c0000000baba3af0] [c0000000021f96c8] trace_event_buffer_commit+0x1b8/0x280 (unreliable)
  [c0000000baba3b60] [c00000000220f750] trace_event_buffer_reserve+0x80/0xd0
  [c0000000baba3b90] [c0000000021196b8] trace_event_raw_event_sched_switch+0x98/0x180
  [c0000000baba3c10] [c0000000029d9980] __schedule+0x6e0/0xab0
  [c0000000baba3ce0] [c000000002122230] do_task_dead+0x70/0xc0
  [c0000000baba3d10] [c0000000020ea9c8] do_exit+0x828/0xd00
  [c0000000baba3dd0] [c0000000020eaf70] do_group_exit+0x60/0x100
  [c0000000baba3e10] [c0000000020eb034] SyS_exit_group+0x24/0x30
  [c0000000baba3e30] [c00000000200bcec] system_call+0x38/0x54
  Instruction dump:
  60000000 60420000 7d244b78 7f63db78 4bffaa09 393efff8 793e0020 39200000
  4bfffecc 60420000 3c4c00f7 3842a020 <81230008> 2f890000 409e02f0 a14d0008
  ---[ end trace b917b8985d0e650b ]---
  Unable to handle kernel paging request for data at address 0x00000008
  Faulting instruction address: 0xc0000000021edde8
  Unable to handle kernel paging request for data at address 0x00000008
  Faulting instruction address: 0xc0000000021edde8
  Faulting instruction address: 0xc0000000021edde8

To address this, let's clear all registered function probes before
deleting the ftrace instance.

Link: http://lkml.kernel.org/r/c5f1ca624043690bd94642bb6bffd3f2fc504035.1494956770.git.naveen.n.rao@linux.vnet.ibm.com

Reported-by: Michael Ellerman 
Signed-off-by: Naveen N. Rao 
Signed-off-by: Steven Rostedt (VMware)

Merge tag 'trace-v4.12' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace

2017-05-04T01:41:21+00:00

Pull tracing updates from Steven Rostedt:
 "New features for this release:

   - Pretty much a full rewrite of the processing of function plugins.
     i.e. echo do_IRQ:stacktrace > set_ftrace_filter

   - The rewrite was needed to add plugins to be unique to tracing
     instances. i.e. mkdir instance/foo; cd instances/foo; echo
     do_IRQ:stacktrace > set_ftrace_filter The old way was written very
     hacky. This removes a lot of those hacks.

   - New "function-fork" tracing option. When set, pids in the
     set_ftrace_pid will have their children added when the processes
     with their pids listed in the set_ftrace_pid file forks.

   - Exposure of "maxactive" for kretprobe in kprobe_events

   - Allow for builtin init functions to be traced by the function
     tracer (via the kernel command line). Module init function tracing
     will come in the next release.

   - Added more selftests, and have selftests also test in an instance"

* tag 'trace-v4.12' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: (60 commits)
  ring-buffer: Return reader page back into existing ring buffer
  selftests: ftrace: Allow some event trigger tests to run in an instance
  selftests: ftrace: Have some basic tests run in a tracing instance too
  selftests: ftrace: Have event tests also run in an tracing instance
  selftests: ftrace: Make func_event_triggers and func_traceonoff_triggers tests do instances
  selftests: ftrace: Allow some tests to be run in a tracing instance
  tracing/ftrace: Allow for instances to trigger their own stacktrace probes
  tracing/ftrace: Allow for the traceonoff probe be unique to instances
  tracing/ftrace: Enable snapshot function trigger to work with instances
  tracing/ftrace: Allow instances to have their own function probes
  tracing/ftrace: Add a better way to pass data via the probe functions
  ftrace: Dynamically create the probe ftrace_ops for the trace_array
  tracing: Pass the trace_array into ftrace_probe_ops functions
  tracing: Have the trace_array hold the list of registered func probes
  ftrace: If the hash for a probe fails to update then free what was initialized
  ftrace: Have the function probes call their own function
  ftrace: Have each function probe use its own ftrace_ops
  ftrace: Have unregister_ftrace_function_probe_func() return a value
  ftrace: Add helper function ftrace_hash_move_and_update_ops()
  ftrace: Remove data field from ftrace_func_probe structure
  ...

tracing/ftrace: Allow for the traceonoff probe be unique to instances

2017-04-21T02:06:48+00:00

Have the traceon/off function probe triggers affect only the instance they
are set in. This required making the trace_on/off accessible for other files
in the tracing directory.

Signed-off-by: Steven Rostedt (VMware)

tracing/ftrace: Add a better way to pass data via the probe functions

2017-04-21T02:06:46+00:00

With the redesign of the registration and execution of the function probes
(triggers), data can now be passed from the setup of the probe to the probe
callers that are specific to the trace_array it is on. Although, all probes
still only affect the toplevel trace array, this change will allow for
instances to have their own probes separated from other instances and the
top array.

That is, something like the stacktrace probe can be set to trace only in an
instance and not the toplevel trace array. This isn't implement yet, but
this change sets the ground work for the change.

When a probe callback is triggered (someone writes the probe format into
set_ftrace_filter), it calls register_ftrace_function_probe() passing in
init_data that will be used to initialize the probe. Then for every matching
function, register_ftrace_function_probe() will call the probe_ops->init()
function with the init data that was passed to it, as well as an address to
a place holder that is associated with the probe and the instance. The first
occurrence will have a NULL in the pointer. The init() function will then
initialize it. If other probes are added, or more functions are part of the
probe, the place holder will be passed to the init() function with the place
holder data that it was initialized to the last time.

Then this place_holder is passed to each of the other probe_ops functions,
where it can be used in the function callback. When the probe_ops free()
function is called, it can be called either with the rip of the function
that is being removed from the probe, or zero, indicating that there are no
more functions attached to the probe, and the place holder is about to be
freed. This gives the probe_ops a way to free the data it assigned to the
place holder if it was allocade during the first init call.

Signed-off-by: Steven Rostedt (VMware)

ftrace: Dynamically create the probe ftrace_ops for the trace_array

2017-04-21T02:06:46+00:00

In order to eventually have each trace_array instance have its own unique
set of function probes (triggers), the trace array needs to hold the ops and
the filters for the probes.

This is the first step to accomplish this. Instead of having the private
data of the probe ops point to the trace_array, create a separate list that
the trace_array holds. There's only one private_data for a probe, we need
one per trace_array. The probe ftrace_ops will be dynamically created for
each instance, instead of being static.

Signed-off-by: Steven Rostedt (VMware)

tracing: Pass the trace_array into ftrace_probe_ops functions

2017-04-21T02:06:45+00:00

Pass the trace_array associated to a ftrace_probe_ops into the probe_ops
func(), init() and free() functions. The trace_array is the descriptor that
describes a tracing instance. This will help create the infrastructure that
will allow having function probes unique to tracing instances.

Signed-off-by: Steven Rostedt (VMware)

tracing: Have the trace_array hold the list of registered func probes

2017-04-21T02:06:45+00:00

Add a link list to the trace_array to hold func probes that are registered.
Currently, all function probes are the same for all instances as it was
before, that is, only the top level trace_array holds the function probes.
But this lays the ground work to have function probes be attached to
individual instances, and having the event trigger only affect events in the
given instance. But that work is still to be done.

Signed-off-by: Steven Rostedt (VMware)

ftrace: Have the function probes call their own function

2017-04-21T02:06:43+00:00

Now that the function probes have their own ftrace_ops, there's no reason to
continue using the ftrace_func_hash to find which probe to call in the
function callback. The ops that is passed in to the function callback is
part of the probe_ops to call.

Signed-off-by: Steven Rostedt (VMware)

ftrace: Have each function probe use its own ftrace_ops

2017-04-21T02:06:43+00:00

Have the function probes have their own ftrace_ops, and remove the
trace_probe_ops. This simplifies some of the ftrace infrastructure code.

Individual entries for each function is still allocated for the use of the
output for set_ftrace_filter, but they will be removed soon too.

Signed-off-by: Steven Rostedt (VMware)