My static checker complains that if "func" is NULL then "clear_filter"
is uninitialized.  This seems like it could be true, although it's
possible something subtle is happening that I haven't seen.

    kernel/trace/ftrace.c:3844 match_records()
    error: uninitialized symbol 'clear_filter'.

Link: http://lkml.kernel.org/r/20170712073556.h6tkpjcdzjaozozs@mwanda

Cc: stable@vger.kernel.org
Fixes: f0a3b154 ("ftrace: Clarify code for mod command")
Signed-off-by: NDan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>

"func" can't be NULL and it doesn't make sense to check because we've
already derefenced it.

Link: http://lkml.kernel.org/r/20170712073340.4enzeojeoupuds5a@mwandaSigned-off-by: NDan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>

When modules are disabled, we get a harmless build warning:

kernel/trace/ftrace.c:4051:13: error: 'process_cached_mods' defined but not used [-Werror=unused-function]

This adds the same #ifdef around the new code that exists around
its caller.

Link: http://lkml.kernel.org/r/20170710084413.1820568-1-arnd@arndb.de

Fixes: d7fbf8df ("ftrace: Implement cached modules tracing on module load")
Signed-off-by: NArnd Bergmann <arnd@arndb.de>
Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>

The "stack_trace_filter" file only makes sense if DYNAMIC_FTRACE is
configured in. If it is not, then the user can not filter any functions.

Not only that, the open function causes warnings when DYNAMIC_FTRACE is not
set.

Link: http://lkml.kernel.org/r/20170710110521.600806-1-arnd@arndb.deReported-by: NArnd Bergmann <arnd@arndb.de>
Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>

The documentation of ftrace.txt has become rather outdated. Bring it closer
to reality of todays kernel.
Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>

The addition of TGID to the tracing header added a check to see if TGID
shoudl be displayed or not, and updated the header accordingly.
Unfortunately, it broke the default header.

Also add constant strings to use for spacing. This does remove the
visibility of the header a bit, but cuts it down from the extended lines
much greater than 80 characters.

Before this change:

 # tracer: function
 #
 #                            _-----=> irqs-off
 #                           / _----=> need-resched
 #                          | / _---=> hardirq/softirq
 #                          || / _--=> preempt-depth
 #                          ||| /     delay
 #           TASK-PID   CPU#||||    TIMESTAMP  FUNCTION
 #              | |       | ||||       |         |
        swapper/0-1     [000] ....     0.277830: migration_init <-do_one_initcall
        swapper/0-1     [002] d...    13.861967: Unknown type 1201
        swapper/0-1     [002] d..1    13.861970: Unknown type 1202

After this change:

 # tracer: function
 #
 #                              _-----=> irqs-off
 #                             / _----=> need-resched
 #                            | / _---=> hardirq/softirq
 #                            || / _--=> preempt-depth
 #                            ||| /     delay
 #           TASK-PID   CPU#  ||||    TIMESTAMP  FUNCTION
 #              | |       |   ||||       |         |
        swapper/0-1     [000] ....     0.278245: migration_init <-do_one_initcall
        swapper/0-1     [003] d...    13.861189: Unknown type 1201
        swapper/0-1     [003] d..1    13.861192: Unknown type 1202

Cc: Joel Fernandes <joelaf@google.com>
Fixes: 441dae8f ("tracing: Add support for display of tgid in trace output")
Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>

Add a testcase for kprobe event naming. This testcase checks whether the
kprobe events can automatically ganerate its event name on normal
function and dot-suffixed function.  Also it checks whether the kprobe
events can correctly define new event with given event name and group
name.

Link: http://lkml.kernel.org/r/61ae96fd1fcd14ee652c8b6525c218b8661bb0d2.1499453040.git.naveen.n.rao@linux.vnet.ibm.comSigned-off-by: NMasami Hiramatsu <mhiramat@kernel.org>
[Updated tests to use vfs_read and symbols with '.isra.',
added check for kprobe_events and a command to clear it on exit,
various additional checks and tests]
Signed-off-by: NNaveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>

Add a kprobes test to ensure that we are able to add a probe on a
module function using 'p <mod>:<func>' format, with/without having to
specify a probe name.

Link: http://lkml.kernel.org/r/2d8087e25a7ad9206f3e2b7b4bb0c3c86eaa38af.1499453040.git.naveen.n.rao@linux.vnet.ibm.comSuggested-by: NMasami Hiramatsu <mhiramat@kernel.org>
Acked-by: NMasami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: NNaveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>

KPROBES_ON_FTRACE is only available on powerpc64le. Update comment to
clarify this.

Also, we should use an offset of 8 to ensure that the probe does not
fall on ftrace location. The current offset of 4 will fall before the
function local entry point and won't fire, while an offset of 12 or 16
will fall on ftrace location. Offset 8 is currently guaranteed to not be
the ftrace location.

Link: http://lkml.kernel.org/r/3d32e8fa076070e83527476fdfa3a747bb9a1a3a.1499453040.git.naveen.n.rao@linux.vnet.ibm.comAcked-by: NMasami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: NNaveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>

When we derive event names, convert some expected symbols (such as ':'
used to specify module:name and '.' present in some symbols) into
underscores so that the event name is not rejected.

Before this patch:
    # echo 'p kobject_example:foo_store' > kprobe_events
    trace_kprobe: Failed to allocate trace_probe.(-22)
    -sh: write error: Invalid argument

After this patch:
    # echo 'p kobject_example:foo_store' > kprobe_events
    # cat kprobe_events
    p:kprobes/p_kobject_example_foo_store_0 kobject_example:foo_store

Link: http://lkml.kernel.org/r/66c189e09e71361aba91dd4a5bd146a1b62a7a51.1499453040.git.naveen.n.rao@linux.vnet.ibm.comAcked-by: NMasami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: NNaveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>

In recent patches where we record comm and tgid at the same time, we skip
continuing to record if any fail. Fix that by trying to record as many things
as we can even if some couldn't be recorded. If any information isn't recorded,
then we don't set trace_taskinfo_save as before.

Link: http://lkml.kernel.org/r/20170706230023.17942-3-joelaf@google.com

Cc: kernel-team@android.com
Cc: Ingo Molnar <mingo@redhat.com>
Signed-off-by: NJoel Fernandes <joelaf@google.com>
Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>

Currently we stop recording tgid for non-idle tasks when switching from/to idle
task since we treat that as a record failure. Fix that by treat recording of
tgid for idle task as a success.

Link: http://lkml.kernel.org/r/20170706230023.17942-2-joelaf@google.com

Cc: kernel-team@android.com
Cc: Ingo Molnar <mingo@redhat.com>
Reported-by: NMichael Sartain <mikesart@gmail.com>
Signed-off-by: NJoel Fernandes <joelaf@google.com>
Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>

Currently we stop recording comm for non-idle tasks when switching from/to idle
task since we treat that as a record failure. Fix that by treat recording of
comm for idle task as a success.

Link: http://lkml.kernel.org/r/20170706230023.17942-1-joelaf@google.com

Cc: kernel-team@android.com
Cc: Ingo Molnar <mingo@redhat.com>
Reported-by: NMichael Sartain <mikesart@gmail.com>
Signed-off-by: NJoel Fernandes <joelaf@google.com>
Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>

Export the cached pid / tgid mappings in debugfs tracing saved_tgids file.
This allows user apps to translate the pids from a trace to their respective
thread group.

Example saved_tgids file with pid / tgid values separated by ' ':

  # cat saved_tgids
  1048 1048
  1047 1047
  7 7
  1049 1047
  1054 1047
  1053 1047

Link: http://lkml.kernel.org/r/20170630004023.064965233@goodmis.org
Link: http://lkml.kernel.org/r/20170706040713.unwkumbta5menygi@mikesart-cosReviewed-by: NJoel Fernandes <joelaf@google.com>
Signed-off-by: NMichael Sartain <mikesart@fastmail.com>
Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>

As writing into stack_trace_filter, the iter-tr is not set and is NULL.
Check if it is NULL before dereferencing it in ftrace_regex_release().

Fixes: 8c08f0d5 ("ftrace: Have cached module filters be an active filter")
Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>

Need to get the changes from 0f179765 ("ftrace: Fix regression with
module command in stack_trace_filter") as it is required to fix some other
changes with stack_trace_filter and the new development code.
Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>

When doing the following command:

 # echo ":mod:kvm_intel" > /sys/kernel/tracing/stack_trace_filter

it triggered a crash.

This happened with the clean up of probes. It required all callers to the
regex function (doing ftrace filtering) to have ops->private be a pointer to
a trace_array. But for the stack tracer, that is not the case.

Allow for the ops->private to be NULL, and change the function command
callbacks to handle the trace_array pointer being NULL as well.

Fixes: d2afd57a ("tracing/ftrace: Allow instances to have their own function probes")
Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>

Init boot up functions may be traced, but they are also freed when the
kernel finishes booting. These are removed from the ftrace tables, and the
debug variable for dyn_ftrace_total_info needs to reflect that as well.
Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>

If the new_hash fails to allocate, then unlock the hash mutex on error.
Reported-by: NJulia Lawall <julia.lawall@lip6.fr>
Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>

Earlier patches introduced ability to record the tgid using the 'record-tgid'
option. Here we read the tgid and output it if the option is enabled.

Link: http://lkml.kernel.org/r/20170626053844.5746-3-joelaf@google.com

Cc: kernel-team@android.com
Cc: Ingo Molnar <mingo@redhat.com>
Tested-by: NMichael Sartain <mikesart@gmail.com>
Signed-off-by: NJoel Fernandes <joelaf@google.com>
Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>

Inorder to support recording of tgid, the following changes are made:

* Introduce a new API (tracing_record_taskinfo) to additionally record the tgid
  along with the task's comm at the same time. This has has the benefit of not
  setting trace_cmdline_save before all the information for a task is saved.
* Add a new API tracing_record_taskinfo_sched_switch to record task information
  for 2 tasks at a time (previous and next) and use it from sched_switch probe.
* Preserve the old API (tracing_record_cmdline) and create it as a wrapper
  around the new one so that existing callers aren't affected.
* Reuse the existing sched_switch and sched_wakeup probes to record tgid
  information and add a new option 'record-tgid' to enable recording of tgid

When record-tgid option isn't enabled to being with, we take care to make sure
that there's isn't memory or runtime overhead.

Link: http://lkml.kernel.org/r/20170627020155.5139-1-joelaf@google.com

Cc: kernel-team@android.com
Cc: Ingo Molnar <mingo@redhat.com>
Tested-by: NMichael Sartain <mikesart@gmail.com>
Signed-off-by: NJoel Fernandes <joelaf@google.com>
Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>

The dyn_ftrace_total_info file is used to show how many functions have been
converted into nops and can be used by ftrace. The problem is that it does
not get decremented when functions are removed (init boot code being freed,
and modules being freed). That means the number is very inaccurate everytime
functions are removed from the ftrace tables. Decrement it when functions
are removed.
Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>

ftrace_arch_read_dyn_info() was used so that archs could add its own debug
information into the dyn_ftrace_total_info in the tracefs file system. That
file is for debugging usage of dynamic ftrace. No arch uses that function
anymore, so just get rid of it.

This also allows for tracing_read_dyn_info() to be cleaned up a bit.
Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>

I noticed that there's only one user of ftrace_arch_read_dyn_info().
That was used a while ago during the NMI updating in x86, and superh
copied it to implement its version of handling NMIs during
stop_machine().

But that is a debug feature, and this code hasn't been touched since
2009. Also, x86 no longer does the ftrace updates with stop_machine()
and instead uses breakpoints. If superh needs to modify its code, it
should implement the breakpoint conversion, and remove stop_machine().
Which also gets rid of the NMI issue.

Anyway, I want to nuke ftrace_arch_read_dyn_info() and this gets rid of
the one user, which is for an arch that shouldn't need it anymore.

Link: http://lkml.kernel.org/r/20170626181749.2ce954d1@gandalf.local.home

Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Cc: Rich Felker <dalias@libc.org>
Cc: linux-sh@vger.kernel.org
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>
Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>

When a module filter is added to set_ftrace_filter, if the module is not
loaded, it is cached. This should be considered an active filter, and
function tracing should be filtered by this. That is, if a cached module
filter is the only filter set, then no function tracing should be happening,
as all the functions available will be filtered out.

This makes sense, as the reason to add a cached module filter, is to trace
the module when you load it. There shouldn't be any other tracing happening
until then.
Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>

If a module is cached in the set_ftrace_filter, and that module is loaded,
then enable tracing on that module as if the cached module text was written
into set_ftrace_filter just as the module is loaded.

  # echo ":mod:kvm_intel" >
  # cat /sys/kernel/tracing/set_ftrace_filter
 #### all functions enabled ####
 :mod:kvm_intel
  # modprobe kvm_intel
  # cat /sys/kernel/tracing/set_ftrace_filter
 vmx_get_rflags [kvm_intel]
 vmx_get_pkru [kvm_intel]
 vmx_get_interrupt_shadow [kvm_intel]
 vmx_rdtscp_supported [kvm_intel]
 vmx_invpcid_supported [kvm_intel]
 [..]
Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>

When writing in a module filter into set_ftrace_filter for a module that is
not yet loaded, it it cached, and will be executed when the module is loaded
(although that is not implemented yet at this commit). Display the list of
cached modules to be traced.
Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>

This is the start of the infrastructure work to allow for tracing module
functions before it is loaded.

Currently the following command:

  # echo :mod:some-mod > set_ftrace_filter

will enable tracing of all functions within the module "some-mod" if it is
loaded. What we want, is if the module is not loaded, that line will be
saved. When the module is loaded, then the "some-mod" will have that line
executed on it, so that the functions within it starts being traced.
Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>

Currently, when a function is not found in kallsyms, instead of simply
showing the function address, it shows nothing at all:

 # echo ':mod:kvm_intel' > /sys/kernel/tracing/set_ftrace_filter
 # echo function > /sys/kernel/tracing/set_ftrace_filter
 # qemu -enable-kvm /home/my-qemu-image
   <Ctrl-C>
 # rmmod kvm_intel
 # cat /sys/kernel/tracing/trace
 qemu-system-x86-2408  [001] d..2   135.013238:  <-kvm_arch_hardware_enable
 qemu-system-x86-2408  [001] ....   135.014574:  <-kvm_arch_vm_ioctl
 qemu-system-x86-2408  [001] ....   135.015420:  <-kvm_vm_ioctl_check_extension
 qemu-system-x86-2408  [001] ....   135.045411:  <-__do_cpuid_ent
 qemu-system-x86-2408  [001] ....   135.045412:  <-__do_cpuid_ent
 qemu-system-x86-2408  [001] ....   135.045412:  <-__do_cpuid_ent
 qemu-system-x86-2408  [001] ....   135.045412:  <-__do_cpuid_ent
 qemu-system-x86-2408  [001] ...1   135.045413:  <-__do_cpuid_ent
 qemu-system-x86-2408  [001] ....   135.045413:  <-__do_cpuid_ent

When it should show:

 qemu-system-x86-2408  [001] d..2   135.013238: 0xffffffffa02a39f0 <-kvm_arch_hardware_enable
 qemu-system-x86-2408  [001] ....   135.014574: 0xffffffffa02a2ba0 <-kvm_arch_vm_ioctl
 qemu-system-x86-2408  [001] ....   135.015420: 0xffffffffa029e4e0 <-kvm_vm_ioctl_check_extension
 qemu-system-x86-2408  [001] ....   135.045411: 0xffffffffa02a1380 <-__do_cpuid_ent
 qemu-system-x86-2408  [001] ....   135.045412: 0xffffffffa029e160 <-__do_cpuid_ent
 qemu-system-x86-2408  [001] ....   135.045412: 0xffffffffa029e180 <-__do_cpuid_ent
 qemu-system-x86-2408  [001] ....   135.045412: 0xffffffffa029e520 <-__do_cpuid_ent
 qemu-system-x86-2408  [001] ...1   135.045413: 0xffffffffa02a13b0 <-__do_cpuid_ent
 qemu-system-x86-2408  [001] ....   135.045413: 0xffffffffa02a1380 <-__do_cpuid_ent

instead.
Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>

All the enum flags for FTRACE_OPS has a comment except for the RCU one. Add
the comment for that.
Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>

The enum_map file is used to display a list of symbol
to name conversions. As its now used to resolve sizeof
lets update the name and description.

Link: http://lkml.kernel.org/r/20170531215653.3240-13-jeremy.linton@arm.comSigned-off-by: NJeremy Linton <jeremy.linton@arm.com>
Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>

There are a few places in the kernel where sizeof() is already
being used. Update those locations with TRACE_DEFINE_SIZEOF.

Link: http://lkml.kernel.org/r/20170531215653.3240-12-jeremy.linton@arm.comSigned-off-by: NJeremy Linton <jeremy.linton@arm.com>
Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>

Perf has a problem that if sizeof() macros are used within TRACE_EVENT()
macro's they end up in userspace as "sizeof(kernel structure)" which
cannot properly be parsed. Add a macro which can forward this data
through the eval_map for userspace utilization.

Link: http://lkml.kernel.org/r/20170531215653.3240-10-jeremy.linton@arm.comSigned-off-by: NJeremy Linton <jeremy.linton@arm.com>
Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>

The enum_replace stanza works as is for sizeof()
calls as well as enums. Rename it as well.

Link: http://lkml.kernel.org/r/20170531215653.3240-9-jeremy.linton@arm.comSigned-off-by: NJeremy Linton <jeremy.linton@arm.com>
Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>

Rename the core trace enum routines to use eval, to
reflect their use by more than just enum to value mapping.

Link: http://lkml.kernel.org/r/20170531215653.3240-8-jeremy.linton@arm.comSigned-off-by: NJeremy Linton <jeremy.linton@arm.com>
Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>

Rename the init and trace_enum_jmp_to_tail() routines
to reflect their use by more than enumerated types.

Link: http://lkml.kernel.org/r/20170531215653.3240-7-jeremy.linton@arm.comSigned-off-by: NJeremy Linton <jeremy.linton@arm.com>
Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>

There is a lock protecting the trace_enum_map, rename
it to reflect the use by more than enums.

Link: http://lkml.kernel.org/r/20170531215653.3240-6-jeremy.linton@arm.comSigned-off-by: NJeremy Linton <jeremy.linton@arm.com>
Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>

The enum map entries can be exported to userspace
via a sys enum_map file. Rename those functions
and structures to reflect the fact that we are using
them for more than enums.

Link: http://lkml.kernel.org/r/20170531215653.3240-5-jeremy.linton@arm.comSigned-off-by: NJeremy Linton <jeremy.linton@arm.com>
Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>

Each module has a list of enum's its contributing to the
enum map, rename that entry to reflect its use by more than
enums.

Link: http://lkml.kernel.org/r/20170531215653.3240-4-jeremy.linton@arm.comSigned-off-by: NJeremy Linton <jeremy.linton@arm.com>
Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>

Each enum is loaded into the trace_enum_map, as we
are now using this for more than enums rename it.

Link: http://lkml.kernel.org/r/20170531215653.3240-3-jeremy.linton@arm.comSigned-off-by: NJeremy Linton <jeremy.linton@arm.com>
Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>