linux/kernel/trace/trace_events.c, branch v5.17

tracing: Remove duplicate warnings when calling trace_create_file()

2022-01-13T22:02:42Z

Since the same warning message is already printed in the trace_create_file() function, there is no need to print it again. Link: https://lkml.kernel.org/r/20220109162232.361747-1-ytcoode@gmail.com Signed-off-by: Yuntao Wang Signed-off-by: Steven Rostedt

tracing: Test the 'Do not trace this pid' case in create event

2021-11-27T21:50:43Z

When creating a new event (via a module, kprobe, eprobe, etc), the descriptors that are created must add flags for pid filtering if an instance has pid filtering enabled, as the flags are used at the time the event is executed to know if pid filtering should be done or not. The "Only trace this pid" case was added, but a cut and paste error made that case checked twice, instead of checking the "Trace all but this pid" case. Link: https://lore.kernel.org/all/202111280401.qC0z99JB-lkp@intel.com/ Fixes: 6cb206508b62 ("tracing: Check pid filtering when creating events") Reported-by: kernel test robot Signed-off-by: Steven Rostedt (VMware)

tracing: Check pid filtering when creating events

2021-11-26T19:31:23Z

When pid filtering is activated in an instance, all of the events trace files for that instance has the PID_FILTER flag set. This determines whether or not pid filtering needs to be done on the event, otherwise the event is executed as normal. If pid filtering is enabled when an event is created (via a dynamic event or modules), its flag is not updated to reflect the current state, and the events are not filtered properly. Cc: stable@vger.kernel.org Fixes: 3fdaf80f4a836 ("tracing: Implement event pid filtering") Signed-off-by: Steven Rostedt (VMware)

tracing: Disable "other" permission bits in the tracefs files

2021-10-08T22:08:43Z

When building the files in the tracefs file system, do not by default set any permissions for OTH (other). This will make it easier for admins who want to define a group for accessing tracefs and not having to first disable all the permission bits for "other" in the file system. As tracing can leak sensitive information, it should never by default allowing all users access. An admin can still set the permission bits for others to have access, which may be useful for creating a honeypot and seeing who takes advantage of it and roots the machine. Link: https://lkml.kernel.org/r/20210818153038.864149276@goodmis.org Signed-off-by: Steven Rostedt (VMware)

tracing: Place trace_pid_list logic into abstract functions

2021-10-05T21:30:08Z

Instead of having the logic that does trace_pid_list open coded, wrap it in abstract functions. This will allow a rewrite of the logic that implements the trace_pid_list without affecting the users. Note, this causes a change in behavior. Every time a pid is written into the set_*_pid file, it creates a new list and uses RCU to update it. If pid_max is lowered, but there was a pid currently in the list that was higher than pid_max, those pids will now be removed on updating the list. The old behavior kept that from happening. The rewrite of the pid_list logic will no longer depend on pid_max, and will return the old behavior. Signed-off-by: Steven Rostedt (VMware)

tracing: Add migrate-disabled counter to tracing output.

2021-09-03T23:42:35Z

migrate_disable() forbids task migration to another CPU. It is available since v5.11 and has already users such as highmem or BPF. It is useful to observe this task state in tracing which already has other states like the preemption counter. Instead of adding the migrate disable counter as a new entry to struct trace_entry, which would extend the whole struct by four bytes, it is squashed into the preempt-disable counter. The lower four bits represent the preemption counter, the upper four bits represent the migrate disable counter. Both counter shouldn't exceed 15 but if they do, there is a safety net which caps the value at 15. Add the migrate-disable counter to the trace entry so it shows up in the trace. Due to the users mentioned above, it is already possible to observe it: | bash-1108 [000] ...21 73.950578: rss_stat: mm_id=2213312838 curr=0 type=MM_ANONPAGES size=8192B | bash-1108 [000] d..31 73.951222: irq_disable: caller=flush_tlb_mm_range+0x115/0x130 parent=ptep_clear_flush+0x42/0x50 | bash-1108 [000] d..31 73.951222: tlb_flush: pages:1 reason:local mm shootdown (3) The last value is the migrate-disable counter. Things that popped up: - trace_print_lat_context() does not print the migrate counter. Not sure if it should. It is used in "verbose" mode and uses 8 digits and I'm not sure ther is something processing the value. - trace_define_common_fields() now defines a different variable. This probably breaks things. No ide what to do in order to preserve the old behaviour. Since this is used as a filter it should be split somehow to be able to match both nibbles here. Link: https://lkml.kernel.org/r/20210810132625.ylssabmsrkygokuv@linutronix.de Signed-off-by: Thomas Gleixner [bigeasy: patch description.] Signed-off-by: Sebastian Andrzej Siewior [ SDR: Removed change to common_preempt_count field name ] Signed-off-by: Steven Rostedt (VMware)

tracing: Have dynamic events have a ref counter

2021-08-18T22:13:47Z

As dynamic events are not created by modules, if something is attached to one, calling "try_module_get()" on its "mod" field, is not going to keep the dynamic event from going away. Since dynamic events do not need the "mod" pointer of the event structure, make a union out of it in order to save memory (there's one structure for each of the thousand+ events in the kernel), and have any event with the DYNAMIC flag set to use a ref counter instead. Link: https://lore.kernel.org/linux-trace-devel/20210813004448.51c7de69ce432d338f4d226b@kernel.org/ Link: https://lkml.kernel.org/r/20210817035027.174869074@goodmis.org Suggested-by: Masami Hiramatsu Acked-by: Masami Hiramatsu Signed-off-by: Steven Rostedt (VMware)

tracing: Fix various typos in comments

2021-03-23T18:08:18Z

Fix ~59 single-word typos in the tracing code comments, and fix the grammar in a handful of places. Link: https://lore.kernel.org/r/20210322224546.GA1981273@gmail.com Link: https://lkml.kernel.org/r/20210323174935.GA4176821@gmail.com Reviewed-by: Randy Dunlap Signed-off-by: Ingo Molnar Signed-off-by: Steven Rostedt (VMware)

tracing: Add check of trace event print fmts for dereferencing pointers

2021-03-18T16:58:26Z

Trace events record data into the ring buffer at the time of the event. The trace event has a printf logic to display the recorded data at a much later time when the user reads the trace file. This makes using dereferencing pointers unsafe if the dereferenced pointer points to the original source. The safe way to handle this is to create an array within the trace event and copy the source into the array. Then the dereference pointer may point to that array. As this is a easy mistake to make, a check is added to examine all trace event print fmts to make sure that they are safe to use. This only checks the various %p* dereferenced pointers like %pB, %pR, etc. It does not handle dereferencing of strings, as there are some use cases that are OK to dereference the source. That will be dealt with differently. Signed-off-by: Steven Rostedt (VMware)

Merge tag 'trace-v5.12' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace

2021-02-22T22:07:15Z

Pull tracing updates from Steven Rostedt: - Update to the way irqs and preemption is tracked via the trace event PC field - Fix handling of unregistering event failing due to allocate memory. This is only triggered by failure injection, as it is pretty much guaranteed to have less than a page allocation succeed. - Do not show the useless "filter" or "enable" files for the "ftrace" trace system, as they have no effect on doing anything. - Add a warning if kprobes are registered more than once. - Synthetic events now have their fields parsed by semicolons. Old formats without semicolons will still work, but new features will require them. - New option to allow trace events to show %p without hashing in trace file. The trace file can only be read by root, and reading the raw event buffer did not have any pointers hashed, so this does not expose anything new. - New directory in tools called tools/tracing, where a new tool that reads sequential latency reports from the ftrace latency tracers. - Other minor fixes and cleanups. * tag 'trace-v5.12' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: (33 commits) kprobes: Fix to delay the kprobes jump optimization tracing/tools: Add the latency-collector to tools directory tracing: Make hash-ptr option default tracing: Add ptr-hash option to show the hashed pointer value tracing: Update the stage 3 of trace event macro comment tracing: Show real address for trace event arguments selftests/ftrace: Add '!event' synthetic event syntax check selftests/ftrace: Update synthetic event syntax errors tracing: Add a backward-compatibility check for synthetic event creation tracing: Update synth command errors tracing: Rework synthetic event command parsing tracing/dynevent: Delegate parsing to create function kprobes: Warn if the kprobe is reregistered ftrace: Remove unused ftrace_force_update() tracepoints: Code clean up tracepoints: Do not punish non static call users tracepoints: Remove unnecessary "data_args" macro parameter tracing: Do not create "enable" or "filter" files for ftrace event subsystem kernel: trace: preemptirq_delay_test: add cpu affinity tracepoint: Do not fail unregistering a probe due to memory failure ...