linux/kernel/trace/trace.h, branch v5.7

tracing: Create set_event_notrace_pid to not trace tasks

2020-03-27T20:39:02Z

There's currently a way to select a task that should only have its events traced, but there's no way to select a task not to have itsevents traced. Add a set_event_notrace_pid file that acts the same as set_event_pid (and is also affected by event-fork), but the task pids in this file will not be traced even if they are listed in the set_event_pid file. This makes it easy for tools like trace-cmd to "hide" itself from beint traced by events when it is recording other tasks. Signed-off-by: Steven Rostedt (VMware)

ftrace: Create set_ftrace_notrace_pid to not trace tasks

2020-03-27T20:39:02Z

There's currently a way to select a task that should only be traced by functions, but there's no way to select a task not to be traced by the function tracer. Add a set_ftrace_notrace_pid file that acts the same as set_ftrace_pid (and is also affected by function-fork), but the task pids in this file will not be traced even if they are listed in the set_ftrace_pid file. This makes it easy for tools like trace-cmd to "hide" itself from the function tracer when it is recording other tasks. Signed-off-by: Steven Rostedt (VMware)

ftrace: Make function trace pid filtering a bit more exact

2020-03-27T20:39:02Z

The set_ftrace_pid file is used to filter function tracing to only trace tasks that are listed in that file. Instead of testing the pids listed in that file (it's a bitmask) at each function trace event, the logic is done via a sched_switch hook. A flag is set when the next task to run is in the list of pids in the set_ftrace_pid file. But the sched_switch hook is not at the exact location of when the task switches, and the flag gets set before the task to be traced actually runs. This leaves a residue of traced functions that do not belong to the pid that should be filtered on. By changing the logic slightly, where instead of having a boolean flag to test, record the pid that should be traced, with special values for not to trace and always trace. Then at each function call, a check will be made to see if the function should be ignored, or if the current pid matches the function that should be traced, and only trace if it matches (or if it has the special value to always trace). Signed-off-by: Steven Rostedt (VMware)

tracing: Do not disable tracing when reading the trace file

2020-03-27T20:39:01Z

When opening the "trace" file, it is no longer necessary to disable tracing. Note, a new option is created called "pause-on-trace", when set, will cause the trace file to emulate its original behavior. Link: http://lkml.kernel.org/r/20200317213416.903351225@goodmis.org Signed-off-by: Steven Rostedt (VMware)

tracing: Remove unused TRACE_BUFFER bits

2020-03-03T22:34:02Z

Commit 567cd4da54ff ("ring-buffer: User context bit recursion checking") added the TRACE_BUFFER bits to be used in the current task's trace_recursion field. But the final submission of the logic removed the use of those bits, but never removed the bits themselves (they were never used in upstream Linux). These can be safely removed. Signed-off-by: Steven Rostedt (VMware)

Merge tag 'trace-v5.6-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace

2020-02-06T07:12:11Z

Pull tracing updates from Steven Rostedt: - Added new "bootconfig". This looks for a file appended to initrd to add boot config options, and has been discussed thoroughly at Linux Plumbers. Very useful for adding kprobes at bootup. Only enabled if "bootconfig" is on the real kernel command line. - Created dynamic event creation. Merges common code between creating synthetic events and kprobe events. - Rename perf "ring_buffer" structure to "perf_buffer" - Rename ftrace "ring_buffer" structure to "trace_buffer" Had to rename existing "trace_buffer" to "array_buffer" - Allow trace_printk() to work withing (some) tracing code. - Sort of tracing configs to be a little better organized - Fixed bug where ftrace_graph hash was not being protected properly - Various other small fixes and clean ups * tag 'trace-v5.6-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: (88 commits) bootconfig: Show the number of nodes on boot message tools/bootconfig: Show the number of bootconfig nodes bootconfig: Add more parse error messages bootconfig: Use bootconfig instead of boot config ftrace: Protect ftrace_graph_hash with ftrace_sync ftrace: Add comment to why rcu_dereference_sched() is open coded tracing: Annotate ftrace_graph_notrace_hash pointer with __rcu tracing: Annotate ftrace_graph_hash pointer with __rcu bootconfig: Only load bootconfig if "bootconfig" is on the kernel cmdline tracing: Use seq_buf for building dynevent_cmd string tracing: Remove useless code in dynevent_arg_pair_add() tracing: Remove check_arg() callbacks from dynevent args tracing: Consolidate some synth_event_trace code tracing: Fix now invalid var_ref_vals assumption in trace action tracing: Change trace_boot to use synth_event interface tracing: Move tracing selftests to bottom of menu tracing: Move mmio tracer config up with the other tracers tracing: Move tracing test module configs together tracing: Move all function tracing configs together tracing: Documentation for in-kernel synthetic event API ...

ftrace: Protect ftrace_graph_hash with ftrace_sync

2020-02-05T22:16:42Z

As function_graph tracer can run when RCU is not "watching", it can not be protected by synchronize_rcu() it requires running a task on each CPU before it can be freed. Calling schedule_on_each_cpu(ftrace_sync) needs to be used. Link: https://lore.kernel.org/r/20200205131110.GT2935@paulmck-ThinkPad-P72 Cc: stable@vger.kernel.org Fixes: b9b0c831bed26 ("ftrace: Convert graph filter to use hash tables") Reported-by: "Paul E. McKenney" Reviewed-by: Joel Fernandes (Google) Signed-off-by: Steven Rostedt (VMware)

ftrace: Add comment to why rcu_dereference_sched() is open coded

2020-02-05T22:15:57Z

Because the function graph tracer can execute in sections where RCU is not "watching", the rcu_dereference_sched() for the has needs to be open coded. This is fine because the RCU "flavor" of the ftrace hash is protected by its own RCU handling (it does its own little synchronization on every CPU and does not rely on RCU sched). Acked-by: Joel Fernandes (Google) Signed-off-by: Steven Rostedt (VMware)

tracing: Annotate ftrace_graph_notrace_hash pointer with __rcu

2020-02-05T22:14:37Z

Fix following instances of sparse error kernel/trace/ftrace.c:5667:29: error: incompatible types in comparison kernel/trace/ftrace.c:5813:21: error: incompatible types in comparison kernel/trace/ftrace.c:5868:36: error: incompatible types in comparison kernel/trace/ftrace.c:5870:25: error: incompatible types in comparison Use rcu_dereference_protected to dereference the newly annotated pointer. Link: http://lkml.kernel.org/r/20200205055701.30195-1-frextrite@gmail.com Signed-off-by: Amol Grover Signed-off-by: Steven Rostedt (VMware)

tracing: Annotate ftrace_graph_hash pointer with __rcu

2020-02-05T22:14:26Z

Fix following instances of sparse error kernel/trace/ftrace.c:5664:29: error: incompatible types in comparison kernel/trace/ftrace.c:5785:21: error: incompatible types in comparison kernel/trace/ftrace.c:5864:36: error: incompatible types in comparison kernel/trace/ftrace.c:5866:25: error: incompatible types in comparison Use rcu_dereference_protected to access the __rcu annotated pointer. Link: http://lkml.kernel.org/r/20200201072703.17330-1-frextrite@gmail.com Reviewed-by: Joel Fernandes (Google) Signed-off-by: Amol Grover Signed-off-by: Steven Rostedt (VMware)