user/sven/linux.git/kernel/trace/trace_probe.h, branch v5.16

tracing: Add a probe that attaches to trace events

2021-08-20T18:18:40Z

A new dynamic event is introduced: event probe. The event is attached to an existing tracepoint and uses its fields as arguments. The user can specify custom format string of the new event, select what tracepoint arguments will be printed and how to print them. An event probe is created by writing configuration string in 'dynamic_events' ftrace file: e[:[SNAME/]ENAME] SYSTEM/EVENT [FETCHARGS] - Set an event probe -:SNAME/ENAME - Delete an event probe Where: SNAME - System name, if omitted 'eprobes' is used. ENAME - Name of the new event in SNAME, if omitted the SYSTEM_EVENT is used. SYSTEM - Name of the system, where the tracepoint is defined, mandatory. EVENT - Name of the tracepoint event in SYSTEM, mandatory. FETCHARGS - Arguments: =$[:TYPE] - Fetch given filed of the tracepoint and print it as given TYPE with given name. Supported types are: (u8/u16/u32/u64/s8/s16/s32/s64), basic type (x8/x16/x32/x64), hexadecimal types "string", "ustring" and bitfield. Example, attach an event probe on openat system call and print name of the file that will be opened: echo "e:esys/eopen syscalls/sys_enter_openat file=\$filename:string" >> dynamic_events A new dynamic event is created in events/esys/eopen/ directory. It can be deleted with: echo "-:esys/eopen" >> dynamic_events Filters, triggers and histograms can be attached to the new event, it can be matched in synthetic events. There is one limitation - an event probe can not be attached to kprobe, uprobe or another event probe. Link: https://lkml.kernel.org/r/20210812145805.2292326-1-tz.stoyanov@gmail.com Link: https://lkml.kernel.org/r/20210819152825.142428383@goodmis.org Acked-by: Masami Hiramatsu Co-developed-by: Steven Rostedt (VMware) Signed-off-by: Tzvetomir Stoyanov (VMware) Signed-off-by: Steven Rostedt (VMware)

tracing/probes: Reject events which have the same name of existing one

2021-08-19T13:15:19Z

Since kprobe_events and uprobe_events only check whether the other same-type probe event has the same name or not, if the user gives the same name of the existing tracepoint event (or the other type of probe events), it silently fails to create the tracefs entry (but registered.) as below. /sys/kernel/tracing # ls events/task/task_rename enable filter format hist id trigger /sys/kernel/tracing # echo p:task/task_rename vfs_read >> kprobe_events [ 113.048508] Could not create tracefs 'task_rename' directory /sys/kernel/tracing # cat kprobe_events p:task/task_rename vfs_read To fix this issue, check whether the existing events have the same name or not in trace_probe_register_event_call(). If exists, it rejects to register the new event. Link: https://lkml.kernel.org/r/162936876189.187130.17558311387542061930.stgit@devnote2 Signed-off-by: Masami Hiramatsu Signed-off-by: Steven Rostedt (VMware)

tracing/probe: Change traceprobe_set_print_fmt() to take a type

2021-08-19T13:08:29Z

Instead of a boolean "is_return" have traceprobe_set_print_fmt() take a type (currently just PROBE_PRINT_NORMAL and PROBE_PRINT_RETURN). This will simplify adding different types. For example, the development of the event_probe, will need its own type as it prints an event, and not an IP. Link: https://lkml.kernel.org/r/20210819041842.104626301@goodmis.org Acked-by: Masami Hiramatsu Signed-off-by: Steven Rostedt (VMware)

tracing/probe: Have traceprobe_parse_probe_arg() take a const arg

2021-08-18T22:13:52Z

The two places that call traceprobe_parse_probe_arg() allocate a temporary buffer to copy the argv[i] into, because argv[i] is constant and the traceprobe_parse_probe_arg() will modify it to do the parsing. These two places allocate this buffer and then free it right after calling this function, leaving the onus of this allocation to the caller. As there's about to be a third user of this function that will have to do the same thing, instead of having the caller allocate the temporary buffer, simply move that allocation into the traceprobe_parse_probe_arg() itself, which will simplify the code of the callers. Link: https://lkml.kernel.org/r/20210817035027.385422828@goodmis.org 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/dynevent: Delegate parsing to create function

2021-02-09T17:52:15Z

Delegate command parsing to each create function so that the command syntax can be customized. This requires changes to the kprobe/uprobe/synthetic event handling, which are also included here. Link: https://lkml.kernel.org/r/e488726f49cbdbc01568618f8680584306c4c79f.1612208610.git.zanussi@kernel.org Signed-off-by: Masami Hiramatsu [ zanussi@kernel.org: added synthetic event modifications ] Signed-off-by: Tom Zanussi Signed-off-by: Steven Rostedt (VMware)

tracing: Move is_good_name() from trace_probe.h to trace.h

2020-10-15T16:01:13Z

is_good_name() is useful for other trace infrastructure, such as synthetic events, so make it available via trace.h. Link: https://lkml.kernel.org/r/cc6d6a2d7da6957fcbe1e2922e76d18d2bb459b4.1602598160.git.zanussi@kernel.org Acked-by: Masami Hiramatsu Tested-by: Masami Hiramatsu Signed-off-by: Tom Zanussi Signed-off-by: Steven Rostedt (VMware)

tracing/kprobes: Support perf-style return probe

2020-09-22T01:06:03Z

Support perf-style return probe ("SYMBOL%return") for kprobe events. This will allow boot-time tracing user to define a return probe event. Link: https://lkml.kernel.org/r/159972813535.428528.4437029657208468954.stgit@devnote2 Signed-off-by: Masami Hiramatsu Signed-off-by: Steven Rostedt (VMware)

tracing/probe: Replace zero-length array with flexible-array

2020-06-16T04:08:32Z

There is a regular need in the kernel to provide a way to declare having a dynamically sized set of trailing elements in a structure. Kernel code should always use “flexible array members”[1] for these cases. The older style of one-element or zero-length arrays should no longer be used[2]. [1] https://en.wikipedia.org/wiki/Flexible_array_member [2] https://github.com/KSPP/linux/issues/21 Signed-off-by: Gustavo A. R. Silva

tracing/uprobe: Fix to make trace_uprobe_filter alignment safe

2020-01-22T12:09:20Z

Commit 99c9a923e97a ("tracing/uprobe: Fix double perf_event linking on multiprobe uprobe") moved trace_uprobe_filter on trace_probe_event. However, since it introduced a flexible data structure with char array and type casting, the alignment of trace_uprobe_filter can be broken. This changes the type of the array to trace_uprobe_filter data strucure to fix it. Link: http://lore.kernel.org/r/20200120124022.GA14897@hirez.programming.kicks-ass.net Link: http://lkml.kernel.org/r/157966340499.5107.10978352478952144902.stgit@devnote2 Fixes: 99c9a923e97a ("tracing/uprobe: Fix double perf_event linking on multiprobe uprobe") Suggested-by: Peter Zijlstra Signed-off-by: Masami Hiramatsu Signed-off-by: Steven Rostedt (VMware)