1perf-probe(1)
2=============
3
4NAME
5----
6perf-probe - Define new dynamic tracepoints
7
8SYNOPSIS
9--------
10[verse]
11'perf probe' [options] --add='PROBE' [...]
12or
13'perf probe' [options] PROBE
14or
15'perf probe' [options] --del='[GROUP:]EVENT' [...]
16or
17'perf probe' --list
18or
19'perf probe' [options] --line='LINE'
20or
21'perf probe' [options] --vars='PROBEPOINT'
22
23DESCRIPTION
24-----------
25This command defines dynamic tracepoint events, by symbol and registers
26without debuginfo, or by C expressions (C line numbers, C function names,
27and C local variables) with debuginfo.
28
29
30OPTIONS
31-------
32-k::
33--vmlinux=PATH::
34	Specify vmlinux path which has debuginfo (Dwarf binary).
35
36-m::
37--module=MODNAME|PATH::
38	Specify module name in which perf-probe searches probe points
39	or lines. If a path of module file is passed, perf-probe
40	treat it as an offline module (this means you can add a probe on
41        a module which has not been loaded yet).
42
43-s::
44--source=PATH::
45	Specify path to kernel source.
46
47-v::
48--verbose::
49        Be more verbose (show parsed arguments, etc).
50
51-a::
52--add=::
53	Define a probe event (see PROBE SYNTAX for detail).
54
55-d::
56--del=::
57	Delete probe events. This accepts glob wildcards('*', '?') and character
58	classes(e.g. [a-z], [!A-Z]).
59
60-l::
61--list::
62	List up current probe events.
63
64-L::
65--line=::
66	Show source code lines which can be probed. This needs an argument
67	which specifies a range of the source code. (see LINE SYNTAX for detail)
68
69-V::
70--vars=::
71	Show available local variables at given probe point. The argument
72	syntax is same as PROBE SYNTAX, but NO ARGs.
73
74--externs::
75	(Only for --vars) Show external defined variables in addition to local
76	variables.
77
78-F::
79--funcs::
80	Show available functions in given module or kernel.
81
82--filter=FILTER::
83	(Only for --vars and --funcs) Set filter. FILTER is a combination of glob
84	pattern, see FILTER PATTERN for detail.
85	Default FILTER is "!__k???tab_* & !__crc_*" for --vars, and "!_*"
86	for --funcs.
87	If several filters are specified, only the last filter is used.
88
89-f::
90--force::
91	Forcibly add events with existing name.
92
93-n::
94--dry-run::
95	Dry run. With this option, --add and --del doesn't execute actual
96	adding and removal operations.
97
98--max-probes::
99	Set the maximum number of probe points for an event. Default is 128.
100
101PROBE SYNTAX
102------------
103Probe points are defined by following syntax.
104
105    1) Define event based on function name
106     [EVENT=]FUNC[@SRC][:RLN|+OFFS|%return|;PTN] [ARG ...]
107
108    2) Define event based on source file with line number
109     [EVENT=]SRC:ALN [ARG ...]
110
111    3) Define event based on source file with lazy pattern
112     [EVENT=]SRC;PTN [ARG ...]
113
114
115'EVENT' specifies the name of new event, if omitted, it will be set the name of the probed function. Currently, event group name is set as 'probe'.
116'FUNC' specifies a probed function name, and it may have one of the following options; '+OFFS' is the offset from function entry address in bytes, ':RLN' is the relative-line number from function entry line, and '%return' means that it probes function return. And ';PTN' means lazy matching pattern (see LAZY MATCHING). Note that ';PTN' must be the end of the probe point definition.  In addition, '@SRC' specifies a source file which has that function.
117It is also possible to specify a probe point by the source line number or lazy matching by using 'SRC:ALN' or 'SRC;PTN' syntax, where 'SRC' is the source file path, ':ALN' is the line number and ';PTN' is the lazy matching pattern.
118'ARG' specifies the arguments of this probe point, (see PROBE ARGUMENT).
119
120PROBE ARGUMENT
121--------------
122Each probe argument follows below syntax.
123
124 [NAME=]LOCALVAR|$retval|%REG|@SYMBOL[:TYPE]
125
126'NAME' specifies the name of this argument (optional). You can use the name of local variable, local data structure member (e.g. var->field, var.field2), local array with fixed index (e.g. array[1], var->array[0], var->pointer[2]), or kprobe-tracer argument format (e.g. $retval, %ax, etc). Note that the name of this argument will be set as the last member name if you specify a local data structure member (e.g. field2 for 'var->field1.field2'.)
127'TYPE' casts the type of this argument (optional). If omitted, perf probe automatically set the type based on debuginfo. You can specify 'string' type only for the local variable or structure member which is an array of or a pointer to 'char' or 'unsigned char' type.
128
129LINE SYNTAX
130-----------
131Line range is described by following syntax.
132
133 "FUNC[@SRC][:RLN[+NUM|-RLN2]]|SRC[:ALN[+NUM|-ALN2]]"
134
135FUNC specifies the function name of showing lines. 'RLN' is the start line
136number from function entry line, and 'RLN2' is the end line number. As same as
137probe syntax, 'SRC' means the source file path, 'ALN' is start line number,
138and 'ALN2' is end line number in the file. It is also possible to specify how
139many lines to show by using 'NUM'. Moreover, 'FUNC@SRC' combination is good
140for searching a specific function when several functions share same name.
141So, "source.c:100-120" shows lines between 100th to l20th in source.c file. And "func:10+20" shows 20 lines from 10th line of func function.
142
143LAZY MATCHING
144-------------
145 The lazy line matching is similar to glob matching but ignoring spaces in both of pattern and target. So this accepts wildcards('*', '?') and character classes(e.g. [a-z], [!A-Z]).
146
147e.g.
148 'a=*' can matches 'a=b', 'a = b', 'a == b' and so on.
149
150This provides some sort of flexibility and robustness to probe point definitions against minor code changes. For example, actual 10th line of schedule() can be moved easily by modifying schedule(), but the same line matching 'rq=cpu_rq*' may still exist in the function.)
151
152FILTER PATTERN
153--------------
154 The filter pattern is a glob matching pattern(s) to filter variables.
155 In addition, you can use "!" for specifying filter-out rule. You also can give several rules combined with "&" or "|", and fold those rules as one rule by using "(" ")".
156
157e.g.
158 With --filter "foo* | bar*", perf probe -V shows variables which start with "foo" or "bar".
159 With --filter "!foo* & *bar", perf probe -V shows variables which don't start with "foo" and end with "bar", like "fizzbar". But "foobar" is filtered out.
160
161EXAMPLES
162--------
163Display which lines in schedule() can be probed:
164
165 ./perf probe --line schedule
166
167Add a probe on schedule() function 12th line with recording cpu local variable:
168
169 ./perf probe schedule:12 cpu
170 or
171 ./perf probe --add='schedule:12 cpu'
172
173 this will add one or more probes which has the name start with "schedule".
174
175 Add probes on lines in schedule() function which calls update_rq_clock().
176
177 ./perf probe 'schedule;update_rq_clock*'
178 or
179 ./perf probe --add='schedule;update_rq_clock*'
180
181Delete all probes on schedule().
182
183 ./perf probe --del='schedule*'
184
185
186SEE ALSO
187--------
188linkperf:perf-trace[1], linkperf:perf-record[1]
189