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[=[GROUP:]EVENT]
18or
19'perf probe' [options] --line='LINE'
20or
21'perf probe' [options] --vars='PROBEPOINT'
22or
23'perf probe' [options] --funcs
24
25DESCRIPTION
26-----------
27This command defines dynamic tracepoint events, by symbol and registers
28without debuginfo, or by C expressions (C line numbers, C function names,
29and C local variables) with debuginfo.
30
31
32OPTIONS
33-------
34-k::
35--vmlinux=PATH::
36	Specify vmlinux path which has debuginfo (Dwarf binary).
37
38-m::
39--module=MODNAME|PATH::
40	Specify module name in which perf-probe searches probe points
41	or lines. If a path of module file is passed, perf-probe
42	treat it as an offline module (this means you can add a probe on
43        a module which has not been loaded yet).
44
45-s::
46--source=PATH::
47	Specify path to kernel source.
48
49-v::
50--verbose::
51        Be more verbose (show parsed arguments, etc).
52	Can not use with -q.
53
54-q::
55--quiet::
56	Be quiet (do not show any messages including errors).
57	Can not use with -v.
58
59-a::
60--add=::
61	Define a probe event (see PROBE SYNTAX for detail).
62
63-d::
64--del=::
65	Delete probe events. This accepts glob wildcards('*', '?') and character
66	classes(e.g. [a-z], [!A-Z]).
67
68-l::
69--list[=[GROUP:]EVENT]::
70	List up current probe events. This can also accept filtering patterns of event names.
71
72-L::
73--line=::
74	Show source code lines which can be probed. This needs an argument
75	which specifies a range of the source code. (see LINE SYNTAX for detail)
76
77-V::
78--vars=::
79	Show available local variables at given probe point. The argument
80	syntax is same as PROBE SYNTAX, but NO ARGs.
81
82--externs::
83	(Only for --vars) Show external defined variables in addition to local
84	variables.
85
86-F::
87--funcs[=FILTER]::
88	Show available functions in given module or kernel. With -x/--exec,
89	can also list functions in a user space executable / shared library.
90	This also can accept a FILTER rule argument.
91
92--filter=FILTER::
93	(Only for --vars and --funcs) Set filter. FILTER is a combination of glob
94	pattern, see FILTER PATTERN for detail.
95	Default FILTER is "!__k???tab_* & !__crc_*" for --vars, and "!_*"
96	for --funcs.
97	If several filters are specified, only the last filter is used.
98
99-f::
100--force::
101	Forcibly add events with existing name.
102
103-n::
104--dry-run::
105	Dry run. With this option, --add and --del doesn't execute actual
106	adding and removal operations.
107
108--max-probes=NUM::
109	Set the maximum number of probe points for an event. Default is 128.
110
111-x::
112--exec=PATH::
113	Specify path to the executable or shared library file for user
114	space tracing. Can also be used with --funcs option.
115
116--demangle::
117	Demangle application symbols. --no-demangle is also available
118	for disabling demangling.
119
120--demangle-kernel::
121	Demangle kernel symbols. --no-demangle-kernel is also available
122	for disabling kernel demangling.
123
124In absence of -m/-x options, perf probe checks if the first argument after
125the options is an absolute path name. If its an absolute path, perf probe
126uses it as a target module/target user space binary to probe.
127
128PROBE SYNTAX
129------------
130Probe points are defined by following syntax.
131
132    1) Define event based on function name
133     [EVENT=]FUNC[@SRC][:RLN|+OFFS|%return|;PTN] [ARG ...]
134
135    2) Define event based on source file with line number
136     [EVENT=]SRC:ALN [ARG ...]
137
138    3) Define event based on source file with lazy pattern
139     [EVENT=]SRC;PTN [ARG ...]
140
141
142'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'.
143'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.
144It 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.
145'ARG' specifies the arguments of this probe point, (see PROBE ARGUMENT).
146
147PROBE ARGUMENT
148--------------
149Each probe argument follows below syntax.
150
151 [NAME=]LOCALVAR|$retval|%REG|@SYMBOL[:TYPE]
152
153'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. $retval, %ax, etc). Note that the name of this argument will be set as the last member name if you specify a local data structure member (e.g. field2 for 'var->field1.field2'.)
154'$vars' and '$params' special arguments are also available for NAME, '$vars' is expanded to the local variables (including function parameters) which can access at given probe point. '$params' is expanded to only the function parameters.
155'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.
156
157On x86 systems %REG is always the short form of the register: for example %AX. %RAX or %EAX is not valid.
158
159LINE SYNTAX
160-----------
161Line range is described by following syntax.
162
163 "FUNC[@SRC][:RLN[+NUM|-RLN2]]|SRC[:ALN[+NUM|-ALN2]]"
164
165FUNC specifies the function name of showing lines. 'RLN' is the start line
166number from function entry line, and 'RLN2' is the end line number. As same as
167probe syntax, 'SRC' means the source file path, 'ALN' is start line number,
168and 'ALN2' is end line number in the file. It is also possible to specify how
169many lines to show by using 'NUM'. Moreover, 'FUNC@SRC' combination is good
170for searching a specific function when several functions share same name.
171So, "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.
172
173LAZY MATCHING
174-------------
175 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]).
176
177e.g.
178 'a=*' can matches 'a=b', 'a = b', 'a == b' and so on.
179
180This 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.)
181
182FILTER PATTERN
183--------------
184 The filter pattern is a glob matching pattern(s) to filter variables.
185 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 "(" ")".
186
187e.g.
188 With --filter "foo* | bar*", perf probe -V shows variables which start with "foo" or "bar".
189 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.
190
191EXAMPLES
192--------
193Display which lines in schedule() can be probed:
194
195 ./perf probe --line schedule
196
197Add a probe on schedule() function 12th line with recording cpu local variable:
198
199 ./perf probe schedule:12 cpu
200 or
201 ./perf probe --add='schedule:12 cpu'
202
203 this will add one or more probes which has the name start with "schedule".
204
205 Add probes on lines in schedule() function which calls update_rq_clock().
206
207 ./perf probe 'schedule;update_rq_clock*'
208 or
209 ./perf probe --add='schedule;update_rq_clock*'
210
211Delete all probes on schedule().
212
213 ./perf probe --del='schedule*'
214
215Add probes at zfree() function on /bin/zsh
216
217 ./perf probe -x /bin/zsh zfree or ./perf probe /bin/zsh zfree
218
219Add probes at malloc() function on libc
220
221 ./perf probe -x /lib/libc.so.6 malloc or ./perf probe /lib/libc.so.6 malloc
222
223SEE ALSO
224--------
225linkperf:perf-trace[1], linkperf:perf-record[1]
226