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	Can not use with -q.
51
52-q::
53--quiet::
54	Be quiet (do not show any messages including errors).
55	Can not use with -v.
56
57-a::
58--add=::
59	Define a probe event (see PROBE SYNTAX for detail).
60
61-d::
62--del=::
63	Delete probe events. This accepts glob wildcards('*', '?') and character
64	classes(e.g. [a-z], [!A-Z]).
65
66-l::
67--list::
68	List up current probe events.
69
70-L::
71--line=::
72	Show source code lines which can be probed. This needs an argument
73	which specifies a range of the source code. (see LINE SYNTAX for detail)
74
75-V::
76--vars=::
77	Show available local variables at given probe point. The argument
78	syntax is same as PROBE SYNTAX, but NO ARGs.
79
80--externs::
81	(Only for --vars) Show external defined variables in addition to local
82	variables.
83
84-F::
85--funcs::
86	Show available functions in given module or kernel. With -x/--exec,
87	can also list functions in a user space executable / shared library.
88
89--filter=FILTER::
90	(Only for --vars and --funcs) Set filter. FILTER is a combination of glob
91	pattern, see FILTER PATTERN for detail.
92	Default FILTER is "!__k???tab_* & !__crc_*" for --vars, and "!_*"
93	for --funcs.
94	If several filters are specified, only the last filter is used.
95
96-f::
97--force::
98	Forcibly add events with existing name.
99
100-n::
101--dry-run::
102	Dry run. With this option, --add and --del doesn't execute actual
103	adding and removal operations.
104
105--max-probes=NUM::
106	Set the maximum number of probe points for an event. Default is 128.
107
108-x::
109--exec=PATH::
110	Specify path to the executable or shared library file for user
111	space tracing. Can also be used with --funcs option.
112
113--demangle::
114	Demangle application symbols. --no-demangle is also available
115	for disabling demangling.
116
117--demangle-kernel::
118	Demangle kernel symbols. --no-demangle-kernel is also available
119	for disabling kernel demangling.
120
121In absence of -m/-x options, perf probe checks if the first argument after
122the options is an absolute path name. If its an absolute path, perf probe
123uses it as a target module/target user space binary to probe.
124
125PROBE SYNTAX
126------------
127Probe points are defined by following syntax.
128
129    1) Define event based on function name
130     [EVENT=]FUNC[@SRC][:RLN|+OFFS|%return|;PTN] [ARG ...]
131
132    2) Define event based on source file with line number
133     [EVENT=]SRC:ALN [ARG ...]
134
135    3) Define event based on source file with lazy pattern
136     [EVENT=]SRC;PTN [ARG ...]
137
138
139'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'.
140'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.
141It 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.
142'ARG' specifies the arguments of this probe point, (see PROBE ARGUMENT).
143
144PROBE ARGUMENT
145--------------
146Each probe argument follows below syntax.
147
148 [NAME=]LOCALVAR|$retval|%REG|@SYMBOL[:TYPE]
149
150'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. $retval, %ax, etc). Note that the name of this argument will be set as the last member name if you specify a local data structure member (e.g. field2 for 'var->field1.field2'.)
151'$vars' special argument is also available for NAME, it is expanded to the local variables which can access at given probe point.
152'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.
153
154On x86 systems %REG is always the short form of the register: for example %AX. %RAX or %EAX is not valid.
155
156LINE SYNTAX
157-----------
158Line range is described by following syntax.
159
160 "FUNC[@SRC][:RLN[+NUM|-RLN2]]|SRC[:ALN[+NUM|-ALN2]]"
161
162FUNC specifies the function name of showing lines. 'RLN' is the start line
163number from function entry line, and 'RLN2' is the end line number. As same as
164probe syntax, 'SRC' means the source file path, 'ALN' is start line number,
165and 'ALN2' is end line number in the file. It is also possible to specify how
166many lines to show by using 'NUM'. Moreover, 'FUNC@SRC' combination is good
167for searching a specific function when several functions share same name.
168So, "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.
169
170LAZY MATCHING
171-------------
172 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]).
173
174e.g.
175 'a=*' can matches 'a=b', 'a = b', 'a == b' and so on.
176
177This 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.)
178
179FILTER PATTERN
180--------------
181 The filter pattern is a glob matching pattern(s) to filter variables.
182 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 "(" ")".
183
184e.g.
185 With --filter "foo* | bar*", perf probe -V shows variables which start with "foo" or "bar".
186 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.
187
188EXAMPLES
189--------
190Display which lines in schedule() can be probed:
191
192 ./perf probe --line schedule
193
194Add a probe on schedule() function 12th line with recording cpu local variable:
195
196 ./perf probe schedule:12 cpu
197 or
198 ./perf probe --add='schedule:12 cpu'
199
200 this will add one or more probes which has the name start with "schedule".
201
202 Add probes on lines in schedule() function which calls update_rq_clock().
203
204 ./perf probe 'schedule;update_rq_clock*'
205 or
206 ./perf probe --add='schedule;update_rq_clock*'
207
208Delete all probes on schedule().
209
210 ./perf probe --del='schedule*'
211
212Add probes at zfree() function on /bin/zsh
213
214 ./perf probe -x /bin/zsh zfree or ./perf probe /bin/zsh zfree
215
216Add probes at malloc() function on libc
217
218 ./perf probe -x /lib/libc.so.6 malloc or ./perf probe /lib/libc.so.6 malloc
219
220SEE ALSO
221--------
222linkperf:perf-trace[1], linkperf:perf-record[1]
223