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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--no-inlines::
87 (Only for --add) Search only for non-inlined functions. The functions
88 which do not have instances are ignored.
89
90-F::
91--funcs[=FILTER]::
92 Show available functions in given module or kernel. With -x/--exec,
93 can also list functions in a user space executable / shared library.
94 This also can accept a FILTER rule argument.
95
96--filter=FILTER::
97 (Only for --vars and --funcs) Set filter. FILTER is a combination of glob
98 pattern, see FILTER PATTERN for detail.
99 Default FILTER is "!__k???tab_* & !__crc_*" for --vars, and "!_*"
100 for --funcs.
101 If several filters are specified, only the last filter is used.
102
103-f::
104--force::
105 Forcibly add events with existing name.
106
107-n::
108--dry-run::
109 Dry run. With this option, --add and --del doesn't execute actual
110 adding and removal operations.
111
112--max-probes=NUM::
113 Set the maximum number of probe points for an event. Default is 128.
114
115-x::
116--exec=PATH::
117 Specify path to the executable or shared library file for user
118 space tracing. Can also be used with --funcs option.
119
120--demangle::
121 Demangle application symbols. --no-demangle is also available
122 for disabling demangling.
123
124--demangle-kernel::
125 Demangle kernel symbols. --no-demangle-kernel is also available
126 for disabling kernel demangling.
127
128In absence of -m/-x options, perf probe checks if the first argument after
129the options is an absolute path name. If its an absolute path, perf probe
130uses it as a target module/target user space binary to probe.
131
132PROBE SYNTAX
133------------
134Probe points are defined by following syntax.
135
136 1) Define event based on function name
137 [EVENT=]FUNC[@SRC][:RLN|+OFFS|%return|;PTN] [ARG ...]
138
139 2) Define event based on source file with line number
140 [EVENT=]SRC:ALN [ARG ...]
141
142 3) Define event based on source file with lazy pattern
143 [EVENT=]SRC;PTN [ARG ...]
144
145
146'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'.
147'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.
148It 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.
149'ARG' specifies the arguments of this probe point, (see PROBE ARGUMENT).
150
151PROBE ARGUMENT
152--------------
153Each probe argument follows below syntax.
154
155 [NAME=]LOCALVAR|$retval|%REG|@SYMBOL[:TYPE]
156
157'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. $retval, %ax, etc). Note that the name of this argument will be set as the last member name if you specify a local data structure member (e.g. field2 for 'var->field1.field2'.)
158'$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.
159'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.
160
161On x86 systems %REG is always the short form of the register: for example %AX. %RAX or %EAX is not valid.
162
163LINE SYNTAX
164-----------
165Line range is described by following syntax.
166
167 "FUNC[@SRC][:RLN[+NUM|-RLN2]]|SRC[:ALN[+NUM|-ALN2]]"
168
169FUNC specifies the function name of showing lines. 'RLN' is the start line
170number from function entry line, and 'RLN2' is the end line number. As same as
171probe syntax, 'SRC' means the source file path, 'ALN' is start line number,
172and 'ALN2' is end line number in the file. It is also possible to specify how
173many lines to show by using 'NUM'. Moreover, 'FUNC@SRC' combination is good
174for searching a specific function when several functions share same name.
175So, "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.
176
177LAZY MATCHING
178-------------
179 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]).
180
181e.g.
182 'a=*' can matches 'a=b', 'a = b', 'a == b' and so on.
183
184This 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.)
185
186FILTER PATTERN
187--------------
188 The filter pattern is a glob matching pattern(s) to filter variables.
189 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 "(" ")".
190
191e.g.
192 With --filter "foo* | bar*", perf probe -V shows variables which start with "foo" or "bar".
193 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.
194
195EXAMPLES
196--------
197Display which lines in schedule() can be probed:
198
199 ./perf probe --line schedule
200
201Add a probe on schedule() function 12th line with recording cpu local variable:
202
203 ./perf probe schedule:12 cpu
204 or
205 ./perf probe --add='schedule:12 cpu'
206
207 this will add one or more probes which has the name start with "schedule".
208
209 Add probes on lines in schedule() function which calls update_rq_clock().
210
211 ./perf probe 'schedule;update_rq_clock*'
212 or
213 ./perf probe --add='schedule;update_rq_clock*'
214
215Delete all probes on schedule().
216
217 ./perf probe --del='schedule*'
218
219Add probes at zfree() function on /bin/zsh
220
221 ./perf probe -x /bin/zsh zfree or ./perf probe /bin/zsh zfree
222
223Add probes at malloc() function on libc
224
225 ./perf probe -x /lib/libc.so.6 malloc or ./perf probe /lib/libc.so.6 malloc
226
227SEE ALSO
228--------
229linkperf:perf-trace[1], linkperf:perf-record[1]
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
24or
25'perf probe' [options] --definition='PROBE' [...]
26
27DESCRIPTION
28-----------
29This command defines dynamic tracepoint events, by symbol and registers
30without debuginfo, or by C expressions (C line numbers, C function names,
31and C local variables) with debuginfo.
32
33
34OPTIONS
35-------
36-k::
37--vmlinux=PATH::
38 Specify vmlinux path which has debuginfo (Dwarf binary).
39 Only when using this with --definition, you can give an offline
40 vmlinux file.
41
42-m::
43--module=MODNAME|PATH::
44 Specify module name in which perf-probe searches probe points
45 or lines. If a path of module file is passed, perf-probe
46 treat it as an offline module (this means you can add a probe on
47 a module which has not been loaded yet).
48
49-s::
50--source=PATH::
51 Specify path to kernel source.
52
53-v::
54--verbose::
55 Be more verbose (show parsed arguments, etc).
56 Can not use with -q.
57
58-q::
59--quiet::
60 Do not show any warnings or messages.
61 Can not use with -v.
62
63-a::
64--add=::
65 Define a probe event (see PROBE SYNTAX for detail).
66
67-d::
68--del=::
69 Delete probe events. This accepts glob wildcards('*', '?') and character
70 classes(e.g. [a-z], [!A-Z]).
71
72-l::
73--list[=[GROUP:]EVENT]::
74 List up current probe events. This can also accept filtering patterns of
75 event names.
76 When this is used with --cache, perf shows all cached probes instead of
77 the live probes.
78
79-L::
80--line=::
81 Show source code lines which can be probed. This needs an argument
82 which specifies a range of the source code. (see LINE SYNTAX for detail)
83
84-V::
85--vars=::
86 Show available local variables at given probe point. The argument
87 syntax is same as PROBE SYNTAX, but NO ARGs.
88
89--externs::
90 (Only for --vars) Show external defined variables in addition to local
91 variables.
92
93--no-inlines::
94 (Only for --add) Search only for non-inlined functions. The functions
95 which do not have instances are ignored.
96
97-F::
98--funcs[=FILTER]::
99 Show available functions in given module or kernel. With -x/--exec,
100 can also list functions in a user space executable / shared library.
101 This also can accept a FILTER rule argument.
102
103-D::
104--definition=::
105 Show trace-event definition converted from given probe-event instead
106 of write it into tracing/[k,u]probe_events.
107
108--filter=FILTER::
109 (Only for --vars and --funcs) Set filter. FILTER is a combination of glob
110 pattern, see FILTER PATTERN for detail.
111 Default FILTER is "!__k???tab_* & !__crc_*" for --vars, and "!_*"
112 for --funcs.
113 If several filters are specified, only the last filter is used.
114
115-f::
116--force::
117 Forcibly add events with existing name.
118
119-n::
120--dry-run::
121 Dry run. With this option, --add and --del doesn't execute actual
122 adding and removal operations.
123
124--cache::
125 (With --add) Cache the probes. Any events which successfully added
126 are also stored in the cache file.
127 (With --list) Show cached probes.
128 (With --del) Remove cached probes.
129
130--max-probes=NUM::
131 Set the maximum number of probe points for an event. Default is 128.
132
133--target-ns=PID:
134 Obtain mount namespace information from the target pid. This is
135 used when creating a uprobe for a process that resides in a
136 different mount namespace from the perf(1) utility.
137
138-x::
139--exec=PATH::
140 Specify path to the executable or shared library file for user
141 space tracing. Can also be used with --funcs option.
142
143--demangle::
144 Demangle application symbols. --no-demangle is also available
145 for disabling demangling.
146
147--demangle-kernel::
148 Demangle kernel symbols. --no-demangle-kernel is also available
149 for disabling kernel demangling.
150
151In absence of -m/-x options, perf probe checks if the first argument after
152the options is an absolute path name. If its an absolute path, perf probe
153uses it as a target module/target user space binary to probe.
154
155PROBE SYNTAX
156------------
157Probe points are defined by following syntax.
158
159 1) Define event based on function name
160 [[GROUP:]EVENT=]FUNC[@SRC][:RLN|+OFFS|%return|;PTN] [ARG ...]
161
162 2) Define event based on source file with line number
163 [[GROUP:]EVENT=]SRC:ALN [ARG ...]
164
165 3) Define event based on source file with lazy pattern
166 [[GROUP:]EVENT=]SRC;PTN [ARG ...]
167
168 4) Pre-defined SDT events or cached event with name
169 %[sdt_PROVIDER:]SDTEVENT
170 or,
171 sdt_PROVIDER:SDTEVENT
172
173'EVENT' specifies the name of new event, if omitted, it will be set the name of the probed function, and for return probes, a "\_\_return" suffix is automatically added to the function name. You can also specify a group name by 'GROUP', if omitted, set 'probe' is used for kprobe and 'probe_<bin>' is used for uprobe.
174Note that using existing group name can conflict with other events. Especially, using the group name reserved for kernel modules can hide embedded events in the
175modules.
176'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.
177It 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.
178'ARG' specifies the arguments of this probe point, (see PROBE ARGUMENT).
179'SDTEVENT' and 'PROVIDER' is the pre-defined event name which is defined by user SDT (Statically Defined Tracing) or the pre-cached probes with event name.
180Note that before using the SDT event, the target binary (on which SDT events are defined) must be scanned by linkperf:perf-buildid-cache[1] to make SDT events as cached events.
181
182For details of the SDT, see below.
183https://sourceware.org/gdb/onlinedocs/gdb/Static-Probe-Points.html
184
185ESCAPED CHARACTER
186-----------------
187
188In the probe syntax, '=', '@', '+', ':' and ';' are treated as a special character. You can use a backslash ('\') to escape the special characters.
189This is useful if you need to probe on a specific versioned symbols, like @GLIBC_... suffixes, or also you need to specify a source file which includes the special characters.
190Note that usually single backslash is consumed by shell, so you might need to pass double backslash (\\) or wrapping with single quotes (\'AAA\@BBB').
191See EXAMPLES how it is used.
192
193PROBE ARGUMENT
194--------------
195Each probe argument follows below syntax.
196
197 [NAME=]LOCALVAR|$retval|%REG|@SYMBOL[:TYPE][@user]
198
199'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. $retval, %ax, etc). Note that the name of this argument will be set as the last member name if you specify a local data structure member (e.g. field2 for 'var->field1.field2'.)
200'$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.
201'TYPE' casts the type of this argument (optional). If omitted, perf probe automatically set the type based on debuginfo (*). Currently, basic types (u8/u16/u32/u64/s8/s16/s32/s64), hexadecimal integers (x/x8/x16/x32/x64), signedness casting (u/s), "string" and bitfield are supported. (see TYPES for detail)
202On x86 systems %REG is always the short form of the register: for example %AX. %RAX or %EAX is not valid.
203"@user" is a special attribute which means the LOCALVAR will be treated as a user-space memory. This is only valid for kprobe event.
204
205TYPES
206-----
207Basic types (u8/u16/u32/u64/s8/s16/s32/s64) and hexadecimal integers (x8/x16/x32/x64) are integer types. Prefix 's' and 'u' means those types are signed and unsigned respectively, and 'x' means that is shown in hexadecimal format. Traced arguments are shown in decimal (sNN/uNN) or hex (xNN). You can also use 's' or 'u' to specify only signedness and leave its size auto-detected by perf probe. Moreover, you can use 'x' to explicitly specify to be shown in hexadecimal (the size is also auto-detected).
208String type is a special type, which fetches a "null-terminated" string from kernel space. This means it will fail and store NULL if the string container has been paged out. 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.
209Bitfield is another special type, which takes 3 parameters, bit-width, bit-offset, and container-size (usually 32). The syntax is;
210
211 b<bit-width>@<bit-offset>/<container-size>
212
213LINE SYNTAX
214-----------
215Line range is described by following syntax.
216
217 "FUNC[@SRC][:RLN[+NUM|-RLN2]]|SRC[:ALN[+NUM|-ALN2]]"
218
219FUNC specifies the function name of showing lines. 'RLN' is the start line
220number from function entry line, and 'RLN2' is the end line number. As same as
221probe syntax, 'SRC' means the source file path, 'ALN' is start line number,
222and 'ALN2' is end line number in the file. It is also possible to specify how
223many lines to show by using 'NUM'. Moreover, 'FUNC@SRC' combination is good
224for searching a specific function when several functions share same name.
225So, "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.
226
227LAZY MATCHING
228-------------
229The 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]).
230
231e.g.
232 'a=*' can matches 'a=b', 'a = b', 'a == b' and so on.
233
234This 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.)
235
236FILTER PATTERN
237--------------
238The filter pattern is a glob matching pattern(s) to filter variables.
239In 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 "(" ")".
240
241e.g.
242 With --filter "foo* | bar*", perf probe -V shows variables which start with "foo" or "bar".
243 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.
244
245EXAMPLES
246--------
247Display which lines in schedule() can be probed:
248
249 ./perf probe --line schedule
250
251Add a probe on schedule() function 12th line with recording cpu local variable:
252
253 ./perf probe schedule:12 cpu
254 or
255 ./perf probe --add='schedule:12 cpu'
256
257Add one or more probes which has the name start with "schedule".
258
259 ./perf probe schedule*
260 or
261 ./perf probe --add='schedule*'
262
263Add probes on lines in schedule() function which calls update_rq_clock().
264
265 ./perf probe 'schedule;update_rq_clock*'
266 or
267 ./perf probe --add='schedule;update_rq_clock*'
268
269Delete all probes on schedule().
270
271 ./perf probe --del='schedule*'
272
273Add probes at zfree() function on /bin/zsh
274
275 ./perf probe -x /bin/zsh zfree or ./perf probe /bin/zsh zfree
276
277Add probes at malloc() function on libc
278
279 ./perf probe -x /lib/libc.so.6 malloc or ./perf probe /lib/libc.so.6 malloc
280
281Add a uprobe to a target process running in a different mount namespace
282
283 ./perf probe --target-ns <target pid> -x /lib64/libc.so.6 malloc
284
285Add a USDT probe to a target process running in a different mount namespace
286
287 ./perf probe --target-ns <target pid> -x /usr/lib/jvm/java-1.8.0-openjdk-1.8.0.121-0.b13.el7_3.x86_64/jre/lib/amd64/server/libjvm.so %sdt_hotspot:thread__sleep__end
288
289Add a probe on specific versioned symbol by backslash escape
290
291 ./perf probe -x /lib64/libc-2.25.so 'malloc_get_state\@GLIBC_2.2.5'
292
293Add a probe in a source file using special characters by backslash escape
294
295 ./perf probe -x /opt/test/a.out 'foo\+bar.c:4'
296
297
298PERMISSIONS AND SYSCTL
299----------------------
300Since perf probe depends on ftrace (tracefs) and kallsyms (/proc/kallsyms), you have to care about the permission and some sysctl knobs.
301
302 - Since tracefs and kallsyms requires root or privileged user to access it, the following perf probe commands also require it; --add, --del, --list (except for --cache option)
303
304 - The system admin can remount the tracefs with 755 (`sudo mount -o remount,mode=755 /sys/kernel/tracing/`) to allow unprivileged user to run the perf probe --list command.
305
306 - /proc/sys/kernel/kptr_restrict = 2 (restrict all users) also prevents perf probe to retrieve the important information from kallsyms. You also need to set to 1 (restrict non CAP_SYSLOG users) for the above commands. Since the user-space probe doesn't need to access kallsyms, this is only for probing the kernel function (kprobes).
307
308 - Since the perf probe commands read the vmlinux (for kernel) and/or the debuginfo file (including user-space application), you need to ensure that you can read those files.
309
310
311SEE ALSO
312--------
313linkperf:perf-trace[1], linkperf:perf-record[1], linkperf:perf-buildid-cache[1]