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' 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:: 70 List up current probe events. 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:: 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 91--filter=FILTER:: 92 (Only for --vars and --funcs) Set filter. FILTER is a combination of glob 93 pattern, see FILTER PATTERN for detail. 94 Default FILTER is "!__k???tab_* & !__crc_*" for --vars, and "!_*" 95 for --funcs. 96 If several filters are specified, only the last filter is used. 97 98-f:: 99--force:: 100 Forcibly add events with existing name. 101 102-n:: 103--dry-run:: 104 Dry run. With this option, --add and --del doesn't execute actual 105 adding and removal operations. 106 107--max-probes=NUM:: 108 Set the maximum number of probe points for an event. Default is 128. 109 110-x:: 111--exec=PATH:: 112 Specify path to the executable or shared library file for user 113 space tracing. Can also be used with --funcs option. 114 115--demangle:: 116 Demangle application symbols. --no-demangle is also available 117 for disabling demangling. 118 119--demangle-kernel:: 120 Demangle kernel symbols. --no-demangle-kernel is also available 121 for disabling kernel demangling. 122 123In absence of -m/-x options, perf probe checks if the first argument after 124the options is an absolute path name. If its an absolute path, perf probe 125uses it as a target module/target user space binary to probe. 126 127PROBE SYNTAX 128------------ 129Probe points are defined by following syntax. 130 131 1) Define event based on function name 132 [EVENT=]FUNC[@SRC][:RLN|+OFFS|%return|;PTN] [ARG ...] 133 134 2) Define event based on source file with line number 135 [EVENT=]SRC:ALN [ARG ...] 136 137 3) Define event based on source file with lazy pattern 138 [EVENT=]SRC;PTN [ARG ...] 139 140 141'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'. 142'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. 143It 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. 144'ARG' specifies the arguments of this probe point, (see PROBE ARGUMENT). 145 146PROBE ARGUMENT 147-------------- 148Each probe argument follows below syntax. 149 150 [NAME=]LOCALVAR|$retval|%REG|@SYMBOL[:TYPE] 151 152'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. $retval, %ax, etc). Note that the name of this argument will be set as the last member name if you specify a local data structure member (e.g. field2 for 'var->field1.field2'.) 153'$vars' special argument is also available for NAME, it is expanded to the local variables which can access at given probe point. 154'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. 155 156On x86 systems %REG is always the short form of the register: for example %AX. %RAX or %EAX is not valid. 157 158LINE SYNTAX 159----------- 160Line range is described by following syntax. 161 162 "FUNC[@SRC][:RLN[+NUM|-RLN2]]|SRC[:ALN[+NUM|-ALN2]]" 163 164FUNC specifies the function name of showing lines. 'RLN' is the start line 165number from function entry line, and 'RLN2' is the end line number. As same as 166probe syntax, 'SRC' means the source file path, 'ALN' is start line number, 167and 'ALN2' is end line number in the file. It is also possible to specify how 168many lines to show by using 'NUM'. Moreover, 'FUNC@SRC' combination is good 169for searching a specific function when several functions share same name. 170So, "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. 171 172LAZY MATCHING 173------------- 174 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]). 175 176e.g. 177 'a=*' can matches 'a=b', 'a = b', 'a == b' and so on. 178 179This 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.) 180 181FILTER PATTERN 182-------------- 183 The filter pattern is a glob matching pattern(s) to filter variables. 184 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 "(" ")". 185 186e.g. 187 With --filter "foo* | bar*", perf probe -V shows variables which start with "foo" or "bar". 188 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. 189 190EXAMPLES 191-------- 192Display which lines in schedule() can be probed: 193 194 ./perf probe --line schedule 195 196Add a probe on schedule() function 12th line with recording cpu local variable: 197 198 ./perf probe schedule:12 cpu 199 or 200 ./perf probe --add='schedule:12 cpu' 201 202 this will add one or more probes which has the name start with "schedule". 203 204 Add probes on lines in schedule() function which calls update_rq_clock(). 205 206 ./perf probe 'schedule;update_rq_clock*' 207 or 208 ./perf probe --add='schedule;update_rq_clock*' 209 210Delete all probes on schedule(). 211 212 ./perf probe --del='schedule*' 213 214Add probes at zfree() function on /bin/zsh 215 216 ./perf probe -x /bin/zsh zfree or ./perf probe /bin/zsh zfree 217 218Add probes at malloc() function on libc 219 220 ./perf probe -x /lib/libc.so.6 malloc or ./perf probe /lib/libc.so.6 malloc 221 222SEE ALSO 223-------- 224linkperf:perf-trace[1], linkperf:perf-record[1] 225