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. With -x/--exec, 81 can also list functions in a user space executable / shared library. 82 83--filter=FILTER:: 84 (Only for --vars and --funcs) Set filter. FILTER is a combination of glob 85 pattern, see FILTER PATTERN for detail. 86 Default FILTER is "!__k???tab_* & !__crc_*" for --vars, and "!_*" 87 for --funcs. 88 If several filters are specified, only the last filter is used. 89 90-f:: 91--force:: 92 Forcibly add events with existing name. 93 94-n:: 95--dry-run:: 96 Dry run. With this option, --add and --del doesn't execute actual 97 adding and removal operations. 98 99--max-probes:: 100 Set the maximum number of probe points for an event. Default is 128. 101 102-x:: 103--exec=PATH:: 104 Specify path to the executable or shared library file for user 105 space tracing. Can also be used with --funcs option. 106 107--demangle-kernel:: 108 Demangle kernel symbols. 109 110In absence of -m/-x options, perf probe checks if the first argument after 111the options is an absolute path name. If its an absolute path, perf probe 112uses it as a target module/target user space binary to probe. 113 114PROBE SYNTAX 115------------ 116Probe points are defined by following syntax. 117 118 1) Define event based on function name 119 [EVENT=]FUNC[@SRC][:RLN|+OFFS|%return|;PTN] [ARG ...] 120 121 2) Define event based on source file with line number 122 [EVENT=]SRC:ALN [ARG ...] 123 124 3) Define event based on source file with lazy pattern 125 [EVENT=]SRC;PTN [ARG ...] 126 127 128'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'. 129'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. 130It 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. 131'ARG' specifies the arguments of this probe point, (see PROBE ARGUMENT). 132 133PROBE ARGUMENT 134-------------- 135Each probe argument follows below syntax. 136 137 [NAME=]LOCALVAR|$retval|%REG|@SYMBOL[:TYPE] 138 139'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'.) 140'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. 141 142On x86 systems %REG is always the short form of the register: for example %AX. %RAX or %EAX is not valid. 143 144LINE SYNTAX 145----------- 146Line range is described by following syntax. 147 148 "FUNC[@SRC][:RLN[+NUM|-RLN2]]|SRC[:ALN[+NUM|-ALN2]]" 149 150FUNC specifies the function name of showing lines. 'RLN' is the start line 151number from function entry line, and 'RLN2' is the end line number. As same as 152probe syntax, 'SRC' means the source file path, 'ALN' is start line number, 153and 'ALN2' is end line number in the file. It is also possible to specify how 154many lines to show by using 'NUM'. Moreover, 'FUNC@SRC' combination is good 155for searching a specific function when several functions share same name. 156So, "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. 157 158LAZY MATCHING 159------------- 160 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]). 161 162e.g. 163 'a=*' can matches 'a=b', 'a = b', 'a == b' and so on. 164 165This 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.) 166 167FILTER PATTERN 168-------------- 169 The filter pattern is a glob matching pattern(s) to filter variables. 170 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 "(" ")". 171 172e.g. 173 With --filter "foo* | bar*", perf probe -V shows variables which start with "foo" or "bar". 174 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. 175 176EXAMPLES 177-------- 178Display which lines in schedule() can be probed: 179 180 ./perf probe --line schedule 181 182Add a probe on schedule() function 12th line with recording cpu local variable: 183 184 ./perf probe schedule:12 cpu 185 or 186 ./perf probe --add='schedule:12 cpu' 187 188 this will add one or more probes which has the name start with "schedule". 189 190 Add probes on lines in schedule() function which calls update_rq_clock(). 191 192 ./perf probe 'schedule;update_rq_clock*' 193 or 194 ./perf probe --add='schedule;update_rq_clock*' 195 196Delete all probes on schedule(). 197 198 ./perf probe --del='schedule*' 199 200Add probes at zfree() function on /bin/zsh 201 202 ./perf probe -x /bin/zsh zfree or ./perf probe /bin/zsh zfree 203 204Add probes at malloc() function on libc 205 206 ./perf probe -x /lib/libc.so.6 malloc or ./perf probe /lib/libc.so.6 malloc 207 208SEE ALSO 209-------- 210linkperf:perf-trace[1], linkperf:perf-record[1] 211