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 71 event names. 72 When this is used with --cache, perf shows all cached probes instead of 73 the live probes. 74 75-L:: 76--line=:: 77 Show source code lines which can be probed. This needs an argument 78 which specifies a range of the source code. (see LINE SYNTAX for detail) 79 80-V:: 81--vars=:: 82 Show available local variables at given probe point. The argument 83 syntax is same as PROBE SYNTAX, but NO ARGs. 84 85--externs:: 86 (Only for --vars) Show external defined variables in addition to local 87 variables. 88 89--no-inlines:: 90 (Only for --add) Search only for non-inlined functions. The functions 91 which do not have instances are ignored. 92 93-F:: 94--funcs[=FILTER]:: 95 Show available functions in given module or kernel. With -x/--exec, 96 can also list functions in a user space executable / shared library. 97 This also can accept a FILTER rule argument. 98 99--filter=FILTER:: 100 (Only for --vars and --funcs) Set filter. FILTER is a combination of glob 101 pattern, see FILTER PATTERN for detail. 102 Default FILTER is "!__k???tab_* & !__crc_*" for --vars, and "!_*" 103 for --funcs. 104 If several filters are specified, only the last filter is used. 105 106-f:: 107--force:: 108 Forcibly add events with existing name. 109 110-n:: 111--dry-run:: 112 Dry run. With this option, --add and --del doesn't execute actual 113 adding and removal operations. 114 115--cache:: 116 (With --add) Cache the probes. Any events which successfully added 117 are also stored in the cache file. 118 (With --list) Show cached probes. 119 (With --del) Remove cached probes. 120 121--max-probes=NUM:: 122 Set the maximum number of probe points for an event. Default is 128. 123 124-x:: 125--exec=PATH:: 126 Specify path to the executable or shared library file for user 127 space tracing. Can also be used with --funcs option. 128 129--demangle:: 130 Demangle application symbols. --no-demangle is also available 131 for disabling demangling. 132 133--demangle-kernel:: 134 Demangle kernel symbols. --no-demangle-kernel is also available 135 for disabling kernel demangling. 136 137In absence of -m/-x options, perf probe checks if the first argument after 138the options is an absolute path name. If its an absolute path, perf probe 139uses it as a target module/target user space binary to probe. 140 141PROBE SYNTAX 142------------ 143Probe points are defined by following syntax. 144 145 1) Define event based on function name 146 [[GROUP:]EVENT=]FUNC[@SRC][:RLN|+OFFS|%return|;PTN] [ARG ...] 147 148 2) Define event based on source file with line number 149 [[GROUP:]EVENT=]SRC:ALN [ARG ...] 150 151 3) Define event based on source file with lazy pattern 152 [[GROUP:]EVENT=]SRC;PTN [ARG ...] 153 154 4) Pre-defined SDT events or cached event with name 155 %[sdt_PROVIDER:]SDTEVENT 156 or, 157 sdt_PROVIDER:SDTEVENT 158 159'EVENT' specifies the name of new event, if omitted, it will be set the name of the probed function. You can also specify a group name by 'GROUP', if omitted, set 'probe' is used for kprobe and 'probe_<bin>' is used for uprobe. 160Note 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 161modules. 162'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. 163It 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. 164'ARG' specifies the arguments of this probe point, (see PROBE ARGUMENT). 165'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. 166Note 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. 167 168For details of the SDT, see below. 169https://sourceware.org/gdb/onlinedocs/gdb/Static-Probe-Points.html 170 171PROBE ARGUMENT 172-------------- 173Each probe argument follows below syntax. 174 175 [NAME=]LOCALVAR|$retval|%REG|@SYMBOL[:TYPE] 176 177'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. $retval, %ax, etc). Note that the name of this argument will be set as the last member name if you specify a local data structure member (e.g. field2 for 'var->field1.field2'.) 178'$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. 179'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), signedness casting (u/s), "string" and bitfield are supported. (see TYPES for detail) 180 181On x86 systems %REG is always the short form of the register: for example %AX. %RAX or %EAX is not valid. 182 183TYPES 184----- 185Basic types (u8/u16/u32/u64/s8/s16/s32/s64) are integer types. Prefix 's' and 'u' means those types are signed and unsigned respectively. Traced arguments are shown in decimal (signed) or hex (unsigned). You can also use 's' or 'u' to specify only signedness and leave its size auto-detected by perf probe. 186String 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. 187Bitfield is another special type, which takes 3 parameters, bit-width, bit-offset, and container-size (usually 32). The syntax is; 188 189 b<bit-width>@<bit-offset>/<container-size> 190 191LINE SYNTAX 192----------- 193Line range is described by following syntax. 194 195 "FUNC[@SRC][:RLN[+NUM|-RLN2]]|SRC[:ALN[+NUM|-ALN2]]" 196 197FUNC specifies the function name of showing lines. 'RLN' is the start line 198number from function entry line, and 'RLN2' is the end line number. As same as 199probe syntax, 'SRC' means the source file path, 'ALN' is start line number, 200and 'ALN2' is end line number in the file. It is also possible to specify how 201many lines to show by using 'NUM'. Moreover, 'FUNC@SRC' combination is good 202for searching a specific function when several functions share same name. 203So, "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. 204 205LAZY MATCHING 206------------- 207 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]). 208 209e.g. 210 'a=*' can matches 'a=b', 'a = b', 'a == b' and so on. 211 212This 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.) 213 214FILTER PATTERN 215-------------- 216 The filter pattern is a glob matching pattern(s) to filter variables. 217 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 "(" ")". 218 219e.g. 220 With --filter "foo* | bar*", perf probe -V shows variables which start with "foo" or "bar". 221 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. 222 223EXAMPLES 224-------- 225Display which lines in schedule() can be probed: 226 227 ./perf probe --line schedule 228 229Add a probe on schedule() function 12th line with recording cpu local variable: 230 231 ./perf probe schedule:12 cpu 232 or 233 ./perf probe --add='schedule:12 cpu' 234 235 this will add one or more probes which has the name start with "schedule". 236 237 Add probes on lines in schedule() function which calls update_rq_clock(). 238 239 ./perf probe 'schedule;update_rq_clock*' 240 or 241 ./perf probe --add='schedule;update_rq_clock*' 242 243Delete all probes on schedule(). 244 245 ./perf probe --del='schedule*' 246 247Add probes at zfree() function on /bin/zsh 248 249 ./perf probe -x /bin/zsh zfree or ./perf probe /bin/zsh zfree 250 251Add probes at malloc() function on libc 252 253 ./perf probe -x /lib/libc.so.6 malloc or ./perf probe /lib/libc.so.6 malloc 254 255SEE ALSO 256-------- 257linkperf:perf-trace[1], linkperf:perf-record[1], linkperf:perf-buildid-cache[1] 258