linux/tools/perf/Documentation/perf-probe.txt
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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
  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::
  38        Specify module name in which perf-probe searches probe points
  39        or lines.
  40
  41-s::
  42--source=PATH::
  43        Specify path to kernel source.
  44
  45-v::
  46--verbose::
  47        Be more verbose (show parsed arguments, etc).
  48
  49-a::
  50--add=::
  51        Define a probe event (see PROBE SYNTAX for detail).
  52
  53-d::
  54--del=::
  55        Delete probe events. This accepts glob wildcards('*', '?') and character
  56        classes(e.g. [a-z], [!A-Z]).
  57
  58-l::
  59--list::
  60        List up current probe events.
  61
  62-L::
  63--line=::
  64        Show source code lines which can be probed. This needs an argument
  65        which specifies a range of the source code. (see LINE SYNTAX for detail)
  66
  67-V::
  68--vars=::
  69        Show available local variables at given probe point. The argument
  70        syntax is same as PROBE SYNTAX, but NO ARGs.
  71
  72--externs::
  73        (Only for --vars) Show external defined variables in addition to local
  74        variables.
  75
  76-F::
  77--funcs::
  78        Show available functions in given module or kernel.
  79
  80--filter=FILTER::
  81        (Only for --vars and --funcs) Set filter. FILTER is a combination of glob
  82        pattern, see FILTER PATTERN for detail.
  83        Default FILTER is "!__k???tab_* & !__crc_*" for --vars, and "!_*"
  84        for --funcs.
  85        If several filters are specified, only the last filter is used.
  86
  87-f::
  88--force::
  89        Forcibly add events with existing name.
  90
  91-n::
  92--dry-run::
  93        Dry run. With this option, --add and --del doesn't execute actual
  94        adding and removal operations.
  95
  96--max-probes::
  97        Set the maximum number of probe points for an event. Default is 128.
  98
  99PROBE SYNTAX
 100------------
 101Probe points are defined by following syntax.
 102
 103    1) Define event based on function name
 104     [EVENT=]FUNC[@SRC][:RLN|+OFFS|%return|;PTN] [ARG ...]
 105
 106    2) Define event based on source file with line number
 107     [EVENT=]SRC:ALN [ARG ...]
 108
 109    3) Define event based on source file with lazy pattern
 110     [EVENT=]SRC;PTN [ARG ...]
 111
 112
 113'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'.
 114'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.
 115It 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.
 116'ARG' specifies the arguments of this probe point, (see PROBE ARGUMENT).
 117
 118PROBE ARGUMENT
 119--------------
 120Each probe argument follows below syntax.
 121
 122 [NAME=]LOCALVAR|$retval|%REG|@SYMBOL[:TYPE]
 123
 124'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'.)
 125'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.
 126
 127LINE SYNTAX
 128-----------
 129Line range is described by following syntax.
 130
 131 "FUNC[@SRC][:RLN[+NUM|-RLN2]]|SRC[:ALN[+NUM|-ALN2]]"
 132
 133FUNC specifies the function name of showing lines. 'RLN' is the start line
 134number from function entry line, and 'RLN2' is the end line number. As same as
 135probe syntax, 'SRC' means the source file path, 'ALN' is start line number,
 136and 'ALN2' is end line number in the file. It is also possible to specify how
 137many lines to show by using 'NUM'. Moreover, 'FUNC@SRC' combination is good
 138for searching a specific function when several functions share same name.
 139So, "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.
 140
 141LAZY MATCHING
 142-------------
 143 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]).
 144
 145e.g.
 146 'a=*' can matches 'a=b', 'a = b', 'a == b' and so on.
 147
 148This 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.)
 149
 150FILTER PATTERN
 151--------------
 152 The filter pattern is a glob matching pattern(s) to filter variables.
 153 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 "(" ")".
 154
 155e.g.
 156 With --filter "foo* | bar*", perf probe -V shows variables which start with "foo" or "bar".
 157 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.
 158
 159EXAMPLES
 160--------
 161Display which lines in schedule() can be probed:
 162
 163 ./perf probe --line schedule
 164
 165Add a probe on schedule() function 12th line with recording cpu local variable:
 166
 167 ./perf probe schedule:12 cpu
 168 or
 169 ./perf probe --add='schedule:12 cpu'
 170
 171 this will add one or more probes which has the name start with "schedule".
 172
 173 Add probes on lines in schedule() function which calls update_rq_clock().
 174
 175 ./perf probe 'schedule;update_rq_clock*'
 176 or
 177 ./perf probe --add='schedule;update_rq_clock*'
 178
 179Delete all probes on schedule().
 180
 181 ./perf probe --del='schedule*'
 182
 183
 184SEE ALSO
 185--------
 186linkperf:perf-trace[1], linkperf:perf-record[1]
 187