Commit 143aa5cb authored by Konrad Sztyber's avatar Konrad Sztyber Committed by Jim Harris
Browse files

scripts/bpftrace: use SO names in bpftrace scripts 



If an USDT probe is defined within a shared object, bpftrace expects the
path to that shared object instead of an executable.  This means that we
need to replace __EXE__ in the bpftrace scripts differently, depending
on whether the application was linked statically or dynamically.

This is now done by the `scripts/bpf/gen.py` script.  It lists all
available probes, along with their locations, of a process.  Then, it
matches them to those described in a bpftrace script replacing the
__EXE__ markers with the listed location (either a path to the
executable or a shared library).  If a bpftrace script uses a probe that
isn't listed, its __EXE__ will be replaced by a path to the executable.

Signed-off-by: default avatarKonrad Sztyber <konrad.sztyber@intel.com>
Change-Id: I7c323d5f7d948ea57cf8d4d3132e4d59a2de594f
Reviewed-on: https://review.spdk.io/gerrit/c/spdk/spdk/+/9807


Community-CI: Broadcom CI <spdk-ci.pdl@broadcom.com>
Tested-by: default avatarSPDK CI Jenkins <sys_sgci@intel.com>
Reviewed-by: default avatarTomasz Zawadzki <tomasz.zawadzki@intel.com>
Reviewed-by: default avatarJim Harris <james.r.harris@intel.com>
parent 9072c4ad

scripts/bpf/gen.py

0 → 100755
+53 −0
Original line number Diff line number Diff line 
#!/usr/bin/env python3



from argparse import ArgumentParser

import os

import re

import subprocess

import sys





class TraceProcess:

    def __init__(self, pid):

        self._path = os.readlink(f'/proc/{pid}/exe')

        self._pid = pid

        self._probes = self._init_probes()



    def _init_probes(self):

        lines = subprocess.check_output(['bpftrace', '-l', '-p', str(self._pid)], text=True)

        probes = {}

        for line in lines.split('\n'):

            parts = line.split(':')

            if len(parts) < 3:

                continue

            ptype, path, function = parts[0], parts[1], parts[-1]

            probes[(ptype, function)] = path

        return probes



    def fixup(self, script):

        pregs = [re.compile(r'({}):__EXE__:(\w+)'.format(ptype)) for ptype in ['usdt', 'uprobe']]

        with open(script, 'r') as file:

            lines = file.readlines()

        result = ''

        for line in lines:

            for regex in pregs:

                match = regex.match(line)

                if match is not None:

                    ptype, function = match.groups()

                    path = self._probes.get((ptype, function), self._path)

                    line = line.replace('__EXE__', path)

                    break

            result += line.replace('__EXE__', self._path).replace('__PID__', str(self._pid))

        return result





if __name__ == '__main__':

    parser = ArgumentParser(description='bpftrace script generator replacing special ' +

                            'variables in the scripts with appropriate values')

    parser.add_argument('-p', '--pid', type=int, required=True, help='PID of a traced process')

    parser.add_argument('scripts', metavar='SCRIPTS', type=str, nargs='+',

                        help='bpftrace scripts to process')

    args = parser.parse_args(sys.argv[1:])

    proc = TraceProcess(args.pid)

    for script in args.scripts:

        print(proc.fixup(script))

scripts/bpftrace.sh

+1 −1
Original line number Diff line number Diff line
@@ -10,7 +10,7 @@ if [ $# -lt 2 ]; then 
fi

SCRIPTS_DIR=$(readlink -f $(dirname $0))

BIN_PATH=$(readlink -f /proc/$1/exe)

BPF_SCRIPT=$(sed "s#__EXE__#${BIN_PATH}#g" "${@:2}" | sed "s#__PID__#${1}#g")

BPF_SCRIPT=$($SCRIPTS_DIR/bpf/gen.py -p $1 "${@:2}")

BPF_SCRIPT+=$($SCRIPTS_DIR/bpf/gen_enums.sh)

if [ -n "$ECHO_SCRIPT" ]; then

	echo "$BPF_SCRIPT"