linux-kernel - [BUG] perf probe can't remove probes

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Date:   Wed, 25 Nov 2020 14:27:55 -0300
From:   Arnaldo Carvalho de Melo <acme@...nel.org>
To:     Masami Hiramatsu <mhiramat@...nel.org>
Cc:     Jiri Olsa <jolsa@...nel.org>, Namhyung Kim <namhyung@...nel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Clark Williams <williams@...hat.com>,
        linux-perf-users@...r.kernel.org
Subject: [BUG] perf probe can't remove probes

Masami, have you stumbled on this already?

[root@...enth ~]# perf probe security_locked_down%return 'ret=$retval'
Added new event:
  probe:security_locked_down__return (on security_locked_down%return with ret=$retval)

You can now use it in all perf tools, such as:

	perf record -e probe:security_locked_down__return -aR sleep 1

[root@...enth ~]# perf probe security_locked_down what
Added new event:
  probe:security_locked_down (on security_locked_down with what)

You can now use it in all perf tools, such as:

	perf record -e probe:security_locked_down -aR sleep 1

[root@...enth ~]#

[root@...enth ~]# uname -r
5.10.0-rc3.bpfsign+
[root@...enth ~]# perf probe -l
  probe:security_locked_down (on security_locked_down@.../bpf/security/security.c with what)
  probe:security_locked_down__return (on security_locked_down%return@.../bpf/security/security.c with ret)
[root@...enth ~]# perf probe -D '*:*'
Semantic error :There is non-digit char in line number.

 Usage: perf probe [<options>] 'PROBEDEF' ['PROBEDEF' ...]
    or: perf probe [<options>] --add 'PROBEDEF' [--add 'PROBEDEF' ...]
    or: perf probe [<options>] --del '[GROUP:]EVENT' ...
    or: perf probe --list [GROUP:]EVENT ...
    or: perf probe [<options>] --line 'LINEDESC'
    or: perf probe [<options>] --vars 'PROBEPOINT'
    or: perf probe [<options>] --funcs

    -D, --definition <[EVENT=]FUNC[@SRC][+OFF|%return|:RL|;PT]|SRC:AL|SRC;PT [[NAME=]ARG ...]>
                          Show trace event definition of given traceevent for k/uprobe_events.
[root@...enth ~]# perf probe probe:security_locked_down
Semantic error :There is non-digit char in line number.
  Error: Command Parse Error.
[root@...enth ~]# perf probe probe:security_locked_down__return
Semantic error :There is non-digit char in line number.
  Error: Command Parse Error.
[root@...enth ~]# cat /sys/kernel/debug/kprobes/
blacklist  enabled    list
[root@...enth ~]# cat /sys/kernel/debug/kprobes/list
ffffffff8248b350  k  security_locked_down+0x0    [FTRACE]
ffffffff8248b350  r  security_locked_down+0x0    [FTRACE]
[root@...enth ~]#

[root@...enth ~]# cat /etc/fedora-release
Fedora release 33 (Thirty Three)
[root@...enth ~]# gcc -v
Using built-in specs.
COLLECT_GCC=/usr/bin/gcc
COLLECT_LTO_WRAPPER=/usr/libexec/gcc/x86_64-redhat-linux/10/lto-wrapper
OFFLOAD_TARGET_NAMES=nvptx-none
OFFLOAD_TARGET_DEFAULT=1
Target: x86_64-redhat-linux
Configured with: ../configure --enable-bootstrap --enable-languages=c,c++,fortran,objc,obj-c++,ada,go,d,lto --prefix=/usr --mandir=/usr/share/man --infodir=/usr/share/info --with-bugurl=http://bugzilla.redhat.com/bugzilla --enable-shared --enable-threads=posix --enable-checking=release --enable-multilib --with-system-zlib --enable-__cxa_atexit --disable-libunwind-exceptions --enable-gnu-unique-object --enable-linker-build-id --with-gcc-major-version-only --with-linker-hash-style=gnu --enable-plugin --enable-initfini-array --with-isl --enable-offload-targets=nvptx-none --without-cuda-driver --enable-gnu-indirect-function --enable-cet --with-tune=generic --with-arch_32=i686 --build=x86_64-redhat-linux
Thread model: posix
Supported LTO compression algorithms: zlib zstd
gcc version 10.2.1 20201016 (Red Hat 10.2.1-6) (GCC)
[root@...enth ~]# rpm -q elfutils
elfutils-0.182-1.fc33.x86_64
[root@...enth ~]#

- Arnaldo