linux.git/kernel/trace/trace_eprobe.c, branch v6.12.80

tracing/eprobe: Fix to release eprobe when failed to add dyn_event

2024-12-14T19:04:13+00:00

[ Upstream commit 494b332064c0ce2f7392fa92632bc50191c1b517 ]

Fix eprobe event to unregister event call and release eprobe when it fails
to add dynamic event correctly.

Link: https://lore.kernel.org/all/173289886698.73724.1959899350183686006.stgit@devnote2/

Fixes: 7491e2c44278 ("tracing: Add a probe that attaches to trace events")
Signed-off-by: Masami Hiramatsu (Google) 
Signed-off-by: Sasha Levin

tracing/probes: Fix MAX_TRACE_ARGS limit handling

2024-10-23T08:24:44+00:00

When creating a trace_probe we would set nr_args prior to truncating the
arguments to MAX_TRACE_ARGS. However, we would only initialize arguments
up to the limit.

This caused invalid memory access when attempting to set up probes with
more than 128 fetchargs.

  BUG: kernel NULL pointer dereference, address: 0000000000000020
  #PF: supervisor read access in kernel mode
  #PF: error_code(0x0000) - not-present page
  PGD 0 P4D 0
  Oops: Oops: 0000 [#1] PREEMPT SMP PTI
  CPU: 0 UID: 0 PID: 1769 Comm: cat Not tainted 6.11.0-rc7+ #8
  Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.3-1.fc39 04/01/2014
  RIP: 0010:__set_print_fmt+0x134/0x330

Resolve the issue by applying the MAX_TRACE_ARGS limit earlier. Return
an error when there are too many arguments instead of silently
truncating.

Link: https://lore.kernel.org/all/20240930202656.292869-1-mikel@mikelr.com/

Fixes: 035ba76014c0 ("tracing/probes: cleanup: Set trace_probe::nr_args at trace_probe_init")
Signed-off-by: Mikel Rychliski 
Signed-off-by: Masami Hiramatsu (Google)

tracing/probes: Support $argN in return probe (kprobe and fprobe)

2024-03-06T15:27:34+00:00

Support accessing $argN in the return probe events. This will help users to
record entry data in function return (exit) event for simplfing the function
entry/exit information in one event, and record the result values (e.g.
allocated object/initialized object) at function exit.

For example, if we have a function `int init_foo(struct foo *obj, int param)`
sometimes we want to check how `obj` is initialized. In such case, we can
define a new return event like below;

 # echo 'r init_foo retval=$retval param=$arg2 field1=+0($arg1)' >> kprobe_events

Thus it records the function parameter `param` and its result `obj->field1`
(the dereference will be done in the function exit timing) value at once.

This also support fprobe, BTF args and'$arg*'. So if CONFIG_DEBUG_INFO_BTF
is enabled, we can trace both function parameters and the return value
by following command.

 # echo 'f target_function%return $arg* $retval' >> dynamic_events

Link: https://lore.kernel.org/all/170952365552.229804.224112990211602895.stgit@devnote2/

Signed-off-by: Masami Hiramatsu (Google)

tracing/probes: cleanup: Set trace_probe::nr_args at trace_probe_init

2024-03-06T15:27:15+00:00

Instead of incrementing the trace_probe::nr_args, init it at
trace_probe_init(). Without this change, there is no way to get the number
of trace_probe arguments while parsing it.
This is a cleanup, so the behavior is not changed.

Link: https://lore.kernel.org/all/170952363585.229804.13060759900346411951.stgit@devnote2/

Signed-off-by: Masami Hiramatsu (Google)

tracing/eprobe: drop unneeded breaks

2023-10-09T16:03:48+00:00

Drop break after return.

Link: https://lore.kernel.org/all/20230928104334.41215-1-Julia.Lawall@inria.fr/

Signed-off-by: Julia Lawall 
Acked-by: Masami Hiramatsu (Google) 
Signed-off-by: Masami Hiramatsu (Google)

tracing/probes: Support BTF argument on module functions

2023-08-23T00:39:15+00:00

Since the btf returned from bpf_get_btf_vmlinux() only covers functions in
the vmlinux, BTF argument is not available on the functions in the modules.
Use bpf_find_btf_id() instead of bpf_get_btf_vmlinux()+btf_find_name_kind()
so that BTF argument can find the correct struct btf and btf_type in it.
With this fix, fprobe events can use `$arg*` on module functions as below

 # grep nf_log_ip_packet /proc/kallsyms
ffffffffa0005c00 t nf_log_ip_packet	[nf_log_syslog]
ffffffffa0005bf0 t __pfx_nf_log_ip_packet	[nf_log_syslog]
 # echo 'f nf_log_ip_packet $arg*' > dynamic_events
 # cat dynamic_events
f:fprobes/nf_log_ip_packet__entry nf_log_ip_packet net=net pf=pf hooknum=hooknum skb=skb in=in out=out loginfo=loginfo prefix=prefix

To support the module's btf which is removable, the struct btf needs to be
ref-counted. So this also records the btf in the traceprobe_parse_context
and returns the refcount when the parse has done.

Link: https://lore.kernel.org/all/169272154223.160970.3507930084247934031.stgit@devnote2/

Suggested-by: Alexei Starovoitov 
Signed-off-by: Masami Hiramatsu (Google) 
Acked-by: Steven Rostedt (Google)

tracing/eprobe: Iterate trace_eprobe directly

2023-08-23T00:38:56+00:00

Refer to the description in [1], we can skip "container_of()" following
"list_for_each_entry()" by using "list_for_each_entry()" with
"struct trace_eprobe" and "tp.list".

Also, this patch defines "for_each_trace_eprobe_tp" to simplify the code
of the same logic.

[1] https://lore.kernel.org/all/CAHk-=wjakjw6-rDzDDBsuMoDCqd+9ogifR_EE1F0K-jYek1CdA@mail.gmail.com/

Link: https://lore.kernel.org/all/20230822022433.262478-1-nashuiliang@gmail.com/

Signed-off-by: Chuang Wang 
Acked-by: Masami Hiramatsu (Google) 
Signed-off-by: Masami Hiramatsu (Google)

Merge tag 'probes-fixes-v6.5-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace

2023-07-12T19:01:16+00:00

Pull probes fixes from Masami Hiramatsu:

 - Fix fprobe's rethook release issues:

     - Release rethook after ftrace_ops is unregistered so that the
       rethook is not accessed after free.

     - Stop rethook before ftrace_ops is unregistered so that the
       rethook is NOT used after exiting unregister_fprobe()

 - Fix eprobe cleanup logic. If it attaches to multiple events and
   failes to enable one of them, rollback all enabled events correctly.

 - Fix fprobe to unlock ftrace recursion lock correctly when it missed
   by another running kprobe.

 - Cleanup kprobe to remove unnecessary NULL.

 - Cleanup kprobe to remove unnecessary 0 initializations.

* tag 'probes-fixes-v6.5-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  fprobe: Ensure running fprobe_exit_handler() finished before calling rethook_free()
  kernel: kprobes: Remove unnecessary ‘0’ values
  kprobes: Remove unnecessary ‘NULL’ values from correct_ret_addr
  fprobe: add unlock to match a succeeded ftrace_test_recursion_trylock
  kernel/trace: Fix cleanup logic of enable_trace_eprobe
  fprobe: Release rethook after the ftrace_ops is unregistered

kernel/trace: Fix cleanup logic of enable_trace_eprobe

2023-07-10T15:44:57+00:00

The enable_trace_eprobe() function enables all event probes, attached
to given trace probe. If an error occurs in enabling one of the event
probes, all others should be roll backed. There is a bug in that roll
back logic - instead of all event probes, only the failed one is
disabled.

Link: https://lore.kernel.org/all/20230703042853.1427493-1-tz.stoyanov@gmail.com/

Reported-by: Dan Carpenter 
Fixes: 7491e2c44278 ("tracing: Add a probe that attaches to trace events")
Signed-off-by: Tzvetomir Stoyanov (VMware) 
Acked-by: Masami Hiramatsu (Google) 
Reviewed-by: Steven Rostedt (Google) 
Signed-off-by: Masami Hiramatsu (Google)

tracing/probes: Move event parameter fetching code to common parser

2023-06-06T12:39:56+00:00

Move trace event parameter fetching code to common parser in
trace_probe.c. This simplifies eprobe's trace-event variable fetching
code by introducing a parse context data structure.

Link: https://lore.kernel.org/all/168507472950.913472.2812253181558471278.stgit@mhiramat.roam.corp.google.com/

Signed-off-by: Masami Hiramatsu (Google)