linux-stable.git/kernel/trace/trace_probe.c, branch v6.4.8

Revert "tracing: Add "(fault)" name injection to kernel probes"

2023-07-23T11:54:14+00:00

commit 4ed8f337dee32df71435689c19d22e4ee846e15a upstream.

This reverts commit 2e9906f84fc7c99388bb7123ade167250d50f1c0.

It was turned out that commit 2e9906f84fc7 ("tracing: Add "(fault)"
name injection to kernel probes") did not work correctly and probe
events still show just '(fault)' (instead of '"(fault)"'). Also,
current '(fault)' is more explicit that it faulted.

This also moves FAULT_STRING macro to trace.h so that synthetic
event can keep using it, and uses it in trace_probe.c too.

Link: https://lore.kernel.org/all/168908495772.123124.1250788051922100079.stgit@devnote2/
Link: https://lore.kernel.org/all/20230706230642.3793a593@rorschach.local.home/

Cc: stable@vger.kernel.org
Cc: Andrew Morton 
Cc: Tom Zanussi 
Signed-off-by: Masami Hiramatsu (Google) 
Reviewed-by: Steven Rostedt (Google) 
Signed-off-by: Greg Kroah-Hartman

tracing: Rename kvfree_rcu() to kvfree_rcu_mightsleep()

2023-04-05T13:48:03+00:00

The kvfree_rcu() macro's single-argument form is deprecated.  Therefore
switch to the new kvfree_rcu_mightsleep() variant. The goal is to
avoid accidental use of the single-argument forms, which can introduce
functionality bugs in atomic contexts and latency bugs in non-atomic
contexts.

Cc: Steven Rostedt (VMware) 
Acked-by: Daniel Bristot de Oliveira 
Acked-by: Paul E. McKenney 
Signed-off-by: Uladzislau Rezki (Sony) 
Signed-off-by: Paul E. McKenney 
Signed-off-by: Joel Fernandes (Google)

kernel/trace: Introduce trace_probe_print_args and use it in *probes

2023-02-24T00:44:15+00:00

print_probe_args is currently inplemented in trace_probe_tmpl.h and
included by *probes, as a result, each probe has an identical copy.

This patch will move it to trace_probe.c as an new API, each probe
calls it to print their args in trace file.

Link: https://lore.kernel.org/all/1672382000-18304-1-git-send-email-chensong_2000@189.cn/

Signed-off-by: Song Chen 
Acked-by: Masami Hiramatsu (Google) 
Signed-off-by: Masami Hiramatsu (Google)

tracing/probe: add a char type to show the character value of traced arguments

2023-02-20T23:52:42+00:00

There are scenes that we want to show the character value of traced
arguments other than a decimal or hexadecimal or string value for debug
convinience. I add a new type named 'char' to do it and a new test case
file named 'kprobe_args_char.tc' to do selftest for char type.

For example:

The to be traced function is 'void demo_func(char type, char *name);', we
can add a kprobe event as follows to show argument values as we want:

echo  'p:myprobe demo_func $arg1:char +0($arg2):char[5]' > kprobe_events

we will get the following trace log:

... myprobe: (demo_func+0x0/0x29) arg1='A' arg2={'b','p','f','1',''}

Link: https://lore.kernel.org/all/20221219110613.367098-1-dolinux.peng@gmail.com/

Signed-off-by: Donglin Peng 
Acked-by: Masami Hiramatsu (Google) 
Reported-by: kernel test robot 
Signed-off-by: Masami Hiramatsu (Google)

Merge tag 'trace-probes-v6.2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace

2022-12-22T02:57:24+00:00

Pull trace probes updates from Steven Rostedt:

 - New "symstr" type for dynamic events that writes the name of the
   function+offset into the ring buffer and not just the address

 - Prevent kernel symbol processing on addresses in user space probes
   (uprobes).

 - And minor fixes and clean ups

* tag 'trace-probes-v6.2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  tracing/probes: Reject symbol/symstr type for uprobe
  tracing/probes: Add symstr type for dynamic events
  kprobes: kretprobe events missing on 2-core KVM guest
  kprobes: Fix check for probe enabled in kill_kprobe()
  test_kprobes: Fix implicit declaration error of test_kprobes
  tracing: Fix race where eprobes can be called before the event

tracing/probes: Reject symbol/symstr type for uprobe

2022-12-15T00:00:20+00:00

Since uprobe's argument must contain the user-space data, that
should not be converted to kernel symbols. Reject if user
specifies these types on uprobe events. e.g.

 /sys/kernel/debug/tracing # echo 'p /bin/sh:10 %ax:symbol' >> uprobe_events
 sh: write error: Invalid argument
 /sys/kernel/debug/tracing # echo 'p /bin/sh:10 %ax:symstr' >> uprobe_events
 sh: write error: Invalid argument
 /sys/kernel/debug/tracing # cat error_log
 [ 1783.134883] trace_uprobe: error: Unknown type is specified
   Command: p /bin/sh:10 %ax:symbol
                             ^
 [ 1792.201120] trace_uprobe: error: Unknown type is specified
   Command: p /bin/sh:10 %ax:symstr
                             ^
Link: https://lore.kernel.org/all/166679931679.1528100.15540755370726009882.stgit@devnote3/

Signed-off-by: Masami Hiramatsu (Google)

tracing/probes: Add symstr type for dynamic events

2022-12-14T23:48:57+00:00

Add 'symstr' type for storing the kernel symbol as a string data
instead of the symbol address. This allows us to filter the
events by wildcard symbol name.

e.g.
  # echo 'e:wqfunc workqueue.workqueue_execute_start symname=$function:symstr' >> dynamic_events
  # cat events/eprobes/wqfunc/format
  name: wqfunc
  ID: 2110
  format:
  	field:unsigned short common_type;	offset:0;	size:2;	signed:0;
  	field:unsigned char common_flags;	offset:2;	size:1;	signed:0;
  	field:unsigned char common_preempt_count;	offset:3;	size:1;	signed:0;
  	field:int common_pid;	offset:4;	size:4;	signed:1;

  	field:__data_loc char[] symname;	offset:8;	size:4;	signed:1;

  print fmt: " symname=\"%s\"", __get_str(symname)

Note that there is already 'symbol' type which just change the
print format (so it still stores the symbol address in the tracing
ring buffer.) On the other hand, 'symstr' type stores the actual
"symbol+offset/size" data as a string.

Link: https://lore.kernel.org/all/166679930847.1528100.4124308529180235965.stgit@devnote3/

Signed-off-by: Masami Hiramatsu (Google)

tracing/probes: Handle system names with hyphens

2022-12-10T04:48:05+00:00

When creating probe names, a check is done to make sure it matches basic C
standard variable naming standards. Basically, starts with alphabetic or
underline, and then the rest of the characters have alpha-numeric or
underline in them.

But system names do not have any true naming conventions, as they are
created by the TRACE_SYSTEM macro and nothing tests to see what they are.
The "xhci-hcd" trace events has a '-' in the system name. When trying to
attach a eprobe to one of these trace points, it fails because the system
name does not follow the variable naming convention because of the
hyphen, and the eprobe checks fail on this.

Allow hyphens in the system name so that eprobes can attach to the
"xhci-hcd" trace events.

Link: https://lore.kernel.org/all/Y3eJ8GiGnEvVd8%2FN@macondo/
Link: https://lore.kernel.org/linux-trace-kernel/20221122122345.160f5077@gandalf.local.home

Cc: Masami Hiramatsu 
Cc: stable@vger.kernel.org
Fixes: 5b7a96220900e ("tracing/probe: Check event/group naming rule at parsing")
Reported-by: Rafael Mendonca 
Signed-off-by: Steven Rostedt (Google)

tracing/probes: Have kprobes and uprobes use $COMM too

2022-08-21T19:56:08+00:00

Both $comm and $COMM can be used to get current->comm in eprobes and the
filtering and histogram logic. Make kprobes and uprobes consistent in this
regard and allow both $comm and $COMM as well. Currently kprobes and
uprobes only handle $comm, which is inconsistent with the other utilities,
and can be confusing to users.

Link: https://lkml.kernel.org/r/20220820134401.317014913@goodmis.org
Link: https://lore.kernel.org/all/20220820220442.776e1ddaf8836e82edb34d01@kernel.org/

Cc: stable@vger.kernel.org
Cc: Ingo Molnar 
Cc: Andrew Morton 
Cc: Tzvetomir Stoyanov 
Cc: Tom Zanussi 
Fixes: 533059281ee5 ("tracing: probeevent: Introduce new argument fetching code")
Suggested-by: Masami Hiramatsu (Google) 
Acked-by: Masami Hiramatsu (Google) 
Signed-off-by: Steven Rostedt (Google)

tracing/eprobes: Do not hardcode $comm as a string

2022-08-21T19:56:08+00:00

The variable $comm is hard coded as a string, which is true for both
kprobes and uprobes, but for event probes (eprobes) it is a field name. In
most cases the "comm" field would be a string, but there's no guarantee of
that fact.

Do not assume that comm is a string. Not to mention, it currently forces
comm fields to fault, as string processing for event probes is currently
broken.

Link: https://lkml.kernel.org/r/20220820134400.756152112@goodmis.org

Cc: stable@vger.kernel.org
Cc: Ingo Molnar 
Cc: Andrew Morton 
Cc: Masami Hiramatsu 
Cc: Tzvetomir Stoyanov 
Cc: Tom Zanussi 
Fixes: 7491e2c44278 ("tracing: Add a probe that attaches to trace events")
Signed-off-by: Steven Rostedt (Google)