Commit Graph

33 Commits

Author SHA1 Message Date
Linus Torvalds
70a663205d Probes updates for v6.10:
- tracing/probes: Adding new pseudo-types %pd and %pD support for dumping
   dentry name from 'struct dentry *' and file name from 'struct file *'.
 
 - uprobes: Some performance optimizations have been done.
  . Speed up the BPF uprobe event by delaying the fetching of the uprobe
    event arguments that are not used in BPF.
  . Avoid locking by speculatively checking whether uprobe event is valid.
  . Reduce lock contention by using read/write_lock instead of spinlock for
    uprobe list operation. This improved BPF uprobe benchmark result 43% on
    average.
 
 - rethook: Removes non-fatal warning messages when tracing stack from BPF
   and skip rcu_is_watching() validation in rethook if possible.
 
 - objpool: Optimizing objpool (which is used by kretprobes and fprobe as
   rethook backend storage) by inlining functions and avoid caching nr_cpu_ids
   because it is a const value.
 
 - fprobe: Add entry/exit callbacks types (code cleanup)
 - kprobes: Check ftrace was killed in kprobes if it uses ftrace.
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Merge tag 'probes-v6.10' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace

Pull probes updates from Masami Hiramatsu:

 - tracing/probes: Add new pseudo-types %pd and %pD support for dumping
   dentry name from 'struct dentry *' and file name from 'struct file *'

 - uprobes performance optimizations:
    - Speed up the BPF uprobe event by delaying the fetching of the
      uprobe event arguments that are not used in BPF
    - Avoid locking by speculatively checking whether uprobe event is
      valid
    - Reduce lock contention by using read/write_lock instead of
      spinlock for uprobe list operation. This improved BPF uprobe
      benchmark result 43% on average

 - rethook: Remove non-fatal warning messages when tracing stack from
   BPF and skip rcu_is_watching() validation in rethook if possible

 - objpool: Optimize objpool (which is used by kretprobes and fprobe as
   rethook backend storage) by inlining functions and avoid caching
   nr_cpu_ids because it is a const value

 - fprobe: Add entry/exit callbacks types (code cleanup)

 - kprobes: Check ftrace was killed in kprobes if it uses ftrace

* tag 'probes-v6.10' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  kprobe/ftrace: bail out if ftrace was killed
  selftests/ftrace: Fix required features for VFS type test case
  objpool: cache nr_possible_cpus() and avoid caching nr_cpu_ids
  objpool: enable inlining objpool_push() and objpool_pop() operations
  rethook: honor CONFIG_FTRACE_VALIDATE_RCU_IS_WATCHING in rethook_try_get()
  ftrace: make extra rcu_is_watching() validation check optional
  uprobes: reduce contention on uprobes_tree access
  rethook: Remove warning messages printed for finding return address of a frame.
  fprobe: Add entry/exit callbacks types
  selftests/ftrace: add fprobe test cases for VFS type "%pd" and "%pD"
  selftests/ftrace: add kprobe test cases for VFS type "%pd" and "%pD"
  Documentation: tracing: add new type '%pd' and '%pD' for kprobe
  tracing/probes: support '%pD' type for print struct file's name
  tracing/probes: support '%pd' type for print struct dentry's name
  uprobes: add speculative lockless system-wide uprobe filter check
  uprobes: prepare uprobe args buffer lazily
  uprobes: encapsulate preparation of uprobe args buffer
2024-05-17 18:29:30 -07:00
Saurav Shah
dd29dfe78b Documentation: tracing: Fix spelling mistakes
Fix spelling mistakes in the documentation.

Signed-off-by: Saurav Shah <sauravshah.31@gmail.com>
Link: https://lore.kernel.org/r/20240501233659.25441-1-sauravshah.31@gmail.com
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2024-05-07 08:00:25 -06:00
Ye Bin
5e37460f5f Documentation: tracing: add new type '%pd' and '%pD' for kprobe
Similar to printk() '%pd' is for fetch dentry's name from struct dentry's
pointer, and '%pD' is for fetch file's name from struct file's pointer.

Link: https://lore.kernel.org/all/20240322064308.284457-4-yebin10@huawei.com/

Signed-off-by: Ye Bin <yebin10@huawei.com>
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
2024-05-01 23:18:47 +09:00
Masami Hiramatsu (Google)
e8c32f2476 Documentation: tracing: Add entry argument access at function exit
Add a notes about the entry argument access at function exit probes for
kprobes and fprobe trace event.

Link: https://lore.kernel.org/all/170952367549.229804.8843506960483577062.stgit@devnote2/

Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
2024-03-07 00:27:53 +09:00
Masami Hiramatsu (Google)
b2a866975f Documentation: tracing: Add a note about argument and retval access
Add a note about the argument and return value accecss will be best
effort. Depending on the type, it will be passed via stack or a
pair of the registers, but $argN and $retval only support the
single register access.

Link: https://lore.kernel.org/all/169556269377.146934.14829235476649685954.stgit@devnote2/

Suggested-by: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
2023-11-10 19:59:03 +09:00
Masami Hiramatsu (Google)
590e7b2804 Documentation: tracing/probes: Add fprobe event tracing document
Add a documentation about fprobe event tracing including
tracepoint probe event and BTF argument.

Link: https://lore.kernel.org/all/168507479345.913472.2804569685436422001.stgit@mhiramat.roam.corp.google.com/

Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Reviewed-by: Bagas Sanjaya <bagasdotme@gmail.com>
2023-06-06 21:39:56 +09:00
Linus Torvalds
2b79eb73e2 probes updates for 6.3:
- Skip negative return code check for snprintf in eprobe.
 
 - Add recursive call test cases for kprobe unit test
 
 - Add 'char' type to probe events to show it as the character instead of value.
 
 - Update kselftest kprobe-event testcase to ignore '__pfx_' symbols.
 
 - Fix kselftest to check filter on eprobe event correctly.
 
 - Add filter on eprobe to the README file in tracefs.
 
 - Fix optprobes to check whether there is 'under unoptimizing' optprobe when optimizing another kprobe correctly.
 
 - Fix optprobe to check whether there is 'under unoptimizing' optprobe when fetching the original instruction correctly.
 
 - Fix optprobe to free 'forcibly unoptimized' optprobe correctly.
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Merge tag 'probes-v6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace

Pull kprobes updates from Masami Hiramatsu:

 - Skip negative return code check for snprintf in eprobe

 - Add recursive call test cases for kprobe unit test

 - Add 'char' type to probe events to show it as the character instead
   of value

 - Update kselftest kprobe-event testcase to ignore '__pfx_' symbols

 - Fix kselftest to check filter on eprobe event correctly

 - Add filter on eprobe to the README file in tracefs

 - Fix optprobes to check whether there is 'under unoptimizing' optprobe
   when optimizing another kprobe correctly

 - Fix optprobe to check whether there is 'under unoptimizing' optprobe
   when fetching the original instruction correctly

 - Fix optprobe to free 'forcibly unoptimized' optprobe correctly

* tag 'probes-v6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  tracing/eprobe: no need to check for negative ret value for snprintf
  test_kprobes: Add recursed kprobe test case
  tracing/probe: add a char type to show the character value of traced arguments
  selftests/ftrace: Fix probepoint testcase to ignore __pfx_* symbols
  selftests/ftrace: Fix eprobe syntax test case to check filter support
  tracing/eprobe: Fix to add filter on eprobe description in README file
  x86/kprobes: Fix arch_check_optimized_kprobe check within optimized_kprobe range
  x86/kprobes: Fix __recover_optprobed_insn check optimizing logic
  kprobes: Fix to handle forcibly unoptimized kprobes on freeing_list
2023-02-23 13:03:08 -08:00
Donglin Peng
8478cca1e3 tracing/probe: add a char type to show the character value of traced arguments
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 <dolinux.peng@gmail.com>
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
2023-02-21 08:52:42 +09:00
Ross Zwisler
2abfcd293b docs: ftrace: always use canonical ftrace path
The canonical location for the tracefs filesystem is at /sys/kernel/tracing.

But, from Documentation/trace/ftrace.rst:

  Before 4.1, all ftrace tracing control files were within the debugfs
  file system, which is typically located at /sys/kernel/debug/tracing.
  For backward compatibility, when mounting the debugfs file system,
  the tracefs file system will be automatically mounted at:

  /sys/kernel/debug/tracing

Many parts of Documentation still reference this older debugfs path, so
let's update them to avoid confusion.

Signed-off-by: Ross Zwisler <zwisler@google.com>
Reviewed-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Link: https://lore.kernel.org/r/20230125213251.2013791-1-zwisler@google.com
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2023-01-31 14:02:30 -07:00
Yoann Congal
5d18c23c76 Documentation: kprobetrace: Split paragraphs
Add an empty line to force the output to split paragraphs like it is
splitin the REST source.

Signed-off-by: Yoann Congal <yoann.congal@smile.fr>
Reviewed-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Link: https://lore.kernel.org/r/20230121225304.1711635-4-yoann.congal@smile.fr
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2023-01-24 15:00:34 -07:00
Yoann Congal
015b5162be Documentation: kprobetrace: Fix code block markup
This display the following code extract as a code block instead of a
normal paragraph.

Signed-off-by: Yoann Congal <yoann.congal@smile.fr>
Reviewed-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Link: https://lore.kernel.org/r/20230121225304.1711635-3-yoann.congal@smile.fr
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2023-01-24 15:00:28 -07:00
Yoann Congal
776b32b756 Documentation: kprobetrace: Fix some typos
* Uncapitalise tracepoint
* Hyphen in *-based
* Plurals
* fetch-args -> fetchargs
* 2bytes hex -> 2-byte hex
* .. -> .
* arch -> architecture

Signed-off-by: Yoann Congal <yoann.congal@smile.fr>
Reviewed-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Link: https://lore.kernel.org/r/20230121225304.1711635-2-yoann.congal@smile.fr
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2023-01-24 15:00:17 -07:00
Masami Hiramatsu (Google)
b26a124cbf tracing/probes: Add symstr type for dynamic events
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) <mhiramat@kernel.org>
2022-12-15 08:48:57 +09:00
Linyu Yuan
95c104c378 tracing: Auto generate event name when creating a group of events
Currently when creating a specific group of trace events,
take kprobe event as example, the user must use the following format:
p:GRP/EVENT [MOD:]KSYM[+OFFS]|KADDR [FETCHARGS],
which means user must enter EVENT name, one example is:

  echo 'p:usb_gadget/config_usb_cfg_link config_usb_cfg_link $arg1' >> kprobe_events

It is not simple if there are too many entries because the event name is
the same as symbol name.

This change allows user to specify no EVENT name, format changed as:

   p:GRP/ [MOD:]KSYM[+OFFS]|KADDR [FETCHARGS]

It will generate event name automatically and one example is:

  echo 'p:usb_gadget/ config_usb_cfg_link $arg1' >> kprobe_events.

Link: https://lore.kernel.org/all/1656296348-16111-4-git-send-email-quic_linyyuan@quicinc.com/

Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Reviewed-by: Tom Zanussi <zanussi@kernel.org>
Signed-off-by: Linyu Yuan <quic_linyyuan@quicinc.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
2022-07-24 19:11:17 -04:00
Linus Torvalds
fefa636d81 Updates for tracing and bootconfig:
- Add support for "bool" type in synthetic events
 
 - Add per instance tracing for bootconfig
 
 - Support perf-style return probe ("SYMBOL%return") in kprobes and uprobes
 
 - Allow for kprobes to be enabled earlier in boot up
 
 - Added tracepoint helper function to allow testing if tracepoints are
   enabled in headers
 
 - Synthetic events can now have dynamic strings (variable length)
 
 - Various fixes and cleanups
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Merge tag 'trace-v5.10' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace

Pull tracing updates from Steven Rostedt:
 "Updates for tracing and bootconfig:

   - Add support for "bool" type in synthetic events

   - Add per instance tracing for bootconfig

   - Support perf-style return probe ("SYMBOL%return") in kprobes and
     uprobes

   - Allow for kprobes to be enabled earlier in boot up

   - Added tracepoint helper function to allow testing if tracepoints
     are enabled in headers

   - Synthetic events can now have dynamic strings (variable length)

   - Various fixes and cleanups"

* tag 'trace-v5.10' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: (58 commits)
  tracing: support "bool" type in synthetic trace events
  selftests/ftrace: Add test case for synthetic event syntax errors
  tracing: Handle synthetic event array field type checking correctly
  selftests/ftrace: Change synthetic event name for inter-event-combined test
  tracing: Add synthetic event error logging
  tracing: Check that the synthetic event and field names are legal
  tracing: Move is_good_name() from trace_probe.h to trace.h
  tracing: Don't show dynamic string internals in synthetic event description
  tracing: Fix some typos in comments
  tracing/boot: Add ftrace.instance.*.alloc_snapshot option
  tracing: Fix race in trace_open and buffer resize call
  tracing: Check return value of __create_val_fields() before using its result
  tracing: Fix synthetic print fmt check for use of __get_str()
  tracing: Remove a pointless assignment
  ftrace: ftrace_global_list is renamed to ftrace_ops_list
  ftrace: Format variable declarations of ftrace_allocate_records
  ftrace: Simplify the calculation of page number for ftrace_page->records
  ftrace: Simplify the dyn_ftrace->flags macro
  ftrace: Simplify the hash calculation
  ftrace: Use fls() to get the bits for dup_hash()
  ...
2020-10-15 15:51:28 -07:00
Masami Hiramatsu
638e476d1d Documentation: tracing: Add %return suffix description
Add a description of the %return suffix option for kprobe event and
uprobe event.

Link: https://lkml.kernel.org/r/159972815624.428528.10450874184415697524.stgit@devnote2

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2020-09-21 21:06:03 -04:00
Mauro Carvalho Chehab
7f9a2357c4 docs: trace: fix the location of kprobes.rst
This patch was moved out of staging.

Fixes: 2165b82fde ("docs: Move kprobes.rst from staging/ to trace/")

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Link: https://lore.kernel.org/r/a6d4c62e19ab1510789418a3a5ad42980cd7ae3a.1599660067.git.mchehab+huawei@kernel.org
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2020-09-10 10:46:24 -06:00
Mauro Carvalho Chehab
8e2a46a40f docs: move remaining stuff under Documentation/*.txt to Documentation/staging
There are several files that I was unable to find a proper place
for them, and 3 ones that are still in plain old text format.

Let's place those stuff behind the carpet, as we'd like to keep the
root directory clean.

We can later discuss and move those into better places.

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Link: https://lore.kernel.org/r/11bd0d75e65a874f7c276a0aeab0fe13f3376f5f.1592203650.git.mchehab+huawei@kernel.org
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2020-06-19 14:17:05 -06:00
Sameer Rahmani
ff1e81a7e2 Documentation: build warnings related to missing blank lines after explicit markups has been fixed
Fix for several documentation build warnings related to missing blank lines
after explicit mark up.

Exact warning message:
 WARNING: Explicit markup ends without a blank line; unexpected unindent.

Signed-off-by: Sameer Rahmani <lxsameer@gnu.org>
Link: https://lore.kernel.org/r/20200203201543.24834-1-lxsameer@gnu.org
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2020-02-05 10:30:03 -07:00
Masami Hiramatsu
6218bf9f4d tracing/probe: Add immediate parameter support
Add immediate value parameter (\1234) support to
probe events. This allows you to specify an immediate
(or dummy) parameter instead of fetching from memory
or register.

This feature looks odd, but imagine when you put a probe
on a code to trace some data. If the code is compiled into
2 instructions and 1 instruction has a value but other has
nothing since it is optimized out.
In that case, you can not fold those into one event, even
if ftrace supported multiple probes on one event.
With this feature, you can set a dummy value like
foo=\deadbeef instead of something like foo=%di.

Link: http://lkml.kernel.org/r/156095690733.28024.13258186548822649469.stgit@devnote2

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2019-08-31 12:19:39 -04:00
Linus Torvalds
818e95c768 The main changes in this release include:
- Add user space specific memory reading for kprobes
  - Allow kprobes to be executed earlier in boot
 
 The rest are mostly just various clean ups and small fixes.
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Merge tag 'trace-v5.3' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace

Pull tracing updates from Steven Rostedt:
 "The main changes in this release include:

   - Add user space specific memory reading for kprobes

   - Allow kprobes to be executed earlier in boot

  The rest are mostly just various clean ups and small fixes"

* tag 'trace-v5.3' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: (33 commits)
  tracing: Make trace_get_fields() global
  tracing: Let filter_assign_type() detect FILTER_PTR_STRING
  tracing: Pass type into tracing_generic_entry_update()
  ftrace/selftest: Test if set_event/ftrace_pid exists before writing
  ftrace/selftests: Return the skip code when tracing directory not configured in kernel
  tracing/kprobe: Check registered state using kprobe
  tracing/probe: Add trace_event_call accesses APIs
  tracing/probe: Add probe event name and group name accesses APIs
  tracing/probe: Add trace flag access APIs for trace_probe
  tracing/probe: Add trace_event_file access APIs for trace_probe
  tracing/probe: Add trace_event_call register API for trace_probe
  tracing/probe: Add trace_probe init and free functions
  tracing/uprobe: Set print format when parsing command
  tracing/kprobe: Set print format right after parsed command
  kprobes: Fix to init kprobes in subsys_initcall
  tracepoint: Use struct_size() in kmalloc()
  ring-buffer: Remove HAVE_64BIT_ALIGNED_ACCESS
  ftrace: Enable trampoline when rec count returns back to one
  tracing/kprobe: Do not run kprobe boot tests if kprobe_event is on cmdline
  tracing: Make a separate config for trace event self tests
  ...
2019-07-18 11:51:00 -07:00
Mauro Carvalho Chehab
7e6294cdc0 docs: trace: add a missing blank line
Sphinx expects a blank line after a literal block markup.

Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2019-06-20 14:05:46 -06:00
Lecopzer Chen
78a89463a3 Documentation: {u,k}probes: add tracing_on before tracing
After following the document step by step, the `cat trace` can't be
worked without enabling tracing_on and might mislead newbies about
the functionality.

Signed-off-by: Lecopzer Chen <lecopzer.chen@mediatek.com>
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2019-06-07 11:56:51 -06:00
Masami Hiramatsu
970988e19e tracing/kprobe: Add kprobe_event= boot parameter
Add kprobe_event= boot parameter to define kprobe events
at boot time.
The definition syntax is similar to tracefs/kprobe_events
interface, but use ',' and ';' instead of ' ' and '\n'
respectively. e.g.

  kprobe_event=p,vfs_read,$arg1,$arg2

This puts a probe on vfs_read with argument1 and 2, and
enable the new event.

Link: http://lkml.kernel.org/r/155851395498.15728.830529496248543583.stgit@devnote2

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2019-05-25 23:04:43 -04:00
Masami Hiramatsu
e65f7ae7f4 tracing/probe: Support user-space dereference
Support user-space dereference syntax for probe event arguments
to dereference the data-structure or array in user-space.

The syntax is just adding 'u' before an offset value.

 +|-u<OFFSET>(<FETCHARG>)

e.g. +u8(%ax), +u0(+0(%si))

For example, if you probe do_sched_setscheduler(pid, policy,
param) and record param->sched_priority, you can add new
probe as below;

 p do_sched_setscheduler priority=+u0($arg3)

Note that kprobe event provides this and it doesn't change the
dereference method automatically because we do not know whether
the given address is in userspace or kernel on some archs.

So as same as "ustring", this is an option for user, who has to
carefully choose the dereference method.

Link: http://lkml.kernel.org/r/155789872187.26965.4468456816590888687.stgit@devnote2

Acked-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2019-05-25 23:04:42 -04:00
Masami Hiramatsu
88903c4643 tracing/probe: Add ustring type for user-space string
Add "ustring" type for fetching user-space string from kprobe event.
User can specify ustring type at uprobe event, and it is same as
"string" for uprobe.

Note that probe-event provides this option but it doesn't choose the
correct type automatically since we have not way to decide the address
is in user-space or not on some arch (and on some other arch, you can
fetch the string by "string" type). So user must carefully check the
target code (e.g. if you see __user on the target variable) and
use this new type.

Link: http://lkml.kernel.org/r/155789871009.26965.14167558859557329331.stgit@devnote2

Acked-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2019-05-25 23:04:42 -04:00
Masami Hiramatsu
6212dd2968 tracing/kprobes: Use dyn_event framework for kprobe events
Use dyn_event framework for kprobe events. This shows
kprobe events on "tracing/dynamic_events" file.

User can also define new events via tracing/dynamic_events.

Link: http://lkml.kernel.org/r/154140855646.17322.6619219995865980392.stgit@devbox

Reviewed-by: Tom Zanussi <tom.zanussi@linux.intel.com>
Tested-by: Tom Zanussi <tom.zanussi@linux.intel.com>
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2018-12-08 20:54:09 -05:00
Masami Hiramatsu
a1303af5d7 tracing: probeevent: Add $argN for accessing function args
Add $argN special fetch variable for accessing function
arguments. This allows user to trace the Nth argument easily
at the function entry.

Note that this returns most probably assignment of registers
and stacks. In some case, it may not work well. If you need
to access correct registers or stacks you should use perf-probe.

Link: http://lkml.kernel.org/r/152465888632.26224.3412465701570253696.stgit@devbox

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2018-10-10 22:19:11 -04:00
Masami Hiramatsu
40b53b7718 tracing: probeevent: Add array type support
Add array type support for probe events.
This allows user to get arraied types from memory address.
The array type syntax is

	TYPE[N]

Where TYPE is one of types (u8/16/32/64,s8/16/32/64,
x8/16/32/64, symbol, string) and N is a fixed value less
than 64.

The string array type is a bit different from other types. For
other base types, <base-type>[1] is equal to <base-type>
(e.g. +0(%di):x32[1] is same as +0(%di):x32.) But string[1] is not
equal to string. The string type itself represents "char array",
but string array type represents "char * array". So, for example,
+0(%di):string[1] is equal to +0(+0(%di)):string.

Link: http://lkml.kernel.org/r/152465891533.26224.6150658225601339931.stgit@devbox

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2018-10-10 22:19:10 -04:00
Masami Hiramatsu
60c2e0cebf tracing: probeevent: Add symbol type
Add "symbol" type to probeevent, which is an alias of u32 or u64
(depends on BITS_PER_LONG). This shows the result value in
symbol+offset style. This type is only available with kprobe
events.

Link: http://lkml.kernel.org/r/152465882860.26224.14779072294412467338.stgit@devbox

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2018-10-10 22:19:10 -04:00
Andreas Ziegler
31130c8ec8 Documentation: kprobetrace: document 'trigger' file
As the other files are documented explicitly, let's add a
short description for 'trigger' as well.

Signed-off-by: Andreas Ziegler <andreas.ziegler@fau.de>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2018-07-23 09:26:42 -06:00
Andreas Ziegler
e50891d6ef Documentation: {u,k}probes: fix filename for event enabling
The per-event files to enable or disable kprobes and uprobes
are named 'enable', not 'enabled'. Fix the corresponding
documentation.

Signed-off-by: Andreas Ziegler <andreas.ziegler@fau.de>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2018-07-23 09:26:37 -06:00
Changbin Du
263ee77574 trace doc: convert trace/kprobetrace.txt to rst format
This converts the plain text documentation to reStructuredText format and
add it into Sphinx TOC tree. No essential content change.

Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Changbin Du <changbin.du@intel.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2018-03-07 10:23:15 -07:00