linux/tools/testing/selftests/ftrace
Linus Torvalds 6439079365 Probes updates for v7.3:
- probes: Advanced BTF typecasting and variable fetch enhancements
   . Typecast support across probe events: Extended BTF typecasting syntax
     (e.g., (STRUCT)PARAM->MEMBER) to kprobes, uprobes, and fprobes on
     function entry and return.
   . Nested typecasts: Added support for chaining and nesting typecasts up
     to 3 levels, including casting registers and stack variables.
   . Field specifier option: Added (STRUCT,FIELD) syntax to emulate
     container_of(), allowing retrieval of parent structures from member
     pointers.
   . $current variable support: Introduced $current special variable to
     access the running task_struct via BTF dereferencing.
   . Per-CPU variable access: Added this_cpu_read() and this_cpu_ptr()
     fetcharg methods to trace CPU-local data safely.
   . Fetcharg bytecode dumper: Added CONFIG_PROBE_EVENTS_DUMP_FETCHARG to
     dump the compiled fetcharg bytecode instructions as comments in
     dynamic_events.
   . Extended symbol name handling: Removed the MAX_COMMON_HEAD_LEN limit
     and extended MAX_ARGSTR_LEN to 256 bytes, enabling probing of long
     symbols, mangled Rust symbols and complex BTF expressions.
   . eprobe variable syntax: Allowed eprobes to reference event fields
     directly without requiring a '$' prefix.
   . Cleanup unused parameters, redundant codes, duplicate macros and
     pointer arithmetic.
   . Use a ternary operator for simplifying fetch_type_from_btf_type().
 
 - bootconfig / boottime-trace: Expanded dynamic probe support
   . Added boot-time tracing configuration support for event probes
     (eprobes), function probes (fprobes), and tracepoint probes
     (tprobes).
   . ftrace2bootconfig: Allowed comment lines ('#') in dynamic_events file.
 
 - fprobe / kprobe: Optimization, robustness, and cleanups
   . fprobe: Simplified fprobe_remove_ips() by reusing graph and ftrace
     helpers.
   . fprobe: Removed __packed attribute from struct __fprobe_header to avoid
     unaligned memory access penalties on RISC architectures.
   . kprobe & fprobe: Removed redundant memset() calls in perf event probe
     handlers.
   . kprobes: Replaced legacy __ASSEMBLY__ with __ASSEMBLER__ in header
     files.
 
 - selftests & refactoring:
   . Refactored parse_probe_arg() and parse_probe_vars(), and eliminated
     recursion in probe argument parsing to protect kernel stack depth.
   . Added selftests for BTF typecasts and module probing without module
     prefixes.
   . Forced LC_ALL=C in ftracetest to prevent test failures on localized
     systems.
   . Refactored btf_type_skip_modifiers() to remove ignored id parameter.
   . Sorted ERRORS list in trace_probe.h alphabetically.
   . Fixed typo in fprobe docs, and trace_fprobe function name.
   . Renamed FETCH_OP_DATA to FETCH_OP_IMMSTR.
   . Made file offset error message probe-agnostic.
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Merge tag 'probes-v7.3' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace

Pull probes updates from Masami Hiramatsu:
 "BTF typecasting and variable fetch enhancements:

   - Typecast support across probe events: Extended BTF typecasting
     syntax (e.g., (STRUCT)PARAM->MEMBER) to kprobes, uprobes, and
     fprobes on function entry and return

   - Nested typecasts: Added support for chaining and nesting typecasts
     up to 3 levels, including casting registers and stack variables

   - Field specifier option: Added (STRUCT,FIELD) syntax to emulate
     container_of(), allowing retrieval of parent structures from member
     pointers

   - $current variable support: Introduced $current special variable to
     access the running task_struct via BTF dereferencing

   - Per-CPU variable access: Added this_cpu_read() and this_cpu_ptr()
     fetcharg methods to trace CPU-local data safely

   - Fetcharg bytecode dumper: Added CONFIG_PROBE_EVENTS_DUMP_FETCHARG
     to dump the compiled fetcharg bytecode instructions as comments in
     dynamic_events

   - Extended symbol name handling: Removed the MAX_COMMON_HEAD_LEN
     limit and extended MAX_ARGSTR_LEN to 256 bytes, enabling probing of
     long symbols, mangled Rust symbols and complex BTF expressions

   - eprobe variable syntax: Allowed eprobes to reference event fields
     directly without requiring a '$' prefix

   - Cleanup unused parameters, redundant codes, duplicate macros and
     pointer arithmetic

   - Use a ternary operator for simplifying fetch_type_from_btf_type()

  Expanded boot time dynamic probe support:

   - Add boot-time tracing configuration support for event probes
     (eprobes), function probes (fprobes), and tracepoint probes
     (tprobes)

   - Allow comment lines ('#') in dynamic_events file

  Optimization, robustness, and cleanups:

   - Simplify fprobe_remove_ips() by reusing graph and ftrace helpers

   - Remove __packed attribute from struct __fprobe_header to avoid
     unaligned memory access penalties on RISC architectures

   - Remove redundant memset() calls in perf event probe handlers

   - Replace legacy __ASSEMBLY__ with __ASSEMBLER__ in header files

  Selftests & refactoring:

   - Refactor parse_probe_arg() and parse_probe_vars(), and eliminate
     recursion in probe argument parsing to protect kernel stack depth

   - Add selftests for BTF typecasts and module probing without module
     prefixes

   - Force LC_ALL=C in ftracetest to prevent test failures on localized
     systems

   - Refactor btf_type_skip_modifiers() to remove ignored id parameter

   - Sort ERRORS list in trace_probe.h alphabetically

   - Fix typo in fprobe docs, and trace_fprobe function name

   - Rename FETCH_OP_DATA to FETCH_OP_IMMSTR

   - Make file offset error message probe-agnostic"

* tag 'probes-v7.3' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: (37 commits)
  fprobe: Simplify fprobe_remove_ips() by reusing existing helpers
  tracing/boot: Add support for eprobe, fprobe, and tprobe events
  selftests/ftrace: Force C locale in ftracetest
  tracing/probes: Treating longer symbol name on event comparation
  docs: trace: fprobe: fix 'thos' spelling
  tracing/probes: Fix extra whitespace in trace_probe_kernel.h
  tracing/kprobe: Remove redundant memset in kprobe_perf_func()
  tracing/fprobe: Remove redundant memset in fentry_perf_func()
  tracing/fprobe: Remove redundant snprintf in trace_fprobe_match_command_head()
  tracing/probes: Simplify BTF_KIND_PTR case in fetch_type_from_btf_type()
  tracing/probes: Cleanup pointer arithmetic in store_trace_entry_data()
  tracing/probes: Remove unused parameter from parse_probe_var_retval()
  tracing/probes: Remove redundant bounds check in trace_probe_compare_arg_type()
  tracing/probes: Remove redundant boolean conversion in trace_probe_has_single_file()
  tracing/probes: Remove duplicate MAX_ARRAY_LEN macro definition
  selftests/ftrace: Add test case for a symbol in a module without module name
  tracing/probes: Eliminate recursion in parse_probe_arg()
  tracing/probes: Extend max length of argument string
  tracing/probes: Sort ERRORS list in trace_probe.h alphabetically
  tracing/probes: Refactor parse_probe_arg()
  ...
2026-08-20 15:11:52 -07:00
..
samples ftracetest: Add POSIX.3 standard and XFAIL result codes 2014-10-03 16:44:02 -04:00
test.d Probes updates for v7.3: 2026-08-20 15:11:52 -07:00
.gitignore selftests/ftrace: add 'poll' binary to gitignore 2025-03-04 08:51:17 -07:00
config sefltests/tracing: Add a test for tracepoint events on modules 2024-09-25 23:23:44 +09:00
ftracetest Probes updates for v7.3: 2026-08-20 15:11:52 -07:00
ftracetest-ktap tracing/selftests: Default to verbose mode when running in kselftest 2024-05-06 13:57:20 -06:00
Makefile selftests/ftrace: Convert poll to a gen_file 2025-05-09 12:43:10 -06:00
poll.c selftests/ftrace: fix spelling error in poll test comment 2026-07-10 11:29:22 -06:00
README ftracetest: Add POSIX.3 standard and XFAIL result codes 2014-10-03 16:44:02 -04:00
settings tracing/selftests: Turn off timeout setting 2019-11-14 13:15:11 -05:00

Linux Ftrace Testcases

This is a collection of testcases for ftrace tracing feature in the Linux
kernel. Since ftrace exports interfaces via the debugfs, we just need
shell scripts for testing. Feel free to add new test cases.

Running the ftrace testcases
============================

At first, you need to be the root user to run this script.
To run all testcases:

  $ sudo ./ftracetest

To run specific testcases:

  # ./ftracetest test.d/basic3.tc

Or you can also run testcases under given directory:

  # ./ftracetest test.d/kprobe/

Contributing new testcases
==========================

Copy test.d/template to your testcase (whose filename must have *.tc
extension) and rewrite the test description line.

 * The working directory of the script is <debugfs>/tracing/.

 * Take care with side effects as the tests are run with root privilege.

 * The tests should not run for a long period of time (more than 1 min.)
   These are to be unit tests.

 * You can add a directory for your testcases under test.d/ if needed.

 * The test cases should run on dash (busybox shell) for testing on
   minimal cross-build environments.

 * Note that the tests are run with "set -e" (errexit) option. If any
   command fails, the test will be terminated immediately.

 * The tests can return some result codes instead of pass or fail by
   using exit_unresolved, exit_untested, exit_unsupported and exit_xfail.

Result code
===========

Ftracetest supports following result codes.

 * PASS: The test succeeded as expected. The test which exits with 0 is
         counted as passed test.

 * FAIL: The test failed, but was expected to succeed. The test which exits
         with !0 is counted as failed test.

 * UNRESOLVED: The test produced unclear or intermidiate results.
             for example, the test was interrupted
                       or the test depends on a previous test, which failed.
                       or the test was set up incorrectly
             The test which is in above situation, must call exit_unresolved.

 * UNTESTED: The test was not run, currently just a placeholder.
             In this case, the test must call exit_untested.

 * UNSUPPORTED: The test failed because of lack of feature.
               In this case, the test must call exit_unsupported.

 * XFAIL: The test failed, and was expected to fail.
          To return XFAIL, call exit_xfail from the test.

There are some sample test scripts for result code under samples/.
You can also run samples as below:

  # ./ftracetest samples/

TODO
====

 * Fancy colored output :)