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

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) <mhiramat@kernel.org>

selftests/ftrace: Add BTF arguments test cases

Add test cases to check the BTF arguments correctly supported.

Link: https://lore.kernel.org/all/168507478292.913472.25631899274942311.stgit@mhiramat.roam.corp.google.com/

Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>

tracing/probes: Add fprobe events for tracing function entry and exit.

Add fprobe events for tracing function entry and exit instead of kprobe
events. With this change, we can continue to trace function entry/exit
even if the CONFIG_KPROBES_ON_FTRACE is not available. Since
CONFIG_KPROBES_ON_FTRACE requires the CONFIG_DYNAMIC_FTRACE_WITH_REGS,
it is not available if the architecture only supports
CONFIG_DYNAMIC_FTRACE_WITH_ARGS. And that means kprobe events can not
probe function entry/exit effectively on such architecture.
But this can be solved if the dynamic events supports fprobe events.

The fprobe event is a new dynamic events which is only for the function
(symbol) entry and exit. This event accepts non register fetch arguments
so that user can trace the function arguments and return values.

The fprobe events syntax is here;

f[:[GRP/][EVENT]] FUNCTION [FETCHARGS]
f[MAXACTIVE][:[GRP/][EVENT]] FUNCTION%return [FETCHARGS]

E.g.

# echo 'f vfs_read $arg1' >> dynamic_events
# echo 'f vfs_read%return $retval' >> dynamic_events
# cat dynamic_events
f:fprobes/vfs_read__entry vfs_read arg1=$arg1
f:fprobes/vfs_read__exit vfs_read%return arg1=$retval
# echo 1 > events/fprobes/enable
# head -n 20 trace | tail
# TASK-PID CPU# ||||| TIMESTAMP FUNCTION
# | | | ||||| | |
sh-142 [005] ...1. 448.386420: vfs_read__entry: (vfs_read+0x4/0x340) arg1=0xffff888007f7c540
sh-142 [005] ..... 448.386436: vfs_read__exit: (ksys_read+0x75/0x100 <- vfs_read) arg1=0x1
sh-142 [005] ...1. 448.386451: vfs_read__entry: (vfs_read+0x4/0x340) arg1=0xffff888007f7c540
sh-142 [005] ..... 448.386458: vfs_read__exit: (ksys_read+0x75/0x100 <- vfs_read) arg1=0x1
sh-142 [005] ...1. 448.386469: vfs_read__entry: (vfs_read+0x4/0x340) arg1=0xffff888007f7c540
sh-142 [005] ..... 448.386476: vfs_read__exit: (ksys_read+0x75/0x100 <- vfs_read) arg1=0x1
sh-142 [005] ...1. 448.602073: vfs_read__entry: (vfs_read+0x4/0x340) arg1=0xffff888007f7c540
sh-142 [005] ..... 448.602089: vfs_read__exit: (ksys_read+0x75/0x100 <- vfs_read) arg1=0x1

Link: https://lore.kernel.org/all/168507469754.913472.6112857614708350210.stgit@mhiramat.roam.corp.google.com/

Reported-by: kernel test robot <lkp@intel.com>
Link: https://lore.kernel.org/all/202302011530.7vm4O8Ro-lkp@intel.com/
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>

selftests/kprobe: Update test for no event name syntax error

The commit 208003254c32 ("selftests/kprobe: Do not test for GRP/
without event failures") removed a syntax which is no more cause
a syntax error (NO_EVENT_NAME error with GRP/).
However, there are another case (NO_EVENT_NAME error without GRP/)
which causes a same error. This adds a test for that case.

Link: https://lkml.kernel.org/r/165812790993.1377963.9762767354560397298.stgit@devnote2

Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

selftests/kprobe: Do not test for GRP/ without event failures

A new feature is added where kprobes (and other probes) do not need to
explicitly state the event name when creating a probe. The event name will
come from what is being attached.

That is:

# echo 'p:foo/ vfs_read' > kprobe_events

Will no longer error, but instead create an event:

# cat kprobe_events
p:foo/p_vfs_read_0 vfs_read

This should not be tested as an error case anymore. Remove it from the
selftest as now this feature "breaks" the selftest as it no longer fails
as expected.

Link: https://lore.kernel.org/all/1656296348-16111-1-git-send-email-quic_linyyuan@quicinc.com/
Link: https://lkml.kernel.org/r/20220712161707.6dc08a14@gandalf.local.home

Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

selftests/ftrace: Use $FUNCTION_FORK to reference kernel fork function

Commit cad6967ac108 ("fork: introduce kernel_clone()") replaced "_do_fork()"
with "kernel_clone()". The ftrace selftests reference the fork function in
several of the tests. The rename will make the tests break, but if those
names are changed in the tests, they would then break on older kernels. The
same set of tests should pass older kernels if they have previously passed.
Obviously, a new test may not work on older kernels if the test was added
due to a bug or a new feature.

The setup of ftracetest will now create a $FUNCTION_FORK bash variable
that will contain "_do_fork" for older kernels and "kernel_clone" for newer
ones. It figures out the proper name by examining /proc/kallsyms.

Note, available_filter_functions could also be used, but because some tests
should be able to pass without function tracing enabled, it could not be
used.

Fixes: eea11285dab3 ("tracing: switch to kernel_clone()")
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>

selftests/ftrace: Add %return suffix tests

Add kprobe %return suffix testcase and syntax error tests
for %return suffix.

Link: https://lkml.kernel.org/r/159972817653.428528.9180599115849301184.stgit@devnote2

Acked-by: Shuah Khan <skhan@linuxfoundation.org>
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

tracing: switch to kernel_clone()

The old _do_fork() helper is removed in favor of the new kernel_clone() helper.
The latter adheres to naming conventions for kernel internal syscall helpers.

Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
Cc: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Cc: Alexandre Chartre <alexandre.chartre@oracle.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Xiao Yang <yangx.jy@cn.fujitsu.com>
Cc: Tom Zanussi <zanussi@kernel.org>
Cc: linux-doc@vger.kernel.org
Cc: linux-kselftest@vger.kernel.org
Link: https://lore.kernel.org/r/20200819104655.436656-11-christian.brauner@ubuntu.com

selftests/ftrace: Convert required interface checks into requires list

Convert the required tracefs interface checking code with
requires: list.

Fixed merge conflicts in trigger-hist.tc and trigger-trace-marker-hist.tc
Shuah Khan <skhan@linuxfoundation.org>

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Reviewed-by: Tom Zanussi <zanussi@kernel.org>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>

selftests/ftrace: Use printf for backslash included command

Since the built-in echo has different behavior in POSIX shell
(dash) and bash, kprobe_syntax_errors.tc can fail on dash which
interpret backslash escape automatically.

To fix this issue, we explicitly use printf "%s" (not interpret
backslash escapes) if the command string can include backslash.

Reported-by: Liu Yiding <yidingx.liu@intel.com>
Suggested-by: Xiao Yang <yangx.jy@cn.fujitsu.com>
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>

selftests/ftrace: Fix same probe error test

The "same probe" selftest that tests that adding the same probe fails
doesn't add the same probe and passes, which fails the test.

Fixes: b78b94b82122 ("selftests/ftrace: Update kprobe event error testcase")
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

selftests/ftrace: Update kprobe event error testcase

Update kprobe event error testcase to test if it correctly
finds the exact same probe event.

Link: http://lkml.kernel.org/r/156879695513.31056.1580235733738840126.stgit@devnote2

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

selftests/ftrace: Add syntax error test for multiprobe

Add syntax error test cases for multiprobe appending
errors.

Link: http://lkml.kernel.org/r/156095694541.28024.11918630805148623119.stgit@devnote2

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

selftests/ftrace: Add syntax error test for immediates

Add syntax error test cases for immediate value and
immediate string.

Link: http://lkml.kernel.org/r/156095693553.28024.7730929892585591691.stgit@devnote2

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

selftests/ftrace: Move kprobe/uprobe check_error() to test.d/functions

The k/uprobe_sytax_errors test case defines a check_error() function
used to run a command and check the position of the caret in the
output.

This would be useful for other ftrace facilities too, so move it to
test.d/functions for use by anyone. In the process, rename it to
ftrace_errlog_check() and parametrize it for general use.

Link: http://lkml.kernel.org/r/9f88080a06f1755811f69081926afe7e5cb53178.1554072478.git.tom.zanussi@linux.intel.com

Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Tom Zanussi <tom.zanussi@linux.intel.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

selftests/ftrace: Add error_log testcase for probe errors

Add error_log testcase for error logs on probe events.
This tests most of error cases and checks the error position
is correct.

Link: http://lkml.kernel.org/r/63d695b74e0965988fa54ffa12beeb2c3475250d.1554072478.git.tom.zanussi@linux.intel.com

Acked-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
[tom.zanussi@linux.intel.com: changed >& redirection to 2>]
Signed-off-by: Tom Zanussi <tom.zanussi@linux.intel.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>