samples: add hung_task detector mutex blocking sample

Add a hung_task detector mutex blocking test sample code.

This module will create a dummy file on the debugfs. That file will cause
the read p

samples: add hung_task detector mutex blocking sample

Add a hung_task detector mutex blocking test sample code.

This module will create a dummy file on the debugfs. That file will cause
the read process to sleep for enough long time (256 seconds) while holding
a mutex. As a result, the second process will wait on the mutex for a
prolonged duration and be detected by the hung_task detector.

Usage is;

> cd /sys/kernel/debug/hung_task
> cat mutex & cat mutex

and wait for hung_task message.

[[email protected]: make `hung_task_dir' static]
Closes: https://lore.kernel.org/oe-kbuild-all/[email protected]/
Link: https://lkml.kernel.org/r/174046696281.2194069.4567490148001547311.stgit@mhiramat.tok.corp.google.com
Signed-off-by: Masami Hiramatsu (Google) <[email protected]>
Cc: Anna Schumaker <[email protected]>
Cc: Boqun Feng <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Joel Granados <[email protected]>
Cc: Kent Overstreet <[email protected]>
Cc: Lance Yang <[email protected]>
Cc: Sergey Senozhatsky <[email protected]>
Cc: Steven Rostedt <[email protected]>
Cc: Tomasz Figa <[email protected]>
Cc: Waiman Long <[email protected]>
Cc: Will Deacon <[email protected]>
Cc: Yongliang Gao <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

show more ...

samples/damon: introduce a skeleton of a smaple DAMON module for proactive reclamation

DAMON is not only for monitoring of access patterns, but also for
access-aware system operations. For the syst

samples/damon: introduce a skeleton of a smaple DAMON module for proactive reclamation

DAMON is not only for monitoring of access patterns, but also for
access-aware system operations. For the system operations, DAMON provides
a feature called DAMOS (Data Access Monitoring-based Operation Schemes).
There is no sample API usage of DAMOS, though. Copy the working set size
estimation sample modules with changed names of the module and symbols, to
use it as a skeleton for a sample module showing the DAMOS API usage. The
following commit will make it proactively reclaim cold memory of the given
process, using DAMOS.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: SeongJae Park <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

show more ...

samples: add a skeleton of a sample DAMON module for working set size estimation

Patch series "mm/damon: add sample modules".

Implement a proactive cold memory regions reclaiming logic of prcl samp

samples: add a skeleton of a sample DAMON module for working set size estimation

Patch series "mm/damon: add sample modules".

Implement a proactive cold memory regions reclaiming logic of prcl sample
module using DAMOS. The logic treats memory regions that not accessed at
all for five or more seconds as cold, and reclaim those as soon as found.


This patch (of 5):

Add a skeleton for a sample DAMON static module that can be used for
estimating working set size of a given process. Note that it is a static
module since DAMON is not exporting symbols to loadable modules for now.
It exposes two module parameters, namely 'pid' and 'enable'. 'pid' will
specify the process that the module will estimate the working set size of.
'enable' will receive whether to start or stop the estimation. Because
this is just a skeleton, the parameters do nothing, though. The
functionalities will be implemented by following commits.

Link: https://lkml.kernel.org/r/[email protected]
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: SeongJae Park <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

show more ...

samples/check-exec: Add set-exec

Add a simple tool to set SECBIT_EXEC_RESTRICT_FILE or
SECBIT_EXEC_DENY_INTERACTIVE before executing a command. This is useful
to easily test against enlighten scrip

samples/check-exec: Add set-exec

Add a simple tool to set SECBIT_EXEC_RESTRICT_FILE or
SECBIT_EXEC_DENY_INTERACTIVE before executing a command. This is useful
to easily test against enlighten script interpreters.

Cc: Al Viro <[email protected]>
Cc: Christian Brauner <[email protected]>
Cc: Kees Cook <[email protected]>
Cc: Paul Moore <[email protected]>
Cc: Serge Hallyn <[email protected]>
Signed-off-by: Mickaël Salaün <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Kees Cook <[email protected]>

show more ...

samples: introduce new samples subdir for cgroup

Patch series "samples: introduce cgroup events listeners", v3.

To begin with, this patch series relocates the cgroup example code to the
samples/cgr

samples: introduce new samples subdir for cgroup

Patch series "samples: introduce cgroup events listeners", v3.

To begin with, this patch series relocates the cgroup example code to the
samples/cgroup directory, which is the appropriate location for such code
snippets.

Furthermore, a new memcg events listener is introduced. This listener is
a simple yet effective tool for monitoring memory events and managing
counter changes during runtime.

Additionally, as per Andrew Morton's suggestion, a helpful reminder
comment is included in the memcontrol implementation. This comment serves
to ensure that the samples code is updated whenever new events are added.


This patch (of 3):

Move the cgroup_event_listener for cgroup v1 to the samples directory.
This suggestion was proposed by Andrew Morton during the discussion [1].

Link: https://lore.kernel.org/all/[email protected]/ [1]
Link: https://lkml.kernel.org/r/[email protected]
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Dmitry Rokosov <[email protected]>
Cc: Johannes Weiner <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: Muchun Song <[email protected]>
Cc: Roman Gushchin <[email protected]>
Cc: Shakeel Butt <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

show more ...

samples: Add userspace example for TI TPS6594 PFSM

This patch adds an example showing how to use PFSM devices
from a userspace application. The PMIC is armed to be triggered
by a RTC alarm to execut

samples: Add userspace example for TI TPS6594 PFSM

This patch adds an example showing how to use PFSM devices
from a userspace application. The PMIC is armed to be triggered
by a RTC alarm to execute state transition.

Signed-off-by: Julien Panis <[email protected]>
Message-ID: <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>

show more ...

kmemleak-test: fix kmemleak_test.c build logic

kmemleak-test.c was moved to the samples directory in 1abbef4f51724
("mm,kmemleak-test.c: move kmemleak-test.c to samples dir").

If CONFIG_DEBUG_KMEML

kmemleak-test: fix kmemleak_test.c build logic

kmemleak-test.c was moved to the samples directory in 1abbef4f51724
("mm,kmemleak-test.c: move kmemleak-test.c to samples dir").

If CONFIG_DEBUG_KMEMLEAK_TEST=m and CONFIG_SAMPLES is unset,
kmemleak-test.c will be unnecessarily compiled.

So move the entry for CONFIG_DEBUG_KMEMLEAK_TEST from mm/Kconfig and add a
new CONFIG_SAMPLE_KMEMLEAK in samples/ to control whether kmemleak-test.c
is built or not.

Link: https://lkml.kernel.org/r/[email protected]
Fixes: 1abbef4f51724 ("mm,kmemleak-test.c: move kmemleak-test.c to samples dir")
Signed-off-by: Hao Ge <[email protected]>
Cc: Catalin Marinas <[email protected]>
Cc: Alex Gaynor <[email protected]>
Cc: Alex Williamson <[email protected]>
Cc: Arnd Bergmann <[email protected]>
Cc: Finn Behrens <[email protected]>
Cc: Greg Kroah-Hartman <[email protected]>
Cc: Jason Gunthorpe <[email protected]>
Cc: Mark Rutland <[email protected]>
Cc: Miguel Ojeda <[email protected]>
Cc: Tony Krowiak <[email protected]>
Cc: Ye Xingchen <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

show more ...

ftrace: Add sample with custom ops

When reworking core ftrace code or architectural ftrace code, it's often
necessary to test/analyse/benchmark a number of ftrace_ops
configurations. This patch adds

ftrace: Add sample with custom ops

When reworking core ftrace code or architectural ftrace code, it's often
necessary to test/analyse/benchmark a number of ftrace_ops
configurations. This patch adds a module which can be used to explore
some of those configurations.

I'm using this to benchmark various options for changing the way
trampolines and handling of ftrace_ops work on arm64, and ensuring other
architectures aren't adversely affected.

For example, in a QEMU+KVM VM running on a 2GHz Xeon E5-2660
workstation, loading the module in various configurations produces:

| # insmod ftrace-ops.ko
| ftrace_ops: registering:
| relevant ops: 1
| tracee: tracee_relevant [ftrace_ops]
| tracer: ops_func_nop [ftrace_ops]
| irrelevant ops: 0
| tracee: tracee_irrelevant [ftrace_ops]
| tracer: ops_func_nop [ftrace_ops]
| saving registers: NO
| assist recursion: NO
| assist RCU: NO
| ftrace_ops: Attempted 100000 calls to tracee_relevant [ftrace_ops] in 1681558ns (16ns / call)

| # insmod ftrace-ops.ko nr_ops_irrelevant=5
| ftrace_ops: registering:
| relevant ops: 1
| tracee: tracee_relevant [ftrace_ops]
| tracer: ops_func_nop [ftrace_ops]
| irrelevant ops: 5
| tracee: tracee_irrelevant [ftrace_ops]
| tracer: ops_func_nop [ftrace_ops]
| saving registers: NO
| assist recursion: NO
| assist RCU: NO
| ftrace_ops: Attempted 100000 calls to tracee_relevant [ftrace_ops] in 1693042ns (16ns / call)

| # insmod ftrace-ops.ko nr_ops_relevant=2
| ftrace_ops: registering:
| relevant ops: 2
| tracee: tracee_relevant [ftrace_ops]
| tracer: ops_func_nop [ftrace_ops]
| irrelevant ops: 0
| tracee: tracee_irrelevant [ftrace_ops]
| tracer: ops_func_nop [ftrace_ops]
| saving registers: NO
| assist recursion: NO
| assist RCU: NO
| ftrace_ops: Attempted 100000 calls to tracee_relevant [ftrace_ops] in 11965582ns (119ns / call)

| # insmod ftrace-ops.ko save_regs=true
| ftrace_ops: registering:
| relevant ops: 1
| tracee: tracee_relevant [ftrace_ops]
| tracer: ops_func_nop [ftrace_ops]
| irrelevant ops: 0
| tracee: tracee_irrelevant [ftrace_ops]
| tracer: ops_func_nop [ftrace_ops]
| saving registers: YES
| assist recursion: NO
| assist RCU: NO
| ftrace_ops: Attempted 100000 calls to tracee_relevant [ftrace_ops] in 4459624ns (44ns / call)

Link: https://lkml.kernel.org/r/[email protected]

Cc: Florent Revest <[email protected]>
Acked-by: Masami Hiramatsu (Google) <[email protected]>
Signed-off-by: Mark Rutland <[email protected]>
Signed-off-by: Steven Rostedt (Google) <[email protected]>

show more ...

samples: add first Rust examples

The beginning of a set of Rust modules that showcase how Rust
modules look like and how to use the abstracted kernel features.

It also includes an example of a Rust

samples: add first Rust examples

The beginning of a set of Rust modules that showcase how Rust
modules look like and how to use the abstracted kernel features.

It also includes an example of a Rust host program with
several modules.

These samples also double as tests in the CI.

Reviewed-by: Kees Cook <[email protected]>
Reviewed-by: Greg Kroah-Hartman <[email protected]>
Co-developed-by: Alex Gaynor <[email protected]>
Signed-off-by: Alex Gaynor <[email protected]>
Co-developed-by: Finn Behrens <[email protected]>
Signed-off-by: Finn Behrens <[email protected]>
Co-developed-by: Wedson Almeida Filho <[email protected]>
Signed-off-by: Wedson Almeida Filho <[email protected]>
Co-developed-by: Milan Landaverde <[email protected]>
Signed-off-by: Milan Landaverde <[email protected]>
Signed-off-by: Miguel Ojeda <[email protected]>

show more ...

fprobe: Add sample program for fprobe

Add a sample program for the fprobe. The sample_fprobe puts a fprobe on
kernel_clone() by default. This dump stack and some called address info
at the function

fprobe: Add sample program for fprobe

Add a sample program for the fprobe. The sample_fprobe puts a fprobe on
kernel_clone() by default. This dump stack and some called address info
at the function entry and exit.

The sample_fprobe.ko gets 2 parameters.
- symbol: you can specify the comma separated symbols or wildcard symbol
pattern (in this case you can not use comma)
- stackdump: a bool value to enable or disable stack dump in the fprobe
handler.

Signed-off-by: Masami Hiramatsu <[email protected]>
Signed-off-by: Steven Rostedt (Google) <[email protected]>
Tested-by: Steven Rostedt (Google) <[email protected]>
Signed-off-by: Alexei Starovoitov <[email protected]>
Link: https://lore.kernel.org/bpf/164735291987.1084943.4449670993752806840.stgit@devnote2

show more ...

tracing: Add sample code for custom trace events

Add sample code to show how to create custom trace events in the tracefs
directory that can be enabled and modified like any event in tracefs
(includ

tracing: Add sample code for custom trace events

Add sample code to show how to create custom trace events in the tracefs
directory that can be enabled and modified like any event in tracefs
(including triggers, histograms, synthetic events and event probes).

The example is creating a custom sched_switch and a sched_waking to limit
what is recorded:

If the custom sched switch only records the prev_prio, next_prio and
next_pid, it can bring the size from 64 bytes per event, down to just 16
bytes!

If sched_waking only records the prio and pid of the woken event, it will
bring the size down from 36 bytes to 12 bytes per event.

This will allow for a much smaller footprint into the ring buffer and keep
more events from dropping.

Link: https://lkml.kernel.org/r/[email protected]

Cc: Ingo Molnar <[email protected]>
Cc: Andrew Morton <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Masami Hiramatsu <[email protected]>
Cc: Tom Zanussi <[email protected]>
Suggested-by: Joel Fernandes <[email protected]>
Signed-off-by: Steven Rostedt (Google) <[email protected]>

show more ...

coresight: syscfg: Example CoreSight configuration loadable module

An example of creating a loadable module to add CoreSight configurations
into a system.

In the Kernel samples/coresight directory.

coresight: syscfg: Example CoreSight configuration loadable module

An example of creating a loadable module to add CoreSight configurations
into a system.

In the Kernel samples/coresight directory.

Signed-off-by: Mike Leach <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Mathieu Poirier <[email protected]>

show more ...

ftrace/samples: add missing Kconfig option for ftrace direct multi sample

Currently it is not possible to build the ftrace direct multi example
anymore due to broken config dependencies. Fix this by

ftrace/samples: add missing Kconfig option for ftrace direct multi sample

Currently it is not possible to build the ftrace direct multi example
anymore due to broken config dependencies. Fix this by adding
SAMPLE_FTRACE_DIRECT_MULTI config option.

This broke when merging s390-5.16-1 due to an incorrect merge conflict
resolution proposed by me.

Also rename SAMPLE_FTRACE_MULTI_DIRECT to SAMPLE_FTRACE_DIRECT_MULTI
so it matches the module name.

Fixes: 0b707e572a19 ("Merge tag 's390-5.16-1' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux")
Acked-by: Steven Rostedt (VMware) <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Heiko Carstens <[email protected]>

show more ...

samples: Add fs error monitoring example

Introduce an example of a FAN_FS_ERROR fanotify user to track filesystem
errors.

Link: https://lore.kernel.org/r/[email protected]

samples: Add fs error monitoring example

Introduce an example of a FAN_FS_ERROR fanotify user to track filesystem
errors.

Link: https://lore.kernel.org/r/[email protected]
Reviewed-by: Amir Goldstein <[email protected]>
Reviewed-by: Jan Kara <[email protected]>
Signed-off-by: Gabriel Krisman Bertazi <[email protected]>
Signed-off-by: Jan Kara <[email protected]>

show more ...

samples/landlock: Add a sandbox manager example

Add a basic sandbox tool to launch a command which can only access a
list of file hierarchies in a read-only or read-write way.

Cc: James Morris <jmo

samples/landlock: Add a sandbox manager example

Add a basic sandbox tool to launch a command which can only access a
list of file hierarchies in a read-only or read-write way.

Cc: James Morris <[email protected]>
Cc: Serge E. Hallyn <[email protected]>
Signed-off-by: Mickaël Salaün <[email protected]>
Reviewed-by: Jann Horn <[email protected]>
Reviewed-by: Kees Cook <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: James Morris <[email protected]>

show more ...

mm,kmemleak-test.c: move kmemleak-test.c to samples dir

kmemleak-test.c is just a kmemleak test module, which also can not be used
as a built-in kernel module. Thus, i think it may should not be in

mm,kmemleak-test.c: move kmemleak-test.c to samples dir

kmemleak-test.c is just a kmemleak test module, which also can not be used
as a built-in kernel module. Thus, i think it may should not be in mm
dir, and move the kmemleak-test.c to samples/kmemleak/kmemleak-test.c.
Fix the spelling of built-in by the way.

Signed-off-by: Hui Su <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Cc: Catalin Marinas <[email protected]>
Cc: Jonathan Corbet <[email protected]>
Cc: Mauro Carvalho Chehab <[email protected]>
Cc: David S. Miller <[email protected]>
Cc: Rob Herring <[email protected]>
Cc: Masahiro Yamada <[email protected]>
Cc: Sam Ravnborg <[email protected]>
Cc: Josh Poimboeuf <[email protected]>
Cc: Steven Rostedt (VMware) <[email protected]>
Cc: Miguel Ojeda <[email protected]>
Cc: Divya Indi <[email protected]>
Cc: Tomas Winkler <[email protected]>
Cc: David Howells <[email protected]>
Link: https://lkml.kernel.org/r/20200925183729.GA172837@rlk
Signed-off-by: Linus Torvalds <[email protected]>

show more ...

samples: binderfs: really compile this sample and fix build issues

Even after commit c624adc9cb6e ("samples: fix binderfs sample"), this
sample is never compiled.

'hostprogs' teaches Kbuild that th

samples: binderfs: really compile this sample and fix build issues

Even after commit c624adc9cb6e ("samples: fix binderfs sample"), this
sample is never compiled.

'hostprogs' teaches Kbuild that this is a host program, but not enough
to order to compile it. You must add it to 'always-y' to really compile
it.

Since this sample has never been compiled in upstream, various issues
are left unnoticed.

[1] compilers without <linux/android/binderfs.h> are still widely used

<linux/android/binderfs.h> is only available since commit c13295ad219d
("binderfs: rename header to binderfs.h"), i.e., Linux 5.0

If your compiler is based on UAPI headers older than Linux 5.0, you
will see the following error:

samples/binderfs/binderfs_example.c:16:10: fatal error: linux/android/binderfs.h: No such file or directory
#include <linux/android/binderfs.h>
^~~~~~~~~~~~~~~~~~~~~~~~~~
compilation terminated.

You cannot rely on compilers having such a new header.

The common approach is to install UAPI headers of this kernel into
usr/include, and then add it to the header search path.

I added 'depends on HEADERS_INSTALL' in Kconfig, and '-I usr/include'
compiler flag in Makefile.

[2] compile the sample for target architecture

Because headers_install works for the target architecture, only the
native compiler was able to build sample code that requires
'-I usr/include'.

Commit 7f3a59db274c ("kbuild: add infrastructure to build userspace
programs") added the new syntax 'userprogs' to compile user-space
programs for the target architecture.

Use it, and then 'ifndef CROSS_COMPILE' will go away.

I added 'depends on CC_CAN_LINK' because $(CC) is not necessarily
capable of linking user-space programs.

[3] use subdir-y to descend into samples/binderfs

Since this directory does not contain any kernel-space code, it has no
point in generating built-in.a or modules.order.

Replace obj-$(CONFIG_...) with subdir-$(CONFIG_...).

[4] -Wunused-variable warning

If I compile this, I see the following warning.

samples/binderfs/binderfs_example.c: In function 'main':
samples/binderfs/binderfs_example.c:21:9: warning: unused variable 'len' [-Wunused-variable]
21 | size_t len;
| ^~~

I removed the unused 'len'.

[5] CONFIG_ANDROID_BINDERFS is not required

Since this is a user-space standalone program, it is independent of
the kernel configuration.

Remove 'depends on ANDROID_BINDERFS'.

Fixes: 9762dc1432e1 ("samples: add binderfs sample program")
Fixes: c624adc9cb6e ("samples: fix binderfs sample")
Signed-off-by: Masahiro Yamada <[email protected]>
Acked-by: Christian Brauner <[email protected]>

show more ...

Add sample notification program

The sample program is run like:

./samples/watch_queue/watch_test

and watches "/" for mount changes and the current session keyring for key
changes:

# keyctl add

Add sample notification program

The sample program is run like:

./samples/watch_queue/watch_test

and watches "/" for mount changes and the current session keyring for key
changes:

# keyctl add user a a @s
1035096409
# keyctl unlink 1035096409 @s

producing:

# ./watch_test
read() = 16
NOTIFY[000]: ty=000001 sy=02 i=00000110
KEY 2ffc2e5d change=2[linked] aux=1035096409
read() = 16
NOTIFY[000]: ty=000001 sy=02 i=00000110
KEY 2ffc2e5d change=3[unlinked] aux=1035096409

Other events may be produced, such as with a failing disk:

read() = 22
NOTIFY[000]: ty=000003 sy=02 i=00000416
USB 3-7.7 dev-reset e=0 r=0
read() = 24
NOTIFY[000]: ty=000002 sy=06 i=00000418
BLOCK 00800050 e=6[critical medium] s=64000ef8

This corresponds to:

blk_update_request: critical medium error, dev sdf, sector 1677725432 op 0x0:(READ) flags 0x0 phys_seg 1 prio class 0

in dmesg.

Signed-off-by: David Howells <[email protected]>

show more ...

samples: watchdog: use 'userprogs' syntax

Kbuild now supports the 'userprogs' syntax to compile userspace
programs for the same architecture as the kernel.

Add the entry to samples/Makefile to put

samples: watchdog: use 'userprogs' syntax

Kbuild now supports the 'userprogs' syntax to compile userspace
programs for the same architecture as the kernel.

Add the entry to samples/Makefile to put this into the build bot
coverage.

I also added the CONFIG option guarded by 'depends on CC_CAN_LINK'
because $(CC) may not provide libc.

Signed-off-by: Masahiro Yamada <[email protected]>
Acked-by: Sam Ravnborg <[email protected]>

show more ...

samples: timers: use 'userprogs' syntax

Kbuild now supports the 'userprogs' syntax to compile userspace
programs for the same architecture as the kernel.

Add the entry to samples/Makefile to put th

samples: timers: use 'userprogs' syntax

Kbuild now supports the 'userprogs' syntax to compile userspace
programs for the same architecture as the kernel.

Add the entry to samples/Makefile to put this into the build bot
coverage.

I also added the CONFIG option guarded by 'depends on CC_CAN_LINK'
because $(CC) may not provide libc.

Signed-off-by: Masahiro Yamada <[email protected]>
Acked-by: Sam Ravnborg <[email protected]>

show more ...

samples: auxdisplay: use 'userprogs' syntax

Kbuild now supports the 'userprogs' syntax to compile userspace
programs for the same architecture as the kernel.

Add the entry to samples/Makefile to pu

samples: auxdisplay: use 'userprogs' syntax

Kbuild now supports the 'userprogs' syntax to compile userspace
programs for the same architecture as the kernel.

Add the entry to samples/Makefile to put this into the build bot
coverage.

I also added the CONFIG option guarded by 'depends on CC_CAN_LINK'
because $(CC) may not provide libc.

Signed-off-by: Masahiro Yamada <[email protected]>
Acked-by: Miguel Ojeda <[email protected]>
Acked-by: Sam Ravnborg <[email protected]>

show more ...

samples: uhid: build sample program for target architecture

This userspace program includes UAPI headers exported to usr/include/.
'make headers' always works for the target architecture (i.e. the s

samples: uhid: build sample program for target architecture

This userspace program includes UAPI headers exported to usr/include/.
'make headers' always works for the target architecture (i.e. the same
architecture as the kernel), so the sample program should be built for
the target as well. Kbuild now supports 'userprogs' for that.

Add the entry to samples/Makefile to put this into the build bot
coverage.

I also added the CONFIG option guarded by 'depends on CC_CAN_LINK'
because $(CC) may not provide libc.

Signed-off-by: Masahiro Yamada <[email protected]>
Acked-by: Sam Ravnborg <[email protected]>

show more ...

Revert "objtool: Skip samples subdirectory"

This reverts commit 8728497895794d1f207a836e02dae762ad175d56.

samples/ contains only sub-directories.

Because OBJECT_FILES_NON_STANDARD does not work re

Revert "objtool: Skip samples subdirectory"

This reverts commit 8728497895794d1f207a836e02dae762ad175d56.

samples/ contains only sub-directories.

Because OBJECT_FILES_NON_STANDARD does not work recursively,
this line has no effect.

Signed-off-by: Masahiro Yamada <[email protected]>
Acked-by: Josh Poimboeuf <[email protected]>
Acked-by: Sam Ravnborg <[email protected]>

show more ...

objtool: Skip samples subdirectory

The code in the 'samples' subdirectory isn't part of the kernel, so
there's no need to validate it.

Reported-by: Randy Dunlap <[email protected]>
Signed-off-b

objtool: Skip samples subdirectory

The code in the 'samples' subdirectory isn't part of the kernel, so
there's no need to validate it.

Reported-by: Randy Dunlap <[email protected]>
Signed-off-by: Josh Poimboeuf <[email protected]>
Signed-off-by: Ingo Molnar <[email protected]>
Link: https://lore.kernel.org/r/c4cb4ef635ec606454ab834cb49fc3e9381fb1b1.1579543924.git.jpoimboe@redhat.com

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tracing: Sample module to demonstrate kernel access to Ftrace instances.

This is a sample module to demonstrate the use of the newly introduced and
exported APIs to access Ftrace instances from with

tracing: Sample module to demonstrate kernel access to Ftrace instances.

This is a sample module to demonstrate the use of the newly introduced and
exported APIs to access Ftrace instances from within the kernel.

Newly introduced APIs used here -

1. Create/Lookup a trace array with the given name.
struct trace_array *trace_array_get_by_name(const char *name)

2. Destroy/Remove a trace array.
int trace_array_destroy(struct trace_array *tr)

4. Enable/Disable trace events:
int trace_array_set_clr_event(struct trace_array *tr, const char *system,
const char *event, bool enable);

Exported APIs -
1. trace_printk equivalent for instances.
int trace_array_printk(struct trace_array *tr,
unsigned long ip, const char *fmt, ...);

2. Helper function.
void trace_printk_init_buffers(void);

3. To decrement the reference counter.
void trace_array_put(struct trace_array *tr)

Sample output(contents of /sys/kernel/tracing/instances/sample-instance)
NOTE: Tracing disabled after ~5 sec)

_-----=> irqs-off
/ _----=> need-resched
| / _---=> hardirq/softirq
|| / _--=> preempt-depth
||| / delay
TASK-PID CPU# |||| TIMESTAMP FUNCTION
| | | |||| | |
sample-instance-1452 [002] .... 49.430948: simple_thread: trace_array_printk: count=0
sample-instance-1452 [002] .... 49.430951: sample_event: count value=0 at jiffies=4294716608
sample-instance-1452 [002] .... 50.454847: simple_thread: trace_array_printk: count=1
sample-instance-1452 [002] .... 50.454849: sample_event: count value=1 at jiffies=4294717632
sample-instance-1452 [002] .... 51.478748: simple_thread: trace_array_printk: count=2
sample-instance-1452 [002] .... 51.478750: sample_event: count value=2 at jiffies=4294718656
sample-instance-1452 [002] .... 52.502652: simple_thread: trace_array_printk: count=3
sample-instance-1452 [002] .... 52.502655: sample_event: count value=3 at jiffies=4294719680
sample-instance-1452 [002] .... 53.526533: simple_thread: trace_array_printk: count=4
sample-instance-1452 [002] .... 53.526535: sample_event: count value=4 at jiffies=4294720704
sample-instance-1452 [002] .... 54.550438: simple_thread: trace_array_printk: count=5
sample-instance-1452 [002] .... 55.574336: simple_thread: trace_array_printk: count=6

Link: http://lkml.kernel.org/r/[email protected]

Reviewed-by: Aruna Ramakrishna <[email protected]>
Signed-off-by: Divya Indi <[email protected]>
[ Moved to samples/ftrace ]
Signed-off-by: Steven Rostedt (VMware) <[email protected]>

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