Adding upstream version 6.1.76.upstream/6.1.76upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

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+======================
+Linux Kernel Selftests
+======================
+
+The kernel contains a set of "self tests" under the tools/testing/selftests/
+directory. These are intended to be small tests to exercise individual code
+paths in the kernel. Tests are intended to be run after building, installing
+and booting a kernel.
+
+Kselftest from mainline can be run on older stable kernels. Running tests
+from mainline offers the best coverage. Several test rings run mainline
+kselftest suite on stable releases. The reason is that when a new test
+gets added to test existing code to regression test a bug, we should be
+able to run that test on an older kernel. Hence, it is important to keep
+code that can still test an older kernel and make sure it skips the test
+gracefully on newer releases.
+
+You can find additional information on Kselftest framework, how to
+write new tests using the framework on Kselftest wiki:
+
+https://kselftest.wiki.kernel.org/
+
+On some systems, hot-plug tests could hang forever waiting for cpu and
+memory to be ready to be offlined. A special hot-plug target is created
+to run the full range of hot-plug tests. In default mode, hot-plug tests run
+in safe mode with a limited scope. In limited mode, cpu-hotplug test is
+run on a single cpu as opposed to all hotplug capable cpus, and memory
+hotplug test is run on 2% of hotplug capable memory instead of 10%.
+
+kselftest runs as a userspace process.  Tests that can be written/run in
+userspace may wish to use the `Test Harness`_.  Tests that need to be
+run in kernel space may wish to use a `Test Module`_.
+
+Running the selftests (hotplug tests are run in limited mode)
+=============================================================
+
+To build the tests::
+
+  $ make -C tools/testing/selftests
+
+To run the tests::
+
+  $ make -C tools/testing/selftests run_tests
+
+To build and run the tests with a single command, use::
+
+  $ make kselftest
+
+Note that some tests will require root privileges.
+
+Kselftest supports saving output files in a separate directory and then
+running tests. To locate output files in a separate directory two syntaxes
+are supported. In both cases the working directory must be the root of the
+kernel src. This is applicable to "Running a subset of selftests" section
+below.
+
+To build, save output files in a separate directory with O= ::
+
+  $ make O=/tmp/kselftest kselftest
+
+To build, save output files in a separate directory with KBUILD_OUTPUT ::
+
+  $ export KBUILD_OUTPUT=/tmp/kselftest; make kselftest
+
+The O= assignment takes precedence over the KBUILD_OUTPUT environment
+variable.
+
+The above commands by default run the tests and print full pass/fail report.
+Kselftest supports "summary" option to make it easier to understand the test
+results. Please find the detailed individual test results for each test in
+/tmp/testname file(s) when summary option is specified. This is applicable
+to "Running a subset of selftests" section below.
+
+To run kselftest with summary option enabled ::
+
+  $ make summary=1 kselftest
+
+Running a subset of selftests
+=============================
+
+You can use the "TARGETS" variable on the make command line to specify
+single test to run, or a list of tests to run.
+
+To run only tests targeted for a single subsystem::
+
+  $ make -C tools/testing/selftests TARGETS=ptrace run_tests
+
+You can specify multiple tests to build and run::
+
+  $  make TARGETS="size timers" kselftest
+
+To build, save output files in a separate directory with O= ::
+
+  $ make O=/tmp/kselftest TARGETS="size timers" kselftest
+
+To build, save output files in a separate directory with KBUILD_OUTPUT ::
+
+  $ export KBUILD_OUTPUT=/tmp/kselftest; make TARGETS="size timers" kselftest
+
+Additionally you can use the "SKIP_TARGETS" variable on the make command
+line to specify one or more targets to exclude from the TARGETS list.
+
+To run all tests but a single subsystem::
+
+  $ make -C tools/testing/selftests SKIP_TARGETS=ptrace run_tests
+
+You can specify multiple tests to skip::
+
+  $  make SKIP_TARGETS="size timers" kselftest
+
+You can also specify a restricted list of tests to run together with a
+dedicated skiplist::
+
+  $  make TARGETS="bpf breakpoints size timers" SKIP_TARGETS=bpf kselftest
+
+See the top-level tools/testing/selftests/Makefile for the list of all
+possible targets.
+
+Running the full range hotplug selftests
+========================================
+
+To build the hotplug tests::
+
+  $ make -C tools/testing/selftests hotplug
+
+To run the hotplug tests::
+
+  $ make -C tools/testing/selftests run_hotplug
+
+Note that some tests will require root privileges.
+
+
+Install selftests
+=================
+
+You can use the "install" target of "make" (which calls the `kselftest_install.sh`
+tool) to install selftests in the default location (`tools/testing/selftests/kselftest_install`),
+or in a user specified location via the `INSTALL_PATH` "make" variable.
+
+To install selftests in default location::
+
+   $ make -C tools/testing/selftests install
+
+To install selftests in a user specified location::
+
+   $ make -C tools/testing/selftests install INSTALL_PATH=/some/other/path
+
+Running installed selftests
+===========================
+
+Found in the install directory, as well as in the Kselftest tarball,
+is a script named `run_kselftest.sh` to run the tests.
+
+You can simply do the following to run the installed Kselftests. Please
+note some tests will require root privileges::
+
+   $ cd kselftest_install
+   $ ./run_kselftest.sh
+
+To see the list of available tests, the `-l` option can be used::
+
+   $ ./run_kselftest.sh -l
+
+The `-c` option can be used to run all the tests from a test collection, or
+the `-t` option for specific single tests. Either can be used multiple times::
+
+   $ ./run_kselftest.sh -c bpf -c seccomp -t timers:posix_timers -t timer:nanosleep
+
+For other features see the script usage output, seen with the `-h` option.
+
+Packaging selftests
+===================
+
+In some cases packaging is desired, such as when tests need to run on a
+different system. To package selftests, run::
+
+   $ make -C tools/testing/selftests gen_tar
+
+This generates a tarball in the `INSTALL_PATH/kselftest-packages` directory. By
+default, `.gz` format is used. The tar compression format can be overridden by
+specifying a `FORMAT` make variable. Any value recognized by `tar's auto-compress`_
+option is supported, such as::
+
+    $ make -C tools/testing/selftests gen_tar FORMAT=.xz
+
+`make gen_tar` invokes `make install` so you can use it to package a subset of
+tests by using variables specified in `Running a subset of selftests`_
+section::
+
+    $ make -C tools/testing/selftests gen_tar TARGETS="bpf" FORMAT=.xz
+
+.. _tar's auto-compress: https://www.gnu.org/software/tar/manual/html_node/gzip.html#auto_002dcompress
+
+Contributing new tests
+======================
+
+In general, the rules for selftests are
+
+ * Do as much as you can if you're not root;
+
+ * Don't take too long;
+
+ * Don't break the build on any architecture, and
+
+ * Don't cause the top-level "make run_tests" to fail if your feature is
+   unconfigured.
+
+Contributing new tests (details)
+================================
+
+ * In your Makefile, use facilities from lib.mk by including it instead of
+   reinventing the wheel. Specify flags and binaries generation flags on
+   need basis before including lib.mk. ::
+
+    CFLAGS = $(KHDR_INCLUDES)
+    TEST_GEN_PROGS := close_range_test
+    include ../lib.mk
+
+ * Use TEST_GEN_XXX if such binaries or files are generated during
+   compiling.
+
+   TEST_PROGS, TEST_GEN_PROGS mean it is the executable tested by
+   default.
+
+   TEST_CUSTOM_PROGS should be used by tests that require custom build
+   rules and prevent common build rule use.
+
+   TEST_PROGS are for test shell scripts. Please ensure shell script has
+   its exec bit set. Otherwise, lib.mk run_tests will generate a warning.
+
+   TEST_CUSTOM_PROGS and TEST_PROGS will be run by common run_tests.
+
+   TEST_PROGS_EXTENDED, TEST_GEN_PROGS_EXTENDED mean it is the
+   executable which is not tested by default.
+   TEST_FILES, TEST_GEN_FILES mean it is the file which is used by
+   test.
+
+ * First use the headers inside the kernel source and/or git repo, and then the
+   system headers.  Headers for the kernel release as opposed to headers
+   installed by the distro on the system should be the primary focus to be able
+   to find regressions. Use KHDR_INCLUDES in Makefile to include headers from
+   the kernel source.
+
+ * If a test needs specific kernel config options enabled, add a config file in
+   the test directory to enable them.
+
+   e.g: tools/testing/selftests/android/config
+
+ * Create a .gitignore file inside test directory and add all generated objects
+   in it.
+
+ * Add new test name in TARGETS in selftests/Makefile::
+
+    TARGETS += android
+
+ * All changes should pass::
+
+    kselftest-{all,install,clean,gen_tar}
+    kselftest-{all,install,clean,gen_tar} O=abo_path
+    kselftest-{all,install,clean,gen_tar} O=rel_path
+    make -C tools/testing/selftests {all,install,clean,gen_tar}
+    make -C tools/testing/selftests {all,install,clean,gen_tar} O=abs_path
+    make -C tools/testing/selftests {all,install,clean,gen_tar} O=rel_path
+
+Test Module
+===========
+
+Kselftest tests the kernel from userspace.  Sometimes things need
+testing from within the kernel, one method of doing this is to create a
+test module.  We can tie the module into the kselftest framework by
+using a shell script test runner.  ``kselftest/module.sh`` is designed
+to facilitate this process.  There is also a header file provided to
+assist writing kernel modules that are for use with kselftest:
+
+- ``tools/testing/selftests/kselftest_module.h``
+- ``tools/testing/selftests/kselftest/module.sh``
+
+Note that test modules should taint the kernel with TAINT_TEST. This will
+happen automatically for modules which are in the ``tools/testing/``
+directory, or for modules which use the ``kselftest_module.h`` header above.
+Otherwise, you'll need to add ``MODULE_INFO(test, "Y")`` to your module
+source. selftests which do not load modules typically should not taint the
+kernel, but in cases where a non-test module is loaded, TEST_TAINT can be
+applied from userspace by writing to ``/proc/sys/kernel/tainted``.
+
+How to use
+----------
+
+Here we show the typical steps to create a test module and tie it into
+kselftest.  We use kselftests for lib/ as an example.
+
+1. Create the test module
+
+2. Create the test script that will run (load/unload) the module
+   e.g. ``tools/testing/selftests/lib/printf.sh``
+
+3. Add line to config file e.g. ``tools/testing/selftests/lib/config``
+
+4. Add test script to makefile  e.g. ``tools/testing/selftests/lib/Makefile``
+
+5. Verify it works:
+
+.. code-block:: sh
+
+   # Assumes you have booted a fresh build of this kernel tree
+   cd /path/to/linux/tree
+   make kselftest-merge
+   make modules
+   sudo make modules_install
+   make TARGETS=lib kselftest
+
+Example Module
+--------------
+
+A bare bones test module might look like this:
+
+.. code-block:: c
+
+   // SPDX-License-Identifier: GPL-2.0+
+
+   #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+   #include "../tools/testing/selftests/kselftest_module.h"
+
+   KSTM_MODULE_GLOBALS();
+
+   /*
+    * Kernel module for testing the foobinator
+    */
+
+   static int __init test_function()
+   {
+           ...
+   }
+
+   static void __init selftest(void)
+   {
+           KSTM_CHECK_ZERO(do_test_case("", 0));
+   }
+
+   KSTM_MODULE_LOADERS(test_foo);
+   MODULE_AUTHOR("John Developer <jd@fooman.org>");
+   MODULE_LICENSE("GPL");
+   MODULE_INFO(test, "Y");
+
+Example test script
+-------------------
+
+.. code-block:: sh
+
+    #!/bin/bash
+    # SPDX-License-Identifier: GPL-2.0+
+    $(dirname $0)/../kselftest/module.sh "foo" test_foo
+
+
+Test Harness
+============
+
+The kselftest_harness.h file contains useful helpers to build tests.  The
+test harness is for userspace testing, for kernel space testing see `Test
+Module`_ above.
+
+The tests from tools/testing/selftests/seccomp/seccomp_bpf.c can be used as
+example.
+
+Example
+-------
+
+.. kernel-doc:: tools/testing/selftests/kselftest_harness.h
+    :doc: example
+
+
+Helpers
+-------
+
+.. kernel-doc:: tools/testing/selftests/kselftest_harness.h
+    :functions: TH_LOG TEST TEST_SIGNAL FIXTURE FIXTURE_DATA FIXTURE_SETUP
+                FIXTURE_TEARDOWN TEST_F TEST_HARNESS_MAIN FIXTURE_VARIANT
+                FIXTURE_VARIANT_ADD
+
+Operators
+---------
+
+.. kernel-doc:: tools/testing/selftests/kselftest_harness.h
+    :doc: operators
+
+.. kernel-doc:: tools/testing/selftests/kselftest_harness.h
+    :functions: ASSERT_EQ ASSERT_NE ASSERT_LT ASSERT_LE ASSERT_GT ASSERT_GE
+                ASSERT_NULL ASSERT_TRUE ASSERT_NULL ASSERT_TRUE ASSERT_FALSE
+                ASSERT_STREQ ASSERT_STRNE EXPECT_EQ EXPECT_NE EXPECT_LT
+                EXPECT_LE EXPECT_GT EXPECT_GE EXPECT_NULL EXPECT_TRUE
+                EXPECT_FALSE EXPECT_STREQ EXPECT_STRNE