- Linux-kselftest-mirror - lists.linaro.org

[PATCH v2] Documentation: dev-tools: Add Testing Overview

by David Gow

The kernel now has a number of testing and debugging tools, and we've seen a bit of confusion about what the differences between them are. Add a basic documentation outlining the testing tools, when to use each, and how they interact. This is a pretty quick overview rather than the idealised "kernel testing guide" that'd probably be optimal, but given the number of times questions like "When do you use KUnit and when do you use Kselftest?" are being asked, it seemed worth at least having something. Hopefully this can form the basis for more detailed documentation later. Signed-off-by: David Gow <davidgow(a)google.com> --- Thanks, everyone, for the comments on the doc. I've made a few of the suggested changes. Please let me know what you think! -- David Changes since v1: https://lore.kernel.org/linux-kselftest/20210410070529.4113432-1-davidgow@g… - Note KUnit's speed and that one should provide selftests for syscalls - Mention lockdep as a Dynamic Analysis Tool - Refer to "Dynamic Analysis Tools" instead of "Sanitizers" - A number of minor formatting tweaks and rewordings for clarity. Not changed: - I haven't included an exhaustive list of differences, advantages, etc, between KUnit and kselftest: for now, the doc continues to focus on the difference between 'in-kernel' and 'userspace' testing here. - Similarly, I'm not linking out to docs defining and describing "Unit" tests versus "End-to-end" tests. None of the existing documentation elsewhere quite matches what we do in the kernel perfectly, so it seems less confusing to focus on the 'in-kernel'/'userspace' distinction, and leave other definitions as a passing mention for those who are already familiar with the concepts. - I haven't linked to any talk videos here: a few of them are linked on (e.g.) the KUnit webpage, but I wanted to keep the Kernel documentation more self-contained for now. No objection to adding them in a follow-up patch if people feel strongly about it, though. - The link from index.rst to this doc is unchanged. I personally think that the link is prominent enough there: it's the first link, and shows up a few times. One possibility if people disagreed would be to merge this page with the index, but given not all dev-tools are going to be testing-related, it seemed a bit arrogant. :-) Documentation/dev-tools/index.rst | 3 + Documentation/dev-tools/testing-overview.rst | 117 +++++++++++++++++++ 2 files changed, 120 insertions(+) create mode 100644 Documentation/dev-tools/testing-overview.rst diff --git a/Documentation/dev-tools/index.rst b/Documentation/dev-tools/index.rst index 1b1cf4f5c9d9..f590e5860794 100644 --- a/Documentation/dev-tools/index.rst +++ b/Documentation/dev-tools/index.rst @@ -7,6 +7,8 @@ be used to work on the kernel. For now, the documents have been pulled together without any significant effort to integrate them into a coherent whole; patches welcome! +A brief overview of testing-specific tools can be found in :doc:`testing-overview`. + .. class:: toc-title Table of contents @@ -14,6 +16,7 @@ whole; patches welcome! .. toctree:: :maxdepth: 2 + testing-overview coccinelle sparse kcov diff --git a/Documentation/dev-tools/testing-overview.rst b/Documentation/dev-tools/testing-overview.rst new file mode 100644 index 000000000000..ce36a8cdf6b5 --- /dev/null +++ b/Documentation/dev-tools/testing-overview.rst @@ -0,0 +1,117 @@ +.. SPDX-License-Identifier: GPL-2.0 + +==================== +Kernel Testing Guide +==================== + + +There are a number of different tools for testing the Linux kernel, so knowing +when to use each of them can be a challenge. This document provides a rough +overview of their differences, and how they fit together. + + +Writing and Running Tests +========================= + +The bulk of kernel tests are written using either the kselftest or KUnit +frameworks. These both provide infrastructure to help make running tests and +groups of tests easier, as well as providing helpers to aid in writing new +tests. + +If you're looking to verify the behaviour of the Kernel — particularly specific +parts of the kernel — then you'll want to use KUnit or kselftest. + + +The Difference Between KUnit and kselftest +------------------------------------------ + +KUnit (Documentation/dev-tools/kunit/index.rst) is an entirely in-kernel system +for "white box" testing: because test code is part of the kernel, it can access +internal structures and functions which aren't exposed to userspace. + +KUnit tests therefore are best written against small, self-contained parts +of the kernel, which can be tested in isolation. This aligns well with the +concept of 'unit' testing. + +For example, a KUnit test might test an individual kernel function (or even a +single codepath through a function, such as an error handling case), rather +than a feature as a whole. + +This also makes KUnit tests very fast to build and run, allowing them to be +run frequently as part of the development process. + +There is a KUnit test style guide which may give further pointers in +Documentation/dev-tools/kunit/style.rst + + +kselftest (Documentation/dev-tools/kselftest.rst), on the other hand, is +largely implemented in userspace, and tests are normal userspace scripts or +programs. + +This makes it easier to write more complicated tests, or tests which need to +manipulate the overall system state more (e.g., spawning processes, etc.). +However, it's not possible to call kernel functions directly from kselftest. +This means that only kernel functionality which is exposed to userspace somhow +(e.g. by a syscall, device, filesystem, etc.) can be tested with kselftest. To +work around this, some tests include a companion kernel module which exposes +more information or functionality. If a test runs mostly or entirely within the +kernel, however, KUnit may be the more appropriate tool. + +kselftest is therefore suited well to tests of whole features, as these will +expose an interface to userspace, which can be tested, but not implementation +details. This aligns well with 'system' or 'end-to-end' testing. + +For example, all new system calls should be accompanied by kselftest tests. + +Code Coverage Tools +=================== + +The Linux Kernel supports two different code coverage measurement tools. These +can be used to verify that a test is executing particular functions or lines +of code. This is useful for determining how much of the kernel is being tested, +and for finding corner-cases which are not covered by the appropriate test. + +:doc:`gcov` is GCC's coverage testing tool, which can be used with the kernel +to get global or per-module coverage. Unlike KCOV, it does not record per-task +coverage. Coverage data can be read from debugfs, and interpreted using the +usual gcov tooling. + +:doc:`kcov` is a feature which can be built in to the kernel to allow +capturing coverage on a per-task level. It's therefore useful for fuzzing and +other situations where information about code executed during, for example, a +single syscall is useful. + + +Dynamic Analysis Tools +====================== + +The kernel also supports a number of dynamic analysis tools, which attempt to +detect classes of issues when the occur in a running kernel. These typically +look for undefined behaviour of some kind, such as invalid memory accesses, +concurrency issues such as data races, or other undefined behaviour like +integer overflows. + +Some of these tools are listed below: + +* kmemleak detects possible memory leaks. See + Documentation/dev-tools/kmemleak.rst +* KASAN detects invalid memory accesses such as out-of-bounds and + use-after-free errors. See Documentation/dev-tools/kasan.rst +* UBSAN detects behaviour that is undefined by the C standard, like integer + overflows. See Documentation/dev-tools/ubsan.rst +* KCSAN detects data races. See Documentation/dev-tools/kcsan.rst +* KFENCE is a low-overhead detector of memory issues, which is much faster than + KASAN and can be used in production. See Documentation/dev-tools/kfence.rst +* lockdep is a locking correctness validator. See + Documentation/locking/lockdep-design.rst +* There are several other pieces of debug instrumentation in the kernel, many + of which can be found in lib/Kconfig.debug + +These tools tend to test the kernel as a whole, and do not "pass" like +kselftest or KUnit tests. They can be combined with KUnit or kselftest by +running tests on a kernel with a sanitizer enabled: you can then be sure +that none of these errors are occurring during the test. + +Some of these tools integrate with KUnit or kselftest and will +automatically fail tests if an issue is detected. + -- 2.31.1.295.g9ea45b61b8-goog

4 years, 5 months

3
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[PATCH v3] Documentation: kunit: add tips for running KUnit

by Daniel Latypov

This is long overdue. There are several things that aren't nailed down (in-tree .kunitconfig's), or partially broken (GCOV on UML), but having them documented, warts and all, is better than having nothing. This covers a bunch of the more recent features * kunit_filter_glob * kunit.py run --kunitconfig * slightly more detail on building tests as modules * CONFIG_KUNIT_DEBUGFS By my count, the only headline features now not mentioned are the KASAN integration and KernelCI json output support (kunit.py run --json). And then it also discusses how to get code coverage reports under UML and non-UML since this is a question people have repeatedly asked. Non-UML coverage collection is no different from normal, but we should probably explicitly call this out. As for UML, I was able to get it working again with two small hacks.* E.g. with CONFIG_KUNIT=y && CONFIG_KUNIT_ALL_TESTS=y Overall coverage rate: lines......: 15.1% (18294 of 120776 lines) functions..: 16.8% (1860 of 11050 functions) Note: this doesn't document --alltests since this is not stable yet. Hopefully being run more frequently as part of KernelCI will help... *Using gcc/gcov-6 and not using uml_abort() in os_dump_core(). I've documented these hacks in "Notes" but left TODOs for brendanhiggins(a)google.com who tracked down the runtime issue in GCC. To be clear: these are not issues specific to KUnit, but rather to UML. Signed-off-by: Daniel Latypov <dlatypov(a)google.com> --- v2 -> v3: * Suggest --make_options=CC=/usr/bin/gcc-6 instead of manually editing kunit_kernel.py * update instructions on how to remove uml_abort() call v1 -> v2: Fix typos, drop --alltests, changed wordiing on config fragments. --- Documentation/dev-tools/kunit/index.rst | 1 + .../dev-tools/kunit/running_tips.rst | 258 ++++++++++++++++++ Documentation/dev-tools/kunit/start.rst | 2 + 3 files changed, 261 insertions(+) create mode 100644 Documentation/dev-tools/kunit/running_tips.rst diff --git a/Documentation/dev-tools/kunit/index.rst b/Documentation/dev-tools/kunit/index.rst index 848478838347..7f7cf8d2ab20 100644 --- a/Documentation/dev-tools/kunit/index.rst +++ b/Documentation/dev-tools/kunit/index.rst @@ -14,6 +14,7 @@ KUnit - Unit Testing for the Linux Kernel style faq tips + running_tips What is KUnit? ============== diff --git a/Documentation/dev-tools/kunit/running_tips.rst b/Documentation/dev-tools/kunit/running_tips.rst new file mode 100644 index 000000000000..e2e9af711d1b --- /dev/null +++ b/Documentation/dev-tools/kunit/running_tips.rst @@ -0,0 +1,258 @@ +.. SPDX-License-Identifier: GPL-2.0 + +============================ +Tips For Running KUnit Tests +============================ + +Using ``kunit.py run`` ("kunit tool") +===================================== + +Running from any directory +-------------------------- + +It can be handy to create a bash function like: + +.. code-block:: bash + + function run_kunit() { + ( cd "$(git rev-parse --show-toplevel)" && ./tools/testing/kunit/kunit.py run $@ ) + } + +.. note:: + Early versions of ``kunit.py`` (before 5.6) didn't work unless run from + the kernel root, hence the use of a subshell and ``cd``. + +Running a subset of tests +------------------------- + +``kunit.py run`` accepts an optional glob argument to filter tests. Currently +this only matches against suite names, but this may change in the future. + +Say that we wanted to run the sysctl tests, we could do so via: + +.. code-block:: bash + + $ echo -e 'CONFIG_KUNIT=y\nCONFIG_KUNIT_ALL_TESTS=y' > .kunit/.kunitconfig + $ ./tools/testing/kunit/kunit.py run 'sysctl*' + +We're paying the cost of building more tests than we need this way, but it's +easier than fiddling with ``.kunitconfig`` files or commenting out +``kunit_suite``'s. + +However, if we wanted to define a set of tests in a less ad hoc way, the next +tip is useful. + +Defining a set of tests +----------------------- + +``kunit.py run`` (along with ``build``, and ``config``) supports a +``--kunitconfig`` flag. So if you have a set of tests that you want to run on a +regular basis (especially if they have other dependencies), you can create a +specific ``.kunitconfig`` for them. + +E.g. kunit has one for its tests: + +.. code-block:: bash + + $ ./tools/testing/kunit/kunit.py run --kunitconfig=lib/kunit/.kunitconfig + +Alternatively, if you're following the convention of naming your +file ``.kunitconfig``, you can just pass in the dir, e.g. + +.. code-block:: bash + + $ ./tools/testing/kunit/kunit.py run --kunitconfig=lib/kunit + +.. note:: + This is a relatively new feature (5.12+) so we don't have any + conventions yet about on what files should be checked in versus just + kept around locally. It's up to you and your maintainer to decide if a + config is useful enough to submit (and therefore have to maintain). + +.. note:: + Having ``.kunitconfig`` fragments in a parent and child directory is + iffy. There's discussion about adding an "import" statement in these + files to make it possible to have a top-level config run tests from all + child directories. But that would mean ``.kunitconfig`` files are no + longer just simple .config fragments. + + One alternative would be to have kunit tool recursively combine configs + automagically, but tests could theoretically depend on incompatible + options, so handling that would be tricky. + +Generating code coverage reports under UML +------------------------------------------ + +.. note:: + TODO(brendanhiggins(a)google.com): There are various issues with UML and + versions of gcc 7 and up. You're likely to run into missing ``.gcda`` + files or compile errors. We know one `faulty GCC commit + <https://github.com/gcc-mirror/gcc/commit/8c9434c2f9358b8b8bad2c1990edf10a21…>`_ + but not how we'd go about getting this fixed. The compile errors still + need some investigation. + +.. note:: + TODO(brendanhiggins(a)google.com): for recent versions of Linux + (5.10-5.12, maybe earlier), there's a bug with gcov counters not being + flushed in UML. This translates to very low (<1%) reported coverage. This is + related to the above issue and can be worked around by replacing the + one call to ``uml_abort()`` with a plain ``exit()``. + + +This is different from the "normal" way of getting coverage information that is +documented in Documentation/dev-tools/gcov.rst. + +Instead of enabling ``CONFIG_GCOV_KERNEL=y``, we can set these options: + +.. code-block:: none + + CONFIG_DEBUG_KERNEL=y + CONFIG_DEBUG_INFO=y + CONFIG_GCOV=y + + +Putting it together into a copy-pastable sequence of commands: + +.. code-block:: bash + + # Append coverage options to the current config + $ echo -e "CONFIG_DEBUG_KERNEL=y\nCONFIG_DEBUG_INFO=y\nCONFIG_GCOV=y" >> .kunit/.kunitconfig + $ ./tools/testing/kunit/kunit.py run + # Extract the coverage information from the build dir (.kunit/) + $ lcov -t "my_kunit_tests" -o coverage.info -c -d .kunit/ + + # From here on, it's the same process as with CONFIG_GCOV_KERNEL=y + # E.g. can generate an HTML report in a tmp dir like so: + $ genhtml -o /tmp/coverage_html coverage.info + + +If your installed version of gcc doesn't work, you can tweak the steps: + +.. code-block:: bash + + $ ./tools/testing/kunit/kunit.py run --make_options=CC=/usr/bin/gcc-6 + $ lcov -t "my_kunit_tests" -o coverage.info -c -d .kunit/ --gcov-tool=/usr/bin/gcov-6 + + +Running tests manually +====================== + +Running tests without using ``kunit.py run`` is also an important use case. +Currently it's your only option if you want to test on architectures other than +UML. + +As running the tests under UML is fairly straightforward (configure and compile +the kernel, run the ``./linux`` binary), this section will focus on testing +non-UML architectures. + + +Running built-in tests +---------------------- + +When setting tests to ``=y``, the tests will run as part of boot and print +results to dmesg in TAP format. So you just need to add your tests to your +``.config``, build and boot your kernel as normal. + +So if we compiled our kernel with: + +.. code-block:: none + + CONFIG_KUNIT=y + CONFIG_KUNIT_EXAMPLE_TEST=y + +Then we'd see output like this in dmesg signaling the test ran and passed: + +.. code-block:: none + + TAP version 14 + 1..1 + # Subtest: example + 1..1 + # example_simple_test: initializing + ok 1 - example_simple_test + ok 1 - example + +Running tests as modules +------------------------ + +Depending on the tests, you can build them as loadable modules. + +For example, we'd change the config options from before to + +.. code-block:: none + + CONFIG_KUNIT=y + CONFIG_KUNIT_EXAMPLE_TEST=m + +Then after booting into our kernel, we can run the test via + +.. code-block:: none + + $ modprobe kunit-example-test + +This will then cause it to print TAP output to stdout. + +.. note:: + The ``modprobe`` will *not* have a non-zero exit code if any test + failed (as of 5.13). But ``kunit.py parse`` would, see below. + +.. note:: + You can set ``CONFIG_KUNIT=m`` as well, however, some features will not + work and thus some tests might break. Ideally tests would specify they + depend on ``KUNIT=y`` in their ``Kconfig``'s, but this is an edge case + most test authors won't think about. + As of 5.13, the only difference is that ``current->kunit_test`` will + not exist. + +Pretty-printing results +----------------------- + +You can use ``kunit.py parse`` to parse dmesg for test output and print out +results in the same familiar format that ``kunit.py run`` does. + +.. code-block:: bash + + $ ./tools/testing/kunit/kunit.py parse /var/log/dmesg + + +Retrieving per suite results +---------------------------- + +Regardless of how you're running your tests, you can enable +``CONFIG_KUNIT_DEBUGFS`` to expose per-suite TAP-formatted results: + +.. code-block:: none + + CONFIG_KUNIT=y + CONFIG_KUNIT_EXAMPLE_TEST=m + CONFIG_KUNIT_DEBUGFS=y + +The results for each suite will be exposed under +``/sys/kernel/debug/kunit/<suite>/results``. +So using our example config: + +.. code-block:: bash + + $ modprobe kunit-example-test > /dev/null + $ cat /sys/kernel/debug/kunit/example/results + ... <TAP output> ... + + # After removing the module, the corresponding files will go away + $ modprobe -r kunit-example-test + $ cat /sys/kernel/debug/kunit/example/results + /sys/kernel/debug/kunit/example/results: No such file or directory + +Generating code coverage reports +-------------------------------- + +See Documentation/dev-tools/gcov.rst for details on how to do this. + +The only vaguely KUnit-specific advice here is that you probably want to build +your tests as modules. That way you can isolate the coverage from tests from +other code executed during boot, e.g. + +.. code-block:: bash + + # Reset coverage counters before running the test. + $ echo 0 > /sys/kernel/debug/gcov/reset + $ modprobe kunit-example-test diff --git a/Documentation/dev-tools/kunit/start.rst b/Documentation/dev-tools/kunit/start.rst index 0e65cabe08eb..aa56d7ca6bfb 100644 --- a/Documentation/dev-tools/kunit/start.rst +++ b/Documentation/dev-tools/kunit/start.rst @@ -236,5 +236,7 @@ Next Steps ========== * Check out the :doc:`tips` page for tips on writing idiomatic KUnit tests. +* Check out the :doc:`running_tips` page for tips on + how to make running KUnit tests easier. * Optional: see the :doc:`usage` page for a more in-depth explanation of KUnit. base-commit: de2fcb3e62013738f22bbb42cbd757d9a242574e -- 2.31.1.295.g9ea45b61b8-goog

4 years, 5 months

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[PATCH v2] selftests/mincore: get readahead size for check_file_mmap()

by Jeffle Xu

The readahead size used to be 2MB, thus it's reasonable to set the file size as 4MB when checking check_file_mmap(). However since commit c2e4cd57cfa1 ("block: lift setting the readahead size into the block layer"), readahead size could be as large as twice the io_opt, and thus the hardcoded file size no longer works. check_file_mmap() may report "Read-ahead pages reached the end of the file" when the readahead size actually exceeds the file size in this case. Signed-off-by: Jeffle Xu <jefflexu(a)linux.alibaba.com> --- chnages since v1: - add the test name "mincore" in the subject line - add the error message in commit message - rename @filesize to @file_size to keep a more consistent naming convention --- .../selftests/mincore/mincore_selftest.c | 57 +++++++++++++++---- 1 file changed, 47 insertions(+), 10 deletions(-) diff --git a/tools/testing/selftests/mincore/mincore_selftest.c b/tools/testing/selftests/mincore/mincore_selftest.c index 5a1e85ff5d32..3ca542934080 100644 --- a/tools/testing/selftests/mincore/mincore_selftest.c +++ b/tools/testing/selftests/mincore/mincore_selftest.c @@ -15,6 +15,11 @@ #include <string.h> #include <fcntl.h> #include <string.h> +#include <sys/types.h> +#include <sys/stat.h> +#include <sys/ioctl.h> +#include <sys/sysmacros.h> +#include <sys/mount.h> #include "../kselftest.h" #include "../kselftest_harness.h" @@ -195,10 +200,42 @@ TEST(check_file_mmap) int fd; int i; int ra_pages = 0; + long ra_size, file_size; + struct stat stats; + dev_t devt; + unsigned int major, minor; + char devpath[32]; + + retval = stat(".", &stats); + ASSERT_EQ(0, retval) { + TH_LOG("Can't stat pwd: %s", strerror(errno)); + } + + devt = stats.st_dev; + major = major(devt); + minor = minor(devt); + snprintf(devpath, sizeof(devpath), "/dev/block/%u:%u", major, minor); + + fd = open(devpath, O_RDONLY); + ASSERT_NE(-1, fd) { + TH_LOG("Can't open underlying disk %s", strerror(errno)); + } + + retval = ioctl(fd, BLKRAGET, &ra_size); + ASSERT_EQ(0, retval) { + TH_LOG("Error ioctl with the underlying disk: %s", strerror(errno)); + } + + /* + * BLKRAGET ioctl returns the readahead size in sectors (512 bytes). + * Make file_size large enough to contain the readahead window. + */ + ra_size *= 512; + file_size = ra_size * 2; page_size = sysconf(_SC_PAGESIZE); - vec_size = FILE_SIZE / page_size; - if (FILE_SIZE % page_size) + vec_size = file_size / page_size; + if (file_size % page_size) vec_size++; vec = calloc(vec_size, sizeof(unsigned char)); @@ -213,7 +250,7 @@ TEST(check_file_mmap) strerror(errno)); } errno = 0; - retval = fallocate(fd, 0, 0, FILE_SIZE); + retval = fallocate(fd, 0, 0, file_size); ASSERT_EQ(0, retval) { TH_LOG("Error allocating space for the temporary file: %s", strerror(errno)); @@ -223,12 +260,12 @@ TEST(check_file_mmap) * Map the whole file, the pages shouldn't be fetched yet. */ errno = 0; - addr = mmap(NULL, FILE_SIZE, PROT_READ | PROT_WRITE, + addr = mmap(NULL, file_size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0); ASSERT_NE(MAP_FAILED, addr) { TH_LOG("mmap error: %s", strerror(errno)); } - retval = mincore(addr, FILE_SIZE, vec); + retval = mincore(addr, file_size, vec); ASSERT_EQ(0, retval); for (i = 0; i < vec_size; i++) { ASSERT_EQ(0, vec[i]) { @@ -240,14 +277,14 @@ TEST(check_file_mmap) * Touch a page in the middle of the mapping. We expect the next * few pages (the readahead window) to be populated too. */ - addr[FILE_SIZE / 2] = 1; - retval = mincore(addr, FILE_SIZE, vec); + addr[file_size / 2] = 1; + retval = mincore(addr, file_size, vec); ASSERT_EQ(0, retval); - ASSERT_EQ(1, vec[FILE_SIZE / 2 / page_size]) { + ASSERT_EQ(1, vec[file_size / 2 / page_size]) { TH_LOG("Page not found in memory after use"); } - i = FILE_SIZE / 2 / page_size + 1; + i = file_size / 2 / page_size + 1; while (i < vec_size && vec[i]) { ra_pages++; i++; @@ -271,7 +308,7 @@ TEST(check_file_mmap) } } - munmap(addr, FILE_SIZE); + munmap(addr, file_size); close(fd); free(vec); } -- 2.27.0

4 years, 5 months

3
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[PATCH] kunit: add unit test for filtering suites by names

by Daniel Latypov

This adds unit tests for kunit_filter_subsuite() and kunit_filter_suites(). Note: what the executor means by "subsuite" is the array of suites corresponding to each test file. This patch lightly refactors executor.c to avoid the use of global variables to make it testable. It also includes a clever `kfree_at_end()` helper that makes this test easier to write than it otherwise would have been. Tested by running just the new tests using itself $ ./tools/testing/kunit/kunit.py run '*exec*' Signed-off-by: Daniel Latypov <dlatypov(a)google.com> --- lib/kunit/executor.c | 26 ++++---- lib/kunit/executor_test.c | 132 ++++++++++++++++++++++++++++++++++++++ 2 files changed, 147 insertions(+), 11 deletions(-) create mode 100644 lib/kunit/executor_test.c diff --git a/lib/kunit/executor.c b/lib/kunit/executor.c index 15832ed44668..96a4ae983786 100644 --- a/lib/kunit/executor.c +++ b/lib/kunit/executor.c @@ -19,7 +19,7 @@ MODULE_PARM_DESC(filter_glob, "Filter which KUnit test suites run at boot-time, e.g. list*"); static struct kunit_suite * const * -kunit_filter_subsuite(struct kunit_suite * const * const subsuite) +kunit_filter_subsuite(struct kunit_suite * const * const subsuite, const char *filter_glob) { int i, n = 0; struct kunit_suite **filtered; @@ -52,19 +52,14 @@ struct suite_set { struct kunit_suite * const * const *end; }; -static struct suite_set kunit_filter_suites(void) +static struct suite_set kunit_filter_suites(const struct suite_set *suite_set, + const char *filter_glob) { int i; struct kunit_suite * const **copy, * const *filtered_subsuite; struct suite_set filtered; - const size_t max = __kunit_suites_end - __kunit_suites_start; - - if (!filter_glob) { - filtered.start = __kunit_suites_start; - filtered.end = __kunit_suites_end; - return filtered; - } + const size_t max = suite_set->end - suite_set->start; copy = kmalloc_array(max, sizeof(*filtered.start), GFP_KERNEL); filtered.start = copy; @@ -74,7 +69,7 @@ static struct suite_set kunit_filter_suites(void) } for (i = 0; i < max; ++i) { - filtered_subsuite = kunit_filter_subsuite(__kunit_suites_start[i]); + filtered_subsuite = kunit_filter_subsuite(suite_set->start[i], filter_glob); if (filtered_subsuite) *copy++ = filtered_subsuite; } @@ -98,8 +93,13 @@ static void kunit_print_tap_header(struct suite_set *suite_set) int kunit_run_all_tests(void) { struct kunit_suite * const * const *suites; + struct suite_set suite_set = { + .start = __kunit_suites_start, + .end = __kunit_suites_end, + }; - struct suite_set suite_set = kunit_filter_suites(); + if (filter_glob) + suite_set = kunit_filter_suites(&suite_set, filter_glob); kunit_print_tap_header(&suite_set); @@ -115,4 +115,8 @@ int kunit_run_all_tests(void) return 0; } +#if IS_BUILTIN(CONFIG_KUNIT_TEST) +#include "executor_test.c" +#endif + #endif /* IS_BUILTIN(CONFIG_KUNIT) */ diff --git a/lib/kunit/executor_test.c b/lib/kunit/executor_test.c new file mode 100644 index 000000000000..8e925395beeb --- /dev/null +++ b/lib/kunit/executor_test.c @@ -0,0 +1,132 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * KUnit test for the KUnit executor. + * + * Copyright (C) 2021, Google LLC. + * Author: Daniel Latypov <dlatypov(a)google.com> + */ + +#include <kunit/test.h> + +static void kfree_at_end(struct kunit *test, const void *to_free); +static struct kunit_suite *alloc_fake_suite(struct kunit *test, + const char *suite_name); + +static void filter_subsuite_test(struct kunit *test) +{ + struct kunit_suite *subsuite[3] = {NULL, NULL, NULL}; + struct kunit_suite * const *filtered; + + subsuite[0] = alloc_fake_suite(test, "suite1"); + subsuite[1] = alloc_fake_suite(test, "suite2"); + + /* Want: suite1, suite2, NULL -> suite2, NULL */ + filtered = kunit_filter_subsuite(subsuite, "suite2*"); + KUNIT_ASSERT_NOT_ERR_OR_NULL(test, filtered); + kfree_at_end(test, filtered); + + KUNIT_ASSERT_NOT_ERR_OR_NULL(test, filtered[0]); + KUNIT_EXPECT_STREQ(test, (const char *)filtered[0]->name, "suite2"); + + KUNIT_EXPECT_FALSE(test, filtered[1]); +} + +static void filter_subsuite_to_empty_test(struct kunit *test) +{ + struct kunit_suite *subsuite[3] = {NULL, NULL, NULL}; + struct kunit_suite * const *filtered; + + subsuite[0] = alloc_fake_suite(test, "suite1"); + subsuite[1] = alloc_fake_suite(test, "suite2"); + + filtered = kunit_filter_subsuite(subsuite, "not_found"); + kfree_at_end(test, filtered); /* just in case */ + + KUNIT_EXPECT_FALSE_MSG(test, filtered, + "should be NULL to indicate no match"); +} + +static void kfree_subsuites_at_end(struct kunit *test, struct suite_set *suite_set) +{ + struct kunit_suite * const * const *suites; + + for (suites = suite_set->start; suites < suite_set->end; suites++) + kfree_at_end(test, *suites); +} + +static void filter_suites_test(struct kunit *test) +{ + /* Suites per-file are stored as a NULL terminated array */ + struct kunit_suite *subsuites[2][2] = { + {NULL, NULL}, + {NULL, NULL}, + }; + /* Match the memory layout of suite_set */ + struct kunit_suite * const * const suites[2] = { + subsuites[0], subsuites[1], + }; + + const struct suite_set suite_set = { + .start = suites, + .end = suites + 2, + }; + struct suite_set filtered = {.start = NULL, .end = NULL}; + + /* Emulate two files, each having one suite */ + subsuites[0][0] = alloc_fake_suite(test, "suite0"); + subsuites[1][0] = alloc_fake_suite(test, "suite1"); + + /* Filter out suite1 */ + filtered = kunit_filter_suites(&suite_set, "suite0"); + kfree_subsuites_at_end(test, &filtered); /* let us use ASSERTs without leaking */ + KUNIT_ASSERT_EQ(test, filtered.end - filtered.start, (ptrdiff_t) 1); + + KUNIT_ASSERT_NOT_ERR_OR_NULL(test, filtered.start); + KUNIT_ASSERT_NOT_ERR_OR_NULL(test, filtered.start[0]); + KUNIT_EXPECT_PTR_EQ(test, filtered.start[0][0], subsuites[0][0]); +} + +static struct kunit_case executor_test_cases[] = { + KUNIT_CASE(filter_subsuite_test), + KUNIT_CASE(filter_subsuite_to_empty_test), + KUNIT_CASE(filter_suites_test), + {} +}; + +static struct kunit_suite executor_test_suite = { + .name = "kunit_executor_test", + .test_cases = executor_test_cases, +}; + +kunit_test_suites(&executor_test_suite); + +/* Test helpers */ + +static void kfree_res_free(struct kunit_resource *res) +{ + kfree(res->data); +} + +/* Use the resource API to register a call to kfree(to_free). + * Since we never actually use the resource, it's safe to use on const data. + */ +static void kfree_at_end(struct kunit *test, const void *to_free) +{ + /* kfree() handles NULL already, but avoid allocating a no-op cleanup. */ + if (IS_ERR_OR_NULL(to_free)) + return; + kunit_alloc_and_get_resource(test, NULL, kfree_res_free, GFP_KERNEL, + (void *)to_free); +} + +static struct kunit_suite *alloc_fake_suite(struct kunit *test, + const char *suite_name) +{ + struct kunit_suite *suite; + + /* We normally never expect to allocate suites, hence the non-const cast. */ + suite = kunit_kzalloc(test, sizeof(*suite), GFP_KERNEL); + strncpy((char *)suite->name, suite_name, sizeof(suite->name)); + + return suite; +} base-commit: 1678e493d530e7977cce34e59a86bb86f3c5631e -- 2.31.1.295.g9ea45b61b8-goog

4 years, 5 months

3
3
0 0

[PATCH] selftests/bpf: use !E instead of comparing with NULL

by Yang Li

Fix the following coccicheck warnings: ./tools/testing/selftests/bpf/progs/profiler.inc.h:189:7-11: WARNING comparing pointer to 0, suggest !E ./tools/testing/selftests/bpf/progs/profiler.inc.h:361:7-11: WARNING comparing pointer to 0, suggest !E ./tools/testing/selftests/bpf/progs/profiler.inc.h:386:14-18: WARNING comparing pointer to 0, suggest !E ./tools/testing/selftests/bpf/progs/profiler.inc.h:402:14-18: WARNING comparing pointer to 0, suggest !E ./tools/testing/selftests/bpf/progs/profiler.inc.h:433:7-11: WARNING comparing pointer to 0, suggest !E ./tools/testing/selftests/bpf/progs/profiler.inc.h:534:14-18: WARNING comparing pointer to 0, suggest !E ./tools/testing/selftests/bpf/progs/profiler.inc.h:625:7-11: WARNING comparing pointer to 0, suggest !E ./tools/testing/selftests/bpf/progs/profiler.inc.h:767:7-11: WARNING comparing pointer to 0, suggest !E Reported-by: Abaci Robot <abaci(a)linux.alibaba.com> Signed-off-by: Yang Li <yang.lee(a)linux.alibaba.com> --- tools/testing/selftests/bpf/progs/profiler.inc.h | 22 +++++++++++----------- 1 file changed, 11 insertions(+), 11 deletions(-) diff --git a/tools/testing/selftests/bpf/progs/profiler.inc.h b/tools/testing/selftests/bpf/progs/profiler.inc.h index 4896fdf8..a33066c 100644 --- a/tools/testing/selftests/bpf/progs/profiler.inc.h +++ b/tools/testing/selftests/bpf/progs/profiler.inc.h @@ -189,7 +189,7 @@ static INLINE void populate_ancestors(struct task_struct* task, #endif for (num_ancestors = 0; num_ancestors < MAX_ANCESTORS; num_ancestors++) { parent = BPF_CORE_READ(parent, real_parent); - if (parent == NULL) + if (!parent) break; ppid = BPF_CORE_READ(parent, tgid); if (is_init_process(ppid)) @@ -361,7 +361,7 @@ static INLINE void* populate_var_metadata(struct var_metadata_t* metadata, int zero = 0; struct var_kill_data_t* kill_data = bpf_map_lookup_elem(&data_heap, &zero); - if (kill_data == NULL) + if (!kill_data) return NULL; struct task_struct* task = (struct task_struct*)bpf_get_current_task(); @@ -386,14 +386,14 @@ static INLINE int trace_var_sys_kill(void* ctx, int tpid, int sig) u32 spid = get_userspace_pid(); struct var_kill_data_arr_t* arr_struct = bpf_map_lookup_elem(&var_tpid_to_data, &tpid); - if (arr_struct == NULL) { + if (!arr_struct) { struct var_kill_data_t* kill_data = get_var_kill_data(ctx, spid, tpid, sig); int zero = 0; - if (kill_data == NULL) + if (!kill_data) return 0; arr_struct = bpf_map_lookup_elem(&data_heap, &zero); - if (arr_struct == NULL) + if (!arr_struct) return 0; bpf_probe_read(&arr_struct->array[0], sizeof(arr_struct->array[0]), kill_data); } else { @@ -402,7 +402,7 @@ static INLINE int trace_var_sys_kill(void* ctx, int tpid, int sig) if (index == -1) { struct var_kill_data_t* kill_data = get_var_kill_data(ctx, spid, tpid, sig); - if (kill_data == NULL) + if (!kill_data) return 0; #ifdef UNROLL #pragma unroll @@ -433,7 +433,7 @@ static INLINE int trace_var_sys_kill(void* ctx, int tpid, int sig) } else { struct var_kill_data_t* kill_data = get_var_kill_data(ctx, spid, tpid, sig); - if (kill_data == NULL) + if (!kill_data) return 0; bpf_probe_read(&arr_struct->array[index], sizeof(arr_struct->array[index]), @@ -534,14 +534,14 @@ static INLINE bool is_dentry_allowed_for_filemod(struct dentry* file_dentry, *device_id = dev_id; bool* allowed_device = bpf_map_lookup_elem(&allowed_devices, &dev_id); - if (allowed_device == NULL) + if (!allowed_device) return false; u64 ino = BPF_CORE_READ(file_dentry, d_inode, i_ino); *file_ino = ino; bool* allowed_file = bpf_map_lookup_elem(&allowed_file_inodes, &ino); - if (allowed_file == NULL) + if (!allowed_fil) if (!is_ancestor_in_allowed_inodes(BPF_CORE_READ(file_dentry, d_parent))) return false; return true; @@ -625,7 +625,7 @@ int raw_tracepoint__sched_process_exit(void* ctx) struct var_kill_data_arr_t* arr_struct = bpf_map_lookup_elem(&var_tpid_to_data, &tpid); struct var_kill_data_t* kill_data = bpf_map_lookup_elem(&data_heap, &zero); - if (arr_struct == NULL || kill_data == NULL) + if (!arr_struct || !kill_data) goto out; struct task_struct* task = (struct task_struct*)bpf_get_current_task(); @@ -767,7 +767,7 @@ int kprobe_ret__do_filp_open(struct pt_regs* ctx) struct file* filp = (struct file*)PT_REGS_RC_CORE(ctx); - if (filp == NULL || IS_ERR(filp)) + if (!filp || IS_ERR(filp)) goto out; unsigned int flags = BPF_CORE_READ(filp, f_flags); if ((flags & (O_RDWR | O_WRONLY)) == 0) -- 1.8.3.1

4 years, 5 months

3
8
0 0

[PATCH v4] userfaultfd/shmem: fix MCOPY_ATOMIC_CONTINUE behavior

by Axel Rasmussen

Previously, the continue implementation in shmem_mcopy_atomic_pte was incorrect for two main reasons: - It didn't correctly skip some sections of code which make sense for newly allocated pages, but absolutely don't make sense for pre-existing page cache pages. - Because shmem_mcopy_continue_pte is called only if VM_SHARED is detected in mm/userfaultd.c, we were incorrectly not supporting the case where a tmpfs file had been mmap()-ed with MAP_PRIVATE. So, this patch does the following: In mm/userfaultfd.c, break the logic to install PTEs out of mcopy_atomic_pte, into a separate helper function. In mfill_atomic_pte, for the MCOPY_ATOMIC_CONTINUE case, simply look up the existing page in the page cache, and then use the PTE installation helper to setup the mapping. This addresses the two issues noted above. The previous code's bugs manifested clearly in the error handling path. So, to detect this kind of issue in the future, modify the selftest to exercise the error handling path as well. Note that this patch is based on linux-next/akpm; the "fixes" line refers to a SHA1 in that branch. Changes since v3: - Significantly refactored the patch. Continue handling now happens in mm/userfaultfd.c, via a PTE installation helper. Most of the mm/shmem.c changes from the patch being fixed [1] are reverted. Changes since v2: - Drop the ClearPageDirty() entirely, instead of trying to remember the old value. - Modify both pgoff / max_off checks to use pgoff. It's equivalent to offset, but offset wasn't initialized until the first check (which we're skipping). - Keep the second pgoff / max_off check in the continue case. Changes since v1: - Refactor to skip ahead with goto, instead of adding several more "if (!is_continue)". - Fix unconditional ClearPageDirty(). - Don't pte_mkwrite() when is_continue && !VM_SHARED. [1] https://lore.kernel.org/patchwork/patch/1392464/ Fixes: 00da60b9d0a0 ("userfaultfd: support minor fault handling for shmem") Signed-off-by: Axel Rasmussen <axelrasmussen(a)google.com> --- mm/shmem.c | 56 ++++++--------- mm/userfaultfd.c | 183 ++++++++++++++++++++++++++++++++++------------- 2 files changed, 156 insertions(+), 83 deletions(-) diff --git a/mm/shmem.c b/mm/shmem.c index 5cfd2fb6e52b..9d9a9f254f33 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -2366,7 +2366,6 @@ int shmem_mcopy_atomic_pte(struct mm_struct *dst_mm, pmd_t *dst_pmd, unsigned long dst_addr, unsigned long src_addr, enum mcopy_atomic_mode mode, struct page **pagep) { - bool is_continue = (mode == MCOPY_ATOMIC_CONTINUE); struct inode *inode = file_inode(dst_vma->vm_file); struct shmem_inode_info *info = SHMEM_I(inode); struct address_space *mapping = inode->i_mapping; @@ -2377,18 +2376,17 @@ int shmem_mcopy_atomic_pte(struct mm_struct *dst_mm, pmd_t *dst_pmd, struct page *page; pte_t _dst_pte, *dst_pte; int ret; - pgoff_t offset, max_off; + pgoff_t max_off; + + /* Handled by mcontinue_atomic_pte instead. */ + if (WARN_ON_ONCE(mode == MCOPY_ATOMIC_CONTINUE)) + return -EINVAL; ret = -ENOMEM; if (!shmem_inode_acct_block(inode, 1)) goto out; - if (is_continue) { - ret = -EFAULT; - page = find_lock_page(mapping, pgoff); - if (!page) - goto out_unacct_blocks; - } else if (!*pagep) { + if (!*pagep) { page = shmem_alloc_page(gfp, info, pgoff); if (!page) goto out_unacct_blocks; @@ -2415,27 +2413,21 @@ int shmem_mcopy_atomic_pte(struct mm_struct *dst_mm, pmd_t *dst_pmd, *pagep = NULL; } - if (!is_continue) { - VM_BUG_ON(PageSwapBacked(page)); - VM_BUG_ON(PageLocked(page)); - __SetPageLocked(page); - __SetPageSwapBacked(page); - __SetPageUptodate(page); - } + VM_BUG_ON(PageSwapBacked(page)); + VM_BUG_ON(PageLocked(page)); + __SetPageLocked(page); + __SetPageSwapBacked(page); + __SetPageUptodate(page); ret = -EFAULT; - offset = linear_page_index(dst_vma, dst_addr); max_off = DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE); - if (unlikely(offset >= max_off)) + if (unlikely(pgoff >= max_off)) goto out_release; - /* If page wasn't already in the page cache, add it. */ - if (!is_continue) { - ret = shmem_add_to_page_cache(page, mapping, pgoff, NULL, - gfp & GFP_RECLAIM_MASK, dst_mm); - if (ret) - goto out_release; - } + ret = shmem_add_to_page_cache(page, mapping, pgoff, NULL, + gfp & GFP_RECLAIM_MASK, dst_mm); + if (ret) + goto out_release; _dst_pte = mk_pte(page, dst_vma->vm_page_prot); if (dst_vma->vm_flags & VM_WRITE) @@ -2455,22 +2447,20 @@ int shmem_mcopy_atomic_pte(struct mm_struct *dst_mm, pmd_t *dst_pmd, ret = -EFAULT; max_off = DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE); - if (unlikely(offset >= max_off)) + if (unlikely(pgoff >= max_off)) goto out_release_unlock; ret = -EEXIST; if (!pte_none(*dst_pte)) goto out_release_unlock; - if (!is_continue) { - lru_cache_add(page); + lru_cache_add(page); - spin_lock_irq(&info->lock); - info->alloced++; - inode->i_blocks += BLOCKS_PER_PAGE; - shmem_recalc_inode(inode); - spin_unlock_irq(&info->lock); - } + spin_lock_irq(&info->lock); + info->alloced++; + inode->i_blocks += BLOCKS_PER_PAGE; + shmem_recalc_inode(inode); + spin_unlock_irq(&info->lock); inc_mm_counter(dst_mm, mm_counter_file(page)); page_add_file_rmap(page, false); diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c index cbb7c8d79a4d..286d0657fbe2 100644 --- a/mm/userfaultfd.c +++ b/mm/userfaultfd.c @@ -48,21 +48,103 @@ struct vm_area_struct *find_dst_vma(struct mm_struct *dst_mm, return dst_vma; } +/* + * Install PTEs, to map dst_addr (within dst_vma) to page. + * + * This function handles MCOPY_ATOMIC_CONTINUE (which is always file-backed), + * whether or not dst_vma is VM_SHARED. It also handles the more general + * MCOPY_ATOMIC_NORMAL case, when dst_vma is *not* VM_SHARED (it may be file + * backed, or not). + * + * Note that MCOPY_ATOMIC_NORMAL for a VM_SHARED dst_vma is handled by + * shmem_mcopy_atomic_pte instead. + */ +static int mcopy_atomic_install_ptes(struct mm_struct *dst_mm, pmd_t *dst_pmd, + struct vm_area_struct *dst_vma, + unsigned long dst_addr, struct page *page, + enum mcopy_atomic_mode mode, bool wp_copy) +{ + int ret; + pte_t _dst_pte, *dst_pte; + bool is_continue = mode == MCOPY_ATOMIC_CONTINUE; + int writable; + bool vm_shared = dst_vma->vm_flags & VM_SHARED; + bool is_file_backed = dst_vma->vm_file; + spinlock_t *ptl; + struct inode *inode; + pgoff_t offset, max_off; + + _dst_pte = mk_pte(page, dst_vma->vm_page_prot); + writable = dst_vma->vm_flags & VM_WRITE; + /* For CONTINUE on a non-shared VMA, don't pte_mkwrite for CoW. */ + if (is_continue && !vm_shared) + writable = 0; + + if (writable) { + _dst_pte = pte_mkdirty(_dst_pte); + if (wp_copy) + _dst_pte = pte_mkuffd_wp(_dst_pte); + else + _dst_pte = pte_mkwrite(_dst_pte); + } else if (vm_shared) { + /* + * Since we didn't pte_mkdirty(), mark the page dirty or it + * could be freed from under us. We could do this + * unconditionally, but doing it only if !writable is faster. + */ + set_page_dirty(page); + } + + dst_pte = pte_offset_map_lock(dst_mm, dst_pmd, dst_addr, &ptl); + + if (is_file_backed) { + /* The shmem MAP_PRIVATE case requires checking the i_size */ + inode = dst_vma->vm_file->f_inode; + offset = linear_page_index(dst_vma, dst_addr); + max_off = DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE); + ret = -EFAULT; + if (unlikely(offset >= max_off)) + goto out_unlock; + } + + ret = -EEXIST; + if (!pte_none(*dst_pte)) + goto out_unlock; + + inc_mm_counter(dst_mm, mm_counter(page)); + if (is_file_backed) + page_add_file_rmap(page, false); + else + page_add_new_anon_rmap(page, dst_vma, dst_addr, false); + + if (!is_continue) + lru_cache_add_inactive_or_unevictable(page, dst_vma); + + set_pte_at(dst_mm, dst_addr, dst_pte, _dst_pte); + + /* No need to invalidate - it was non-present before */ + update_mmu_cache(dst_vma, dst_addr, dst_pte); + pte_unmap_unlock(dst_pte, ptl); + ret = 0; +out: + return ret; +out_unlock: + pte_unmap_unlock(dst_pte, ptl); + goto out; +} + static int mcopy_atomic_pte(struct mm_struct *dst_mm, pmd_t *dst_pmd, struct vm_area_struct *dst_vma, unsigned long dst_addr, unsigned long src_addr, struct page **pagep, + enum mcopy_atomic_mode mode, bool wp_copy) { - pte_t _dst_pte, *dst_pte; - spinlock_t *ptl; void *page_kaddr; int ret; struct page *page; - pgoff_t offset, max_off; - struct inode *inode; if (!*pagep) { ret = -ENOMEM; @@ -99,43 +181,12 @@ static int mcopy_atomic_pte(struct mm_struct *dst_mm, if (mem_cgroup_charge(page, dst_mm, GFP_KERNEL)) goto out_release; - _dst_pte = pte_mkdirty(mk_pte(page, dst_vma->vm_page_prot)); - if (dst_vma->vm_flags & VM_WRITE) { - if (wp_copy) - _dst_pte = pte_mkuffd_wp(_dst_pte); - else - _dst_pte = pte_mkwrite(_dst_pte); - } - - dst_pte = pte_offset_map_lock(dst_mm, dst_pmd, dst_addr, &ptl); - if (dst_vma->vm_file) { - /* the shmem MAP_PRIVATE case requires checking the i_size */ - inode = dst_vma->vm_file->f_inode; - offset = linear_page_index(dst_vma, dst_addr); - max_off = DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE); - ret = -EFAULT; - if (unlikely(offset >= max_off)) - goto out_release_uncharge_unlock; - } - ret = -EEXIST; - if (!pte_none(*dst_pte)) - goto out_release_uncharge_unlock; - - inc_mm_counter(dst_mm, MM_ANONPAGES); - page_add_new_anon_rmap(page, dst_vma, dst_addr, false); - lru_cache_add_inactive_or_unevictable(page, dst_vma); - - set_pte_at(dst_mm, dst_addr, dst_pte, _dst_pte); - - /* No need to invalidate - it was non-present before */ - update_mmu_cache(dst_vma, dst_addr, dst_pte); - - pte_unmap_unlock(dst_pte, ptl); - ret = 0; + ret = mcopy_atomic_install_ptes(dst_mm, dst_pmd, dst_vma, dst_addr, + page, mode, wp_copy); + if (ret) + goto out_release; out: return ret; -out_release_uncharge_unlock: - pte_unmap_unlock(dst_pte, ptl); out_release: put_page(page); goto out; @@ -176,6 +227,38 @@ static int mfill_zeropage_pte(struct mm_struct *dst_mm, return ret; } +static int mcontinue_atomic_pte(struct mm_struct *dst_mm, + pmd_t *dst_pmd, + struct vm_area_struct *dst_vma, + unsigned long dst_addr, + bool wp_copy) +{ + struct inode *inode = file_inode(dst_vma->vm_file); + struct address_space *mapping = inode->i_mapping; + pgoff_t pgoff = linear_page_index(dst_vma, dst_addr); + struct page *page; + int ret; + + ret = -EFAULT; + page = find_lock_page(mapping, pgoff); + if (!page) + goto out; + + ret = mcopy_atomic_install_ptes(dst_mm, dst_pmd, dst_vma, dst_addr, + page, MCOPY_ATOMIC_CONTINUE, wp_copy); + if (ret) + goto out_release; + + unlock_page(page); + ret = 0; +out: + return ret; +out_release: + unlock_page(page); + put_page(page); + goto out; +} + static pmd_t *mm_alloc_pmd(struct mm_struct *mm, unsigned long address) { pgd_t *pgd; @@ -418,7 +501,13 @@ static __always_inline ssize_t mfill_atomic_pte(struct mm_struct *dst_mm, enum mcopy_atomic_mode mode, bool wp_copy) { - ssize_t err; + ssize_t err = 0; + + if (mode == MCOPY_ATOMIC_CONTINUE) { + err = mcontinue_atomic_pte(dst_mm, dst_pmd, dst_vma, dst_addr, + wp_copy); + goto out; + } /* * The normal page fault path for a shmem will invoke the @@ -431,26 +520,20 @@ static __always_inline ssize_t mfill_atomic_pte(struct mm_struct *dst_mm, * and not in the radix tree. */ if (!(dst_vma->vm_flags & VM_SHARED)) { - switch (mode) { - case MCOPY_ATOMIC_NORMAL: + if (mode == MCOPY_ATOMIC_NORMAL) err = mcopy_atomic_pte(dst_mm, dst_pmd, dst_vma, dst_addr, src_addr, page, - wp_copy); - break; - case MCOPY_ATOMIC_ZEROPAGE: + mode, wp_copy); + else if (mode == MCOPY_ATOMIC_ZEROPAGE) err = mfill_zeropage_pte(dst_mm, dst_pmd, dst_vma, dst_addr); - break; - case MCOPY_ATOMIC_CONTINUE: - err = -EINVAL; - break; - } } else { VM_WARN_ON_ONCE(wp_copy); err = shmem_mcopy_atomic_pte(dst_mm, dst_pmd, dst_vma, dst_addr, src_addr, mode, page); } +out: return err; } -- 2.31.0.208.g409f899ff0-goog

4 years, 5 months

3
6
0 0

[PATCH v2] Documentation: kunit: add tips for running KUnit

by Daniel Latypov

This is long overdue. There are several things that aren't nailed down (in-tree .kunitconfig's), or partially broken (GCOV on UML), but having them documented, warts and all, is better than having nothing. This covers a bunch of the more recent features * kunit_filter_glob * kunit.py run --kunitconfig * slightly more detail on building tests as modules * CONFIG_KUNIT_DEBUGFS By my count, the only headline features now not mentioned are the KASAN integration and KernelCI json output support (kunit.py run --json). And then it also discusses how to get code coverage reports under UML and non-UML since this is a question people have repeatedly asked. Non-UML coverage collection is no different from normal, but we should probably explicitly call this out. As for UML, I was able to get it working again with two small hacks.* E.g. with CONFIG_KUNIT=y && CONFIG_KUNIT_ALL_TESTS=y Overall coverage rate: lines......: 15.1% (18294 of 120776 lines) functions..: 16.8% (1860 of 11050 functions) Note: this doesn't document --alltests since this is not stable yet. Hopefully being run more frequently as part of KernelCI will help... *Using gcc/gcov-6 and not using uml_abort() in os_dump_core(). I've documented these hacks in "Notes" but left TODOs for brendanhiggins(a)google.com who tracked down the runtime issue in GCC. To be clear: these are not issues specific to KUnit, but rather to UML. Signed-off-by: Daniel Latypov <dlatypov(a)google.com> --- Documentation/dev-tools/kunit/index.rst | 1 + .../dev-tools/kunit/running_tips.rst | 260 ++++++++++++++++++ Documentation/dev-tools/kunit/start.rst | 2 + 3 files changed, 263 insertions(+) create mode 100644 Documentation/dev-tools/kunit/running_tips.rst diff --git a/Documentation/dev-tools/kunit/index.rst b/Documentation/dev-tools/kunit/index.rst index 848478838347..7f7cf8d2ab20 100644 --- a/Documentation/dev-tools/kunit/index.rst +++ b/Documentation/dev-tools/kunit/index.rst @@ -14,6 +14,7 @@ KUnit - Unit Testing for the Linux Kernel style faq tips + running_tips What is KUnit? ============== diff --git a/Documentation/dev-tools/kunit/running_tips.rst b/Documentation/dev-tools/kunit/running_tips.rst new file mode 100644 index 000000000000..52cc62d1c83b --- /dev/null +++ b/Documentation/dev-tools/kunit/running_tips.rst @@ -0,0 +1,260 @@ +.. SPDX-License-Identifier: GPL-2.0 + +============================ +Tips For Running KUnit Tests +============================ + +Using ``kunit.py run`` ("kunit tool") +===================================== + +Running from any directory +-------------------------- + +It can be handy to create a bash function like: + +.. code-block:: bash + + function run_kunit() { + ( cd "$(git rev-parse --show-toplevel)" && ./tools/testing/kunit/kunit.py run $@ ) + } + +.. note:: + Early versions of ``kunit.py`` (before 5.6) didn't work unless run from + the kernel root, hence the use of a subshell and ``cd``. + +Running a subset of tests +------------------------- + +``kunit.py run`` accepts an optional glob argument to filter tests. Currently +this only matches against suite names, but this may change in the future. + +Say that we wanted to run the sysctl tests, we could do so via: + +.. code-block:: bash + + $ echo -e 'CONFIG_KUNIT=y\nCONFIG_KUNIT_ALL_TESTS=y' > .kunit/.kunitconfig + $ ./tools/testing/kunit/kunit.py run 'sysctl*' + +We're paying the cost of building more tests than we need this way, but it's +easier than fiddling with ``.kunitconfig`` files or commenting out +``kunit_suite``'s. + +However, if we wanted to define a set of tests in a less ad hoc way, the next +tip is useful. + +Defining a set of tests +----------------------- + +``kunit.py run`` (along with ``build``, and ``config``) supports a +``--kunitconfig`` flag. So if you have a set of tests that you want to run on a +regular basis (especially if they have other dependencies), you can create a +specific ``.kunitconfig`` for them. + +E.g. kunit has one for its tests: + +.. code-block:: bash + + $ ./tools/testing/kunit/kunit.py run --kunitconfig=lib/kunit/.kunitconfig + +Alternatively, if you're following the convention of naming your +file ``.kunitconfig``, you can just pass in the dir, e.g. + +.. code-block:: bash + + $ ./tools/testing/kunit/kunit.py run --kunitconfig=lib/kunit + +.. note:: + This is a relatively new feature (5.12+) so we don't have any + conventions yet about on what files should be checked in versus just + kept around locally. It's up to you and your maintainer to decide if a + config is useful enough to submit (and therefore have to maintain). + +.. note:: + Having ``.kunitconfig`` fragments in a parent and child directory is + iffy. There's discussion about adding an "import" statement in these + files to make it possible to have a top-level config run tests from all + child directories. But that would mean ``.kunitconfig`` files are no + longer just simple .config fragments. + + One alternative would be to have kunit tool recursively combine configs + automagically, but tests could theoretically depend on incompatible + options, so handling that would be tricky. + +Generating code coverage reports under UML +------------------------------------------ + +.. note:: + TODO(brendanhiggins(a)google.com): There are various issues with UML and + versions of gcc 7 and up. You're likely to run into missing ``.gcda`` + files or compile errors. We know one `faulty GCC commit + <https://github.com/gcc-mirror/gcc/commit/8c9434c2f9358b8b8bad2c1990edf10a21…>`_ + but not how we'd go about getting this fixed. The compile errors still + need some investigation. + +.. note:: + TODO(brendanhiggins(a)google.com): for recent versions of Linux + (5.10-5.12, maybe earlier), there's a bug with gcov counters not being + flushed in UML. This translates to very low (<1%) reported coverage. This is + related to the above issue and can be worked around by replacing the + one call to ``uml_abort()`` with a plain ``exit()``. + + +This is different from the "normal" way of getting coverage information that is +documented in Documentation/dev-tools/gcov.rst. + +Instead of enabling ``CONFIG_GCOV_KERNEL=y``, we can set these options: + +.. code-block:: none + + CONFIG_DEBUG_KERNEL=y + CONFIG_DEBUG_INFO=y + CONFIG_GCOV=y + + +Putting it together into a copy-pastable sequence of commands: + +.. code-block:: bash + + # Append coverage options to the current config + $ echo -e "CONFIG_DEBUG_KERNEL=y\nCONFIG_DEBUG_INFO=y\nCONFIG_GCOV=y" >> .kunit/.kunitconfig + $ ./tools/testing/kunit/kunit.py run + # Extract the coverage information from the build dir (.kunit/) + $ lcov -t "my_kunit_tests" -o coverage.info -c -d .kunit/ + + # From here on, it's the same process as with CONFIG_GCOV_KERNEL=y + # E.g. can generate an HTML report in a tmp dir like so: + $ genhtml -o /tmp/coverage_html coverage.info + + +If your installed version of gcc doesn't work, you can tweak the steps: + +.. code-block:: bash + + # need to edit tools/testing/kunit/kunit_kernel.py to call make with 'CC=/usr/bin/gcc-6' + $ $EDITOR tools/testing/kunit/kunit_kernel.py + + $ lcov -t "my_kunit_tests" -o coverage.info -c -d .kunit/ --gcov-tool=/usr/bin/gcov-6 + + +Running tests manually +====================== + +Running tests without using ``kunit.py run`` is also an important use case. +Currently it's your only option if you want to test on architectures other than +UML. + +As running the tests under UML is fairly straightforward (configure and compile +the kernel, run the ``./linux`` binary), this section will focus on testing +non-UML architectures. + + +Running built-in tests +---------------------- + +When setting tests to ``=y``, the tests will run as part of boot and print +results to dmesg in TAP format. So you just need to add your tests to your +``.config``, build and boot your kernel as normal. + +So if we compiled our kernel with: + +.. code-block:: none + + CONFIG_KUNIT=y + CONFIG_KUNIT_EXAMPLE_TEST=y + +Then we'd see output like this in dmesg signaling the test ran and passed: + +.. code-block:: none + + TAP version 14 + 1..1 + # Subtest: example + 1..1 + # example_simple_test: initializing + ok 1 - example_simple_test + ok 1 - example + +Running tests as modules +------------------------ + +Depending on the tests, you can build them as loadable modules. + +For example, we'd change the config options from before to + +.. code-block:: none + + CONFIG_KUNIT=y + CONFIG_KUNIT_EXAMPLE_TEST=m + +Then after booting into our kernel, we can run the test via + +.. code-block:: none + + $ modprobe kunit-example-test + +This will then cause it to print TAP output to stdout. + +.. note:: + The ``modprobe`` will *not* have a non-zero exit code if any test + failed (as of 5.13). But ``kunit.py parse`` would, see below. + +.. note:: + You can set ``CONFIG_KUNIT=m`` as well, however, some features will not + work and thus some tests might break. Ideally tests would specify they + depend on ``KUNIT=y`` in their ``Kconfig``'s, but this is an edge case + most test authors won't think about. + As of 5.13, the only difference is that ``current->kunit_test`` will + not exist. + +Pretty-printing results +----------------------- + +You can use ``kunit.py parse`` to parse dmesg for test output and print out +results in the same familiar format that ``kunit.py run`` does. + +.. code-block:: bash + + $ ./tools/testing/kunit/kunit.py parse /var/log/dmesg + + +Retrieving per suite results +---------------------------- + +Regardless of how you're running your tests, you can enable +``CONFIG_KUNIT_DEBUGFS`` to expose per-suite TAP-formatted results: + +.. code-block:: none + + CONFIG_KUNIT=y + CONFIG_KUNIT_EXAMPLE_TEST=m + CONFIG_KUNIT_DEBUGFS=y + +The results for each suite will be exposed under +``/sys/kernel/debug/kunit/<suite>/results``. +So using our example config: + +.. code-block:: bash + + $ modprobe kunit-example-test > /dev/null + $ cat /sys/kernel/debug/kunit/example/results + ... <TAP output> ... + + # After removing the module, the corresponding files will go away + $ modprobe -r kunit-example-test + $ cat /sys/kernel/debug/kunit/example/results + /sys/kernel/debug/kunit/example/results: No such file or directory + +Generating code coverage reports +-------------------------------- + +See Documentation/dev-tools/gcov.rst for details on how to do this. + +The only vaguely KUnit-specific advice here is that you probably want to build +your tests as modules. That way you can isolate the coverage from tests from +other code executed during boot, e.g. + +.. code-block:: bash + + # Reset coverage counters before running the test. + $ echo 0 > /sys/kernel/debug/gcov/reset + $ modprobe kunit-example-test diff --git a/Documentation/dev-tools/kunit/start.rst b/Documentation/dev-tools/kunit/start.rst index 0e65cabe08eb..aa56d7ca6bfb 100644 --- a/Documentation/dev-tools/kunit/start.rst +++ b/Documentation/dev-tools/kunit/start.rst @@ -236,5 +236,7 @@ Next Steps ========== * Check out the :doc:`tips` page for tips on writing idiomatic KUnit tests. +* Check out the :doc:`running_tips` page for tips on + how to make running KUnit tests easier. * Optional: see the :doc:`usage` page for a more in-depth explanation of KUnit. base-commit: de2fcb3e62013738f22bbb42cbd757d9a242574e -- 2.31.1.295.g9ea45b61b8-goog

4 years, 5 months

1
0
0 0

[PATCH] Documentation: kunit: add tips for running KUnit

by Daniel Latypov

This is long overdue. There are several things that aren't nailed down (in-tree .kunitconfig's), or partially broken (GCOV on UML), but having them documented, warts and all, is better than having nothing. This covers a bunch of the more recent features * kunit_filter_glob * kunit.py run --kunitconfig * kunit.py run --alltests * slightly more detail on building tests as modules * CONFIG_KUNIT_DEBUGFS By my count, the only headline features now not mentioned are the KASAN integration and KernelCI json output support (kunit.py run --json). And then it also discusses how to get code coverage reports under UML and non-UML since this is a question people have repeatedly asked. Non-UML coverage collection is no differnt from normal, but we should probably explicitly call thsi out. As for UML, I was able to get it working again with two small hacks.* E.g. with CONFIG_KUNIT=y && CONFIG_KUNIT_ALL_TESTS=y Overall coverage rate: lines......: 15.1% (18294 of 120776 lines) functions..: 16.8% (1860 of 11050 functions) *Switching to use gcc/gcov-6 and not using uml_abort(). I've documented these hacks in "Notes" but left TODOs for brendanhiggins(a)google.com who tracked down the runtime issue in GCC. To be clear: these are not issues specific to KUnit, but rather to UML. Signed-off-by: Daniel Latypov <dlatypov(a)google.com> --- Documentation/dev-tools/kunit/index.rst | 1 + .../dev-tools/kunit/running_tips.rst | 278 ++++++++++++++++++ Documentation/dev-tools/kunit/start.rst | 2 + 3 files changed, 281 insertions(+) create mode 100644 Documentation/dev-tools/kunit/running_tips.rst diff --git a/Documentation/dev-tools/kunit/index.rst b/Documentation/dev-tools/kunit/index.rst index 848478838347..7f7cf8d2ab20 100644 --- a/Documentation/dev-tools/kunit/index.rst +++ b/Documentation/dev-tools/kunit/index.rst @@ -14,6 +14,7 @@ KUnit - Unit Testing for the Linux Kernel style faq tips + running_tips What is KUnit? ============== diff --git a/Documentation/dev-tools/kunit/running_tips.rst b/Documentation/dev-tools/kunit/running_tips.rst new file mode 100644 index 000000000000..d38e665e530f --- /dev/null +++ b/Documentation/dev-tools/kunit/running_tips.rst @@ -0,0 +1,278 @@ +.. SPDX-License-Identifier: GPL-2.0 + +============================ +Tips For Running KUnit Tests +============================ + +Using ``kunit.py run`` ("kunit tool") +===================================== + +Running from any directory +-------------------------- + +It can be handy to create a bash function like: + +.. code-block:: bash + + function run_kunit() { + ( cd "$(git rev-parse --show-toplevel)" && ./tools/testing/kunit/kunit.py run $@ ) + } + +.. note:: + Early versions of ``kunit.py`` (before 5.6) didn't work unless run from + the kernel root, hence the use of a subshell and ``cd``. + +Running a subset of tests +------------------------- + +``kunit.py run`` accepts an optional glob argument to filter tests. Currently +this only matches against suite names, but this may change in the future. + +Say that we wanted to run the sysctl tests, we could do so via: + +.. code-block:: bash + + $ echo -e 'CONFIG_KUNIT=y\nCONFIG_KUNIT_ALL_TESTS=y' > .kunit/.kunitconfig + $ ./tools/testing/kunit/kunit.py run 'sysctl*' + +We're paying the cost of building more tests than we need this way, but it's +easier than fiddling with ``.kunitconfig`` files or commenting out +``kunit_suite``'s. + +However, if we wanted to define a set of tests in a less ad hoc way, the next +tip is useful. + +Defining a set of tests +----------------------- + +``kunit.py run`` (along with ``build``, and ``config``) supports a +``--kunitconfig`` flag. So if you have a set of tests that you want to run on a +regular basis (especially if they have other dependencies), you can create a +specific ``.kunitconfig`` for them. + +E.g. kunit has own for its tests: + +.. code-block:: bash + + $ ./tools/testing/kunit/kunit.py run --kunitconfig=lib/kunit/.kunitconfig + +Alternatively, if you're following the convention of naming your +file ``.kunitconfig``, you can just pass in the dir, e.g. + +.. code-block:: bash + + $ ./tools/testing/kunit/kunit.py run --kunitconfig=lib/kunit + +.. note:: + This is a relatively new feature (5.12+) so we don't have any + conventions yet about on what files should be checked in versus just + kept around locally. But if the tests don't have any dependencies + (beyond ``CONFIG_KUNIT``), it's probably not worth writing and + maintaining a ``.kunitconfig`` fragment. Running with + ``CONFIG_KUNIT_ALL_TESTS=y`` is probably easier. + +.. note:: + Having ``.kunitconfig`` fragments in a parent and child directory is + iffy. There's discussion about adding an "import" statement in these + files to make it possible to have a top-level config run tests from all + child directories. But that would mean ``.kunitconfig`` files are no + longer just simple .config fragments. + + One alternative would be to have kunit tool recursively combine configs + automagically, but tests could theoretically depend on incompatible + options, so handling that would be tricky. + +Running with ``allyesconfig`` +----------------------------- + +.. code-block:: bash + + $ ./tools/testing/kunit/kunit.py run --alltests + +This will try and use ``allyesconfig``, or rather ``allyesconfig`` with a list +of UML-incompatible configs turned off. That list is maintained in +``tools/testing/kunit/configs/broken_on_uml.config``. + +.. note:: + This will take a *lot* longer to run and might be broken from time to + time, especially on -next. It's not recommended to use this unless you + need to or are morbidly curious. + +Generating code coverage reports under UML +------------------------------------------ + +.. note:: + TODO(brendanhiggins(a)google.com): There are various issues with UML and + versions of gcc 7 and up. You're likely to run into missing ``.gcda`` + files or compile errors. We know one `faulty GCC commit + <https://github.com/gcc-mirror/gcc/commit/8c9434c2f9358b8b8bad2c1990edf10a21…>`_ + but not how we'd go about getting this fixed. The compile errors still + need some investigation. + +.. note:: + TODO(brendanhiggins(a)google.com): for recent versions of Linux + (5.10-5.12, maybe earlier), there's a bug with gcov counters not being + flushed in UML. This translates to very low (<1%) reported coverage. This is + related to the above issue and can be worked around by replacing the + one call to ``uml_abort()`` with a plain ``exit()``. + + +This is different from the "normal" way of getting coverage information that is +documented in Documentation/dev-tools/gcov.rst. + +Instead of enabling ``CONFIG_GCOV_KERNEL=y``, we can set these options: + +.. code-block:: none + + CONFIG_DEBUG_KERNEL=y + CONFIG_DEBUG_INFO=y + CONFIG_GCOV=y + + +Putting it together into a copy-pastable sequence of commands: + +.. code-block:: bash + + # Append coverage options to the current config + $ echo -e "CONFIG_DEBUG_KERNEL=y\nCONFIG_DEBUG_INFO=y\nCONFIG_GCOV=y" >> .kunit/.kunitconfig + $ ./tools/testing/kunit/kunit.py run + # Extract the coverage information from the build dir (.kunit/) + $ lcov -t "my_kunit_tests" -o coverage.info -c -d .kunit/ + + # From here on, it's the same process as with CONFIG_GCOV_KERNEL=y + # E.g. can generate an HTML report in a tmp dir like so: + $ genhtml -o /tmp/coverage_html coverage.info + + +If your installed version of gcc doesn't work, you can tweak the steps: + +.. code-block:: bash + + # need to edit tools/testing/kunit/kunit_kernel.py to call make with 'CC=/usr/bin/gcc-6' + $ $EDITOR tools/testing/kunit/kunit_kernel.py + + $ lcov -t "my_kunit_tests" -o coverage.info -c -d .kunit/ --gcov-tool=/usr/bin/gcov-6 + + +Running tests manually +====================== + +Running tests without using ``kunit.py run`` is also an important use case. +Currently it's your only option if you want to test on architectures other than +UML. + +As running the tests under UML is fairly straightforward (configure and compile +the kernel, run the ``./linux`` binary), this section will focus on testing +non-UML architectures. + + +Running built-in tests +---------------------- + +When setting tests to ``=y``, the tests will run as part of boot and print +results to dmesg in TAP format. So you just need to add your tests to your +``.config``, build and boot your kernel as normal. + +So if we compiled our kernel with: + +.. code-block:: none + + CONFIG_KUNIT=y + CONFIG_KUNIT_EXAMPLE_TEST=y + +Then we'd see output like this in dmesg signaling the test ran and passed: + +.. code-block:: none + + TAP version 14 + 1..1 + # Subtest: example + 1..1 + # example_simple_test: initializing + ok 1 - example_simple_test + ok 1 - example + +Running tests as modules +------------------------ + +Depending on the tests, you can build them as loadable modules. + +For example, we'd change the config options from before to + +.. code-block:: none + + CONFIG_KUNIT=y + CONFIG_KUNIT_EXAMPLE_TEST=m + +Then after booting into our kernel, we can run the test via + +.. code-block:: none + + $ modprobe kunit-example-test + +This will then cause it to print TAP output to stdout. + +.. note:: + The ``modprobe`` will *not* have a non-zero exit code if any test + failed (as of 5.13). But ``kunit.py parse`` would, see below. + +.. note:: + You can set ``CONFIG_KUNIT=m`` as well, however, some features will not + work and thus some tests might break. Ideally tests would specify they + depend on ``KUNIT=y`` in their ``Kconfig``'s, but this is an edge case + most test authors won't think about. + As of 5.13, the only difference is that ``current->kunit_test`` will + not exist. + +Pretty-printing results +----------------------- + +You can use ``kunit.py parse`` to parse dmesg for test output and print out +results in the same familiar format that ``kunit.py run`` does. + +.. code-block:: bash + + $ ./tools/testing/kunit/kunit.py parse /var/log/dmesg + + +Retrieving per suite results +---------------------------- + +Regardless of how you're running your tests, you can enable +``CONFIG_KUNIT_DEBUGFS`` to expose per-suite TAP-formatted results: + +.. code-block:: none + + CONFIG_KUNIT=y + CONFIG_KUNIT_EXAMPLE_TEST=m + CONFIG_KUNIT_DEBUGFS=y + +The results for each suite will be exposed under +``/sys/kernel/debug/kunit/<suite>/results``. +So using our example config: + +.. code-block:: bash + + $ modprobe kunit-example-test > /dev/null + $ cat /sys/kernel/debug/kunit/example/results + ... <TAP output> ... + + # After removing the module, the corresponding files will go away + $ modprobe -r kunit-example-test + $ cat /sys/kernel/debug/kunit/example/results + /sys/kernel/debug/kunit/example/results: No such file or directory + +Generating code coverage reports +-------------------------------- + +See Documentation/dev-tools/gcov.rst for details on how to do this. + +The only vaguely KUnit-specific advice here is that you probably want to build +your tests as modules. That way you can isolate the coverage from tests from +other code executed during boot, e.g. + +.. code-block:: bash + + # Reset coverage counters before running the test. + $ echo 0 > /sys/kernel/debug/gcov/reset + $ modprobe kunit-example-test diff --git a/Documentation/dev-tools/kunit/start.rst b/Documentation/dev-tools/kunit/start.rst index 0e65cabe08eb..aa56d7ca6bfb 100644 --- a/Documentation/dev-tools/kunit/start.rst +++ b/Documentation/dev-tools/kunit/start.rst @@ -236,5 +236,7 @@ Next Steps ========== * Check out the :doc:`tips` page for tips on writing idiomatic KUnit tests. +* Check out the :doc:`running_tips` page for tips on + how to make running KUnit tests easier. * Optional: see the :doc:`usage` page for a more in-depth explanation of KUnit. base-commit: de2fcb3e62013738f22bbb42cbd757d9a242574e -- 2.31.1.295.g9ea45b61b8-goog

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[PATCH bpf-next v3 0/3] add batched ops for percpu array

by Pedro Tammela

This patchset introduces batched operations for the per-cpu variant of the array map. It also removes the percpu macros from 'bpf_util.h'. This change was suggested by Andrii in a earlier iteration of this patchset. The tests were updated to reflect all the new changes. v2 -> v3: - Remove percpu macros as suggested by Andrii - Update tests that used the per cpu macros v1 -> v2: - Amended a more descriptive commit message Pedro Tammela (3): bpf: add batched ops support for percpu array bpf: selftests: remove percpu macros from bpf_util.h bpf: selftests: update array map tests for per-cpu batched ops kernel/bpf/arraymap.c | 2 + tools/testing/selftests/bpf/bpf_util.h | 7 -- .../bpf/map_tests/array_map_batch_ops.c | 110 +++++++++++++----- .../bpf/map_tests/htab_map_batch_ops.c | 71 ++++++----- .../selftests/bpf/prog_tests/map_init.c | 9 +- tools/testing/selftests/bpf/test_maps.c | 84 +++++++------ 6 files changed, 171 insertions(+), 112 deletions(-) -- 2.25.1

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[PATCH] Documentation: dev-tools: Add Testing Overview

by David Gow

The kernel now has a number of testing and debugging tools, and we've seen a bit of confusion about what the differences between them are. Add a basic documentation outlining the testing tools, when to use each, and how they interact. This is a pretty quick overview rather than the idealised "kernel testing guide" that'd probably be optimal, but given the number of times questions like "When do you use KUnit and when do you use Kselftest?" are being asked, it seemed worth at least having something. Hopefully this can form the basis for more detailed documentation later. Signed-off-by: David Gow <davidgow(a)google.com> --- Documentation/dev-tools/index.rst | 3 + Documentation/dev-tools/testing-overview.rst | 102 +++++++++++++++++++ 2 files changed, 105 insertions(+) create mode 100644 Documentation/dev-tools/testing-overview.rst diff --git a/Documentation/dev-tools/index.rst b/Documentation/dev-tools/index.rst index 1b1cf4f5c9d9..f590e5860794 100644 --- a/Documentation/dev-tools/index.rst +++ b/Documentation/dev-tools/index.rst @@ -7,6 +7,8 @@ be used to work on the kernel. For now, the documents have been pulled together without any significant effort to integrate them into a coherent whole; patches welcome! +A brief overview of testing-specific tools can be found in :doc:`testing-overview`. + .. class:: toc-title Table of contents @@ -14,6 +16,7 @@ whole; patches welcome! .. toctree:: :maxdepth: 2 + testing-overview coccinelle sparse kcov diff --git a/Documentation/dev-tools/testing-overview.rst b/Documentation/dev-tools/testing-overview.rst new file mode 100644 index 000000000000..8452adcb8608 --- /dev/null +++ b/Documentation/dev-tools/testing-overview.rst @@ -0,0 +1,102 @@ +.. SPDX-License-Identifier: GPL-2.0 + +==================== +Kernel Testing Guide +==================== + + +There are a number of different tools for testing the Linux kernel, so knowing +when to use each of them can be a challenge. This document provides a rough +overview of their differences, and how they fit together. + + +Writing and Running Tests +========================= + +The bulk of kernel tests are written using either the :doc:`kselftest +<kselftest>` or :doc:`KUnit <kunit/index>` frameworks. These both provide +infrastructure to help make running tests and groups of tests easier, as well +as providing helpers to aid in writing new tests. + +If you're looking to verify the behaviour of the Kernel — particularly specific +parts of the kernel — then you'll want to use `KUnit` or `kselftest`. + + +The Difference Between KUnit and kselftest +------------------------------------------ + +:doc:`KUnit <kunit/index>` is an entirely in-kernel system for "white box" +testing: because test code is part of the kernel, it can access internal +structures and functions which aren't exposed to userspace. + +`KUnit` tests therefore are best written against small, self-contained parts +of the kernel, which can be tested in isolation. This aligns well with the +concept of Unit testing. + +For example, a KUnit test might test an individual kernel function (or even a +single codepath through a function, such as an error handling case), rather +than a feature as a whole. + +There is a KUnit test style guide which may give further pointers + + +:doc:`kselftest <kselftest>`, on the other hand, is largely implemented in +userspace, and tests are normal userspace scripts or programs. + +This makes it easier to write more complicated tests, or tests which need to +manipulate the overall system state more (e.g., spawning processes, etc.). +However, it's not possible to call kernel functions directly unless they're +exposed to userspace (by a syscall, device, filesystem, etc.) Some tests to +also provide a kernel module which is loaded by the test, though for tests +which run mostly or entirely within the kernel, `KUnit` may be the better tool. + +`kselftest` is therefore suited well to tests of whole features, as these will +expose an interface to userspace, which can be tested, but not implementation +details. This aligns well with 'system' or 'end-to-end' testing. + + +Code Coverage Tools +=================== + +The Linux Kernel supports two different code coverage mesurement tools. These +can be used to verify that a test is executing particular functions or lines +of code. This is useful for determining how much of the kernel is being tested, +and for finding corner-cases which are not covered by the appropriate test. + +:doc:`kcov` is a feature which can be built in to the kernel to allow +capturing coverage on a per-task level. It's therefore useful for fuzzing and +other situations where information about code executed during, for example, a +single syscall is useful. + +:doc:`gcov` is GCC's coverage testing tool, which can be used with the kernel +to get global or per-module coverage. Unlike KCOV, it does not record per-task +coverage. Coverage data can be read from debugfs, and interpreted using the +usual gcov tooling. + + +Sanitizers +========== + +The kernel also supports a number of sanitizers, which attempt to detect +classes of issues when the occur in a running kernel. These typically +look for undefined behaviour of some kind, such as invalid memory accesses, +concurrency issues such as data races, or other undefined behaviour like +integer overflows. + +* :doc:`kmemleak` (Kmemleak) detects possible memory leaks. +* :doc:`kasan` detects invalid memory accesses such as out-of-bounds and + use-after-free errors. +* :doc:`ubsan` detects behaviour that is undefined by the C standard, like + integer overflows. +* :doc:`kcsan` detects data races. +* :doc:`kfence` is a low-overhead detector of memory issues, which is much + faster than KASAN and can be used in production. + +These tools tend to test the kernel as a whole, and do not "pass" like +kselftest or KUnit tests. They can be combined with KUnit or kselftest by +running tests on a kernel with a sanitizer enabled: you can then be sure +that none of these errors are occurring during the test. + +Some of these sanitizers integrate with KUnit or kselftest and will +automatically fail tests if an issue is detected by a sanitizer. + -- 2.31.1.295.g9ea45b61b8-goog

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