From 08f28b54cfe5a11abb03a9bac2cb830ffd392346 Mon Sep 17 00:00:00 2001 From: Eric Biggers Date: Thu, 24 Sep 2026 22:25:02 -0700 Subject: [PATCH] Documentation: libcrypto: Add additional testing information Link to the KUnit documentation, mention the existence of the benchmarks and how to enable them, explicitly mention that the tests can be run on real hardware, and mention that it's often possible to clear CPU features via the kernel command line. Acked-by: Ard Biesheuvel Link: https://patch.msgid.link/20260925052502.188024-1-ebiggers@kernel.org Signed-off-by: Eric Biggers --- Documentation/crypto/libcrypto.rst | 13 +++++++++++++ 1 file changed, 13 insertions(+) diff --git a/Documentation/crypto/libcrypto.rst b/Documentation/crypto/libcrypto.rst index 9533c12caa79..494541c8a8e0 100644 --- a/Documentation/crypto/libcrypto.rst +++ b/Documentation/crypto/libcrypto.rst @@ -127,6 +127,8 @@ The crypto library uses standard KUnit tests. Like many of the kernel's other KUnit tests, they are included in the set of tests that is run by ``tools/testing/kunit/kunit.py run --alltests``. +For more information about KUnit, see Documentation/dev-tools/kunit/start.rst. + A ``.kunitconfig`` file is also provided to run just the crypto library tests. For example, here's how to run them in user-mode Linux: @@ -148,6 +150,17 @@ emulate the correct type of hardware for the code to be reached. Since correctness is essential in cryptographic code, new architecture-optimized code is accepted only if it can be tested in QEMU. +Most of the crypto KUnit tests also include benchmarks. To enable these, enable +``CONFIG_CRYPTO_LIB_BENCHMARK=y`` (in addition to the tests themselves). The +benchmark results are printed to the kernel log when the test runs. + +Of course, the crypto KUnit tests can also be run on real hardware. Note that +it is generally still possible to test and benchmark non-default code paths in +this case (for example, the software implementation of AES when the CPU has +hardware-accelerated AES), since on many architectures the kernel supports +disabling CPU features via the kernel command line. For example, on x86, +the ``clearcpuid=aes`` kernel command line option disables AES acceleration. + Note: the crypto library also includes FIPS 140 self-tests. These are lightweight, are designed specifically to meet FIPS 140 requirements, and exist *only* to meet those requirements. Normal testing done by kernel developers and