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2025-07-01selftests: vDSO: chacha: Correctly skip test if necessaryThomas Weißschuh
According to kselftest.h ksft_exit_skip() is not meant to be called when a plan has already been printed. Use the recommended function ksft_test_result_skip(). This fixes a bug, where the TAP output would be invalid when skipping: TAP version 13 1..1 ok 2 # SKIP Not implemented on architecture The SKIP line should start with "ok 1" as the plan only contains one test. Fixes: 3b5992eaf730 ("selftests: vDSO: unconditionally build chacha test") Signed-off-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Muhammad Usama Anjum <usama.anjum@collabora.com> Link: https://lore.kernel.org/all/20250611-selftests-vdso-fixes-v3-1-e62e37a6bcf5@linutronix.de
2024-10-08selftests: vDSO: improve getrandom and chacha error messagesJason A. Donenfeld
Improve the error and skip condition messages to let the developer know precisely where a test has failed. Also make better use of the ksft api for this. Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com> Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>
2024-10-08selftests: vDSO: unconditionally build chacha testJason A. Donenfeld
Rather than using symlinks to find the vgetrandom-chacha.S file for each arch, store this in a file that uses the compiler to determine architecture, and then make use of weak symbols to skip the test on architectures that don't provide the code. Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com> Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>
2024-09-16selftests: vDSO: check cpu caps before running chacha testJason A. Donenfeld
Some archs -- arm64 and s390x -- implemented chacha using instructions that are available most places, but aren't always available. The kernel handles this just fine, but the selftest does not. Check the hwcaps before running, and skip the test if the cpu doesn't support it. As well, on s390x, always emit the fallback instructions of an alternative block, to ensure maximum compatibility. Co-developed-by: Heiko Carstens <hca@linux.ibm.com> Signed-off-by: Heiko Carstens <hca@linux.ibm.com> Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
2024-09-13selftests: vDSO: also test counter in vdso_test_chachaChristophe Leroy
The chacha vDSO selftest doesn't check the way the counter is handled by __arch_chacha20_blocks_nostack(). It indirectly checks that the counter is writen on exit and read back on new entry, but it doesn't check that the format is correct. When implementing this function on powerpc, I missed a case where the counter was writen and read in wrong byte order. Also, the counter uses two words, but the tests with a zero counter and uses a small amount of blocks, so at the end the upper part of the counter is always 0, so it is not checked. Add a verification of counter's content in addition to the verification of the output. Also add two tests where the counter crosses the u32 upper limit. The first test verifies that the function properly writes back the upper word, the second test verifies that the function properly reads back the upper word. Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu> Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
2024-09-13selftests: vDSO: open code basic chacha instead of linking to libsodiumJason A. Donenfeld
Linking to libsodium makes building this test annoying in cross compilation environments and is just way too much. Since this is just a basic correctness test, simply open code a simple, unoptimized, dumb chacha, rather than linking to libsodium. This also fixes a correctness issue on big endian systems. The kernel's random.c doesn't bother doing a le32_to_cpu operation on the random bytes that are passed as the key, and consequently neither does vgetrandom-chacha.S. However, libsodium's chacha _does_ do this, since it takes the key as an array of bytes. This meant that the test was broken on big endian systems, which this commit rectifies. Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
2024-09-13random: vDSO: move prototype of arch chacha function to vdso/getrandom.hJason A. Donenfeld
Having the prototype for __arch_chacha20_blocks_nostack in arch/x86/include/asm/vdso/getrandom.h meant that the prototype and large doc comment were cloned by every architecture, which has been causing unnecessary churn. Instead move it into include/vdso/getrandom.h, where it can be shared by all archs implementing it. As a side bonus, this then lets us use that prototype in the vdso_test_chacha self test, to ensure that it matches the source, and indeed doing so turned up some inconsistencies, which are rectified here. Suggested-by: Christophe Leroy <christophe.leroy@csgroup.eu> Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
2024-07-19selftests/vDSO: add tests for vgetrandomJason A. Donenfeld
This adds two tests for vgetrandom. The first one, vdso_test_chacha, simply checks that the assembly implementation of chacha20 matches that of libsodium, a basic sanity check that should catch most errors. The second, vdso_test_getrandom, is a full "libc-like" implementation of the userspace side of vgetrandom() support. It's meant to be used also as example code for libcs that might be integrating this. Cc: linux-kselftest@vger.kernel.org Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>