pm24.git/tools/testing/selftests/vDSO, branch rust-6.13

selftests: vDSO: align getrandom states to cache line

2024-10-01T14:30:58Z

This prevents false sharing, which makes a large difference on machines with several NUMA nodes, such as on a dual socket Intel(R) Xeon(R) Gold 6338 CPU @ 2.00GHz, where the "bench-multi" test goes from 2.7s down to 1.9s. While this is just test code, it also forms the basis of how folks will wind up implementing this in libraries, so we should implement this simple cache alignment improvement here. Suggested-by: Florian Weimer Cc: Adhemerval Zanella Signed-off-by: Jason A. Donenfeld Signed-off-by: Shuah Khan

Merge tag 'linux_kselftest-next-6.12-rc1-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/shuah/linux-kselftest

2024-09-29T15:37:03Z

Pull kselftest fix from Shuah Khan: "One urgent fix to vDSO as automated testing is failing due to this bug" * tag 'linux_kselftest-next-6.12-rc1-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/shuah/linux-kselftest: selftests: vDSO: align stack for O2-optimized memcpy

selftests: vDSO: align stack for O2-optimized memcpy

2024-09-27T18:17:12Z

When switching on -O2, gcc generates SSE2 instructions that assume a 16-byte aligned stack, which the standalone test's start point wasn't aligning. Fix this with the usual alignment sequence. Fixes: ecb8bd70d51 ("selftests: vDSO: build tests with O2 optimization") Reported-by: kernel test robot Closes: https://lore.kernel.org/oe-lkp/202409241558.98e13f6f-oliver.sang@intel.com Signed-off-by: Jason A. Donenfeld Signed-off-by: Shuah Khan

selftests: vDSO: check cpu caps before running chacha test

2024-09-16T11:22:04Z

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 Signed-off-by: Heiko Carstens Signed-off-by: Jason A. Donenfeld

s390/vdso: Wire up getrandom() vdso implementation

2024-09-13T18:57:31Z

Provide the s390 specific vdso getrandom() architecture backend. _vdso_rng_data required data is placed within the _vdso_data vvar page, by using a hardcoded offset larger than vdso_data. As required the chacha20 implementation does not write to the stack. The implementation follows more or less the arm64 implementations and makes use of vector instructions. It has a fallback to the getrandom() system call for machines where the vector facility is not installed. The check if the vector facility is installed, as well as an optimization for machines with the vector-enhancements facility 2, is implemented with alternatives, avoiding runtime checks. Note that __kernel_getrandom() is implemented without the vdso user wrapper which would setup a stack frame for odd cases (aka very old glibc variants) where the caller has not done that. All callers of __kernel_getrandom() are required to setup a stack frame, like the C ABI requires it. The vdso testcases vdso_test_getrandom and vdso_test_chacha pass. Benchmark on a z16: $ ./vdso_test_getrandom bench-single vdso: 25000000 times in 0.493703559 seconds syscall: 25000000 times in 6.584025337 seconds Signed-off-by: Heiko Carstens Reviewed-by: Harald Freudenberger Signed-off-by: Jason A. Donenfeld

selftests: vDSO: fix vdso_config for s390

2024-09-13T15:28:36Z

Running vdso_test_correctness on s390x (aka s390 64 bit) emits a warning: Warning: failed to find clock_gettime64 in vDSO This is caused by the "#elif defined (__s390__)" check in vdso_config.h which the defines VDSO_32BIT. If __s390x__ is defined also __s390__ is defined. Therefore the correct check must make sure that only __s390__ is defined. Therefore add the missing !defined(__s390x__). Also use common __s390x__ define instead of __s390X__. Signed-off-by: Heiko Carstens Fixes: 693f5ca08ca0 ("kselftest: Extend vDSO selftest") Signed-off-by: Jason A. Donenfeld

selftests: vDSO: fix ELF hash table entry size for s390x

2024-09-13T15:28:36Z

The vDSO self tests fail on s390x for a vDSO linked with the GNU linker ld as follows: # ./vdso_test_gettimeofday Floating point exception (core dumped) On s390x the ELF hash table entries are 64 bits instead of 32 bits in size (see Glibc sysdeps/unix/sysv/linux/s390/bits/elfclass.h). Fixes: 40723419f407 ("kselftest: Enable vDSO test on non x86 platforms") Reported-by: Heiko Carstens Tested-by: Heiko Carstens Signed-off-by: Jens Remus Signed-off-by: Heiko Carstens Signed-off-by: Jason A. Donenfeld

powerpc/vdso: Wire up getrandom() vDSO implementation on VDSO32

2024-09-13T15:28:36Z

To be consistent with other VDSO functions, the function is called __kernel_getrandom() __arch_chacha20_blocks_nostack() fonction is implemented basically with 32 bits operations. It performs 4 QUARTERROUND operations in parallele. There are enough registers to avoid using the stack: On input: r3: output bytes r4: 32-byte key input r5: 8-byte counter input/output r6: number of 64-byte blocks to write to output During operation: stack: pointer to counter (r5) and non-volatile registers (r14-131) r0: counter of blocks (initialised with r6) r4: Value '4' after key has been read, used for indexing r5-r12: key r14-r15: block counter r16-r31: chacha state At the end: r0, r6-r12: Zeroised r5, r14-r31: Restored Performance on powerpc 885 (using kernel selftest): ~# ./vdso_test_getrandom bench-single vdso: 25000000 times in 62.938002291 seconds libc: 25000000 times in 535.581916866 seconds syscall: 25000000 times in 531.525042806 seconds Performance on powerpc 8321 (using kernel selftest): ~# ./vdso_test_getrandom bench-single vdso: 25000000 times in 16.899318858 seconds libc: 25000000 times in 131.050596522 seconds syscall: 25000000 times in 129.794790389 seconds This first patch adds support for VDSO32. As selftests cannot easily be generated only for VDSO32, and because the following patch brings support for VDSO64 anyway, this patch opts out all code in __arch_chacha20_blocks_nostack() so that vdso_test_chacha will not fail to compile and will not crash on PPC64/PPC64LE, allthough the selftest itself will fail. Signed-off-by: Christophe Leroy Acked-by: Michael Ellerman Signed-off-by: Jason A. Donenfeld

selftests: vDSO: don't include generated headers for chacha test

2024-09-13T15:28:36Z

It's not correct to use $(top_srcdir) for generated header files, for builds that are done out of tree via O=, and $(objtree) isn't valid in the selftests context. Instead, just obviate the need for these generated header files by defining empty stubs in tools/include, which is the same thing that's done for rwlock.h. Reviewed-by: Adhemerval Zanella Signed-off-by: Jason A. Donenfeld

arm64: vDSO: Wire up getrandom() vDSO implementation

2024-09-13T15:28:36Z

Hook up the generic vDSO implementation to the aarch64 vDSO data page. The _vdso_rng_data required data is placed within the _vdso_data vvar page, by using a offset larger than the vdso_data. The vDSO function requires a ChaCha20 implementation that does not write to the stack, and that can do an entire ChaCha20 permutation. The one provided uses NEON on the permute operation, with a fallback to the syscall for chips that do not support AdvSIMD. This also passes the vdso_test_chacha test along with vdso_test_getrandom. The vdso_test_getrandom bench-single result on Neoverse-N1 shows: vdso: 25000000 times in 0.783884250 seconds libc: 25000000 times in 8.780275399 seconds syscall: 25000000 times in 8.786581518 seconds A small fixup to arch/arm64/include/asm/mman.h was required to avoid pulling kernel code into the vDSO, similar to what's already done in arch/arm64/include/asm/rwonce.h. Signed-off-by: Adhemerval Zanella Reviewed-by: Ard Biesheuvel Acked-by: Will Deacon Signed-off-by: Jason A. Donenfeld