From b920aa77be6d57d407b6b6be5d8b4ccc17749cce Mon Sep 17 00:00:00 2001 From: Heiko Carstens Date: Fri, 13 Sep 2024 15:05:43 +0200 Subject: s390/vdso: Wire up getrandom() vdso implementation 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 --- arch/s390/kernel/vdso.c | 7 +------ 1 file changed, 1 insertion(+), 6 deletions(-) (limited to 'arch/s390/kernel/vdso.c') diff --git a/arch/s390/kernel/vdso.c b/arch/s390/kernel/vdso.c index 8e4e6b316337..598b512cde01 100644 --- a/arch/s390/kernel/vdso.c +++ b/arch/s390/kernel/vdso.c @@ -19,6 +19,7 @@ #include #include #include +#include #include #include @@ -31,12 +32,6 @@ static union vdso_data_store vdso_data_store __page_aligned_data; struct vdso_data *vdso_data = vdso_data_store.data; -enum vvar_pages { - VVAR_DATA_PAGE_OFFSET, - VVAR_TIMENS_PAGE_OFFSET, - VVAR_NR_PAGES, -}; - #ifdef CONFIG_TIME_NS struct vdso_data *arch_get_vdso_data(void *vvar_page) { -- cgit