mirror of
https://github.com/torvalds/linux.git
synced 2026-05-04 22:43:04 -04:00
b920aa77be
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 <hca@linux.ibm.com>
Reviewed-by: Harald Freudenberger <freude@linux.ibm.com>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
42 lines
965 B
C
42 lines
965 B
C
/* SPDX-License-Identifier: GPL-2.0 */
|
|
#ifndef __ASM_VDSO_VSYSCALL_H
|
|
#define __ASM_VDSO_VSYSCALL_H
|
|
|
|
#define __VDSO_RND_DATA_OFFSET 768
|
|
|
|
#ifndef __ASSEMBLY__
|
|
|
|
#include <linux/hrtimer.h>
|
|
#include <linux/timekeeper_internal.h>
|
|
#include <vdso/datapage.h>
|
|
#include <asm/vdso.h>
|
|
|
|
enum vvar_pages {
|
|
VVAR_DATA_PAGE_OFFSET,
|
|
VVAR_TIMENS_PAGE_OFFSET,
|
|
VVAR_NR_PAGES
|
|
};
|
|
|
|
/*
|
|
* Update the vDSO data page to keep in sync with kernel timekeeping.
|
|
*/
|
|
|
|
static __always_inline struct vdso_data *__s390_get_k_vdso_data(void)
|
|
{
|
|
return vdso_data;
|
|
}
|
|
#define __arch_get_k_vdso_data __s390_get_k_vdso_data
|
|
|
|
static __always_inline struct vdso_rng_data *__s390_get_k_vdso_rnd_data(void)
|
|
{
|
|
return (void *)vdso_data + __VDSO_RND_DATA_OFFSET;
|
|
}
|
|
#define __arch_get_k_vdso_rng_data __s390_get_k_vdso_rnd_data
|
|
|
|
/* The asm-generic header needs to be included after the definitions above */
|
|
#include <asm-generic/vdso/vsyscall.h>
|
|
|
|
#endif /* !__ASSEMBLY__ */
|
|
|
|
#endif /* __ASM_VDSO_VSYSCALL_H */
|