getrandom.h

 1/* SPDX-License-Identifier: GPL-2.0 */
 2
 3#ifndef __ASM_VDSO_GETRANDOM_H
 4#define __ASM_VDSO_GETRANDOM_H
 5
 6#ifndef __ASSEMBLER__
 7
 8#include <asm/unistd.h>
 9#include <asm/vdso/vsyscall.h>
10#include <vdso/datapage.h>
11
12/**
13 * getrandom_syscall - Invoke the getrandom() syscall.
14 * @buffer:	Destination buffer to fill with random bytes.
15 * @len:	Size of @buffer in bytes.
16 * @flags:	Zero or more GRND_* flags.
17 * Returns:	The number of random bytes written to @buffer, or a negative value indicating an error.
18 */
19static __always_inline ssize_t getrandom_syscall(void *_buffer, size_t _len, unsigned int _flags)
20{
21	register void *buffer asm ("x0") = _buffer;
22	register size_t len asm ("x1") = _len;
23	register unsigned int flags asm ("x2") = _flags;
24	register long ret asm ("x0");
25	register long nr asm ("x8") = __NR_getrandom;
26
27	asm volatile(
28	"       svc #0\n"
29	: "=r" (ret)
30	: "r" (buffer), "r" (len), "r" (flags), "r" (nr)
31	: "memory");
32
33	return ret;
34}
35
36#endif /* !__ASSEMBLER__ */
37
38#endif /* __ASM_VDSO_GETRANDOM_H */