/* SPDX-License-Identifier: GPL-2.0 */

#ifndef __ASM_VDSO_GETRANDOM_H
#define __ASM_VDSO_GETRANDOM_H

#ifndef __ASSEMBLER__

#include <asm/unistd.h>
#include <asm/vdso/vsyscall.h>
#include <vdso/datapage.h>

/**
 * getrandom_syscall - Invoke the getrandom() syscall.
 * @buffer:     Destination buffer to fill with random bytes.
 * @len:        Size of @buffer in bytes.
 * @flags:      Zero or more GRND_* flags.
 * Returns:     The number of random bytes written to @buffer, or a negative value indicating an error.
 */
static __always_inline ssize_t getrandom_syscall(void *_buffer, size_t _len, unsigned int _flags)
{
        register void *buffer asm ("x0") = _buffer;
        register size_t len asm ("x1") = _len;
        register unsigned int flags asm ("x2") = _flags;
        register long ret asm ("x0");
        register long nr asm ("x8") = __NR_getrandom;

        asm volatile(
        "       svc #0\n"
        : "=r" (ret)
        : "r" (buffer), "r" (len), "r" (flags), "r" (nr)
        : "memory");

        return ret;
}

#endif /* !__ASSEMBLER__ */

#endif /* __ASM_VDSO_GETRANDOM_H */