1 /* SPDX-License-Identifier: GPL-2.0 */ 2 /* 3 * Copyright (C) 2022-2024 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved. 4 */ 5 #ifndef __ASM_VDSO_GETRANDOM_H 6 #define __ASM_VDSO_GETRANDOM_H 7 8 #ifndef __ASSEMBLY__ 9 10 #include <asm/unistd.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 */ 19 static __always_inline ssize_t getrandom_syscall(void *buffer, size_t len, unsigned int flags) 20 { 21 long ret; 22 23 asm ("syscall" : "=a" (ret) : 24 "0" (__NR_getrandom), "D" (buffer), "S" (len), "d" (flags) : 25 "rcx", "r11", "memory"); 26 27 return ret; 28 } 29 30 extern struct vdso_rng_data vdso_rng_data 31 __attribute__((visibility("hidden"))); 32 33 static __always_inline const struct vdso_rng_data *__arch_get_vdso_rng_data(void) 34 { 35 if (IS_ENABLED(CONFIG_TIME_NS) && __arch_get_vdso_data()->clock_mode == VDSO_CLOCKMODE_TIMENS) 36 return (void *)&vdso_rng_data + ((void *)&timens_page - (void *)__arch_get_vdso_data()); 37 return &vdso_rng_data; 38 } 39 40 #endif /* !__ASSEMBLY__ */ 41 42 #endif /* __ASM_VDSO_GETRANDOM_H */ 43