1 /* SPDX-License-Identifier: GPL-2.0 */ 2 3 #ifndef __ASM_VDSO_GETRANDOM_H 4 #define __ASM_VDSO_GETRANDOM_H 5 6 #ifndef __ASSEMBLY__ 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 */ getrandom_syscall(void * _buffer,size_t _len,unsigned int _flags)19 static __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 __arch_get_vdso_rng_data(void)36 static __always_inline const struct vdso_rng_data *__arch_get_vdso_rng_data(void) 37 { 38 /* 39 * The RNG data is in the real VVAR data page, but if a task belongs to a time namespace 40 * then VVAR_DATA_PAGE_OFFSET points to the namespace-specific VVAR page and VVAR_TIMENS_ 41 * PAGE_OFFSET points to the real VVAR page. 42 */ 43 if (IS_ENABLED(CONFIG_TIME_NS) && _vdso_data->clock_mode == VDSO_CLOCKMODE_TIMENS) 44 return (void *)&_vdso_rng_data + VVAR_TIMENS_PAGE_OFFSET * (1UL << CONFIG_PAGE_SHIFT); 45 return &_vdso_rng_data; 46 } 47 48 #endif /* !__ASSEMBLY__ */ 49 50 #endif /* __ASM_VDSO_GETRANDOM_H */ 51