1 /* SPDX-License-Identifier: GPL-2.0 */ 2 /* 3 * Copyright (C) 2024 Christophe Leroy <christophe.leroy@csgroup.eu>, CS GROUP France 4 */ 5 #ifndef _ASM_POWERPC_VDSO_GETRANDOM_H 6 #define _ASM_POWERPC_VDSO_GETRANDOM_H 7 8 #ifndef __ASSEMBLY__ 9 10 #include <asm/vdso_datapage.h> 11 12 static __always_inline int do_syscall_3(const unsigned long _r0, const unsigned long _r3, 13 const unsigned long _r4, const unsigned long _r5) 14 { 15 register long r0 asm("r0") = _r0; 16 register unsigned long r3 asm("r3") = _r3; 17 register unsigned long r4 asm("r4") = _r4; 18 register unsigned long r5 asm("r5") = _r5; 19 register int ret asm ("r3"); 20 21 asm volatile( 22 " sc\n" 23 " bns+ 1f\n" 24 " neg %0, %0\n" 25 "1:\n" 26 : "=r" (ret), "+r" (r4), "+r" (r5), "+r" (r0) 27 : "r" (r3) 28 : "memory", "r6", "r7", "r8", "r9", "r10", "r11", "r12", "cr0", "ctr"); 29 30 return ret; 31 } 32 33 /** 34 * getrandom_syscall - Invoke the getrandom() syscall. 35 * @buffer: Destination buffer to fill with random bytes. 36 * @len: Size of @buffer in bytes. 37 * @flags: Zero or more GRND_* flags. 38 * Returns: The number of bytes written to @buffer, or a negative value indicating an error. 39 */ 40 static __always_inline ssize_t getrandom_syscall(void *buffer, size_t len, unsigned int flags) 41 { 42 return do_syscall_3(__NR_getrandom, (unsigned long)buffer, 43 (unsigned long)len, (unsigned long)flags); 44 } 45 46 static __always_inline struct vdso_rng_data *__arch_get_vdso_rng_data(void) 47 { 48 struct vdso_arch_data *data; 49 50 asm ( 51 " bcl 20, 31, .+4 ;" 52 "0: mflr %0 ;" 53 " addis %0, %0, (_vdso_datapage - 0b)@ha ;" 54 " addi %0, %0, (_vdso_datapage - 0b)@l ;" 55 : "=r" (data) : : "lr" 56 ); 57 58 return &data->rng_data; 59 } 60 61 ssize_t __c_kernel_getrandom(void *buffer, size_t len, unsigned int flags, void *opaque_state, 62 size_t opaque_len); 63 64 #endif /* !__ASSEMBLY__ */ 65 66 #endif /* _ASM_POWERPC_VDSO_GETRANDOM_H */ 67