1 /* 2 * This file is part of the Linux kernel. 3 * 4 * Copyright (c) 2011, Intel Corporation 5 * Authors: Fenghua Yu <fenghua.yu@intel.com>, 6 * H. Peter Anvin <hpa@linux.intel.com> 7 * 8 * This program is free software; you can redistribute it and/or modify it 9 * under the terms and conditions of the GNU General Public License, 10 * version 2, as published by the Free Software Foundation. 11 * 12 * This program is distributed in the hope it will be useful, but WITHOUT 13 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 14 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for 15 * more details. 16 * 17 * You should have received a copy of the GNU General Public License along with 18 * this program; if not, write to the Free Software Foundation, Inc., 19 * 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA. 20 * 21 */ 22 23 #ifndef ASM_X86_ARCHRANDOM_H 24 #define ASM_X86_ARCHRANDOM_H 25 26 #include <asm/processor.h> 27 #include <asm/cpufeature.h> 28 #include <asm/alternative.h> 29 #include <asm/nops.h> 30 31 #define RDRAND_RETRY_LOOPS 10 32 33 #define RDRAND_INT ".byte 0x0f,0xc7,0xf0" 34 #ifdef CONFIG_X86_64 35 # define RDRAND_LONG ".byte 0x48,0x0f,0xc7,0xf0" 36 #else 37 # define RDRAND_LONG RDRAND_INT 38 #endif 39 40 #ifdef CONFIG_ARCH_RANDOM 41 42 /* Instead of arch_get_random_long() when alternatives haven't run. */ 43 static inline int rdrand_long(unsigned long *v) 44 { 45 int ok; 46 asm volatile("1: " RDRAND_LONG "\n\t" 47 "jc 2f\n\t" 48 "decl %0\n\t" 49 "jnz 1b\n\t" 50 "2:" 51 : "=r" (ok), "=a" (*v) 52 : "0" (RDRAND_RETRY_LOOPS)); 53 return ok; 54 } 55 56 #define GET_RANDOM(name, type, rdrand, nop) \ 57 static inline int name(type *v) \ 58 { \ 59 int ok; \ 60 alternative_io("movl $0, %0\n\t" \ 61 nop, \ 62 "\n1: " rdrand "\n\t" \ 63 "jc 2f\n\t" \ 64 "decl %0\n\t" \ 65 "jnz 1b\n\t" \ 66 "2:", \ 67 X86_FEATURE_RDRAND, \ 68 ASM_OUTPUT2("=r" (ok), "=a" (*v)), \ 69 "0" (RDRAND_RETRY_LOOPS)); \ 70 return ok; \ 71 } 72 73 #ifdef CONFIG_X86_64 74 75 GET_RANDOM(arch_get_random_long, unsigned long, RDRAND_LONG, ASM_NOP5); 76 GET_RANDOM(arch_get_random_int, unsigned int, RDRAND_INT, ASM_NOP4); 77 78 #else 79 80 GET_RANDOM(arch_get_random_long, unsigned long, RDRAND_LONG, ASM_NOP3); 81 GET_RANDOM(arch_get_random_int, unsigned int, RDRAND_INT, ASM_NOP3); 82 83 #endif /* CONFIG_X86_64 */ 84 85 #else 86 87 static inline int rdrand_long(unsigned long *v) 88 { 89 return 0; 90 } 91 92 #endif /* CONFIG_ARCH_RANDOM */ 93 94 extern void x86_init_rdrand(struct cpuinfo_x86 *c); 95 96 #endif /* ASM_X86_ARCHRANDOM_H */ 97