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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 | #define GET_RANDOM(name, type, rdrand, nop) \ | |
43 | static inline int name(type *v) \ | |
44 | { \ | |
45 | int ok; \ | |
46 | alternative_io("movl $0, %0\n\t" \ | |
47 | nop, \ | |
48 | "\n1: " rdrand "\n\t" \ | |
49 | "jc 2f\n\t" \ | |
50 | "decl %0\n\t" \ | |
51 | "jnz 1b\n\t" \ | |
52 | "2:", \ | |
53 | X86_FEATURE_RDRAND, \ | |
54 | ASM_OUTPUT2("=r" (ok), "=a" (*v)), \ | |
55 | "0" (RDRAND_RETRY_LOOPS)); \ | |
56 | return ok; \ | |
57 | } | |
58 | ||
59 | #ifdef CONFIG_X86_64 | |
60 | ||
61 | GET_RANDOM(arch_get_random_long, unsigned long, RDRAND_LONG, ASM_NOP5); | |
62 | GET_RANDOM(arch_get_random_int, unsigned int, RDRAND_INT, ASM_NOP4); | |
63 | ||
64 | #else | |
65 | ||
66 | GET_RANDOM(arch_get_random_long, unsigned long, RDRAND_LONG, ASM_NOP3); | |
67 | GET_RANDOM(arch_get_random_int, unsigned int, RDRAND_INT, ASM_NOP3); | |
68 | ||
69 | #endif /* CONFIG_X86_64 */ | |
70 | ||
71 | #endif /* CONFIG_ARCH_RANDOM */ | |
72 | ||
73 | #endif /* ASM_X86_ARCHRANDOM_H */ |