1/* SPDX-License-Identifier: GPL-2.0-only */
2/*
3 * This file is part of the Linux kernel.
4 *
5 * Copyright (c) 2011-2014, Intel Corporation
6 * Authors: Fenghua Yu <fenghua.yu@intel.com>,
7 *          H. Peter Anvin <hpa@linux.intel.com>
8 */
9
10#ifndef ASM_X86_ARCHRANDOM_H
11#define ASM_X86_ARCHRANDOM_H
12
13#include <asm/processor.h>
14#include <asm/cpufeature.h>
15
16#define RDRAND_RETRY_LOOPS	10
17
18/* Unconditional execution of RDRAND and RDSEED */
19
20static inline bool __must_check rdrand_long(unsigned long *v)
21{
22	bool ok;
23	unsigned int retry = RDRAND_RETRY_LOOPS;
24	do {
25		asm volatile("rdrand %[out]"
26			     CC_SET(c)
27			     : CC_OUT(c) (ok), [out] "=r" (*v));
28		if (ok)
29			return true;
30	} while (--retry);
31	return false;
32}
33
34static inline bool __must_check rdseed_long(unsigned long *v)
35{
36	bool ok;
37	asm volatile("rdseed %[out]"
38		     CC_SET(c)
39		     : CC_OUT(c) (ok), [out] "=r" (*v));
40	return ok;
41}
42
43/*
44 * These are the generic interfaces; they must not be declared if the
45 * stubs in <linux/random.h> are to be invoked.
46 */
47
48static inline size_t __must_check arch_get_random_longs(unsigned long *v, size_t max_longs)
49{
50	return max_longs && static_cpu_has(X86_FEATURE_RDRAND) && rdrand_long(v) ? 1 : 0;
51}
52
53static inline size_t __must_check arch_get_random_seed_longs(unsigned long *v, size_t max_longs)
54{
55	return max_longs && static_cpu_has(X86_FEATURE_RDSEED) && rdseed_long(v) ? 1 : 0;
56}
57
58#ifndef CONFIG_UML
59void x86_init_rdrand(struct cpuinfo_x86 *c);
60#endif
61
62#endif /* ASM_X86_ARCHRANDOM_H */
63