forked from Minki/linux
4c637cd8de
This patch introduces s390 specific arch random functionality. There exists a generic kernel API for arch specific random number implementation (see include/linux/random.h). Here comes the header file and a very small static code part implementing the arch_random_* API based on the TRNG subfunction coming with the reworked PRNG instruction. The arch random implementation hooks into the kernel initialization and checks for availability of the TRNG function. In accordance to the arch random API all functions return false if the TRNG is not available. Otherwise the new high quality entropy source provides fresh random on each invocation. The s390 arch random feature build is controlled via CONFIG_ARCH_RANDOM. This config option located in arch/s390/Kconfig is enabled by default and appears as entry "s390 architectural random number generation API" in the submenu "Processor type and features" for s390 builds. Signed-off-by: Harald Freudenberger <freude@linux.vnet.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
32 lines
850 B
C
32 lines
850 B
C
/*
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* s390 arch random implementation.
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*
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* Copyright IBM Corp. 2017
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* Author(s): Harald Freudenberger <freude@de.ibm.com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License (version 2 only)
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* as published by the Free Software Foundation.
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*
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*/
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#include <linux/kernel.h>
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#include <linux/atomic.h>
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#include <linux/static_key.h>
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#include <asm/cpacf.h>
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DEFINE_STATIC_KEY_FALSE(s390_arch_random_available);
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atomic64_t s390_arch_random_counter = ATOMIC64_INIT(0);
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EXPORT_SYMBOL(s390_arch_random_counter);
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static int __init s390_arch_random_init(void)
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{
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/* check if subfunction CPACF_PRNO_TRNG is available */
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if (cpacf_query_func(CPACF_PRNO, CPACF_PRNO_TRNG))
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static_branch_enable(&s390_arch_random_available);
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return 0;
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}
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arch_initcall(s390_arch_random_init);
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