Orange Pi5 kernel

^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  1) // SPDX-License-Identifier: GPL-2.0-only
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  2) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  3)  * This file is part of the Linux kernel.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  4)  *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  5)  * Copyright (c) 2011, Intel Corporation
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  6)  * Authors: Fenghua Yu <fenghua.yu@intel.com>,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  7)  *          H. Peter Anvin <hpa@linux.intel.com>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  8)  */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  9) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 10) #include <asm/processor.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 11) #include <asm/archrandom.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 12) #include <asm/sections.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 13) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 14) static int __init x86_rdrand_setup(char *s)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 15) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 16) 	setup_clear_cpu_cap(X86_FEATURE_RDRAND);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 17) 	setup_clear_cpu_cap(X86_FEATURE_RDSEED);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 18) 	return 1;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 19) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 20) __setup("nordrand", x86_rdrand_setup);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 21) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 22) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 23)  * RDRAND has Built-In-Self-Test (BIST) that runs on every invocation.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 24)  * Run the instruction a few times as a sanity check.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 25)  * If it fails, it is simple to disable RDRAND here.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 26)  */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 27) #define SANITY_CHECK_LOOPS 8
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 28) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 29) #ifdef CONFIG_ARCH_RANDOM
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 30) void x86_init_rdrand(struct cpuinfo_x86 *c)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 31) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 32) 	unsigned int changed = 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 33) 	unsigned long tmp, prev;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 34) 	int i;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 35) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 36) 	if (!cpu_has(c, X86_FEATURE_RDRAND))
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 37) 		return;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 38) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 39) 	for (i = 0; i < SANITY_CHECK_LOOPS; i++) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 40) 		if (!rdrand_long(&tmp)) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 41) 			clear_cpu_cap(c, X86_FEATURE_RDRAND);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 42) 			pr_warn_once("rdrand: disabled\n");
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 43) 			return;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 44) 		}
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 45) 	}
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 46) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 47) 	/*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 48) 	 * Stupid sanity-check whether RDRAND does *actually* generate
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 49) 	 * some at least random-looking data.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 50) 	 */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 51) 	prev = tmp;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 52) 	for (i = 0; i < SANITY_CHECK_LOOPS; i++) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 53) 		if (rdrand_long(&tmp)) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 54) 			if (prev != tmp)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 55) 				changed++;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 56) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 57) 			prev = tmp;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 58) 		}
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 59) 	}
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 60) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 61) 	if (WARN_ON_ONCE(!changed))
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 62) 		pr_emerg(
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 63) "RDRAND gives funky smelling output, might consider not using it by booting with \"nordrand\"");
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 64) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 65) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 66) #endif