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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 | // SPDX-License-Identifier: GPL-2.0-or-later /* * Copyright 2013, Michael Ellerman, IBM Corporation. */ #define pr_fmt(fmt) "powernv-rng: " fmt #include <linux/kernel.h> #include <linux/of.h> #include <linux/of_address.h> #include <linux/of_platform.h> #include <linux/slab.h> #include <linux/smp.h> #include <asm/archrandom.h> #include <asm/cputable.h> #include <asm/io.h> #include <asm/prom.h> #include <asm/machdep.h> #include <asm/smp.h> #include "powernv.h" #define DARN_ERR 0xFFFFFFFFFFFFFFFFul struct pnv_rng { void __iomem *regs; void __iomem *regs_real; unsigned long mask; }; static DEFINE_PER_CPU(struct pnv_rng *, pnv_rng); static unsigned long rng_whiten(struct pnv_rng *rng, unsigned long val) { unsigned long parity; /* Calculate the parity of the value */ asm (".machine push; \ .machine power7; \ popcntd %0,%1; \ .machine pop;" : "=r" (parity) : "r" (val)); /* xor our value with the previous mask */ val ^= rng->mask; /* update the mask based on the parity of this value */ rng->mask = (rng->mask << 1) | (parity & 1); return val; } static int pnv_get_random_darn(unsigned long *v) { unsigned long val; /* Using DARN with L=1 - 64-bit conditioned random number */ asm volatile(PPC_DARN(%0, 1) : "=r"(val)); if (val == DARN_ERR) return 0; *v = val; return 1; } static int __init initialise_darn(void) { unsigned long val; int i; if (!cpu_has_feature(CPU_FTR_ARCH_300)) return -ENODEV; for (i = 0; i < 10; i++) { if (pnv_get_random_darn(&val)) { ppc_md.get_random_seed = pnv_get_random_darn; return 0; } } return -EIO; } int pnv_get_random_long(unsigned long *v) { struct pnv_rng *rng; if (mfmsr() & MSR_DR) { rng = get_cpu_var(pnv_rng); *v = rng_whiten(rng, in_be64(rng->regs)); put_cpu_var(rng); } else { rng = raw_cpu_read(pnv_rng); *v = rng_whiten(rng, __raw_rm_readq(rng->regs_real)); } return 1; } EXPORT_SYMBOL_GPL(pnv_get_random_long); static __init void rng_init_per_cpu(struct pnv_rng *rng, struct device_node *dn) { int chip_id, cpu; chip_id = of_get_ibm_chip_id(dn); if (chip_id == -1) pr_warn("No ibm,chip-id found for %pOF.\n", dn); for_each_possible_cpu(cpu) { if (per_cpu(pnv_rng, cpu) == NULL || cpu_to_chip_id(cpu) == chip_id) { per_cpu(pnv_rng, cpu) = rng; } } } static __init int rng_create(struct device_node *dn) { struct pnv_rng *rng; struct resource res; unsigned long val; rng = kzalloc(sizeof(*rng), GFP_KERNEL); if (!rng) return -ENOMEM; if (of_address_to_resource(dn, 0, &res)) { kfree(rng); return -ENXIO; } rng->regs_real = (void __iomem *)res.start; rng->regs = of_iomap(dn, 0); if (!rng->regs) { kfree(rng); return -ENXIO; } val = in_be64(rng->regs); rng->mask = val; rng_init_per_cpu(rng, dn); ppc_md.get_random_seed = pnv_get_random_long; return 0; } static int __init pnv_get_random_long_early(unsigned long *v) { struct device_node *dn; if (!slab_is_available()) return 0; if (cmpxchg(&ppc_md.get_random_seed, pnv_get_random_long_early, NULL) != pnv_get_random_long_early) return 0; for_each_compatible_node(dn, NULL, "ibm,power-rng") rng_create(dn); if (!ppc_md.get_random_seed) return 0; return ppc_md.get_random_seed(v); } void __init pnv_rng_init(void) { struct device_node *dn; /* Prefer darn over the rest. */ if (!initialise_darn()) return; dn = of_find_compatible_node(NULL, NULL, "ibm,power-rng"); if (dn) ppc_md.get_random_seed = pnv_get_random_long_early; of_node_put(dn); } static int __init pnv_rng_late_init(void) { struct device_node *dn; unsigned long v; /* In case it wasn't called during init for some other reason. */ if (ppc_md.get_random_seed == pnv_get_random_long_early) pnv_get_random_long_early(&v); if (ppc_md.get_random_seed == pnv_get_random_long) { for_each_compatible_node(dn, NULL, "ibm,power-rng") of_platform_device_create(dn, NULL, NULL); } return 0; } machine_subsys_initcall(powernv, pnv_rng_late_init); |