write in 30M

hc

2024-02-20 ea08eeccae9297f7aabd2ef7f0c2517ac4549acc

 kernel/arch/powerpc/platforms/powernv/rng.c
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@@ -1,10 +1,6 @@
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+// SPDX-License-Identifier: GPL-2.0-or-later
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 /*
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  * Copyright 2013, Michael Ellerman, IBM Corporation.
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- *
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- * This program is free software; you can redistribute it and/or
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- * modify it under the terms of the GNU General Public License
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- * as published by the Free Software Foundation; either version
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- * 2 of the License, or (at your option) any later version.
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  */
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 #define pr_fmt(fmt)	"powernv-rng: " fmt
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@@ -21,6 +17,7 @@
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 #include <asm/prom.h>
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 #include <asm/machdep.h>
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 #include <asm/smp.h>
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+#include "powernv.h"
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21
 
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 #define DARN_ERR 0xFFFFFFFFFFFFFFFFul
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..
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@@ -31,7 +28,6 @@
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 };
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 static DEFINE_PER_CPU(struct powernv_rng *, powernv_rng);
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-
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 int powernv_hwrng_present(void)
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 {
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@@ -47,7 +43,11 @@
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 	unsigned long parity;
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 	/* Calculate the parity of the value */
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-	asm ("popcntd %0,%1" : "=r" (parity) : "r" (val));
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+	asm (".machine push;   \
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+	      .machine power7; \
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+	      popcntd %0,%1;   \
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+	      .machine pop;"
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+	     : "=r" (parity) : "r" (val));
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51
 
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 	/* xor our value with the previous mask */
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 	val ^= rng->mask;
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@@ -63,13 +63,15 @@
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 	struct powernv_rng *rng;
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 	rng = raw_cpu_read(powernv_rng);
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+	if (!rng)
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+		return 0;
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 	*v = rng_whiten(rng, __raw_rm_readq(rng->regs_real));
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 	return 1;
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 }
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-int powernv_get_random_darn(unsigned long *v)
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+static int powernv_get_random_darn(unsigned long *v)
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 {
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 	unsigned long val;
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..
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@@ -98,9 +100,6 @@
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 			return 0;
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 		}
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 	}
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-
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-	pr_warn("Unable to use DARN for get_random_seed()\n");
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-
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 	return -EIO;
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 }
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@@ -163,32 +162,59 @@
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 	rng_init_per_cpu(rng, dn);
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164
 
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-	pr_info_once("Registering arch random hook.\n");
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-
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 	ppc_md.get_random_seed = powernv_get_random_long;
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 	return 0;
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 }
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-static __init int rng_init(void)
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+static int __init pnv_get_random_long_early(unsigned long *v)
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 {
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 	struct device_node *dn;
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-	int rc;
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-	for_each_compatible_node(dn, NULL, "ibm,power-rng") {
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-		rc = rng_create(dn);
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-		if (rc) {
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-			pr_err("Failed creating rng for %pOF (%d).\n",
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-				dn, rc);
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-			continue;
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-		}
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+	if (!slab_is_available())
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+		return 0;
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-		/* Create devices for hwrng driver */
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-		of_platform_device_create(dn, NULL, NULL);
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+	if (cmpxchg(&ppc_md.get_random_seed, pnv_get_random_long_early,
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+		    NULL) != pnv_get_random_long_early)
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+		return 0;
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+
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+	for_each_compatible_node(dn, NULL, "ibm,power-rng")
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+		rng_create(dn);
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+
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+	if (!ppc_md.get_random_seed)
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+		return 0;
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+	return ppc_md.get_random_seed(v);
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+}
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+
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+void __init pnv_rng_init(void)
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+{
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+	struct device_node *dn;
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+
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+	/* Prefer darn over the rest. */
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+	if (!initialise_darn())
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+		return;
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+
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+	dn = of_find_compatible_node(NULL, NULL, "ibm,power-rng");
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+	if (dn)
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+		ppc_md.get_random_seed = pnv_get_random_long_early;
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+
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+	of_node_put(dn);
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+}
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+
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+static int __init pnv_rng_late_init(void)
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+{
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+	struct device_node *dn;
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+	unsigned long v;
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+
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+	/* In case it wasn't called during init for some other reason. */
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+	if (ppc_md.get_random_seed == pnv_get_random_long_early)
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+		pnv_get_random_long_early(&v);
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+
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+	if (ppc_md.get_random_seed == powernv_get_random_long) {
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+		for_each_compatible_node(dn, NULL, "ibm,power-rng")
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+			of_platform_device_create(dn, NULL, NULL);
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 	}
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-
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-	initialise_darn();
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 	return 0;
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 }
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-machine_subsys_initcall(powernv, rng_init);
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+machine_subsys_initcall(powernv, pnv_rng_late_init);