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Message-Id: <20220620124531.78075-1-Jason@zx2c4.com>
Date: Mon, 20 Jun 2022 14:45:31 +0200
From: "Jason A. Donenfeld" <Jason@...c4.com>
To: Michael Ellerman <mpe@...erman.id.au>,
linuxppc-dev@...ts.ozlabs.org, LKML <linux-kernel@...r.kernel.org>,
stable <stable@...r.kernel.org>,
Christophe Leroy <christophe.leroy@...roup.eu>
Cc: "Jason A. Donenfeld" <Jason@...c4.com>
Subject: [PATCH v4] powerpc/powernv: wire up rng during setup_arch
The platform's RNG must be available before random_init() in order to be
useful for initial seeding, which in turn means that it needs to be
called from setup_arch(), rather than from an init call. Fortunately,
each platform already has a setup_arch function pointer, which means we
can wire it up that way. Complicating things, however, is that POWER8
systems need some per-cpu state and kmalloc, which isn't available at
this stage. So we split things into an early phase and a late phase,
with the early phase working well enough to seed the RNG with a
spinlock, before later getting fast per-cpu allocations. This commit
also removes some noisy log messages that don't add much.
Cc: stable@...r.kernel.org
Cc: Michael Ellerman <mpe@...erman.id.au>
Reviewed-by: Christophe Leroy <christophe.leroy@...roup.eu>
Fixes: a4da0d50b2a0 ("powerpc: Implement arch_get_random_long/int() for powernv")
Signed-off-by: Jason A. Donenfeld <Jason@...c4.com>
---
arch/powerpc/platforms/powernv/powernv.h | 2 +
arch/powerpc/platforms/powernv/rng.c | 68 ++++++++++++++++++------
arch/powerpc/platforms/powernv/setup.c | 2 +
3 files changed, 55 insertions(+), 17 deletions(-)
diff --git a/arch/powerpc/platforms/powernv/powernv.h b/arch/powerpc/platforms/powernv/powernv.h
index e297bf4abfcb..fd3f5e1eb10b 100644
--- a/arch/powerpc/platforms/powernv/powernv.h
+++ b/arch/powerpc/platforms/powernv/powernv.h
@@ -42,4 +42,6 @@ ssize_t memcons_copy(struct memcons *mc, char *to, loff_t pos, size_t count);
u32 __init memcons_get_size(struct memcons *mc);
struct memcons *__init memcons_init(struct device_node *node, const char *mc_prop_name);
+void powernv_rng_init(void);
+
#endif /* _POWERNV_H */
diff --git a/arch/powerpc/platforms/powernv/rng.c b/arch/powerpc/platforms/powernv/rng.c
index e3d44b36ae98..c1beced9c32c 100644
--- a/arch/powerpc/platforms/powernv/rng.c
+++ b/arch/powerpc/platforms/powernv/rng.c
@@ -17,6 +17,7 @@
#include <asm/prom.h>
#include <asm/machdep.h>
#include <asm/smp.h>
+#include "powernv.h"
#define DARN_ERR 0xFFFFFFFFFFFFFFFFul
@@ -28,6 +29,12 @@ struct powernv_rng {
static DEFINE_PER_CPU(struct powernv_rng *, powernv_rng);
+static struct {
+ struct powernv_rng rng;
+ spinlock_t lock;
+} early_state __initdata = {
+ .lock = __SPIN_LOCK_UNLOCKED(powernv_early_rng)
+};
int powernv_hwrng_present(void)
{
@@ -84,7 +91,7 @@ static int powernv_get_random_darn(unsigned long *v)
return 1;
}
-static int __init initialise_darn(void)
+static int __init initialize_darn(void)
{
unsigned long val;
int i;
@@ -98,10 +105,18 @@ static int __init initialise_darn(void)
return 0;
}
}
+ return -EIO;
+}
- pr_warn("Unable to use DARN for get_random_seed()\n");
+static int __init powernv_get_random_long_early(unsigned long *v)
+{
+ unsigned long flags;
- return -EIO;
+ spin_lock_irqsave(&early_state.lock, flags);
+ *v = rng_whiten(&early_state.rng, in_be64(early_state.rng.regs));
+ spin_unlock_irqrestore(&early_state.lock, flags);
+
+ return 1;
}
int powernv_get_random_long(unsigned long *v)
@@ -163,32 +178,51 @@ static __init int rng_create(struct device_node *dn)
rng_init_per_cpu(rng, dn);
- pr_info_once("Registering arch random hook.\n");
-
ppc_md.get_random_seed = powernv_get_random_long;
return 0;
}
-static __init int rng_init(void)
+void __init powernv_rng_init(void)
+{
+ struct device_node *dn;
+ struct resource res;
+
+ /* Prefer darn over the rest. */
+ if (!initialize_darn())
+ return;
+
+ dn = of_find_compatible_node(NULL, NULL, "ibm,power-rng");
+ if (!dn)
+ return;
+ if (of_address_to_resource(dn, 0, &res))
+ return;
+ early_state.rng.regs_real = (void __iomem *)res.start;
+ early_state.rng.regs = of_iomap(dn, 0);
+ if (!early_state.rng.regs)
+ return;
+ early_state.rng.mask = in_be64(early_state.rng.regs);
+ ppc_md.get_random_seed = powernv_get_random_long_early;
+}
+
+static __init int powernv_rng_late_init(void)
{
struct device_node *dn;
- int rc;
+
+ /*
+ * If this didn't get initialized early on, then we're using darn,
+ * or this isn't available at all, so return early.
+ */
+ if (ppc_md.get_random_seed != powernv_get_random_long_early)
+ return 0;
+ ppc_md.get_random_seed = NULL;
for_each_compatible_node(dn, NULL, "ibm,power-rng") {
- rc = rng_create(dn);
- if (rc) {
- pr_err("Failed creating rng for %pOF (%d).\n",
- dn, rc);
+ if (rng_create(dn))
continue;
- }
-
/* Create devices for hwrng driver */
of_platform_device_create(dn, NULL, NULL);
}
-
- initialise_darn();
-
return 0;
}
-machine_subsys_initcall(powernv, rng_init);
+machine_subsys_initcall(powernv, powernv_rng_late_init);
diff --git a/arch/powerpc/platforms/powernv/setup.c b/arch/powerpc/platforms/powernv/setup.c
index 824c3ad7a0fa..a5fcb6796b22 100644
--- a/arch/powerpc/platforms/powernv/setup.c
+++ b/arch/powerpc/platforms/powernv/setup.c
@@ -203,6 +203,8 @@ static void __init pnv_setup_arch(void)
pnv_check_guarded_cores();
/* XXX PMCS */
+
+ powernv_rng_init();
}
static void __init pnv_init(void)
--
2.35.1
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