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.

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 up into an early phase and a later opportunistic phase. This
commit also removes some noisy log messages that don't add much.

Fixes: a4da0d50b2a0 ("powerpc: Implement arch_get_random_long/int() for powernv")
Cc: stable@vger.kernel.org # v3.13+
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu>
[mpe: Add of_node_put(), use pnv naming, minor change log editing]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20220621140849.127227-1-Jason@zx2c4.com

diff --git a/arch/powerpc/platforms/powernv/powernv.h b/arch/powerpc/platforms/powernv/powernv.h
index e297bf4abfcb8033e6bb770e8a70fa253de8c6e1..866efdc103fdd2885123b6db3fd82395fc7c959a 100644 (file)
--- 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 pnv_rng_init(void);
+
 #endif /* _POWERNV_H */

diff --git a/arch/powerpc/platforms/powernv/rng.c b/arch/powerpc/platforms/powernv/rng.c
index e3d44b36ae98fcb5b293e1d7050814cb59d08fe2..463c78c52cc5deb08c365bd62ff0d974375c8b2a 100644 (file)
--- 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
 
@@ -28,7 +29,6 @@ struct powernv_rng {
 
 static DEFINE_PER_CPU(struct powernv_rng *, powernv_rng);
 
-
 int powernv_hwrng_present(void)
 {
        struct powernv_rng *rng;
@@ -98,9 +98,6 @@ static int __init initialise_darn(void)
                        return 0;
                }
        }
-
-       pr_warn("Unable to use DARN for get_random_seed()\n");
-
        return -EIO;
 }
 
@@ -163,32 +160,55 @@ 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)
+static int __init pnv_get_random_long_early(unsigned long *v)
 {
        struct device_node *dn;
-       int rc;
+
+       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") {
-               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();
+       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)
+{
+       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);
        return 0;
 }
-machine_subsys_initcall(powernv, rng_init);
+machine_subsys_initcall(powernv, pnv_rng_late_init);

diff --git a/arch/powerpc/platforms/powernv/setup.c b/arch/powerpc/platforms/powernv/setup.c
index 824c3ad7a0fafb650fd4691b935a857d13a7a70d..dac545aa030824f12c2c87e98c9b000e1991ab14 100644 (file)
--- 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 */
+
+       pnv_rng_init();
 }
 
 static void __init pnv_init(void)