[PATCH 5.15 119/135] powerpc/powernv: wire up rng during setup_arch

Greg Kroah-Hartman
2022-06-27T11:46:50Z

From: Jason A. Donenfeld <Jason@zx2c4.com>

commit f3eac426657d985b97c92fa5f7ae1d43f04721f3 upstream.

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
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
arch/powerpc/platforms/powernv/powernv.h | 2 +
arch/powerpc/platforms/powernv/rng.c | 52 +++++++++++++++++++++----------
arch/powerpc/platforms/powernv/setup.c | 2 +
3 files changed, 40 insertions(+), 16 deletions(-)

--- 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,
u32 memcons_get_size(struct memcons *mc);
struct memcons *memcons_init(struct device_node *node, const char *mc_prop_name);

+void pnv_rng_init(void);
+
#endif /* _POWERNV_H */
--- 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 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 devi

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);
--- a/arch/powerpc/platforms/powernv/setup.c
+++ b/arch/powerpc/platforms/powernv/setup.c
@@ -190,6 +190,8 @@ static void __init pnv_setup_arch(void)
pnv_check_guarded_cores();

/* XXX PMCS */
+
+ pnv_rng_init();
}

static void __init pnv_init(void)