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@vger.kernel.org Cc: Michael Ellerman mpe@ellerman.id.au Reviewed-by: Christophe Leroy christophe.leroy@csgroup.eu Fixes: a4da0d50b2a0 ("powerpc: Implement arch_get_random_long/int() for powernv") Signed-off-by: Jason A. Donenfeld Jason@zx2c4.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)