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    Subject[PATCH 5.4 51/60] powerpc/powernv: wire up rng during setup_arch
    Date
    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
    @@ -35,4 +35,6 @@ 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
    @@ -168,6 +168,8 @@ static void __init pnv_setup_arch(void)
    powersave_nap = 1;

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

    static void __init pnv_init(void)

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