linux-kernel - Re: [PATCH v3 1/3] powerpc/microwatt: wire up rng during setup

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Message-ID: <709c9859-f8db-6f03-9cf5-50b7442953ae@csgroup.eu>
Date:   Sat, 11 Jun 2022 16:25:17 +0000
From:   Christophe Leroy <christophe.leroy@...roup.eu>
To:     "Jason A. Donenfeld" <Jason@...c4.com>,
        "linuxppc-dev@...ts.ozlabs.org" <linuxppc-dev@...ts.ozlabs.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Michael Ellerman <mpe@...erman.id.au>
CC:     "stable@...r.kernel.org" <stable@...r.kernel.org>
Subject: Re: [PATCH v3 1/3] powerpc/microwatt: wire up rng during setup_arch



Le 11/06/2022 à 17:10, Jason A. Donenfeld a écrit :
> 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
> it's easy to wire this up. 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>
> Cc: Christophe Leroy <christophe.leroy@...roup.eu>
> Fixes: c25769fddaec ("powerpc/microwatt: Add support for hardware random number generator")
> Signed-off-by: Jason A. Donenfeld <Jason@...c4.com>

Reviewed-by: Christophe Leroy <christophe.leroy@...roup.eu>

> ---
>   arch/powerpc/platforms/microwatt/microwatt.h |  7 +++++++
>   arch/powerpc/platforms/microwatt/rng.c       | 10 +++-------
>   arch/powerpc/platforms/microwatt/setup.c     |  8 ++++++++
>   3 files changed, 18 insertions(+), 7 deletions(-)
>   create mode 100644 arch/powerpc/platforms/microwatt/microwatt.h
> 
> diff --git a/arch/powerpc/platforms/microwatt/microwatt.h b/arch/powerpc/platforms/microwatt/microwatt.h
> new file mode 100644
> index 000000000000..335417e95e66
> --- /dev/null
> +++ b/arch/powerpc/platforms/microwatt/microwatt.h
> @@ -0,0 +1,7 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +#ifndef _MICROWATT_H
> +#define _MICROWATT_H
> +
> +void microwatt_rng_init(void);
> +
> +#endif /* _MICROWATT_H */
> diff --git a/arch/powerpc/platforms/microwatt/rng.c b/arch/powerpc/platforms/microwatt/rng.c
> index 7bc4d1cbfaf0..8ece87d005c8 100644
> --- a/arch/powerpc/platforms/microwatt/rng.c
> +++ b/arch/powerpc/platforms/microwatt/rng.c
> @@ -11,6 +11,7 @@
>   #include <asm/archrandom.h>
>   #include <asm/cputable.h>
>   #include <asm/machdep.h>
> +#include "microwatt.h"
>   
>   #define DARN_ERR 0xFFFFFFFFFFFFFFFFul
>   
> @@ -29,7 +30,7 @@ static int microwatt_get_random_darn(unsigned long *v)
>   	return 1;
>   }
>   
> -static __init int rng_init(void)
> +void __init microwatt_rng_init(void)
>   {
>   	unsigned long val;
>   	int i;
> @@ -37,12 +38,7 @@ static __init int rng_init(void)
>   	for (i = 0; i < 10; i++) {
>   		if (microwatt_get_random_darn(&val)) {
>   			ppc_md.get_random_seed = microwatt_get_random_darn;
> -			return 0;
> +			return;
>   		}
>   	}
> -
> -	pr_warn("Unable to use DARN for get_random_seed()\n");
> -
> -	return -EIO;
>   }
> -machine_subsys_initcall(, rng_init);
> diff --git a/arch/powerpc/platforms/microwatt/setup.c b/arch/powerpc/platforms/microwatt/setup.c
> index 0b02603bdb74..6b32539395a4 100644
> --- a/arch/powerpc/platforms/microwatt/setup.c
> +++ b/arch/powerpc/platforms/microwatt/setup.c
> @@ -16,6 +16,8 @@
>   #include <asm/xics.h>
>   #include <asm/udbg.h>
>   
> +#include "microwatt.h"
> +
>   static void __init microwatt_init_IRQ(void)
>   {
>   	xics_init();
> @@ -32,10 +34,16 @@ static int __init microwatt_populate(void)
>   }
>   machine_arch_initcall(microwatt, microwatt_populate);
>   
> +static void __init microwatt_setup_arch(void)
> +{
> +	microwatt_rng_init();
> +}
> +
>   define_machine(microwatt) {
>   	.name			= "microwatt",
>   	.probe			= microwatt_probe,
>   	.init_IRQ		= microwatt_init_IRQ,
> +	.setup_arch		= microwatt_setup_arch,
>   	.progress		= udbg_progress,
>   	.calibrate_decr		= generic_calibrate_decr,
>   };