linux-kernel - Re: [PATCH] random: Use arch_get_random_long_early() for init_std

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Message-ID: <20201116132007.GA30323@willie-the-truck>
Date:   Mon, 16 Nov 2020 13:20:07 +0000
From:   Will Deacon <will@...nel.org>
To:     Andre Przywara <andre.przywara@....com>
Cc:     Theodore Ts'o <tytso@....edu>, Mark Rutland <mark.rutland@....com>,
        Catalin Marinas <catalin.marinas@....com>,
        Mark Brown <broonie@...nel.org>,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] random: Use arch_get_random_long_early() for
 init_std_data()

On Fri, Nov 13, 2020 at 04:19:12PM +0000, Andre Przywara wrote:
> In commit 253d3194c2b5 ("random: add arch_get_random_*long_early()") we
> introduced _early versions of arch_get_random_long(), that are used on
> arm64 to use the CPU RNDR instruction early in the boot process, before
> we have established system-wide availability.
> This covers the calls in crng_initialize_primary(), but missed the calls
> in init_std_data(), happening just before that.
> 
> Use the _early versions of the arch_get_random* calls also in
> init_std_data(), to help initialising the pool with proper seed values.
> 
> Fixes: 253d3194c2b5 ("random: add arch_get_random_*long_early()")
> Cc: Mark Rutland <mark.rutland@....com>
> Signed-off-by: Andre Przywara <andre.przywara@....com>
> ---
>  drivers/char/random.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/char/random.c b/drivers/char/random.c
> index 2a41b21623ae..43bb331a67bd 100644
> --- a/drivers/char/random.c
> +++ b/drivers/char/random.c
> @@ -1778,8 +1778,8 @@ static void __init init_std_data(struct entropy_store *r)
>  
>  	mix_pool_bytes(r, &now, sizeof(now));
>  	for (i = r->poolinfo->poolbytes; i > 0; i -= sizeof(rv)) {
> -		if (!arch_get_random_seed_long(&rv) &&
> -		    !arch_get_random_long(&rv))
> +		if (!arch_get_random_seed_long_early(&rv) &&
> +		    !arch_get_random_long_early(&rv))
>  			rv = random_get_entropy();
>  		mix_pool_bytes(r, &rv, sizeof(rv));

Acked-by: Will Deacon <will@...nel.org>

Will