linux-kernel - Re: [PATCH] riscv: don't warn for sifive erratas in modules

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Message-ID: <CAJF2gTT_xihu58V43bQ0X-WS0STCT5RNjiEHdwPBaoXmrnX2OA@mail.gmail.com>
Date:   Thu, 9 Jun 2022 09:39:24 +0800
From:   Guo Ren <guoren@...nel.org>
To:     Heiko Stuebner <heiko@...ech.de>
Cc:     Palmer Dabbelt <palmer@...belt.com>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        linux-riscv <linux-riscv@...ts.infradead.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Wei Fu <wefu@...hat.com>,
        Christoph Muellner <cmuellner@...ux.com>,
        Philipp Tomsich <philipp.tomsich@...ll.eu>,
        Christoph Hellwig <hch@....de>, Ron Economos <re@...z.net>
Subject: Re: [PATCH] riscv: don't warn for sifive erratas in modules

On Wed, Jun 8, 2022 at 8:09 PM Heiko Stuebner <heiko@...ech.de> wrote:
>
> The SiFive errata code contains code checking applicable erratas
> vs. actually applied erratas to suggest missing erratas to the
> user when their Kconfig options are not enabled.
>
> In the main kernel image one can be quite sure that all available
> erratas appear at least once, so that check will succeed.
> On the other hand modules can very well not use any errata-relevant
> code, so the newly added module-alternative support may also patch
> the module code, but not touch SiFive-specific erratas at all.
>
> So to restore the original behaviour don't warn when patching
> modules. This will keep the warning if necessary for the main kernel
> image but prevent spurious warnings for modules.
>
> Of course having such a vendor-specific warning may not be needed at
> all, as CONFIG_ERRATA_SIFIVE is selected by CONFIG_SOC_SIFIVE and the
> individual erratas are default-y so disabling them requires
> deliberate action anyway. But for now just restore the old behaviour.
>
> Fixes: a8e910168bba ("riscv: implement module alternatives")
> Reported-by: Ron Economos <re@...z.net>
> Signed-off-by: Heiko Stuebner <heiko@...ech.de>
> ---
>  arch/riscv/errata/sifive/errata.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/arch/riscv/errata/sifive/errata.c b/arch/riscv/errata/sifive/errata.c
> index 672f02b21ce0..1031038423e7 100644
> --- a/arch/riscv/errata/sifive/errata.c
> +++ b/arch/riscv/errata/sifive/errata.c
> @@ -111,6 +111,7 @@ void __init_or_module sifive_errata_patch_func(struct alt_entry *begin,
>                         cpu_apply_errata |= tmp;
>                 }
>         }
> -       if (cpu_apply_errata != cpu_req_errata)
> +       if (stage != RISCV_ALTERNATIVES_MODULE &&
> +           cpu_apply_errata != cpu_req_errata)
if (cpu_apply_errata &= ~cpu_req_errata)

Shall we still guarantee the module's must be a subset of the main kernel.'s?

>                 warn_miss_errata(cpu_req_errata - cpu_apply_errata);
>  }
> --
> 2.35.1
>


-- 
Best Regards
 Guo Ren

ML: https://lore.kernel.org/linux-csky/