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From:   Guo Ren <guoren@kernel.org>
Date:   Thu, 22 Sep 2022 14:17:04 +0800
Message-ID: <CAJF2gTSW-ixSdV73kqpJ=yYjYnKFQtS3NfzvjBVBVU1D==7YEg@mail.gmail.com>
Subject: Re: [PATCH 1/2] riscv: Fix crash during early errata patching
To:     Samuel Holland <samuel@sholland.org>
Cc:     Palmer Dabbelt <palmer@dabbelt.com>,
        linux-riscv@lists.infradead.org, Albert Ou <aou@eecs.berkeley.edu>,
        Heiko Stuebner <heiko@sntech.de>,
        Paul Walmsley <paul.walmsley@sifive.com>,
        linux-kernel@vger.kernel.org
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Precedence: bulk

Good catch!

Reviewed-by: Guo Ren <guoren@kernel.org>

On Thu, Sep 22, 2022 at 1:47 PM Samuel Holland <samuel@sholland.org> wrote:
>
> The patch function for the T-Head PBMT errata calls __pa_symbol() before
> relocation. This crashes when CONFIG_DEBUG_VIRTUAL is enabled, because
> __pa_symbol() forwards to __phys_addr_symbol(), and __phys_addr_symbol()
> checks against the absolute kernel start/end address.
>
> Fix this by directly using the underlying kernel_mapping_va_to_pa().
>
> Fixes: a35707c3d850 ("riscv: add memory-type errata for T-Head")
> Signed-off-by: Samuel Holland <samuel@sholland.org>
> ---
>
>  arch/riscv/errata/thead/errata.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/arch/riscv/errata/thead/errata.c b/arch/riscv/errata/thead/errata.c
> index 202c83f677b2..83174f13783e 100644
> --- a/arch/riscv/errata/thead/errata.c
> +++ b/arch/riscv/errata/thead/errata.c
> @@ -76,8 +76,9 @@ void __init_or_module thead_errata_patch_func(struct alt_entry *begin, struct al
>                 if (cpu_req_errata & tmp) {
>                         /* On vm-alternatives, the mmu isn't running yet */
>                         if (stage == RISCV_ALTERNATIVES_EARLY_BOOT)
> -                               memcpy((void *)__pa_symbol(alt->old_ptr),
> -                                      (void *)__pa_symbol(alt->alt_ptr), alt->alt_len);
> +                               memcpy((void *)kernel_mapping_va_to_pa((unsigned long)alt->old_ptr),
> +                                      (void *)kernel_mapping_va_to_pa((unsigned long)alt->alt_ptr),
> +                                      alt->alt_len);
>                         else
>                                 patch_text_nosync(alt->old_ptr, alt->alt_ptr, alt->alt_len);
>                 }
> --
> 2.35.1
>


-- 
Best Regards
 Guo Ren