linux-kernel - Re: [PATCH 1/2] riscv: Fix crash during early errata patching

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Date:   Fri, 09 Dec 2022 11:00:40 -0800 (PST)
From:   Palmer Dabbelt <palmer@...belt.com>
To:     samuel@...lland.org
CC:     linux-riscv@...ts.infradead.org, samuel@...lland.org,
        aou@...s.berkeley.edu, guoren@...nel.org, heiko@...ech.de,
        Paul Walmsley <paul.walmsley@...ive.com>,
        linux-kernel@...r.kernel.org
Subject:     Re: [PATCH 1/2] riscv: Fix crash during early errata patching

On Wed, 21 Sep 2022 22:47:41 PDT (-0700), samuel@...lland.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@...lland.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);
>  		}

Thanks, these are on for-next.