Re: [PATCH v1 1/1] riscv: mm: add missing memcpy in kasan_init

[Conor Dooley <conor@kernel.org>]

On Sun, Oct 09, 2022 at 04:30:50PM +0800, panqinglin2020@iscas.ac.cn wrote:
> From: Qinglin Pan <panqinglin2020@iscas.ac.cn>
> 
> Hi Atish,
> 
> It seems that the panic is due to the missing memcpy during kasan_init.
> Could you please check whether this patch is helpful?

If this does solve the problem it would be:
Fixes: 8fbdccd2b173 ("riscv: mm: Support kasan for sv57")
right?

Thanks,
Conor.

> 
> When doing kasan_populate, the new allocated base_pud/base_p4d should
> contain kasan_early_shadow_{pud, p4d}'s content. Add the missing memcpy
> to avoid page fault when read/write kasan shadow region.
> 
> Tested on:
>  - qemu with sv57 and CONFIG_KASAN on.
>  - qemu with sv48 and CONFIG_KASAN on.
> 
> Signed-off-by: Qinglin Pan <panqinglin2020@iscas.ac.cn>
> ---
>  arch/riscv/mm/kasan_init.c | 7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/riscv/mm/kasan_init.c b/arch/riscv/mm/kasan_init.c
> index a22e418dbd82..e1226709490f 100644
> --- a/arch/riscv/mm/kasan_init.c
> +++ b/arch/riscv/mm/kasan_init.c
> @@ -113,6 +113,8 @@ static void __init kasan_populate_pud(pgd_t *pgd,
>  		base_pud = pt_ops.get_pud_virt(pfn_to_phys(_pgd_pfn(*pgd)));
>  	} else if (pgd_none(*pgd)) {
>  		base_pud = memblock_alloc(PTRS_PER_PUD * sizeof(pud_t), PAGE_SIZE);
> +		memcpy(base_pud, (void *)kasan_early_shadow_pud,
> +			sizeof(pud_t) * PTRS_PER_PUD);
>  	} else {
>  		base_pud = (pud_t *)pgd_page_vaddr(*pgd);
>  		if (base_pud == lm_alias(kasan_early_shadow_pud)) {
> @@ -173,8 +175,11 @@ static void __init kasan_populate_p4d(pgd_t *pgd,
>  		base_p4d = pt_ops.get_p4d_virt(pfn_to_phys(_pgd_pfn(*pgd)));
>  	} else {
>  		base_p4d = (p4d_t *)pgd_page_vaddr(*pgd);
> -		if (base_p4d == lm_alias(kasan_early_shadow_p4d))
> +		if (base_p4d == lm_alias(kasan_early_shadow_p4d)) {
>  			base_p4d = memblock_alloc(PTRS_PER_PUD * sizeof(p4d_t), PAGE_SIZE);
> +			memcpy(base_p4d, (void *)kasan_early_shadow_p4d,
> +				sizeof(p4d_t) * PTRS_PER_P4D);
> +		}
>  	}
>  
>  	p4dp = base_p4d + p4d_index(vaddr);
> -- 
> 2.35.1
> 
> 
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