linux-kernel - Re: [PATCH v1 06/46] powerpc/kasan: Refactor update of early shadow mappings

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Date:   Thu, 2 Apr 2020 12:19:13 +0200
From:   Christophe Leroy <christophe.leroy@....fr>
To:     Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Michael Ellerman <mpe@...erman.id.au>
Cc:     linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v1 06/46] powerpc/kasan: Refactor update of early shadow
 mappings

Michael,

Le 16/03/2020 à 13:35, Christophe Leroy a écrit :
> kasan_remap_early_shadow_ro() and kasan_unmap_early_shadow_vmalloc()
> are both updating the early shadow mapping: the first one sets
> the mapping read-only while the other clears the mapping.
> 
> Refactor and create kasan_update_early_region()

There is a trivial conflict with this patch on powerpc/next.
Do you plan to take this series for 5.7 ? I so, I can repost the series 
now with the fix, or just this patch ?

Otherwise, what are your plans ? This series (Patches 18 and 19) will 
conflict with the 40x removal series as both do things about that 
PTE_ATOMIC_UPDATE stuff. Which series would go first ?

Thanks
Christophe

> 
> Signed-off-by: Christophe Leroy <christophe.leroy@....fr>
> ---
>   arch/powerpc/mm/kasan/kasan_init_32.c | 39 +++++++++++++--------------
>   1 file changed, 18 insertions(+), 21 deletions(-)
> 
> diff --git a/arch/powerpc/mm/kasan/kasan_init_32.c b/arch/powerpc/mm/kasan/kasan_init_32.c
> index c9d053078c37..65fd8b891f8e 100644
> --- a/arch/powerpc/mm/kasan/kasan_init_32.c
> +++ b/arch/powerpc/mm/kasan/kasan_init_32.c
> @@ -79,45 +79,42 @@ static int __init kasan_init_region(void *start, size_t size)
>   	return 0;
>   }
>   
> -static void __init kasan_remap_early_shadow_ro(void)
> +static void __init
> +kasan_update_early_region(unsigned long k_start, unsigned long k_end, pte_t pte)
>   {
> -	pgprot_t prot = kasan_prot_ro();
> -	unsigned long k_start = KASAN_SHADOW_START;
> -	unsigned long k_end = KASAN_SHADOW_END;
>   	unsigned long k_cur;
>   	phys_addr_t pa = __pa(kasan_early_shadow_page);
>   
> -	kasan_populate_pte(kasan_early_shadow_pte, prot);
> -
> -	for (k_cur = k_start & PAGE_MASK; k_cur < k_end; k_cur += PAGE_SIZE) {
> +	for (k_cur = k_start; k_cur < k_end; k_cur += PAGE_SIZE) {
>   		pmd_t *pmd = pmd_ptr_k(k_cur);
>   		pte_t *ptep = pte_offset_kernel(pmd, k_cur);
>   
>   		if ((pte_val(*ptep) & PTE_RPN_MASK) != pa)
>   			continue;
>   
> -		__set_pte_at(&init_mm, k_cur, ptep, pfn_pte(PHYS_PFN(pa), prot), 0);
> +		__set_pte_at(&init_mm, k_cur, ptep, pte, 0);
>   	}
> -	flush_tlb_kernel_range(KASAN_SHADOW_START, KASAN_SHADOW_END);
> +
> +	flush_tlb_kernel_range(k_start, k_end);
>   }
>   
> -static void __init kasan_unmap_early_shadow_vmalloc(void)
> +static void __init kasan_remap_early_shadow_ro(void)
>   {
> -	unsigned long k_start = (unsigned long)kasan_mem_to_shadow((void *)VMALLOC_START);
> -	unsigned long k_end = (unsigned long)kasan_mem_to_shadow((void *)VMALLOC_END);
> -	unsigned long k_cur;
> +	pgprot_t prot = kasan_prot_ro();
>   	phys_addr_t pa = __pa(kasan_early_shadow_page);
>   
> -	for (k_cur = k_start & PAGE_MASK; k_cur < k_end; k_cur += PAGE_SIZE) {
> -		pmd_t *pmd = pmd_offset(pud_offset(pgd_offset_k(k_cur), k_cur), k_cur);
> -		pte_t *ptep = pte_offset_kernel(pmd, k_cur);
> +	kasan_populate_pte(kasan_early_shadow_pte, prot);
>   
> -		if ((pte_val(*ptep) & PTE_RPN_MASK) != pa)
> -			continue;
> +	kasan_update_early_region(KASAN_SHADOW_START, KASAN_SHADOW_END,
> +				  pfn_pte(PHYS_PFN(pa), prot));
> +}
>   
> -		__set_pte_at(&init_mm, k_cur, ptep, __pte(0), 0);
> -	}
> -	flush_tlb_kernel_range(k_start, k_end);
> +static void __init kasan_unmap_early_shadow_vmalloc(void)
> +{
> +	unsigned long k_start = (unsigned long)kasan_mem_to_shadow((void *)VMALLOC_START);
> +	unsigned long k_end = (unsigned long)kasan_mem_to_shadow((void *)VMALLOC_END);
> +
> +	kasan_update_early_region(k_start, k_end, __pte(0));
>   }
>   
>   static void __init kasan_mmu_init(void)
>