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Date: Sat, 9 Sep 2017 08:38:20 -0700
From: Laura Abbott <labbott@...hat.com>
To: Tycho Andersen <tycho@...ker.com>, linux-kernel@...r.kernel.org
Cc: linux-mm@...ck.org, kernel-hardening@...ts.openwall.com,
 Marco Benatto <marco.antonio.780@...il.com>,
 Juerg Haefliger <juerg.haefliger@...onical.com>,
 linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v6 09/11] arm64/mm: disable section/contiguous mappings if
 XPFO is enabled

On 09/07/2017 10:36 AM, Tycho Andersen wrote:
> XPFO doesn't support section/contiguous mappings yet, so let's disable it
> if XPFO is turned on.
> 
> Thanks to Laura Abbot for the simplification from v5, and Mark Rutland for
> pointing out we need NO_CONT_MAPPINGS too.
> 
> CC: linux-arm-kernel@...ts.infradead.org
> Signed-off-by: Tycho Andersen <tycho@...ker.com>


This should just be folded into the initial arm64 patch
since it basically bugs out otherwise.

Thanks,
Laura

> ---
>  arch/arm64/mm/mmu.c  | 2 +-
>  include/linux/xpfo.h | 4 ++++
>  mm/xpfo.c            | 6 ++++++
>  3 files changed, 11 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
> index f1eb15e0e864..34bb95303cce 100644
> --- a/arch/arm64/mm/mmu.c
> +++ b/arch/arm64/mm/mmu.c
> @@ -420,7 +420,7 @@ static void __init map_mem(pgd_t *pgd)
>  	struct memblock_region *reg;
>  	int flags = 0;
>  
> -	if (debug_pagealloc_enabled())
> +	if (debug_pagealloc_enabled() || xpfo_enabled())
>  		flags = NO_BLOCK_MAPPINGS | NO_CONT_MAPPINGS;
>  
>  	/*
> diff --git a/include/linux/xpfo.h b/include/linux/xpfo.h
> index d37a06c9d62c..1693af1a0293 100644
> --- a/include/linux/xpfo.h
> +++ b/include/linux/xpfo.h
> @@ -43,6 +43,8 @@ void xpfo_temp_map(const void *addr, size_t size, void **mapping,
>  void xpfo_temp_unmap(const void *addr, size_t size, void **mapping,
>  		     size_t mapping_len);
>  
> +bool xpfo_enabled(void);
> +
>  #else /* !CONFIG_XPFO */
>  
>  static inline void xpfo_kmap(void *kaddr, struct page *page) { }
> @@ -65,6 +67,8 @@ static inline void xpfo_temp_unmap(const void *addr, size_t size,
>  }
>  
>  
> +static inline bool xpfo_enabled(void) { return false; }
> +
>  #endif /* CONFIG_XPFO */
>  
>  #endif /* _LINUX_XPFO_H */
> diff --git a/mm/xpfo.c b/mm/xpfo.c
> index f79075bf7d65..25fba05d01bd 100644
> --- a/mm/xpfo.c
> +++ b/mm/xpfo.c
> @@ -70,6 +70,12 @@ struct page_ext_operations page_xpfo_ops = {
>  	.init = init_xpfo,
>  };
>  
> +bool __init xpfo_enabled(void)
> +{
> +	return !xpfo_disabled;
> +}
> +EXPORT_SYMBOL(xpfo_enabled);
> +
>  static inline struct xpfo *lookup_xpfo(struct page *page)
>  {
>  	struct page_ext *page_ext = lookup_page_ext(page);
> 

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