linux-kernel - Re: [PATCH v2 2/4] arm64: kasan: abstract _text and _end to KERNEL

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Message-ID: <20210204124658.GB20468@willie-the-truck>
Date:   Thu, 4 Feb 2021 12:46:58 +0000
From:   Will Deacon <will@...nel.org>
To:     Lecopzer Chen <lecopzer@...il.com>
Cc:     linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        kasan-dev@...glegroups.com, linux-arm-kernel@...ts.infradead.org,
        dan.j.williams@...el.com, aryabinin@...tuozzo.com,
        glider@...gle.com, dvyukov@...gle.com, akpm@...ux-foundation.org,
        linux-mediatek@...ts.infradead.org, yj.chiang@...iatek.com,
        catalin.marinas@....com, ardb@...nel.org, andreyknvl@...gle.com,
        broonie@...nel.org, linux@...ck-us.net, rppt@...nel.org,
        tyhicks@...ux.microsoft.com, robin.murphy@....com,
        vincenzo.frascino@....com, gustavoars@...nel.org,
        Lecopzer Chen <lecopzer.chen@...iatek.com>
Subject: Re: [PATCH v2 2/4] arm64: kasan: abstract _text and _end to
 KERNEL_START/END

On Sat, Jan 09, 2021 at 06:32:50PM +0800, Lecopzer Chen wrote:
> Arm64 provide defined macro for KERNEL_START and KERNEL_END,
> thus replace them by the abstration instead of using _text and _end.
> 
> Signed-off-by: Lecopzer Chen <lecopzer.chen@...iatek.com>
> ---
>  arch/arm64/mm/kasan_init.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/arch/arm64/mm/kasan_init.c b/arch/arm64/mm/kasan_init.c
> index 39b218a64279..fa8d7ece895d 100644
> --- a/arch/arm64/mm/kasan_init.c
> +++ b/arch/arm64/mm/kasan_init.c
> @@ -218,8 +218,8 @@ static void __init kasan_init_shadow(void)
>  	phys_addr_t pa_start, pa_end;
>  	u64 i;
>  
> -	kimg_shadow_start = (u64)kasan_mem_to_shadow(_text) & PAGE_MASK;
> -	kimg_shadow_end = PAGE_ALIGN((u64)kasan_mem_to_shadow(_end));
> +	kimg_shadow_start = (u64)kasan_mem_to_shadow(KERNEL_START) & PAGE_MASK;
> +	kimg_shadow_end = PAGE_ALIGN((u64)kasan_mem_to_shadow(KERNEL_END));
>  
>  	mod_shadow_start = (u64)kasan_mem_to_shadow((void *)MODULES_VADDR);
>  	mod_shadow_end = (u64)kasan_mem_to_shadow((void *)MODULES_END);
> @@ -241,7 +241,7 @@ static void __init kasan_init_shadow(void)
>  	clear_pgds(KASAN_SHADOW_START, KASAN_SHADOW_END);
>  
>  	kasan_map_populate(kimg_shadow_start, kimg_shadow_end,
> -			   early_pfn_to_nid(virt_to_pfn(lm_alias(_text))));
> +			   early_pfn_to_nid(virt_to_pfn(lm_alias(KERNEL_START))));

To be honest, I think this whole line is pointless. We should be able to
pass NUMA_NO_NODE now that we're not abusing the vmemmap() allocator to
populate the shadow.

Will