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From: Julien Grall <julien.grall@arm.com>
To: Jonathan Daugherty <jtd@galois.com>, xen-devel@lists.xenproject.org
Cc: sstabellini@kernel.org
Subject: Re: [PATCH 2/2] arm/traps: fix bug in dump_guest_s1_walk handling of level 2 page tables
Date: Wed, 20 Jul 2016 13:25:08 +0100	[thread overview]
Message-ID: <48d95a6f-f367-4fa1-76b6-547f52f1b451@arm.com> (raw)
In-Reply-To: <20160719171527.43829-2-jtd@galois.com>



On 19/07/16 18:15, Jonathan Daugherty wrote:
> dump_guest_s1_walk intends to walk to level 2 page table entries but
> was failing to do so because of a check that caused level 2 page table
> descriptors to be ignored. This change fixes the check so that level 2
> page table walks occur as intended by ignoring descriptors unless their
> low two bits match the expected sequence [0,1].
>
> For more information, see the ARMv7-A ARM, section B3.5.

NIT: Could you specify the version of the spec (i.e something similar to 
ARM DDI 0406C.c)?

Also, to be precise the section would be B3.5.1.

>
> Signed-off-by: Jonathan Daugherty <jtd@galois.com>

Reviewed-by: Julien Grall <julien.grall@arm.com>

Regards,

> ---
>  xen/arch/arm/traps.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/xen/arch/arm/traps.c b/xen/arch/arm/traps.c
> index 0c10c4d..dfb1949 100644
> --- a/xen/arch/arm/traps.c
> +++ b/xen/arch/arm/traps.c
> @@ -2350,7 +2350,7 @@ void dump_guest_s1_walk(struct domain *d, vaddr_t addr)
>      printk("1ST[0x%"PRIx32"] (0x%"PRIpaddr") = 0x%08"PRIx32"\n",
>             offset, pfn_to_paddr(mfn_x(mfn)), first[offset]);
>      if ( !(first[offset] & 0x1) ||
> -         !(first[offset] & 0x2) )
> +          (first[offset] & 0x2) )
>          goto done;
>
>      mfn = p2m_lookup(d, _gfn(paddr_to_pfn(first[offset])), NULL);
>

-- 
Julien Grall

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  reply	other threads:[~2016-07-20 12:25 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-07-19 17:15 [PATCH 1/2] arm/traps: fix bug in dump_guest_s1_walk L1 page table offset computation Jonathan Daugherty
2016-07-19 17:15 ` [PATCH 2/2] arm/traps: fix bug in dump_guest_s1_walk handling of level 2 page tables Jonathan Daugherty
2016-07-20 12:25   ` Julien Grall [this message]
2016-07-20 12:23 ` [PATCH 1/2] arm/traps: fix bug in dump_guest_s1_walk L1 page table offset computation Julien Grall
2016-07-20 16:10 Jonathan Daugherty
2016-07-20 16:10 ` [PATCH 2/2] arm/traps: fix bug in dump_guest_s1_walk handling of level 2 page tables Jonathan Daugherty

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