[Xen-devel] [PATCH 2/2] arm/traps: fix bug in dump_guest_s1_walk handling of level 2 page tables

[Jonathan Daugherty <jtd@xxxxxxxxxx>]

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 DDI 0406C.b, section B3.5.1.

Signed-off-by: Jonathan Daugherty <jtd@xxxxxxxxxx>
---
 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);
-- 
2.9.2


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