[PATCH] x86/mm: fix detection of last L1 entry in modify_xen_mappings_lite()

[Roger Pau Monne <roger.pau@citrix.com>]

The current logic to detect when to switch to the next L1 table is incorrectly
using l2_table_offset() in order to notice when the last entry on the current
L1 table has been reached.

It should instead use l1_table_offset() to check whether the index has wrapped
to point to the first entry, and so the next L1 table should be used.

Fixes: 8676092a0f16 ('x86/livepatch: Fix livepatch application when CET is active')
Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
---
This fixes the osstest livepatch related crash, we have been lucky so far that
the .text section didn't seem to have hit this.
---
 xen/arch/x86/mm.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/xen/arch/x86/mm.c b/xen/arch/x86/mm.c
index 2aff6d4b5338..0c6658298de2 100644
--- a/xen/arch/x86/mm.c
+++ b/xen/arch/x86/mm.c
@@ -5959,7 +5959,7 @@ void init_or_livepatch modify_xen_mappings_lite(
 
                 v += 1UL << L1_PAGETABLE_SHIFT;
 
-                if ( l2_table_offset(v) == 0 )
+                if ( l1_table_offset(v) == 0 )
                     break;
             }
 
-- 
2.44.0