File 58526ccc-x86emul-64bit-ignore-most-segment-base... of Package xen

Overview Repositories Revisions Requests Users Attributes Meta

File 58526ccc-x86emul-64bit-ignore-most-segment-bases-in-align-check.patch of Package xen (Revision 18d9f567aa76ad786ec2ce93bd88d638)

Currently displaying revision 18d9f567aa76ad786ec2ce93bd88d638 , Show latest

# Commit 6e616a3cef4d782253787904bf3d641112eafa14
# Date 2016-12-15 11:13:32 +0100
# Author Jan Beulich <jbeulich@suse.com>
# Committer Jan Beulich <jbeulich@suse.com>
x86emul: ignore most segment bases for 64-bit mode in is_aligned()

ops->read_segment() will report whatever is actually there in the
register, so we need to actively distinguish ES/CS/SS/DS from FS/GS.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>

--- a/xen/arch/x86/x86_emulate/x86_emulate.c
+++ b/xen/arch/x86/x86_emulate/x86_emulate.c
@@ -1570,12 +1570,17 @@ static bool is_aligned(enum x86_segment
     /* Expecting powers of two only. */
     ASSERT(!(size & (size - 1)));
 
-    /* No alignment checking when we have no way to read segment data. */
-    if ( !ops->read_segment )
-        return true;
+    if ( mode_64bit() && seg < x86_seg_fs )
+        memset(&reg, 0, sizeof(reg));
+    else
+    {
+        /* No alignment checking when we have no way to read segment data. */
+        if ( !ops->read_segment )
+            return true;
 
-    if ( ops->read_segment(seg, &reg, ctxt) != X86EMUL_OKAY )
-        return false;
+        if ( ops->read_segment(seg, &reg, ctxt) != X86EMUL_OKAY )
+            return false;
+    }
 
     return !((reg.base + offs) & (size - 1));
 }

Places

File 58526ccc-x86emul-64bit-ignore-most-segment-bases-in-align-check.patch of Package xen (Revision 18d9f567aa76ad786ec2ce93bd88d638)

Places