x86: Do not clear EF.TF in crash-debug mode.

Signed-off-by: Keir Fraser <keir.fraser@citrix.com>

diff --git a/xen/arch/x86/traps.c b/xen/arch/x86/traps.c
index 508cd9d3065d745400a3445a4190aa2ccc5fd750..8a066cc41c69f5e8c9b3e065b7876c96cfdc1573 100644 (file)
--- a/xen/arch/x86/traps.c
+++ b/xen/arch/x86/traps.c
@@ -3005,16 +3005,18 @@ asmlinkage void do_debug(struct cpu_user_regs *regs)
             void sysenter_eflags_saved(void);
             /* In SYSENTER entry path we can't zap TF until EFLAGS is saved. */
             if ( (regs->rip >= (unsigned long)sysenter_entry) &&
-                 (regs->rip < (unsigned long)sysenter_eflags_saved) )
+                 (regs->rip <= (unsigned long)sysenter_eflags_saved) )
+            {
+                if ( regs->rip == (unsigned long)sysenter_eflags_saved )
+                    regs->eflags &= ~EF_TF;
                 goto out;
-            if ( (regs->rip != (unsigned long)sysenter_eflags_saved) &&
-                 !debugger_trap_fatal(TRAP_debug, regs) )
-                WARN_ON(1);
-#else
+            }
+#endif
             if ( !debugger_trap_fatal(TRAP_debug, regs) )
+            {
                 WARN_ON(1);
-#endif
-            regs->eflags &= ~EF_TF;
+                regs->eflags &= ~EF_TF;
+            }
         }
         else
         {