[PATCH] x86_64: Some fixes for single step handling

Ported from i386/Linus

Be more careful with TF handling to fix some copy protection codes in Wine

Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 8 insertions, 2 deletions

diff --git a/arch/x86_64/kernel/traps.c b/arch/x86_64/kernel/traps.c
index 2707a27b81cd..09e4a6460e74 100644
--- a/arch/x86_64/kernel/traps.c
+++ b/arch/x86_64/kernel/traps.c
@@ -688,8 +688,14 @@ asmlinkage void *do_debug(struct pt_regs * regs, unsigned long error_code)
                  */
                 if ((regs->cs & 3) == 0)
                        goto clear_TF_reenable;
-                if ((tsk->ptrace & (PT_DTRACE|PT_PTRACED)) == PT_DTRACE)
-                        goto clear_TF;
+                /*
+                 * Was the TF flag set by a debugger? If so, clear it now,
+                 * so that register information is correct.
+                 */
+                if (tsk->ptrace & PT_DTRACE) {
+                        regs->eflags &= ~TF_MASK;
+                        tsk->ptrace &= ~PT_DTRACE;
+                }
         }
 
         /* Ok, finally something we can handle */