hw-breakpoints, perf: Fix broken mmiotrace due to dr6 by reference change

Commit 62edab9056a6cf0c9207339c8892c923a5217e45 (from June 2009
but merged in 2.6.33) changes notify_die to pass dr6 by
reference.

However, it forgets to fix the check for DR_STEP in kmmio.c,
breaking mmiotrace. It also passes a wrong value to the post
handler.

This simple fix makes mmiotrace work again.

Signed-off-by: Luca Barbieri <luca@luca-barbieri.com>
Acked-by: K.Prasad <prasad@linux.vnet.ibm.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <1263634770-14578-1-git-send-email-luca@luca-barbieri.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 4 insertions, 3 deletions

diff --git a/arch/x86/mm/kmmio.c b/arch/x86/mm/kmmio.c
index c0f6198565eb..536fb6823366 100644
--- a/arch/x86/mm/kmmio.c
+++ b/arch/x86/mm/kmmio.c
@@ -538,14 +538,15 @@ static int
 kmmio_die_notifier(struct notifier_block *nb, unsigned long val, void *args)
 {
         struct die_args *arg = args;
+        unsigned long* dr6_p = (unsigned long *)ERR_PTR(arg->err);
 
-        if (val == DIE_DEBUG && (arg->err & DR_STEP))
-                if (post_kmmio_handler(arg->err, arg->regs) == 1) {
+        if (val == DIE_DEBUG && (*dr6_p & DR_STEP))
+                if (post_kmmio_handler(*dr6_p, arg->regs) == 1) {
                         /*
                          * Reset the BS bit in dr6 (pointed by args->err) to
                          * denote completion of processing
                          */
-                        (*(unsigned long *)ERR_PTR(arg->err)) &= ~DR_STEP;
+                        *dr6_p &= ~DR_STEP;
                         return NOTIFY_STOP;
                 }