3 files changed, 20 insertions, 7 deletions

diff --git a/arch/i386/kernel/process.c b/arch/i386/kernel/process.c
index 923bb292f47f..8657c739656a 100644
--- a/arch/i386/kernel/process.c
+++ b/arch/i386/kernel/process.c
@@ -690,8 +690,8 @@ struct task_struct fastcall * __switch_to(struct task_struct *prev_p, struct tas
         /*
          * Now maybe handle debug registers and/or IO bitmaps
          */
-        if (unlikely((task_thread_info(next_p)->flags & _TIF_WORK_CTXSW))
-            || test_tsk_thread_flag(prev_p, TIF_IO_BITMAP))
+        if (unlikely((task_thread_info(next_p)->flags & _TIF_WORK_CTXSW)
+            || test_tsk_thread_flag(prev_p, TIF_IO_BITMAP)))
                 __switch_to_xtra(next_p, tss);
 
         disable_tsc(prev_p, next_p);
diff --git a/arch/i386/kernel/time.c b/arch/i386/kernel/time.c
index 8705c0f05788..edd00f6cee37 100644
--- a/arch/i386/kernel/time.c
+++ b/arch/i386/kernel/time.c
@@ -135,7 +135,7 @@ unsigned long profile_pc(struct pt_regs *regs)
 {
         unsigned long pc = instruction_pointer(regs);
 
-        if (in_lock_functions(pc))
+        if (!user_mode_vm(regs) && in_lock_functions(pc))
                 return *(unsigned long *)(regs->ebp + 4);
 
         return pc;
diff --git a/arch/i386/kernel/traps.c b/arch/i386/kernel/traps.c
index 313ac1f7dc5a..021f8fdc7512 100644
--- a/arch/i386/kernel/traps.c
+++ b/arch/i386/kernel/traps.c
@@ -187,10 +187,21 @@ static void show_trace_log_lvl(struct task_struct *task, struct pt_regs *regs,
                         if (unwind_init_blocked(&info, task) == 0)
                                 unw_ret = show_trace_unwind(&info, log_lvl);
                 }
-                if (unw_ret > 0) {
-                        if (call_trace > 0)
+                if (unw_ret > 0 && !arch_unw_user_mode(&info)) {
+#ifdef CONFIG_STACK_UNWIND
+                        print_symbol("DWARF2 unwinder stuck at %s\n",
+                                     UNW_PC(&info));
+                        if (call_trace == 1) {
+                                printk("Leftover inexact backtrace:\n");
+                                if (UNW_SP(&info))
+                                        stack = (void *)UNW_SP(&info);
+                        } else if (call_trace > 1)
                                 return;
-                        printk("%sLegacy call trace:\n", log_lvl);
+                        else
+                                printk("Full inexact backtrace again:\n");
+#else
+                        printk("Inexact backtrace:\n");
+#endif
                 }
         }
 
@@ -1238,8 +1249,10 @@ static int __init call_trace_setup(char *s)
                 call_trace = -1;
         else if (strcmp(s, "both") == 0)
                 call_trace = 0;
-        else if (strcmp(s, "new") == 0)
+        else if (strcmp(s, "newfallback") == 0)
                 call_trace = 1;
+        else if (strcmp(s, "new") == 2)
+                call_trace = 2;
         return 1;
 }
 __setup("call_trace=", call_trace_setup);