x86, ftrace, hw-branch-tracer: dump trace on oops

Dump the branch trace on an oops (based on ftrace_dump_on_oops).

Signed-off-by: Markus Metzger <markus.t.metzger@intel.com>
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 6 insertions, 0 deletions

diff --git a/arch/x86/kernel/dumpstack.c b/arch/x86/kernel/dumpstack.c
index 6b1f6f6f8661..077c9ea655fc 100644
--- a/arch/x86/kernel/dumpstack.c
+++ b/arch/x86/kernel/dumpstack.c
@@ -14,6 +14,7 @@
 #include <linux/bug.h>
 #include <linux/nmi.h>
 #include <linux/sysfs.h>
+#include <linux/ftrace.h>
 
 #include <asm/stacktrace.h>
 
@@ -195,6 +196,11 @@ unsigned __kprobes long oops_begin(void)
         int cpu;
         unsigned long flags;
 
+        /* notify the hw-branch tracer so it may disable tracing and
+           add the last trace to the trace buffer -
+           the earlier this happens, the more useful the trace. */
+        trace_hw_branch_oops();
+
         oops_enter();
 
         /* racy, but better than risking deadlock. */