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-rw-r--r--kernel/trace/trace_stack.c33
1 files changed, 29 insertions, 4 deletions
diff --git a/kernel/trace/trace_stack.c b/kernel/trace/trace_stack.c
index d21f844..f8bf3df 100644
--- a/kernel/trace/trace_stack.c
+++ b/kernel/trace/trace_stack.c
@@ -17,13 +17,27 @@
#define STACK_TRACE_ENTRIES 500
+/*
+ * If fentry is used, then the function being traced will
+ * jump to fentry directly before it sets up its stack frame.
+ * We need to ignore that one and record the parent. Since
+ * the stack frame for the traced function wasn't set up yet,
+ * the stack_trace wont see the parent. That needs to be added
+ * manually to stack_dump_trace[] as the first element.
+ */
+#ifdef CC_USING_FENTRY
+# define add_func 1
+#else
+# define add_func 0
+#endif
+
static unsigned long stack_dump_trace[STACK_TRACE_ENTRIES+1] =
{ [0 ... (STACK_TRACE_ENTRIES)] = ULONG_MAX };
static unsigned stack_dump_index[STACK_TRACE_ENTRIES];
static struct stack_trace max_stack_trace = {
- .max_entries = STACK_TRACE_ENTRIES,
- .entries = stack_dump_trace,
+ .max_entries = STACK_TRACE_ENTRIES - add_func,
+ .entries = &stack_dump_trace[add_func],
};
static unsigned long max_stack_size;
@@ -38,7 +52,7 @@ int stack_tracer_enabled;
static int last_stack_tracer_enabled;
static inline void
-check_stack(unsigned long *stack)
+check_stack(unsigned long ip, unsigned long *stack)
{
unsigned long this_size, flags;
unsigned long *p, *top, *start;
@@ -69,6 +83,17 @@ check_stack(unsigned long *stack)
save_stack_trace(&max_stack_trace);
/*
+ * When fentry is used, the traced function does not get
+ * its stack frame set up, and we lose the parent.
+ * Add that one in manally. We set up save_stack_trace()
+ * to not touch the first element in this case.
+ */
+ if (add_func) {
+ stack_dump_trace[0] = ip;
+ max_stack_trace.nr_entries++;
+ }
+
+ /*
* Now find where in the stack these are.
*/
i = 0;
@@ -124,7 +149,7 @@ stack_trace_call(unsigned long ip, unsigned long parent_ip)
if (per_cpu(trace_active, cpu)++ != 0)
goto out;
- check_stack(&stack);
+ check_stack(parent_ip, &stack);
out:
per_cpu(trace_active, cpu)--;