trace: Detect an infinite loop

If something is wrong with a board's timer function such that it calls
functions not marked with notrace, U-Boot will hang.

Detect this, print a message and disable the trace.

Signed-off-by: Simon Glass <sjg@chromium.org>

diff --git a/lib/trace.c b/lib/trace.c
index bbc316af29593350e5c5383b4da7777a688b949c..1091a5793a1cab6523e7082a0009c8e874c1b6e8 100644 (file)
--- a/lib/trace.c
+++ b/lib/trace.c
@@ -39,6 +39,7 @@ struct trace_hdr {
        int depth_limit;        /* Depth limit to trace to */
        int max_depth;          /* Maximum depth seen so far */
        int min_depth;          /* Minimum depth seen so far */
+       bool trace_locked;      /* Used to detect recursive tracing */
 };
 
 /* Pointer to start of trace buffer */
@@ -133,6 +134,14 @@ void notrace __cyg_profile_func_enter(void *func_ptr, void *caller)
        if (trace_enabled) {
                int func;
 
+               if (hdr->trace_locked) {
+                       trace_enabled = 0;
+                       puts("trace: recursion detected, disabling\n");
+                       hdr->trace_locked = false;
+                       return;
+               }
+
+               hdr->trace_locked = true;
                trace_swap_gd();
                add_ftrace(func_ptr, caller, FUNCF_ENTRY);
                func = func_ptr_to_num(func_ptr);
@@ -146,6 +155,7 @@ void notrace __cyg_profile_func_enter(void *func_ptr, void *caller)
                if (hdr->depth > hdr->max_depth)
                        hdr->max_depth = hdr->depth;
                trace_swap_gd();
+               hdr->trace_locked = false;
        }
 }