Merge branch 'tip/tracing/urgent-1' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-2.6-trace into tracing/urgent

2 files changed, 40 insertions, 4 deletions

diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
index 4a13e5a01ce3..b17ed8787ded 100644
--- a/kernel/trace/Kconfig
+++ b/kernel/trace/Kconfig
@@ -18,6 +18,13 @@ config HAVE_FUNCTION_TRACER
 config HAVE_FUNCTION_GRAPH_TRACER
         bool
 
+config HAVE_FUNCTION_GRAPH_FP_TEST
+        bool
+        help
+         An arch may pass in a unique value (frame pointer) to both the
+         entering and exiting of a function. On exit, the value is compared
+         and if it does not match, then it will panic the kernel.
+
 config HAVE_FUNCTION_TRACE_MCOUNT_TEST
         bool
         help
@@ -121,6 +128,7 @@ config FUNCTION_GRAPH_TRACER
         bool "Kernel Function Graph Tracer"
         depends on HAVE_FUNCTION_GRAPH_TRACER
         depends on FUNCTION_TRACER
+        depends on !X86_32 || !CC_OPTIMIZE_FOR_SIZE
         default y
         help
           Enable the kernel to trace a function at both its return
diff --git a/kernel/trace/trace_functions_graph.c b/kernel/trace/trace_functions_graph.c
index 8b592418d8b2..d2249abafb53 100644
--- a/kernel/trace/trace_functions_graph.c
+++ b/kernel/trace/trace_functions_graph.c
@@ -57,7 +57,8 @@ static struct tracer_flags tracer_flags = {
 
 /* Add a function return address to the trace stack on thread info.*/
 int
-ftrace_push_return_trace(unsigned long ret, unsigned long func, int *depth)
+ftrace_push_return_trace(unsigned long ret, unsigned long func, int *depth,
+                         unsigned long frame_pointer)
 {
         unsigned long long calltime;
         int index;
@@ -85,6 +86,7 @@ ftrace_push_return_trace(unsigned long ret, unsigned long func, int *depth)
         current->ret_stack[index].func = func;
         current->ret_stack[index].calltime = calltime;
         current->ret_stack[index].subtime = 0;
+        current->ret_stack[index].fp = frame_pointer;
         *depth = index;
 
         return 0;
@@ -92,7 +94,8 @@ ftrace_push_return_trace(unsigned long ret, unsigned long func, int *depth)
 
 /* Retrieve a function return address to the trace stack on thread info.*/
 static void
-ftrace_pop_return_trace(struct ftrace_graph_ret *trace, unsigned long *ret)
+ftrace_pop_return_trace(struct ftrace_graph_ret *trace, unsigned long *ret,
+                        unsigned long frame_pointer)
 {
         int index;
 
@@ -106,6 +109,31 @@ ftrace_pop_return_trace(struct ftrace_graph_ret *trace, unsigned long *ret)
                 return;
         }
 
+#ifdef CONFIG_HAVE_FUNCTION_GRAPH_FP_TEST
+        /*
+         * The arch may choose to record the frame pointer used
+         * and check it here to make sure that it is what we expect it
+         * to be. If gcc does not set the place holder of the return
+         * address in the frame pointer, and does a copy instead, then
+         * the function graph trace will fail. This test detects this
+         * case.
+         *
+         * Currently, x86_32 with optimize for size (-Os) makes the latest
+         * gcc do the above.
+         */
+        if (unlikely(current->ret_stack[index].fp != frame_pointer)) {
+                ftrace_graph_stop();
+                WARN(1, "Bad frame pointer: expected %lx, received %lx\n"
+                     "  from func %pF return to %lx\n",
+                     current->ret_stack[index].fp,
+                     frame_pointer,
+                     (void *)current->ret_stack[index].func,
+                     current->ret_stack[index].ret);
+                *ret = (unsigned long)panic;
+                return;
+        }
+#endif
+
         *ret = current->ret_stack[index].ret;
         trace->func = current->ret_stack[index].func;
         trace->calltime = current->ret_stack[index].calltime;
@@ -117,12 +145,12 @@ ftrace_pop_return_trace(struct ftrace_graph_ret *trace, unsigned long *ret)
  * Send the trace to the ring-buffer.
  * @return the original return address.
  */
-unsigned long ftrace_return_to_handler(void)
+unsigned long ftrace_return_to_handler(unsigned long frame_pointer)
 {
         struct ftrace_graph_ret trace;
         unsigned long ret;
 
-        ftrace_pop_return_trace(&trace, &ret);
+        ftrace_pop_return_trace(&trace, &ret, frame_pointer);
         trace.rettime = trace_clock_local();
         ftrace_graph_return(&trace);
         barrier();