tracing: Simplify print_graph_cpu()

[safe/jmp/linux-2.6] / kernel / trace / trace_functions_graph.c

diff --git a/kernel/trace/trace_functions_graph.c b/kernel/trace/trace_functions_graph.c
index 10f6ad7..e30472d 100644 (file)
--- 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;
@@ -65,6 +66,12 @@ ftrace_push_return_trace(unsigned long ret, unsigned long func, int *depth)
        if (!current->ret_stack)
                return -EBUSY;
 
+       /*
+        * We must make sure the ret_stack is tested before we read
+        * anything else.
+        */
+       smp_rmb();
+
        /* The return trace stack is full */
        if (current->curr_ret_stack == FTRACE_RETFUNC_DEPTH - 1) {
                atomic_inc(&current->trace_overrun);
@@ -79,6 +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;
@@ -86,7 +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;
 
@@ -100,6 +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;
@@ -111,12 +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();
@@ -149,43 +183,19 @@ static void graph_trace_reset(struct trace_array *tr)
        unregister_ftrace_graph();
 }
 
-static inline int log10_cpu(int nb)
-{
-       if (nb / 100)
-               return 3;
-       if (nb / 10)
-               return 2;
-       return 1;
-}
+static int max_bytes_for_cpu;
 
 static enum print_line_t
 print_graph_cpu(struct trace_seq *s, int cpu)
 {
-       int i;
        int ret;
-       int log10_this = log10_cpu(cpu);
-       int log10_all = log10_cpu(cpumask_weight(cpu_online_mask));
-
 
        /*
         * Start with a space character - to make it stand out
         * to the right a bit when trace output is pasted into
         * email:
         */
-       ret = trace_seq_printf(s, " ");
-
-       /*
-        * Tricky - we space the CPU field according to the max
-        * number of online CPUs. On a 2-cpu system it would take
-        * a maximum of 1 digit - on a 128 cpu system it would
-        * take up to 3 digits:
-        */
-       for (i = 0; i < log10_all - log10_this; i++) {
-               ret = trace_seq_printf(s, " ");
-               if (!ret)
-                       return TRACE_TYPE_PARTIAL_LINE;
-       }
-       ret = trace_seq_printf(s, "%d) ", cpu);
+       ret = trace_seq_printf(s, " %*d) ", max_bytes_for_cpu, cpu);
        if (!ret)
                return TRACE_TYPE_PARTIAL_LINE;
 
@@ -531,11 +541,7 @@ print_graph_entry_leaf(struct trace_iterator *iter,
                        return TRACE_TYPE_PARTIAL_LINE;
        }
 
-       ret = seq_print_ip_sym(s, call->func, 0);
-       if (!ret)
-               return TRACE_TYPE_PARTIAL_LINE;
-
-       ret = trace_seq_printf(s, "();\n");
+       ret = trace_seq_printf(s, "%pf();\n", (void *)call->func);
        if (!ret)
                return TRACE_TYPE_PARTIAL_LINE;
 
@@ -578,11 +584,7 @@ print_graph_entry_nested(struct trace_iterator *iter,
                        return TRACE_TYPE_PARTIAL_LINE;
        }
 
-       ret = seq_print_ip_sym(s, call->func, 0);
-       if (!ret)
-               return TRACE_TYPE_PARTIAL_LINE;
-
-       ret = trace_seq_printf(s, "() {\n");
+       ret = trace_seq_printf(s, "%pf() {\n", (void *)call->func);
        if (!ret)
                return TRACE_TYPE_PARTIAL_LINE;
 
@@ -893,6 +895,8 @@ static struct tracer graph_trace __read_mostly = {
 
 static __init int init_graph_trace(void)
 {
+       max_bytes_for_cpu = snprintf(NULL, 0, "%d", nr_cpu_ids - 1);
+
        return register_tracer(&graph_trace);
 }