tracing/fastboot: get the initcall name before it disappears

After some initcall traces, some initcall names may be inconsistent.
That's because these functions will disappear from the .init section
and also their name from the symbols table.

So we have to copy the name of the function in a buffer large enough
during the trace appending. It is not costly for the ring_buffer because
the number of initcall entries is commonly not really large.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 10 insertions, 4 deletions

diff --git a/kernel/trace/trace_boot.c b/kernel/trace/trace_boot.c
index 7c15f3e68ba..b9dc2c0093a 100644
--- a/kernel/trace/trace_boot.c
+++ b/kernel/trace/trace_boot.c
@@ -8,6 +8,7 @@
 #include <linux/init.h>
 #include <linux/debugfs.h>
 #include <linux/ftrace.h>
+#include <linux/kallsyms.h>
 
 #include "trace.h"
 
@@ -56,17 +57,19 @@ static enum print_line_t initcall_print_line(struct trace_iterator *iter)
         struct timespec rettime = ktime_to_timespec(it->rettime);
 
         if (entry->type == TRACE_BOOT) {
-                ret = trace_seq_printf(s, "[%5ld.%06ld] calling  %pF @ %i\n",
+                ret = trace_seq_printf(s, "[%5ld.%06ld] calling  %s @ %i\n",
                                           calltime.tv_sec,
                                           calltime.tv_nsec,
                                           it->func, it->caller);
                 if (!ret)
                         return TRACE_TYPE_PARTIAL_LINE;
-                ret = trace_seq_printf(s, "[%5ld.%06ld] initcall %pF "
+
+                ret = trace_seq_printf(s, "[%5ld.%06ld] initcall %s "
                                           "returned %d after %lld msecs\n",
                                           rettime.tv_sec,
                                           rettime.tv_nsec,
                                           it->func, it->result, it->duration);
+
                 if (!ret)
                         return TRACE_TYPE_PARTIAL_LINE;
                 return TRACE_TYPE_HANDLED;
@@ -83,8 +86,7 @@ struct tracer boot_tracer __read_mostly =
         .print_line     = initcall_print_line,
 };
 
-
-void trace_boot(struct boot_trace *it)
+void trace_boot(struct boot_trace *it, initcall_t fn)
 {
         struct ring_buffer_event *event;
         struct trace_boot *entry;
@@ -95,6 +97,10 @@ void trace_boot(struct boot_trace *it)
         if (!trace_boot_enabled)
                 return;
 
+        /* Get its name now since this function could
+         * disappear because it is in the .init section.
+         */
+        sprint_symbol(it->func, (unsigned long)fn);
         preempt_disable();
         data = tr->data[smp_processor_id()];