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>

diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index 4455490d91bdb62e6be34da1b6074cc0346c1716..e672e51c40a9c7b20ec717165b6970f3f0b11eda 100644 (file)
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -7,6 +7,7 @@
 #include <linux/fs.h>
 #include <linux/init.h>
 #include <linux/types.h>
+#include <linux/kallsyms.h>
 
 extern int ftrace_enabled;
 extern int
@@ -213,7 +214,7 @@ ftrace_init_module(unsigned long *start, unsigned long *end) { }
 
 struct boot_trace {
        pid_t                   caller;
-       initcall_t              func;
+       char                    func[KSYM_NAME_LEN];
        int                     result;
        unsigned long long      duration;
        ktime_t                 calltime;
@@ -221,10 +222,10 @@ struct boot_trace {
 };
 
 #ifdef CONFIG_BOOT_TRACER
-extern void trace_boot(struct boot_trace *it);
+extern void trace_boot(struct boot_trace *it, initcall_t fn);
 extern void start_boot_trace(void);
 #else
-static inline void trace_boot(struct boot_trace *it) { }
+static inline void trace_boot(struct boot_trace *it, initcall_t fn) { }
 static inline void start_boot_trace(void) { }
 #endif
 

diff --git a/init/main.c b/init/main.c
index 61eb661593915cbe9a6e85a1481c3b5b149dcad7..8e96a0ef17f4b04ca1117c1935545c66691bab97 100644 (file)
--- a/init/main.c
+++ b/init/main.c
@@ -712,7 +712,6 @@ int do_one_initcall(initcall_t fn)
 
        if (initcall_debug) {
                it.caller = task_pid_nr(current);
-               it.func = fn;
                printk("calling  %pF @ %i\n", fn, it.caller);
                it.calltime = ktime_get();
        }
@@ -725,7 +724,7 @@ int do_one_initcall(initcall_t fn)
                it.duration = (unsigned long long) delta.tv64 >> 20;
                printk("initcall %pF returned %d after %Ld msecs\n", fn,
                        it.result, it.duration);
-               trace_boot(&it);
+               trace_boot(&it, fn);
        }
 
        msgbuf[0] = 0;

diff --git a/kernel/trace/trace_boot.c b/kernel/trace/trace_boot.c
index 7c15f3e68ba35e25c114e4ed09e017bc27c81d31..b9dc2c0093ab19057cea2196ddb016fc8243ed88 100644 (file)
--- 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()];