trace-cmd: Add plugin_kmem for showing function names of call sites

The kmem events only show a useless hex symbol for the call site name.
This adds a plugin to do a lookup of the function name and still
print the rest of the event format.

Also adds pevent_find_function_address() to let the plugin show the
offset into the function as well.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

4 files changed, 92 insertions, 5 deletions

diff --git a/Makefile b/Makefile
index 1bcc153..6e9be83 100644
--- a/Makefile
+++ b/Makefile
@@ -9,8 +9,10 @@ LIBS = -L. -ltracecmd -ldl
 %.o: %.c
         $(CC) -c $(CFLAGS) $(EXT) $(INCLUDES) $< -o $@
 
-TARGETS = libparsevent.a libtracecmd.a trace-cmd plugin_hrtimer.so plugin_mac80211.so \
-        plugin_sched_switch.so
+PLUGINS =  plugin_hrtimer.so plugin_mac80211.so plugin_sched_switch.so \
+        plugin_kmem.so
+
+TARGETS = libparsevent.a libtracecmd.a trace-cmd  $(PLUGINS)
 
 all: $(TARGETS)
 
@@ -65,19 +67,25 @@ libtracecmd.so: $(TCMD_LIB_OBJS)
 libtracecmd.a: $(TCMD_LIB_OBJS)
         $(RM) $@;  $(AR) rcs $@ $^
 
-plugin_hrtimer.o: plugin_hrtimer.c parse-events.h
+plugin_hrtimer.o: plugin_hrtimer.c parse-events.h trace-cmd.h
         $(CC) -c $(CFLAGS) -fPIC -o $@ $<
 
 plugin_hrtimer.so: plugin_hrtimer.o
         $(CC) -shared -nostartfiles -o $@ $<
 
-plugin_sched_switch.o: plugin_sched_switch.c parse-events.h
+plugin_kmem.o: plugin_kmem.c parse-events.h trace-cmd.h
+        $(CC) -c $(CFLAGS) -fPIC -o $@ $<
+
+plugin_kmem.so: plugin_kmem.o
+        $(CC) -shared -nostartfiles -o $@ $<
+
+plugin_sched_switch.o: plugin_sched_switch.c parse-events.h trace-cmd.h
         $(CC) -c $(CFLAGS) -fPIC -o $@ $<
 
 plugin_sched_switch.so: plugin_sched_switch.o
         $(CC) -shared -nostartfiles -o $@ $<
 
-plugin_mac80211.o: plugin_mac80211.c parse-events.h
+plugin_mac80211.o: plugin_mac80211.c parse-events.h trace-cmd.h
         $(CC) -c $(CFLAGS) -fPIC -o $@ $<
 
 plugin_mac80211.so: plugin_mac80211.o
diff --git a/parse-events.c b/parse-events.c
index d2d7e0a..406b28f 100644
--- a/parse-events.c
+++ b/parse-events.c
@@ -348,6 +348,27 @@ const char *pevent_find_function(struct pevent *pevent, unsigned long long addr)
 }
 
 /**
+ * pevent_find_function_address - find a function address by a given address
+ * @pevent: handle for the pevent
+ * @addr: the address to find the function with
+ *
+ * Returns the address the function starts at. This can be used in
+ * conjunction with pevent_find_function to print both the function
+ * name and the function offset.
+ */
+unsigned long long
+pevent_find_function_address(struct pevent *pevent, unsigned long long addr)
+{
+        struct func_map *map;
+
+        map = find_func(pevent, addr);
+        if (!map)
+                return 0;
+
+        return map->addr;
+}
+
+/**
  * pevent_register_function - register a function with a given address
  * @pevent: handle for the pevent
  * @function: the function name to register
diff --git a/parse-events.h b/parse-events.h
index bfbba5c..e148e7f 100644
--- a/parse-events.h
+++ b/parse-events.h
@@ -366,6 +366,8 @@ struct format_field *pevent_find_field(struct event_format *event, const char *n
 struct format_field *pevent_find_any_field(struct event_format *event, const char *name);
 
 const char *pevent_find_function(struct pevent *pevent, unsigned long long addr);
+unsigned long long
+pevent_find_function_address(struct pevent *pevent, unsigned long long addr);
 unsigned long long pevent_read_number(struct pevent *pevent, const void *ptr, int size);
 int pevent_read_number_field(struct format_field *field, const void *data,
                              unsigned long long *value);
diff --git a/plugin_kmem.c b/plugin_kmem.c
new file mode 100644
index 0000000..d707bf2
--- /dev/null
+++ b/plugin_kmem.c
@@ -0,0 +1,56 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "trace-cmd.h"
+
+static int call_site_handler(struct trace_seq *s, struct record *record,
+                             struct event_format *event)
+{
+        struct format_field *field;
+        unsigned long long val, addr;
+        void *data = record->data;
+        const char *func;
+
+        field = pevent_find_field(event, "call_site");
+        if (!field)
+                return 1;
+
+        if (pevent_read_number_field(field, data, &val))
+                return 1;
+
+        func = pevent_find_function(event->pevent, val);
+        if (!func)
+                return 1;
+        addr = pevent_find_function_address(event->pevent, val);
+
+        trace_seq_printf(s, "(%s+0x%x) ", func, (int)(val - addr));
+
+        return 1;
+}
+
+int PEVENT_PLUGIN_LOADER(struct pevent *pevent)
+{
+        pevent_register_event_handler(pevent, -1, "kmem", "kfree",
+                                      call_site_handler);
+
+        pevent_register_event_handler(pevent, -1, "kmem", "kmalloc",
+                                      call_site_handler);
+
+        pevent_register_event_handler(pevent, -1, "kmem", "kmalloc_node",
+                                      call_site_handler);
+
+        pevent_register_event_handler(pevent, -1, "kmem", "kmem_cache_alloc",
+                                      call_site_handler);
+
+        pevent_register_event_handler(pevent, -1, "kmem", "kmem_cache_alloc_node",
+                                      call_site_handler);
+
+        pevent_register_event_handler(pevent, -1, "kmem", "kfree",
+                                      call_site_handler);
+
+        pevent_register_event_handler(pevent, -1, "kmem", "kmem_cache_free",
+                                      call_site_handler);
+
+        return 0;
+}