tools lib traceevent: Allow setting an alternative symbol resolver

tools/lib/traceevent/event-parse.c +13 -0

+
+	if (!function_resolver.function)
+		return __find_func(pevent, addr);
+
+	map.mod	 = NULL;
+	map.addr = addr;
+	map.func = function_resolver.function(function_resolver.priv, &map.addr, &map.mod);
+	if (map.func == NULL)
+		return NULL;
+
+	return ↦
+}
+

Review

Quoted 4 lines

(quoted diff) +4 -0

+static struct func_map *
+find_func(struct pevent *pevent, unsigned long long addr)
+{
+	static struct func_map map;

I know there's other cases of static variables in functions, but I plan on cleaning that up in the future.

Can you make that map belong to the pevent itself? In case there's two pevent's going parallel, I don't want one to overwrite the other. The pevent code is not re-entrant, but I would like to make it so for different pevents.

tools/lib/traceevent/event-parse.c +8 -1

index cc25f059ab3d..2750e7e7efff 100644
@@ -418,7 +418,7 @@ static int func_map_init(struct pevent *pevent)
 }
 
 static struct func_map *
-find_func(struct pevent *pevent, unsigned long long addr)
+__find_func(struct pevent *pevent, unsigned long long addr)
 {
 	struct func_map *func;
 	struct func_map key;

@@ -434,6 +434,51 @@ find_func(struct pevent *pevent, unsigned long long addr)
 	return func;
 }
 
+static struct {
+	pevent_function_resolver_t *function;
+	void 			   *priv;
+} function_resolver;
+
+/**
+ * pevent_set_function_resolver - set an alternative function resolver

tools/lib/traceevent/event-parse.c +29 -0

+}
+
+static struct func_map *
+find_func(struct pevent *pevent, unsigned long long addr)
+{
+	struct func_map *map;
+
+	if (!function_resolver.function)
+		return __find_func(pevent, addr);
+
+	if (pevent->func_map_resolver == NULL) {
+		pevent->func_map_resolver = malloc(sizeof(*map));
+		if (pevent->func_map_resolver == NULL) {
+			do_warning("Not enough memory for resolving addresses to functions!\n");
+			return NULL;
+		}
+	}
+
+	map = pevent->func_map_resolver;
+	map->mod  = NULL;
+	map->addr = addr;
+	map->func = function_resolver.function(function_resolver.priv, &map->addr, &map->mod);
+	if (map->func == NULL)
+		return NULL;
+
+	return map;
+}
+
 /**
  * pevent_find_function - find a function by a given address
  * @pevent: handle for the pevent

@@ -6564,6 +6609,7 @@ void pevent_free(struct pevent *pevent)
 	free(pevent->trace_clock);
 	free(pevent->events);
 	free(pevent->sort_events);
+	free(pevent->func_map_resolver);
 
 	free(pevent);
 }

tools/lib/traceevent/event-parse.h +5 -0

index 063b1971eb35..6bd526f0d17a 100644
@@ -481,6 +481,7 @@ struct pevent {
 	int cmdline_count;
 
 	struct func_map *func_map;
+	struct func_map *func_map_resolver;
 	struct func_list *funclist;
 	unsigned int func_count;
 

@@ -611,6 +612,10 @@ enum trace_flag_type {
 	TRACE_FLAG_SOFTIRQ		= 0x10,
 };
 
+typedef char *(pevent_function_resolver_t)(void *priv, unsigned long long *addrp, char **modp);
+
+void pevent_set_function_resolver(pevent_function_resolver_t *resolver, void *priv);
+
 int pevent_register_comm(struct pevent *pevent, const char *comm, int pid);
 int pevent_register_trace_clock(struct pevent *pevent, const char *trace_clock);
 int pevent_register_function(struct pevent *pevent, char *name,

Quoted 28 lines · On Thu, 23 Jul 2015 14:25:54 -0300 Arnaldo Carvalho de Melo <[email protected]>…

tools/lib/traceevent/event-parse.c +12 -1

index cc25f059ab3d..2750e7e7efff 100644
@@ -418,7 +418,7 @@ static int func_map_init(struct pevent *pevent)
 }
 
 static struct func_map *
-find_func(struct pevent *pevent, unsigned long long addr)
+__find_func(struct pevent *pevent, unsigned long long addr)
 {
 	struct func_map *func;
 	struct func_map key;

@@ -434,6 +434,51 @@ find_func(struct pevent *pevent, unsigned long long addr)
 	return func;
 }
 
+static struct {
+	pevent_function_resolver_t *function;
+	void 			   *priv;
+} function_resolver;
+
+/**
+ * pevent_set_function_resolver - set an alternative function resolver
+ * @resolver - function to be used
+ * @priv - resolver function private state.
+ *
+ * Some tools may have already a way to resolve kernel functions, allow them

tools/lib/traceevent/event-parse.c find_func(struct pevent *pevent, unsigned long long addr) · line 453

Quoted 6 lines

tools/lib/traceevent/event-parse.c +6 -0

+ * to keep using it instead of duplicating all the entries inside pevent->funclist.
+ */
+void pevent_set_function_resolver(pevent_function_resolver_t *resolver, void *priv)
+{
+	function_resolver.function = resolver;
+	function_resolver.priv	  = priv;

What about passing in pevent, and making the allocation here?

-- Steve

Quoted 2 lines

tools/lib/traceevent/event-parse.c +2 -0

+}
+

Quoted 14 lines

Quoted 12 lines · On Thu, 23 Jul 2015 14:25:54 -0300 Arnaldo Carvalho de Melo <[email protected]>…

tools/lib/traceevent/event-parse.c +11 -0

+static struct {
+	pevent_function_resolver_t *function;
+	void 			   *priv;
+} function_resolver;
+
+/**
+ * pevent_set_function_resolver - set an alternative function resolver
+ * @resolver - function to be used
+ * @priv - resolver function private state.
+ *
+ * Some tools may have already a way to resolve kernel functions, allow them

Quoted 8 lines

tools/lib/traceevent/event-parse.c find_func(struct pevent *pevent, unsigned long long addr) · line 453

Quoted 6 lines

+ * to keep using it instead of duplicating all the entries inside pevent->funclist.
+ */

tools/lib/traceevent/event-parse.c +4 -0

+void pevent_set_function_resolver(pevent_function_resolver_t *resolver, void *priv)
+{
+	function_resolver.function = resolver;
+	function_resolver.priv	  = priv;

What about passing in pevent, and making the allocation here?

In fact, we could remove the global function_resolver, and allocate that here too.

Quoted 31 lines · On Thu, 23 Jul 2015 14:10:39 -0400 Steven Rostedt <[email protected]> wrote:

Quoted 28 lines · On Thu, 23 Jul 2015 14:25:54 -0300 Arnaldo Carvalho de Melo <[email protected]>…

tools/lib/traceevent/event-parse.c +12 -1

index cc25f059ab3d..2750e7e7efff 100644
@@ -418,7 +418,7 @@ static int func_map_init(struct pevent *pevent)
 }
 
 static struct func_map *
-find_func(struct pevent *pevent, unsigned long long addr)
+__find_func(struct pevent *pevent, unsigned long long addr)
 {
 	struct func_map *func;
 	struct func_map key;

@@ -434,6 +434,51 @@ find_func(struct pevent *pevent, unsigned long long addr)
 	return func;
 }
 
+static struct {
+	pevent_function_resolver_t *function;
+	void 			   *priv;
+} function_resolver;
+
+/**
+ * pevent_set_function_resolver - set an alternative function resolver
+ * @resolver - function to be used
+ * @priv - resolver function private state.
+ *
+ * Some tools may have already a way to resolve kernel functions, allow them

Quoted 8 lines

tools/lib/traceevent/event-parse.c find_func(struct pevent *pevent, unsigned long long addr) · line 453

Quoted 6 lines

tools/lib/traceevent/event-parse.c +6 -0

+ * to keep using it instead of duplicating all the entries inside pevent->funclist.
+ */
+void pevent_set_function_resolver(pevent_function_resolver_t *resolver, void *priv)
+{
+	function_resolver.function = resolver;
+	function_resolver.priv	  = priv;

What about passing in pevent, and making the allocation here?

In fact, we could remove the global function_resolver, and allocate that here too.

Like this?

tools/lib/traceevent/event-parse.c +14 -1

index cc25f059ab3d..7f9266225f11 100644
@@ -418,7 +418,7 @@ static int func_map_init(struct pevent *pevent)
 }
 
 static struct func_map *
-find_func(struct pevent *pevent, unsigned long long addr)
+__find_func(struct pevent *pevent, unsigned long long addr)
 {
 	struct func_map *func;
 	struct func_map key;

@@ -434,6 +434,60 @@ find_func(struct pevent *pevent, unsigned long long addr)
 	return func;
 }
 
+struct func_resolver {
+	pevent_func_resolver_t *func;
+	void		       *priv;
+	struct func_map	       map;
+};
+
+/**
+ * pevent_set_function_resolver - set an alternative function resolver
+ * @pevent: handle for the pevent
+ * @resolver: function to be used
+ * @priv: resolver function private state.
+ *
+ * Some tools may have already a way to resolve kernel functions, allow them to

tools/lib/traceevent/event-parse.c +24 -0

+
+	return 0;
+}
+
+static struct func_map *
+find_func(struct pevent *pevent, unsigned long long addr)
+{
+	struct func_map *map;
+
+	if (!pevent->func_resolver)
+		return __find_func(pevent, addr);
+
+	map = &pevent->func_resolver->map;
+	map->mod  = NULL;
+	map->addr = addr;
+	map->func = pevent->func_resolver->func(pevent->func_resolver->priv,
+						&map->addr, &map->mod);
+	if (map->func == NULL)
+		return NULL;
+
+	return map;
+}
+
 /**
  * pevent_find_function - find a function by a given address
  * @pevent: handle for the pevent

@@ -6564,6 +6618,7 @@ void pevent_free(struct pevent *pevent)
 	free(pevent->trace_clock);
 	free(pevent->events);
 	free(pevent->sort_events);
+	free(pevent->func_resolver);
 
 	free(pevent);
 }

tools/lib/traceevent/event-parse.h +7 -0

index 063b1971eb35..416e1bd9fe33 100644
@@ -453,6 +453,10 @@ struct cmdline_list;
 struct func_map;
 struct func_list;
 struct event_handler;
+struct func_resolver;
+
+typedef char *(pevent_func_resolver_t)(void *priv,
+				       unsigned long long *addrp, char **modp);
 
 struct pevent {
 	int ref_count;

@@ -481,6 +485,7 @@ struct pevent {
 	int cmdline_count;
 
 	struct func_map *func_map;
+	struct func_resolver *func_resolver;
 	struct func_list *funclist;
 	unsigned int func_count;
 

@@ -611,6 +616,8 @@ enum trace_flag_type {
 	TRACE_FLAG_SOFTIRQ		= 0x10,
 };
 
+int pevent_set_function_resolver(struct pevent *pevent,
+				 pevent_func_resolver_t *func, void *priv);
 int pevent_register_comm(struct pevent *pevent, const char *comm, int pid);
 int pevent_register_trace_clock(struct pevent *pevent, const char *trace_clock);
 int pevent_register_function(struct pevent *pevent, char *name,

Quoted 1 line · On Thu, 23 Jul 2015 18:25:36 -0300 Arnaldo Carvalho de Melo <[email protected]>…

Like this?

Yep, but some comments.

tools/lib/traceevent/event-parse.c find_func(struct pevent *pevent, unsigned long long addr) · line 459

Quoted 7 lines

tools/lib/traceevent/event-parse.c +7 -0

+int pevent_set_function_resolver(struct pevent *pevent,
+				 pevent_func_resolver_t *func, void *priv)
+{
+	struct func_resolver *resolver = malloc(sizeof(*resolver));
+
+	if (resolver == NULL) {
+		errno = ENOMEM;

Why set errno, wont a failed malloc set it for us?

tools/lib/traceevent/event-parse.c find_func(struct pevent *pevent, unsigned long long addr) · line 467

Quoted 8 lines

tools/lib/traceevent/event-parse.c +8 -0

+		return -1;
+	}
+
+	resolver->func = func;
+	resolver->priv = priv;
+
+	free(pevent->func_resolver);
+	pevent->func_resolver = resolver;

Also I wonder if we should add a way to clear the resolver. That is, you want to use the default resolver?

Not really a necessity, as I don't see any current programs using it, but it would complete the interface.

-- Steve

Quoted 66 lines

tools/lib/traceevent/event-parse.c +24 -0

+
+	return 0;
+}
+
+static struct func_map *
+find_func(struct pevent *pevent, unsigned long long addr)
+{
+	struct func_map *map;
+
+	if (!pevent->func_resolver)
+		return __find_func(pevent, addr);
+
+	map = &pevent->func_resolver->map;
+	map->mod  = NULL;
+	map->addr = addr;
+	map->func = pevent->func_resolver->func(pevent->func_resolver->priv,
+						&map->addr, &map->mod);
+	if (map->func == NULL)
+		return NULL;
+
+	return map;
+}
+
 /**
  * pevent_find_function - find a function by a given address
  * @pevent: handle for the pevent

@@ -6564,6 +6618,7 @@ void pevent_free(struct pevent *pevent)
 	free(pevent->trace_clock);
 	free(pevent->events);
 	free(pevent->sort_events);
+	free(pevent->func_resolver);
 
 	free(pevent);
 }

tools/lib/traceevent/event-parse.h +7 -0

index 063b1971eb35..416e1bd9fe33 100644
@@ -453,6 +453,10 @@ struct cmdline_list;
 struct func_map;
 struct func_list;
 struct event_handler;
+struct func_resolver;
+
+typedef char *(pevent_func_resolver_t)(void *priv,
+				       unsigned long long *addrp, char **modp);
 
 struct pevent {
 	int ref_count;

@@ -481,6 +485,7 @@ struct pevent {
 	int cmdline_count;
 
 	struct func_map *func_map;
+	struct func_resolver *func_resolver;
 	struct func_list *funclist;
 	unsigned int func_count;
 

@@ -611,6 +616,8 @@ enum trace_flag_type {
 	TRACE_FLAG_SOFTIRQ		= 0x10,
 };
 
+int pevent_set_function_resolver(struct pevent *pevent,
+				 pevent_func_resolver_t *func, void *priv);
 int pevent_register_comm(struct pevent *pevent, const char *comm, int pid);
 int pevent_register_trace_clock(struct pevent *pevent, const char *trace_clock);
 int pevent_register_function(struct pevent *pevent, char *name,

Em Thu, Jul 23, 2015 at 05:35:24PM -0400, Steven Rostedt escreveu:

Quoted 6 lines

Review

Quoted 2 lines · On Thu, 23 Jul 2015 18:25:36 -0300 Arnaldo Carvalho de Melo <[email protected]>…

(quoted diff) +2 -0

+	if (resolver == NULL) {
+		errno = ENOMEM;

Why set errno, wont a failed malloc set it for us?

Humm, I thought about that, I've read malloc's man page and it doesn't mention that... in the return section, but later, in NOTES, it says UNIX98 requires that and glibc does it, so I'm ditching this...

Quoted 2 lines

Also I wonder if we should add a way to clear the resolver. That is, you want to use the default resolver?

I am adding a reset_function_resolver(pevent);

Quoted 2 lines

Not really a necessity, as I don't see any current programs using it, but it would complete the interface.

Em Thu, Jul 23, 2015 at 06:52:46PM -0300, Arnaldo Carvalho de Melo escreveu:

Quoted 15 lines

Em Thu, Jul 23, 2015 at 05:35:24PM -0400, Steven Rostedt escreveu:

Quoted 6 lines

Review

Quoted 2 lines · On Thu, 23 Jul 2015 18:25:36 -0300 Arnaldo Carvalho de Melo <[email protected]>…

(quoted diff) +2 -0

+	if (resolver == NULL) {
+		errno = ENOMEM;

Why set errno, wont a failed malloc set it for us?

Humm, I thought about that, I've read malloc's man page and it doesn't mention that... in the return section, but later, in NOTES, it says UNIX98 requires that and glibc does it, so I'm ditching this...

Quoted 2 lines

Also I wonder if we should add a way to clear the resolver. That is, you want to use the default resolver?

Quoted 4 lines

I am adding a reset_function_resolver(pevent);

Quoted 2 lines

Not really a necessity, as I don't see any current programs using it, but it would complete the interface.

One more try:

commit 212a2417baaa89168cbe3112fe7c8efaddee28b8

Author: Arnaldo Carvalho de Melo <[email protected]>
Date:   Wed Jul 22 12:36:55 2015 -0300

tools lib traceevent: Allow setting an alternative symbol resolver

The perf tools have a symbol resolver that includes solving kernel symbols using either kallsyms or ELF symtabs, and it also is using libtraceevent to format the trace events fields, including via subsystem specific plugins, like the "timer" one.

To solve fields like "timer:hrtimer_start"'s "function", libtraceevent needs a way to map from its value to a function name and addr.

This patch provides a way for tools that already have symbol resolving facilities to ask libtraceevent to use it when needing to resolve kernel symbols.

Acked-by David Ahern <[email protected]>

Cc Adrian Hunter <[email protected]>

Cc Borislav Petkov <[email protected]>

Cc Frederic Weisbecker <[email protected]>

Cc Jiri Olsa <[email protected]>

Cc Namhyung Kim <[email protected]>

Cc Stephane Eranian <[email protected]>

Cc Steven Rostedt <[email protected]>

Link http://lkml.kernel.org/n/[email protected] open here

Signed-off-by Arnaldo Carvalho de Melo <[email protected]>

Quoted 4 lines · On Thu, 23 Jul 2015 18:58:36 -0300 Arnaldo Carvalho de Melo <[email protected]>…

Em Thu, Jul 23, 2015 at 06:52:46PM -0300, Arnaldo Carvalho de Melo escreveu:

Quoted 3 lines

Em Thu, Jul 23, 2015 at 05:35:24PM -0400, Steven Rostedt escreveu:

Quoted 2 lines

Also I wonder if we should add a way to clear the resolver. That is, you want to use the default resolver?

Quoted 6 lines

Quoted 4 lines

I am adding a reset_function_resolver(pevent);

Quoted 2 lines

Not really a necessity, as I don't see any current programs using it, but it would complete the interface.

One more try:

Third time's a charm, or was this the forth?

Reviewed-by Steven Rostedt <[email protected]>

Quoted 3 lines

Quoted 1 line

One more try:

Third time's a charm, or was this the forth?

As many as needed would be put forth!