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Commit d8040645 authored by Paul Clarke's avatar Paul Clarke Committed by Arnaldo Carvalho de Melo
Browse files

perf symbols: Allow user probes on versioned symbols 



Symbol versioning, as in glibc, results in symbols being defined as:

  <real symbol>@[@]<version>

(Note that "@@" identifies a default symbol, if the symbol name is
repeated.)

perf is currently unable to deal with this, and is unable to create user
probes at such symbols:

  --
  $ nm /lib/powerpc64le-linux-gnu/libpthread.so.0 | grep pthread_create
  0000000000008d30 t __pthread_create_2_1
  0000000000008d30 T pthread_create@@GLIBC_2.17
  $ /usr/bin/sudo perf probe -v -x /lib/powerpc64le-linux-gnu/libpthread.so.0 pthread_create
  probe-definition(0): pthread_create
  symbol:pthread_create file:(null) line:0 offset:0 return:0 lazy:(null)
  0 arguments
  Open Debuginfo file: /usr/lib/debug/lib/powerpc64le-linux-gnu/libpthread-2.19.so
  Try to find probe point from debuginfo.
  Probe point 'pthread_create' not found.
     Error: Failed to add events. Reason: No such file or directory (Code: -2)
  --

One is not able to specify the fully versioned symbol, either, due to
syntactic conflicts with other uses of "@" by perf:

  --
  $ /usr/bin/sudo perf probe -v -x /lib/powerpc64le-linux-gnu/libpthread.so.0 pthread_create@@GLIBC_2.17
  probe-definition(0): pthread_create@@GLIBC_2.17
  Semantic error :SRC@SRC is not allowed.
  0 arguments
     Error: Command Parse Error. Reason: Invalid argument (Code: -22)
  --

This patch ignores versioning for default symbols, thus allowing probes to be
created for these symbols:

  --
  $ /usr/bin/sudo ./perf probe -x /lib/powerpc64le-linux-gnu/libpthread.so.0 pthread_create
  Added new event:
     probe_libpthread:pthread_create (on pthread_create in /lib/powerpc64le-linux-gnu/libpthread-2.19.so)

  You can now use it in all perf tools, such as:

           perf record -e probe_libpthread:pthread_create -aR sleep 1

  $ /usr/bin/sudo ./perf record -e probe_libpthread:pthread_create -aR ./test 2
  [ perf record: Woken up 1 times to write data ]
  [ perf record: Captured and wrote 0.052 MB perf.data (2 samples) ]
  $ /usr/bin/sudo ./perf script
               test  2915 [000] 19124.260729: probe_libpthread:pthread_create: (3fff99248d38)
               test  2916 [000] 19124.260962: probe_libpthread:pthread_create: (3fff99248d38)
  $ /usr/bin/sudo ./perf probe --del=probe_libpthread:pthread_create
  Removed event: probe_libpthread:pthread_create
  --

Committer note:

Change the variable storing the result of strlen() to 'int', to fix the build
on debian:experimental-x-mipsel, fedora:24-x-ARC-uClibc, ubuntu:16.04-x-arm,
etc:

  util/symbol.c: In function 'symbol__match_symbol_name':
  util/symbol.c:422:11: error: comparison between signed and unsigned integer expressions [-Werror=sign-compare]
     if (len < versioning - name)
             ^

Signed-off-by: default avatarPaul A. Clarke <pc@us.ibm.com>
Tested-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
Acked-by: default avatarMasami Hiramatsu <mhiramat@kernel.org>
Cc: David Ahern <dsahern@gmail.com>
Link: http://lkml.kernel.org/r/c2b18d9c-17f8-9285-4868-f58b6359ccac@us.ibm.com


Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent b843f62a

tools/perf/arch/powerpc/util/sym-handling.c

+12 −0
Original line number Original line Diff line number Diff line
@@ -52,6 +52,18 @@ int arch__compare_symbol_names(const char *namea, const char *nameb) 




	return strcmp(namea, nameb);

	return strcmp(namea, nameb);

}

}



int arch__compare_symbol_names_n(const char *namea, const char *nameb,

				 unsigned int n)

{

	/* Skip over initial dot */

	if (*namea == '.')

		namea++;

	if (*nameb == '.')

		nameb++;



	return strncmp(namea, nameb, n);

}

#endif

#endif





#if defined(_CALL_ELF) && _CALL_ELF == 2

#if defined(_CALL_ELF) && _CALL_ELF == 2

tools/perf/util/map.c

+0 −5
Original line number Original line Diff line number Diff line
@@ -325,11 +325,6 @@ int map__load(struct map *map) 
	return 0;

	return 0;

}

}





int __weak arch__compare_symbol_names(const char *namea, const char *nameb)

{

	return strcmp(namea, nameb);

}



struct symbol *map__find_symbol(struct map *map, u64 addr)

struct symbol *map__find_symbol(struct map *map, u64 addr)

{

{

	if (map__load(map) < 0)

	if (map__load(map) < 0)

tools/perf/util/map.h

+3 −2
Original line number Original line Diff line number Diff line
@@ -130,13 +130,14 @@ struct thread; 
 */

 */

#define __map__for_each_symbol_by_name(map, sym_name, pos)	\

#define __map__for_each_symbol_by_name(map, sym_name, pos)	\

	for (pos = map__find_symbol_by_name(map, sym_name);	\

	for (pos = map__find_symbol_by_name(map, sym_name);	\

	     pos && arch__compare_symbol_names(pos->name, sym_name) == 0;	\

	     pos &&						\

	     !symbol__match_symbol_name(pos->name, sym_name,	\

					SYMBOL_TAG_INCLUDE__DEFAULT_ONLY); \

	     pos = symbol__next_by_name(pos))

	     pos = symbol__next_by_name(pos))





#define map__for_each_symbol_by_name(map, sym_name, pos)		\

#define map__for_each_symbol_by_name(map, sym_name, pos)		\

	__map__for_each_symbol_by_name(map, sym_name, (pos))

	__map__for_each_symbol_by_name(map, sym_name, (pos))





int arch__compare_symbol_names(const char *namea, const char *nameb);

void map__init(struct map *map, enum map_type type,

void map__init(struct map *map, enum map_type type,

	       u64 start, u64 end, u64 pgoff, struct dso *dso);

	       u64 start, u64 end, u64 pgoff, struct dso *dso);

struct map *map__new(struct machine *machine, u64 start, u64 len,

struct map *map__new(struct machine *machine, u64 start, u64 len,

tools/perf/util/symbol.c

+48 −13
Original line number Original line Diff line number Diff line
@@ -90,6 +90,17 @@ static int prefix_underscores_count(const char *str) 
	return tail - str;

	return tail - str;

}

}





int __weak arch__compare_symbol_names(const char *namea, const char *nameb)

{

	return strcmp(namea, nameb);

}



int __weak arch__compare_symbol_names_n(const char *namea, const char *nameb,

					unsigned int n)

{

	return strncmp(namea, nameb, n);

}



int __weak arch__choose_best_symbol(struct symbol *syma,

int __weak arch__choose_best_symbol(struct symbol *syma,

				    struct symbol *symb __maybe_unused)

				    struct symbol *symb __maybe_unused)

{

{
@@ -399,8 +410,26 @@ static void symbols__sort_by_name(struct rb_root *symbols, 
	}

	}

}

}





int symbol__match_symbol_name(const char *name, const char *str,

			      enum symbol_tag_include includes)

{

	const char *versioning;



	if (includes == SYMBOL_TAG_INCLUDE__DEFAULT_ONLY &&

	    (versioning = strstr(name, "@@"))) {

		int len = strlen(str);



		if (len < versioning - name)

			len = versioning - name;



		return arch__compare_symbol_names_n(name, str, len);

	} else

		return arch__compare_symbol_names(name, str);

}



static struct symbol *symbols__find_by_name(struct rb_root *symbols,

static struct symbol *symbols__find_by_name(struct rb_root *symbols,

					    const char *name)

					    const char *name,

					    enum symbol_tag_include includes)

{

{

	struct rb_node *n;

	struct rb_node *n;

	struct symbol_name_rb_node *s = NULL;

	struct symbol_name_rb_node *s = NULL;
@@ -414,11 +443,11 @@ static struct symbol *symbols__find_by_name(struct rb_root *symbols, 
		int cmp;

		int cmp;





		s = rb_entry(n, struct symbol_name_rb_node, rb_node);

		s = rb_entry(n, struct symbol_name_rb_node, rb_node);

		cmp = arch__compare_symbol_names(name, s->sym.name);

		cmp = symbol__match_symbol_name(s->sym.name, name, includes);





		if (cmp < 0)

		if (cmp > 0)

			n = n->rb_left;

			n = n->rb_left;

		else if (cmp > 0)

		else if (cmp < 0)

			n = n->rb_right;

			n = n->rb_right;

		else

		else

			break;

			break;
@@ -427,6 +456,7 @@ static struct symbol *symbols__find_by_name(struct rb_root *symbols, 
	if (n == NULL)

	if (n == NULL)

		return NULL;

		return NULL;





	if (includes != SYMBOL_TAG_INCLUDE__DEFAULT_ONLY)

		/* return first symbol that has same name (if any) */

		/* return first symbol that has same name (if any) */

		for (n = rb_prev(n); n; n = rb_prev(n)) {

		for (n = rb_prev(n); n; n = rb_prev(n)) {

			struct symbol_name_rb_node *tmp;

			struct symbol_name_rb_node *tmp;
@@ -503,7 +533,12 @@ struct symbol *symbol__next_by_name(struct symbol *sym) 
struct symbol *dso__find_symbol_by_name(struct dso *dso, enum map_type type,

struct symbol *dso__find_symbol_by_name(struct dso *dso, enum map_type type,

					const char *name)

					const char *name)

{

{

	return symbols__find_by_name(&dso->symbol_names[type], name);

	struct symbol *s = symbols__find_by_name(&dso->symbol_names[type], name,

						 SYMBOL_TAG_INCLUDE__NONE);

	if (!s)

		s = symbols__find_by_name(&dso->symbol_names[type], name,

					  SYMBOL_TAG_INCLUDE__DEFAULT_ONLY);

	return s;

}

}





void dso__sort_by_name(struct dso *dso, enum map_type type)

void dso__sort_by_name(struct dso *dso, enum map_type type)

tools/perf/util/symbol.h

+11 −0
Original line number Original line Diff line number Diff line
@@ -348,8 +348,19 @@ void arch__sym_update(struct symbol *s, GElf_Sym *sym); 
#define SYMBOL_A 0

#define SYMBOL_A 0

#define SYMBOL_B 1

#define SYMBOL_B 1





int arch__compare_symbol_names(const char *namea, const char *nameb);

int arch__compare_symbol_names_n(const char *namea, const char *nameb,

				 unsigned int n);

int arch__choose_best_symbol(struct symbol *syma, struct symbol *symb);

int arch__choose_best_symbol(struct symbol *syma, struct symbol *symb);





enum symbol_tag_include {

	SYMBOL_TAG_INCLUDE__NONE = 0,

	SYMBOL_TAG_INCLUDE__DEFAULT_ONLY

};



int symbol__match_symbol_name(const char *namea, const char *nameb,

			      enum symbol_tag_include includes);



/* structure containing an SDT note's info */

/* structure containing an SDT note's info */

struct sdt_note {

struct sdt_note {

	char *name;			/* name of the note*/

	char *name;			/* name of the note*/