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Commit 843ff37b authored by Krister Johansen's avatar Krister Johansen Committed by Arnaldo Carvalho de Melo
Browse files

perf symbols: Find symbols in different mount namespace 



Teach perf how to resolve symbols from binaries that are in a different
mount namespace from the tool.  This allows perf to generate meaningful
stack traces even if the binary resides in a different mount namespace
from the tool.

Signed-off-by: default avatarKrister Johansen <kjlx@templeofstupid.com>
Tested-by: default avatarBrendan Gregg <brendan.d.gregg@gmail.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas-Mich Richter <tmricht@linux.vnet.ibm.com>
Link: http://lkml.kernel.org/r/1499305693-1599-2-git-send-email-kjlx@templeofstupid.com


Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent 86bcdb5a

tools/perf/util/dso.c

+1 −0
Original line number Diff line number Diff line
@@ -1236,6 +1236,7 @@ void dso__delete(struct dso *dso) 
	dso_cache__free(dso);

	dso__free_a2l(dso);

	zfree(&dso->symsrc_filename);

	nsinfo__zput(dso->nsinfo);

	pthread_mutex_destroy(&dso->lock);

	free(dso);

}

tools/perf/util/dso.h

+2 −0
Original line number Diff line number Diff line
@@ -10,6 +10,7 @@ 
#include <linux/types.h>

#include <linux/bitops.h>

#include "map.h"

#include "namespaces.h"

#include "build-id.h"



enum dso_binary_type {
@@ -187,6 +188,7 @@ struct dso { 
		void	 *priv;

		u64	 db_id;

	};

	struct nsinfo	*nsinfo;

	refcount_t	 refcnt;

	char		 name[0];

};

tools/perf/util/map.c

+2 −0
Original line number Diff line number Diff line
@@ -16,6 +16,7 @@ 
#include "machine.h"

#include <linux/string.h>

#include "srcline.h"

#include "namespaces.h"

#include "unwind.h"



static void __maps__insert(struct maps *maps, struct map *map);
@@ -200,6 +201,7 @@ struct map *map__new(struct machine *machine, u64 start, u64 len, 
			if (type != MAP__FUNCTION)

				dso__set_loaded(dso, map->type);

		}

		dso->nsinfo = nsinfo__get(thread->nsinfo);

		dso__put(dso);

	}

	return map;

tools/perf/util/namespaces.c

+127 −0
Original line number Diff line number Diff line
@@ -9,9 +9,13 @@ 
#include "namespaces.h"

#include "util.h"

#include "event.h"

#include <sys/types.h>

#include <sys/stat.h>

#include <sched.h>

#include <stdlib.h>

#include <stdio.h>

#include <string.h>

#include <unistd.h>



struct namespaces *namespaces__new(struct namespaces_event *event)

{
@@ -35,3 +39,126 @@ void namespaces__free(struct namespaces *namespaces) 
{

	free(namespaces);

}



void nsinfo__init(struct nsinfo *nsi)

{

	char oldns[PATH_MAX];

	char *newns = NULL;

	struct stat old_stat;

	struct stat new_stat;



	if (snprintf(oldns, PATH_MAX, "/proc/self/ns/mnt") >= PATH_MAX)

		return;



	if (asprintf(&newns, "/proc/%d/ns/mnt", nsi->pid) == -1)

		return;



	if (stat(oldns, &old_stat) < 0)

		goto out;



	if (stat(newns, &new_stat) < 0)

		goto out;



	/* Check if the mount namespaces differ, if so then indicate that we

	 * want to switch as part of looking up dso/map data.

	 */

	if (old_stat.st_ino != new_stat.st_ino) {

		nsi->need_setns = true;

		nsi->mntns_path = newns;

		newns = NULL;

	}



out:

	free(newns);

}



struct nsinfo *nsinfo__new(pid_t pid)

{

	struct nsinfo *nsi = calloc(1, sizeof(*nsi));



	if (nsi != NULL) {

		nsi->pid = pid;

		nsi->need_setns = false;

		nsinfo__init(nsi);

		refcount_set(&nsi->refcnt, 1);

	}



	return nsi;

}



void nsinfo__delete(struct nsinfo *nsi)

{

	zfree(&nsi->mntns_path);

	free(nsi);

}



struct nsinfo *nsinfo__get(struct nsinfo *nsi)

{

	if (nsi)

		refcount_inc(&nsi->refcnt);

	return nsi;

}



void nsinfo__put(struct nsinfo *nsi)

{

	if (nsi && refcount_dec_and_test(&nsi->refcnt))

		nsinfo__delete(nsi);

}



void nsinfo__mountns_enter(struct nsinfo *nsi, struct nscookie *nc)

{

	char curpath[PATH_MAX];

	int oldns = -1;

	int newns = -1;



	if (nc == NULL)

		return;



	nc->oldns = -1;

	nc->newns = -1;



	if (!nsi || !nsi->need_setns)

		return;



	if (snprintf(curpath, PATH_MAX, "/proc/self/ns/mnt") >= PATH_MAX)

		return;



	oldns = open(curpath, O_RDONLY);

	if (oldns < 0)

		return;



	newns = open(nsi->mntns_path, O_RDONLY);

	if (newns < 0)

		goto errout;



	if (setns(newns, CLONE_NEWNS) < 0)

		goto errout;



	nc->oldns = oldns;

	nc->newns = newns;

	return;



errout:

	if (oldns > -1)

		close(oldns);

	if (newns > -1)

		close(newns);

}



void nsinfo__mountns_exit(struct nscookie *nc)

{

	if (nc == NULL || nc->oldns == -1 || nc->newns == -1)

		return;



	setns(nc->oldns, CLONE_NEWNS);



	if (nc->oldns > -1) {

		close(nc->oldns);

		nc->oldns = -1;

	}



	if (nc->newns > -1) {

		close(nc->newns);

		nc->newns = -1;

	}

}

tools/perf/util/namespaces.h

+33 −0
Original line number Diff line number Diff line
@@ -11,6 +11,7 @@ 


#include "../perf.h"

#include <linux/list.h>

#include <linux/refcount.h>



struct namespaces_event;
@@ -23,4 +24,36 @@ struct namespaces { 
struct namespaces *namespaces__new(struct namespaces_event *event);

void namespaces__free(struct namespaces *namespaces);



struct nsinfo {

	pid_t			pid;

	bool			need_setns;

	char			*mntns_path;

	refcount_t		refcnt;

};



struct nscookie {

	int			oldns;

	int			newns;

};



void nsinfo__init(struct nsinfo *nsi);

struct nsinfo *nsinfo__new(pid_t pid);

void nsinfo__delete(struct nsinfo *nsi);



struct nsinfo *nsinfo__get(struct nsinfo *nsi);

void nsinfo__put(struct nsinfo *nsi);



void nsinfo__mountns_enter(struct nsinfo *nsi, struct nscookie *nc);

void nsinfo__mountns_exit(struct nscookie *nc);



static inline void __nsinfo__zput(struct nsinfo **nsip)

{

	if (nsip) {

		nsinfo__put(*nsip);

		*nsip = NULL;

	}

}



#define nsinfo__zput(nsi) __nsinfo__zput(&nsi)



#endif  /* __PERF_NAMESPACES_H */