From 843ff37bb59edbe51d64e77ba1b3245a15a4dd9f Mon Sep 17 00:00:00 2001 From: Krister Johansen Date: Wed, 5 Jul 2017 18:48:08 -0700 Subject: [PATCH] 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: Krister Johansen Tested-by: Brendan Gregg Cc: Alexander Shishkin Cc: Peter Zijlstra Cc: Thomas-Mich Richter Link: http://lkml.kernel.org/r/1499305693-1599-2-git-send-email-kjlx@templeofstupid.com Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/util/dso.c | 1 + tools/perf/util/dso.h | 2 + tools/perf/util/map.c | 2 + tools/perf/util/namespaces.c | 127 +++++++++++++++++++++++++++++++++++++++++++ tools/perf/util/namespaces.h | 33 +++++++++++ tools/perf/util/symbol.c | 11 ++++ tools/perf/util/thread.c | 3 + tools/perf/util/thread.h | 1 + 8 files changed, 180 insertions(+) diff --git a/tools/perf/util/dso.c b/tools/perf/util/dso.c index 4e7ab611377a..beda40ed63b0 100644 --- a/tools/perf/util/dso.c +++ b/tools/perf/util/dso.c @@ -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); } diff --git a/tools/perf/util/dso.h b/tools/perf/util/dso.h index bd061ba7b47c..78ec637fc68b 100644 --- a/tools/perf/util/dso.h +++ b/tools/perf/util/dso.h @@ -10,6 +10,7 @@ #include #include #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]; }; diff --git a/tools/perf/util/map.c b/tools/perf/util/map.c index 2179b2deb730..5dc60ca5a294 100644 --- a/tools/perf/util/map.c +++ b/tools/perf/util/map.c @@ -16,6 +16,7 @@ #include "machine.h" #include #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; diff --git a/tools/perf/util/namespaces.c b/tools/perf/util/namespaces.c index 67dcbcc73c7d..bcc6bb19cf10 100644 --- a/tools/perf/util/namespaces.c +++ b/tools/perf/util/namespaces.c @@ -9,9 +9,13 @@ #include "namespaces.h" #include "util.h" #include "event.h" +#include +#include +#include #include #include #include +#include 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; + } +} diff --git a/tools/perf/util/namespaces.h b/tools/perf/util/namespaces.h index 468f1e9a1484..b20f6ead7b2d 100644 --- a/tools/perf/util/namespaces.h +++ b/tools/perf/util/namespaces.h @@ -11,6 +11,7 @@ #include "../perf.h" #include +#include 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 */ diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c index e7a98dbd2aed..60a9eaa372ef 100644 --- a/tools/perf/util/symbol.c +++ b/tools/perf/util/symbol.c @@ -18,6 +18,8 @@ #include "symbol.h" #include "strlist.h" #include "intlist.h" +#include "namespaces.h" +#include "vdso.h" #include "header.h" #include "path.h" #include "sane_ctype.h" @@ -1436,9 +1438,17 @@ int dso__load(struct dso *dso, struct map *map) struct symsrc *syms_ss = NULL, *runtime_ss = NULL; bool kmod; unsigned char build_id[BUILD_ID_SIZE]; + struct nscookie nsc; + nsinfo__mountns_enter(dso->nsinfo, &nsc); pthread_mutex_lock(&dso->lock); + /* The vdso files always live in the host container, so don't go looking + * for them in the container's mount namespace. + */ + if (dso__is_vdso(dso)) + nsinfo__mountns_exit(&nsc); + /* check again under the dso->lock */ if (dso__loaded(dso, map->type)) { ret = 1; @@ -1584,6 +1594,7 @@ out_free: out: dso__set_loaded(dso, map->type); pthread_mutex_unlock(&dso->lock); + nsinfo__mountns_exit(&nsc); return ret; } diff --git a/tools/perf/util/thread.c b/tools/perf/util/thread.c index 378c418ca0c1..aee9a42102ba 100644 --- a/tools/perf/util/thread.c +++ b/tools/perf/util/thread.c @@ -59,6 +59,8 @@ struct thread *thread__new(pid_t pid, pid_t tid) list_add(&comm->list, &thread->comm_list); refcount_set(&thread->refcnt, 1); RB_CLEAR_NODE(&thread->rb_node); + /* Thread holds first ref to nsdata. */ + thread->nsinfo = nsinfo__new(pid); } return thread; @@ -91,6 +93,7 @@ void thread__delete(struct thread *thread) comm__free(comm); } unwind__finish_access(thread); + nsinfo__zput(thread->nsinfo); free(thread); } diff --git a/tools/perf/util/thread.h b/tools/perf/util/thread.h index 4eb849e9098f..cb1a5dd5c2b9 100644 --- a/tools/perf/util/thread.h +++ b/tools/perf/util/thread.h @@ -34,6 +34,7 @@ struct thread { void *priv; struct thread_stack *ts; + struct nsinfo *nsinfo; #ifdef HAVE_LIBUNWIND_SUPPORT void *addr_space; struct unwind_libunwind_ops *unwind_libunwind_ops; -- 2.11.0