843ff37bb5
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 <kjlx@templeofstupid.com> Tested-by: Brendan 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: Arnaldo Carvalho de Melo <acme@redhat.com>
165 lines
3.0 KiB
C
165 lines
3.0 KiB
C
/*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License, version 2, as
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* published by the Free Software Foundation.
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*
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* Copyright (C) 2017 Hari Bathini, IBM Corporation
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*/
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#include "namespaces.h"
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#include "util.h"
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#include "event.h"
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <sched.h>
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#include <stdlib.h>
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#include <stdio.h>
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#include <string.h>
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#include <unistd.h>
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struct namespaces *namespaces__new(struct namespaces_event *event)
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{
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struct namespaces *namespaces;
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u64 link_info_size = ((event ? event->nr_namespaces : NR_NAMESPACES) *
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sizeof(struct perf_ns_link_info));
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namespaces = zalloc(sizeof(struct namespaces) + link_info_size);
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if (!namespaces)
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return NULL;
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namespaces->end_time = -1;
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if (event)
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memcpy(namespaces->link_info, event->link_info, link_info_size);
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return namespaces;
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}
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void namespaces__free(struct namespaces *namespaces)
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{
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free(namespaces);
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}
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void nsinfo__init(struct nsinfo *nsi)
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{
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char oldns[PATH_MAX];
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char *newns = NULL;
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struct stat old_stat;
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struct stat new_stat;
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if (snprintf(oldns, PATH_MAX, "/proc/self/ns/mnt") >= PATH_MAX)
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return;
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if (asprintf(&newns, "/proc/%d/ns/mnt", nsi->pid) == -1)
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return;
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if (stat(oldns, &old_stat) < 0)
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goto out;
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if (stat(newns, &new_stat) < 0)
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goto out;
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/* Check if the mount namespaces differ, if so then indicate that we
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* want to switch as part of looking up dso/map data.
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*/
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if (old_stat.st_ino != new_stat.st_ino) {
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nsi->need_setns = true;
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nsi->mntns_path = newns;
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newns = NULL;
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}
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out:
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free(newns);
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}
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struct nsinfo *nsinfo__new(pid_t pid)
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{
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struct nsinfo *nsi = calloc(1, sizeof(*nsi));
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if (nsi != NULL) {
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nsi->pid = pid;
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nsi->need_setns = false;
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nsinfo__init(nsi);
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refcount_set(&nsi->refcnt, 1);
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}
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return nsi;
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}
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void nsinfo__delete(struct nsinfo *nsi)
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{
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zfree(&nsi->mntns_path);
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free(nsi);
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}
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struct nsinfo *nsinfo__get(struct nsinfo *nsi)
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{
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if (nsi)
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refcount_inc(&nsi->refcnt);
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return nsi;
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}
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void nsinfo__put(struct nsinfo *nsi)
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{
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if (nsi && refcount_dec_and_test(&nsi->refcnt))
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nsinfo__delete(nsi);
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}
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void nsinfo__mountns_enter(struct nsinfo *nsi, struct nscookie *nc)
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{
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char curpath[PATH_MAX];
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int oldns = -1;
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int newns = -1;
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if (nc == NULL)
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return;
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nc->oldns = -1;
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nc->newns = -1;
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if (!nsi || !nsi->need_setns)
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return;
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if (snprintf(curpath, PATH_MAX, "/proc/self/ns/mnt") >= PATH_MAX)
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return;
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oldns = open(curpath, O_RDONLY);
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if (oldns < 0)
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return;
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newns = open(nsi->mntns_path, O_RDONLY);
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if (newns < 0)
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goto errout;
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if (setns(newns, CLONE_NEWNS) < 0)
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goto errout;
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nc->oldns = oldns;
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nc->newns = newns;
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return;
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errout:
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if (oldns > -1)
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close(oldns);
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if (newns > -1)
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close(newns);
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}
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void nsinfo__mountns_exit(struct nscookie *nc)
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{
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if (nc == NULL || nc->oldns == -1 || nc->newns == -1)
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return;
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setns(nc->oldns, CLONE_NEWNS);
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if (nc->oldns > -1) {
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close(nc->oldns);
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nc->oldns = -1;
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}
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if (nc->newns > -1) {
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close(nc->newns);
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nc->newns = -1;
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}
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}
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