From patchwork Sun Mar 1 13:49:16 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Florian Weimer X-Patchwork-Id: 444963 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from sourceware.org (server1.sourceware.org [209.132.180.131]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id 7FE5114009B for ; Mon, 2 Mar 2015 19:40:56 +1100 (AEDT) Authentication-Results: ozlabs.org; dkim=pass reason="1024-bit key; unprotected key" header.d=sourceware.org header.i=@sourceware.org header.b=G5Dm/p6v; dkim-adsp=none (unprotected policy); dkim-atps=neutral DomainKey-Signature: a=rsa-sha1; c=nofws; d=sourceware.org; h=list-id :list-unsubscribe:list-subscribe:list-archive:list-post :list-help:sender:message-id:in-reply-to:references:from:date :subject:to; q=dns; s=default; b=s7StOXWpNGguRpyfwOPcTy0qremoEKJ TRdLkCE8xz9JDf39tEu1ORxtg8GDLnuG9mSN3X0IsZbcpnSJ9ukDElF+f5QSHOZs 5wLLE0ZpIgLjvKJRbvs1CptIUYjUUgplqO9Ts19/o5BvOHLryYr2lsAwhZwiy7iZ KTNHGT4YuuhE= DKIM-Signature: v=1; a=rsa-sha1; c=relaxed; d=sourceware.org; h=list-id :list-unsubscribe:list-subscribe:list-archive:list-post :list-help:sender:message-id:in-reply-to:references:from:date :subject:to; s=default; bh=DJnP2TTF/h8QlLpExV4uRFYokIg=; b=G5Dm/ p6vQqX72CWOjZaNGVJCUmjy24f3TZGfqYsp+futn1U/BFZowpdQ2DU1XTWMhbQkv wa7GDWh1k3ILPawKFi/iUTP831yB1VhuanUxfwkHHuZfwAJRRJX1zNtAv85hrBog yWJe7L/cFyWGn7EAzeXys6nejHJtrnHaJ7K3Qk= Received: (qmail 77678 invoked by alias); 2 Mar 2015 08:40:28 -0000 Mailing-List: contact libc-alpha-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Unsubscribe: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: libc-alpha-owner@sourceware.org Delivered-To: mailing list libc-alpha@sourceware.org Received: (qmail 77576 invoked by uid 89); 2 Mar 2015 08:40:27 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-1.5 required=5.0 tests=AWL, BAYES_00, DATE_IN_PAST_12_24, SPF_HELO_PASS, SPF_PASS, T_RP_MATCHES_RCVD, UNSUBSCRIBE_BODY autolearn=no version=3.3.2 X-HELO: mx1.redhat.com Message-Id: <4640427f7b0c3de94ac8792a85a7d3c5ef2d5084.1425285061.git.fweimer@redhat.com> In-Reply-To: References: From: Florian Weimer Date: Sun, 1 Mar 2015 14:49:16 +0100 Subject: [PATCH 01/25] _dl_fini: Rewrite to use VLA instead of extend_alloca To: libc-alpha@sourceware.org In this case, extend_alloca is used to work around the lack of deallocation on scope exit. A VLA is automatically deallocated in this way, so it is the more fitting approach. To implement this, it is necessary to eliminate the goto. In addition, this change eliminates the trivially-true assert; the assert is always skipped if nloaded > 0. --- elf/dl-fini.c | 193 +++++++++++++++++++++++++++------------------------------- 1 file changed, 89 insertions(+), 104 deletions(-) diff --git a/elf/dl-fini.c b/elf/dl-fini.c index 6cfe651..0790b04 100644 --- a/elf/dl-fini.c +++ b/elf/dl-fini.c @@ -16,7 +16,6 @@ License along with the GNU C Library; if not, see . */ -#include #include #include #include @@ -140,8 +139,6 @@ _dl_fini (void) using `dlopen' there are possibly several other modules with its dependencies to be taken into account. Therefore we have to start determining the order of the modules once again from the beginning. */ - struct link_map **maps = NULL; - size_t maps_size = 0; /* We run the destructors of the main namespaces last. As for the other namespaces, we pick run the destructors in them in reverse @@ -155,7 +152,6 @@ _dl_fini (void) /* Protect against concurrent loads and unloads. */ __rtld_lock_lock_recursive (GL(dl_load_lock)); - unsigned int nmaps = 0; unsigned int nloaded = GL(dl_ns)[ns]._ns_nloaded; /* No need to do anything for empty namespaces or those used for auditing DSOs. */ @@ -164,118 +160,107 @@ _dl_fini (void) || GL(dl_ns)[ns]._ns_loaded->l_auditing != do_audit #endif ) - goto out; - - /* XXX Could it be (in static binaries) that there is no object - loaded? */ - assert (ns != LM_ID_BASE || nloaded > 0); - - /* Now we can allocate an array to hold all the pointers and copy - the pointers in. */ - if (maps_size < nloaded * sizeof (struct link_map *)) + __rtld_lock_unlock_recursive (GL(dl_load_lock)); + else { - if (maps_size == 0) + /* Now we can allocate an array to hold all the pointers and + copy the pointers in. */ + struct link_map *maps[nloaded]; + + unsigned int i; + struct link_map *l; + assert (nloaded != 0 || GL(dl_ns)[ns]._ns_loaded == NULL); + for (l = GL(dl_ns)[ns]._ns_loaded, i = 0; l != NULL; l = l->l_next) + /* Do not handle ld.so in secondary namespaces. */ + if (l == l->l_real) + { + assert (i < nloaded); + + maps[i] = l; + l->l_idx = i; + ++i; + + /* Bump l_direct_opencount of all objects so that they + are not dlclose()ed from underneath us. */ + ++l->l_direct_opencount; + } + assert (ns != LM_ID_BASE || i == nloaded); + assert (ns == LM_ID_BASE || i == nloaded || i == nloaded - 1); + unsigned int nmaps = i; + + /* Now we have to do the sorting. */ + _dl_sort_fini (maps, nmaps, NULL, ns); + + /* We do not rely on the linked list of loaded object anymore + from this point on. We have our own list here (maps). The + various members of this list cannot vanish since the open + count is too high and will be decremented in this loop. So + we release the lock so that some code which might be called + from a destructor can directly or indirectly access the + lock. */ + __rtld_lock_unlock_recursive (GL(dl_load_lock)); + + /* 'maps' now contains the objects in the right order. Now + call the destructors. We have to process this array from + the front. */ + for (i = 0; i < nmaps; ++i) { - maps_size = nloaded * sizeof (struct link_map *); - maps = (struct link_map **) alloca (maps_size); - } - else - maps = (struct link_map **) - extend_alloca (maps, maps_size, - nloaded * sizeof (struct link_map *)); - } + struct link_map *l = maps[i]; - unsigned int i; - struct link_map *l; - assert (nloaded != 0 || GL(dl_ns)[ns]._ns_loaded == NULL); - for (l = GL(dl_ns)[ns]._ns_loaded, i = 0; l != NULL; l = l->l_next) - /* Do not handle ld.so in secondary namespaces. */ - if (l == l->l_real) - { - assert (i < nloaded); - - maps[i] = l; - l->l_idx = i; - ++i; - - /* Bump l_direct_opencount of all objects so that they are - not dlclose()ed from underneath us. */ - ++l->l_direct_opencount; - } - assert (ns != LM_ID_BASE || i == nloaded); - assert (ns == LM_ID_BASE || i == nloaded || i == nloaded - 1); - nmaps = i; - - /* Now we have to do the sorting. */ - _dl_sort_fini (maps, nmaps, NULL, ns); - - /* We do not rely on the linked list of loaded object anymore from - this point on. We have our own list here (maps). The various - members of this list cannot vanish since the open count is too - high and will be decremented in this loop. So we release the - lock so that some code which might be called from a destructor - can directly or indirectly access the lock. */ - out: - __rtld_lock_unlock_recursive (GL(dl_load_lock)); - - /* 'maps' now contains the objects in the right order. Now call the - destructors. We have to process this array from the front. */ - for (i = 0; i < nmaps; ++i) - { - l = maps[i]; - - if (l->l_init_called) - { - /* Make sure nothing happens if we are called twice. */ - l->l_init_called = 0; - - /* Is there a destructor function? */ - if (l->l_info[DT_FINI_ARRAY] != NULL - || l->l_info[DT_FINI] != NULL) + if (l->l_init_called) { - /* When debugging print a message first. */ - if (__builtin_expect (GLRO(dl_debug_mask) - & DL_DEBUG_IMPCALLS, 0)) - _dl_debug_printf ("\ncalling fini: %s [%lu]\n\n", - DSO_FILENAME (l->l_name), - ns); - - /* First see whether an array is given. */ - if (l->l_info[DT_FINI_ARRAY] != NULL) + /* Make sure nothing happens if we are called twice. */ + l->l_init_called = 0; + + /* Is there a destructor function? */ + if (l->l_info[DT_FINI_ARRAY] != NULL + || l->l_info[DT_FINI] != NULL) { - ElfW(Addr) *array = - (ElfW(Addr) *) (l->l_addr - + l->l_info[DT_FINI_ARRAY]->d_un.d_ptr); - unsigned int i = (l->l_info[DT_FINI_ARRAYSZ]->d_un.d_val - / sizeof (ElfW(Addr))); - while (i-- > 0) - ((fini_t) array[i]) (); + /* When debugging print a message first. */ + if (__builtin_expect (GLRO(dl_debug_mask) + & DL_DEBUG_IMPCALLS, 0)) + _dl_debug_printf ("\ncalling fini: %s [%lu]\n\n", + DSO_FILENAME (l->l_name), + ns); + + /* First see whether an array is given. */ + if (l->l_info[DT_FINI_ARRAY] != NULL) + { + ElfW(Addr) *array = + (ElfW(Addr) *) (l->l_addr + + l->l_info[DT_FINI_ARRAY]->d_un.d_ptr); + unsigned int i = (l->l_info[DT_FINI_ARRAYSZ]->d_un.d_val + / sizeof (ElfW(Addr))); + while (i-- > 0) + ((fini_t) array[i]) (); + } + + /* Next try the old-style destructor. */ + if (l->l_info[DT_FINI] != NULL) + DL_CALL_DT_FINI + (l, l->l_addr + l->l_info[DT_FINI]->d_un.d_ptr); } - /* Next try the old-style destructor. */ - if (l->l_info[DT_FINI] != NULL) - DL_CALL_DT_FINI(l, l->l_addr + l->l_info[DT_FINI]->d_un.d_ptr); - } - #ifdef SHARED - /* Auditing checkpoint: another object closed. */ - if (!do_audit && __builtin_expect (GLRO(dl_naudit) > 0, 0)) - { - struct audit_ifaces *afct = GLRO(dl_audit); - for (unsigned int cnt = 0; cnt < GLRO(dl_naudit); ++cnt) + /* Auditing checkpoint: another object closed. */ + if (!do_audit && __builtin_expect (GLRO(dl_naudit) > 0, 0)) { - if (afct->objclose != NULL) - /* Return value is ignored. */ - (void) afct->objclose (&l->l_audit[cnt].cookie); - - afct = afct->next; + struct audit_ifaces *afct = GLRO(dl_audit); + for (unsigned int cnt = 0; cnt < GLRO(dl_naudit); ++cnt) + { + if (afct->objclose != NULL) + /* Return value is ignored. */ + (void) afct->objclose (&l->l_audit[cnt].cookie); + + afct = afct->next; + } } - } #endif - } + } - /* Correct the previous increment. */ - --l->l_direct_opencount; + /* Correct the previous increment. */ + --l->l_direct_opencount; + } } }