From patchwork Tue May 4 15:15:48 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Florian Weimer X-Patchwork-Id: 43255 Return-Path: X-Original-To: patchwork@sourceware.org Delivered-To: patchwork@sourceware.org Received: from server2.sourceware.org (localhost [IPv6:::1]) by sourceware.org (Postfix) with ESMTP id 59C4F3992417; Tue, 4 May 2021 15:15:42 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 59C4F3992417 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=sourceware.org; s=default; t=1620141342; bh=YBEtzujAD4Jk/n3x/KJjy76/K3ASy3fj6xGYb8rdlxs=; h=To:Subject:In-Reply-To:References:Date:List-Id:List-Unsubscribe: List-Archive:List-Post:List-Help:List-Subscribe:From:Reply-To: From; b=Yi9J6FXh5Rf4pPpAcPQps3/hhaG24RFscYYprFOQO/WzN9vu1Y6ynDtutH4T4BSbD mWmChQVOKHId2imUayv2DGhpgtUGRZJsiFdAzf33PV2FFjwVlDbZ77azXxZ1zu5GQt Mzld9gBn+dDdLtREOC90vMq6cnVc3HiFcA958QSs= X-Original-To: libc-alpha@sourceware.org Delivered-To: libc-alpha@sourceware.org Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [216.205.24.124]) by sourceware.org (Postfix) with ESMTP id AF7C43968C0A for ; Tue, 4 May 2021 15:15:37 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.3.2 sourceware.org AF7C43968C0A Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-243-vA2MxTQdMYmJD4ShC6DXng-1; Tue, 04 May 2021 11:15:34 -0400 X-MC-Unique: vA2MxTQdMYmJD4ShC6DXng-1 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id E56AF192AB7B for ; Tue, 4 May 2021 15:15:33 +0000 (UTC) Received: from oldenburg.str.redhat.com (ovpn-112-137.ams2.redhat.com [10.36.112.137]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 471BD5D9D5 for ; Tue, 4 May 2021 15:15:33 +0000 (UTC) To: libc-alpha@sourceware.org Subject: [PATCH v2 1/2] scripts/versions.awk: Add strings and hashes to In-Reply-To: References: Message-Id: Date: Tue, 04 May 2021 17:15:48 +0200 User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.2 (gnu/linux) MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com X-Spam-Status: No, score=-12.8 required=5.0 tests=BAYES_00, DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, GIT_PATCH_0, KAM_SHORT, RCVD_IN_DNSWL_LOW, RCVD_IN_MSPIKE_H4, RCVD_IN_MSPIKE_WL, SPF_HELO_NONE, SPF_PASS, TXREP autolearn=ham autolearn_force=no version=3.4.2 X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on server2.sourceware.org X-BeenThere: libc-alpha@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Libc-alpha mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-Patchwork-Original-From: Florian Weimer via Libc-alpha From: Florian Weimer Reply-To: Florian Weimer Errors-To: libc-alpha-bounces@sourceware.org Sender: "Libc-alpha" This generates new macros of this from: #define FIRST_VERSION_libc___pthread_mutex_lock_STRING "GLIBC_2.2.5" #define FIRST_VERSION_libc___pthread_mutex_lock_HASH 0x9691a75 They are useful for symbol lookups using _dl_lookup_direct. --- scripts/versions.awk | 36 ++++++++++++++++++++++++++++++++++++ 1 file changed, 36 insertions(+) diff --git a/scripts/versions.awk b/scripts/versions.awk index d56f4e712c..3291123666 100644 --- a/scripts/versions.awk +++ b/scripts/versions.awk @@ -32,6 +32,29 @@ BEGIN { sort = "sort -t. -k 1,1 -k 2n,2n -k 3 > " tmpfile; } +# GNU awk does not implement the ord and chr functions. +# +# says that they are "written very nicely", using code similar to what +# is included here. +function chr(c) { + return sprintf("%c", c) +} + +BEGIN { + for (c = 1; c < 127; c++) { + ord_table[chr(c)] = c; + } +} + +function ord(c) { + if (ord_table[c]) { + return ord_table[c]; + } else { + printf("Invalid character reference: '%c'\n", c) > "/dev/stderr"; + ++lossage; + } +} + # Remove comment lines. /^ *#/ { next; @@ -90,6 +113,17 @@ function close_and_move(name, real_name) { system(move_if_change " " name " " real_name " >&2"); } +# ELF hash, for use with symbol versions. +function elf_hash(s, i, acc) { + acc = 0; + for (i = 1; i <= length(s); ++i) { + acc = and(lshift(acc, 4) + ord(substr(s, i, 1)), 0xffffffff); + top = and(acc, 0xf0000000); + acc = and(xor(acc, rshift(top, 24)), compl(top)); + } + return acc; +} + # Now print the accumulated information. END { close(sort); @@ -145,6 +179,8 @@ END { && oldver ~ "^GLIBC_[0-9]" \ && sym ~ "^[A-Za-z0-9_]*$") { ver_val = oldver; + printf("#define %s_STRING \"%s\"\n", first_ver_macro, ver_val) > first_ver_header; + printf("#define %s_HASH 0x%x\n", first_ver_macro, elf_hash(ver_val)) > first_ver_header; gsub("\\.", "_", ver_val); printf("#define %s %s\n", first_ver_macro, ver_val) > first_ver_header; first_ver_seen[first_ver_macro] = 1; From patchwork Tue May 4 15:15:53 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Florian Weimer X-Patchwork-Id: 43256 Return-Path: X-Original-To: patchwork@sourceware.org Delivered-To: patchwork@sourceware.org Received: from server2.sourceware.org (localhost [IPv6:::1]) by sourceware.org (Postfix) with ESMTP id DF725399240D; Tue, 4 May 2021 15:15:46 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org DF725399240D DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=sourceware.org; s=default; t=1620141346; bh=qKDbSXeGTGSWjjCw2vjGeAslu5a6ofQhd++/5f0C/uU=; h=To:Subject:In-Reply-To:References:Date:List-Id:List-Unsubscribe: List-Archive:List-Post:List-Help:List-Subscribe:From:Reply-To: From; b=WPrwgUvBV9/AspZIQwsKKMGG/0DlWXcTC50bMDObUvLhGGVVde7FaETe7jzufqT2r Bb9zmdg7aeMmISNleNfthUwS4eYhbOf6576WQ8vaZ13Ah63w+JPNoyt5hCEuoXxJQ/ cufboR5duXJobdUHTvlDF2+sxDzKr23BfxzuMfuM= X-Original-To: libc-alpha@sourceware.org Delivered-To: libc-alpha@sourceware.org Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [216.205.24.124]) by sourceware.org (Postfix) with ESMTP id D639A394FC0A for ; Tue, 4 May 2021 15:15:43 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.3.2 sourceware.org D639A394FC0A Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-287-Nb_8TvhZNQ-Tt5BaMQEv6w-1; Tue, 04 May 2021 11:15:40 -0400 X-MC-Unique: Nb_8TvhZNQ-Tt5BaMQEv6w-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 0D2E683DBD0 for ; Tue, 4 May 2021 15:15:39 +0000 (UTC) Received: from oldenburg.str.redhat.com (ovpn-112-137.ams2.redhat.com [10.36.112.137]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 337CD60C4A for ; Tue, 4 May 2021 15:15:38 +0000 (UTC) To: libc-alpha@sourceware.org Subject: [PATCH v2 2/2] elf, nptl: Resolve recursive lock implementation early In-Reply-To: References: Message-Id: <688b28fc77f34d39195dd102f01ece89711e3ac6.1620141231.git.fweimer@redhat.com> Date: Tue, 04 May 2021 17:15:53 +0200 User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.2 (gnu/linux) MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com X-Spam-Status: No, score=-12.0 required=5.0 tests=BAYES_00, DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, GIT_PATCH_0, KAM_SHORT, KAM_STOCKGEN, RCVD_IN_DNSWL_LOW, RCVD_IN_MSPIKE_H4, RCVD_IN_MSPIKE_WL, SPF_HELO_NONE, SPF_PASS, TXREP autolearn=ham autolearn_force=no version=3.4.2 X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on server2.sourceware.org X-BeenThere: libc-alpha@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Libc-alpha mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-Patchwork-Original-From: Florian Weimer via Libc-alpha From: Florian Weimer Reply-To: Florian Weimer Errors-To: libc-alpha-bounces@sourceware.org Sender: "Libc-alpha" If libpthread is included in libc, it is not necessary to delay initialization of the lock/unlock function pointers until libpthread is loaded. This eliminates two unprotected function pointers from _rtld_global and removes some initialization code from libpthread. --- elf/Makefile | 3 +- elf/dl-lock.c | 56 ++++++++++++++++++++++++++++++++++++++ elf/rtld.c | 18 ++++++++++++ nptl/nptl-init.c | 9 ------ sysdeps/generic/ldsodefs.h | 25 ++++++++++++++++- sysdeps/nptl/libc-lockP.h | 17 +++--------- 6 files changed, 104 insertions(+), 24 deletions(-) create mode 100644 elf/dl-lock.c diff --git a/elf/Makefile b/elf/Makefile index f09988f7d2..08cfa75ffe 100644 --- a/elf/Makefile +++ b/elf/Makefile @@ -66,7 +66,8 @@ elide-routines.os = $(all-dl-routines) dl-support enbl-secure dl-origin \ # interpreter and operating independent of libc. rtld-routines = rtld $(all-dl-routines) dl-sysdep dl-environ dl-minimal \ dl-error-minimal dl-conflict dl-hwcaps dl-hwcaps_split dl-hwcaps-subdirs \ - dl-usage dl-diagnostics dl-diagnostics-kernel dl-diagnostics-cpu + dl-usage dl-diagnostics dl-diagnostics-kernel dl-diagnostics-cpu \ + dl-lock all-rtld-routines = $(rtld-routines) $(sysdep-rtld-routines) CFLAGS-dl-runtime.c += -fexceptions -fasynchronous-unwind-tables diff --git a/elf/dl-lock.c b/elf/dl-lock.c new file mode 100644 index 0000000000..2db15e3a2f --- /dev/null +++ b/elf/dl-lock.c @@ -0,0 +1,56 @@ +/* Recursive locking implementation for the dynamic loader. + Copyright (C) 2021 Free Software Foundation, Inc. + This file is part of the GNU C Library. + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 2.1 of the License, or (at your option) any later version. + + The GNU C Library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with the GNU C Library; if not, see + . */ + +/* If libpthread is not part of libc, a legal mechanism using + late-initialized function pointers in _rtld_global is used, and not + the code below. */ +#if PTHREAD_IN_LIBC +# include +# include +# include + +__typeof (pthread_mutex_lock) *___rtld_mutex_lock attribute_relro; +__typeof (pthread_mutex_unlock) *___rtld_mutex_unlock attribute_relro; + +void +__rtld_mutex_init (void) +{ + /* There is an implicit assumption here that the lock counters are + zero and this function is called while nothing is locked. For + early initialization of the mutex functions this is true because + it happens directly in dl_main in elf/rtld.c, and not some ELF + constructor while holding loader locks. */ + + struct link_map *libc_map = GL (dl_ns)[LM_ID_BASE].libc_map; + + const ElfW(Sym) *sym + = _dl_lookup_direct (libc_map, "pthread_mutex_lock", + 0x4f152227, /* dl_new_hash output. */ + FIRST_VERSION_libc_pthread_mutex_lock_STRING, + FIRST_VERSION_libc_pthread_mutex_lock_HASH); + assert (sym != NULL); + ___rtld_mutex_lock = DL_SYMBOL_ADDRESS (libc_map, sym); + + sym = _dl_lookup_direct (libc_map, "pthread_mutex_unlock", + 0x7dd7aaaa, /* dl_new_hash output. */ + FIRST_VERSION_libc_pthread_mutex_unlock_STRING, + FIRST_VERSION_libc_pthread_mutex_unlock_HASH); + assert (sym != NULL); + ___rtld_mutex_unlock = DL_SYMBOL_ADDRESS (libc_map, sym); +} +#endif diff --git a/elf/rtld.c b/elf/rtld.c index 34879016ad..a18439251f 100644 --- a/elf/rtld.c +++ b/elf/rtld.c @@ -857,6 +857,14 @@ rtld_lock_default_unlock_recursive (void *lock) __rtld_lock_default_unlock_recursive (lock); } #endif +#if PTHREAD_IN_LIBC +/* Dummy implementation. See __rtld_mutex_init. */ +static int +rtld_mutex_dummy (pthread_mutex_t *lock) +{ + return 0; +} +#endif static void @@ -1146,6 +1154,10 @@ dl_main (const ElfW(Phdr) *phdr, GL(dl_rtld_lock_recursive) = rtld_lock_default_lock_recursive; GL(dl_rtld_unlock_recursive) = rtld_lock_default_unlock_recursive; #endif +#if PTHREAD_IN_LIBC + ___rtld_mutex_lock = rtld_mutex_dummy; + ___rtld_mutex_unlock = rtld_mutex_dummy; +#endif /* The explicit initialization here is cheaper than processing the reloc in the _rtld_local definition's initializer. */ @@ -2361,6 +2373,9 @@ dl_main (const ElfW(Phdr) *phdr, loader. */ __rtld_malloc_init_real (main_map); + /* Likewise for the locking implementation. */ + __rtld_mutex_init (); + /* Mark all the objects so we know they have been already relocated. */ for (struct link_map *l = main_map; l != NULL; l = l->l_next) { @@ -2466,6 +2481,9 @@ dl_main (const ElfW(Phdr) *phdr, at this point. */ __rtld_malloc_init_real (main_map); + /* Likewise for the locking implementation. */ + __rtld_mutex_init (); + RTLD_TIMING_VAR (start); rtld_timer_start (&start); diff --git a/nptl/nptl-init.c b/nptl/nptl-init.c index b0879bd87e..f7d1c2c21e 100644 --- a/nptl/nptl-init.c +++ b/nptl/nptl-init.c @@ -179,15 +179,6 @@ __pthread_initialize_minimal_internal (void) lll_unlock (__default_pthread_attr_lock, LLL_PRIVATE); #ifdef SHARED - /* Make __rtld_lock_{,un}lock_recursive use pthread_mutex_{,un}lock, - keep the lock count from the ld.so implementation. */ - GL(dl_rtld_lock_recursive) = (void *) __pthread_mutex_lock; - GL(dl_rtld_unlock_recursive) = (void *) __pthread_mutex_unlock; - unsigned int rtld_lock_count = GL(dl_load_lock).mutex.__data.__count; - GL(dl_load_lock).mutex.__data.__count = 0; - while (rtld_lock_count-- > 0) - __pthread_mutex_lock (&GL(dl_load_lock).mutex); - GL(dl_make_stack_executable_hook) = &__make_stacks_executable; #endif diff --git a/sysdeps/generic/ldsodefs.h b/sysdeps/generic/ldsodefs.h index 67c6686015..61326e8e5b 100644 --- a/sysdeps/generic/ldsodefs.h +++ b/sysdeps/generic/ldsodefs.h @@ -403,7 +403,7 @@ struct rtld_global struct auditstate _dl_rtld_auditstate[DL_NNS]; #endif -#if defined SHARED && defined _LIBC_REENTRANT \ +#if !PTHREAD_IN_LIBC && defined SHARED \ && defined __rtld_lock_default_lock_recursive EXTERN void (*_dl_rtld_lock_recursive) (void *); EXTERN void (*_dl_rtld_unlock_recursive) (void *); @@ -1299,6 +1299,29 @@ link_map_audit_state (struct link_map *l, size_t index) } #endif /* SHARED */ +#if PTHREAD_IN_LIBC && defined SHARED +/* Recursive locking implementation for use within the dynamic loader. + Used to define the __rtld_lock_lock_recursive and + __rtld_lock_unlock_recursive via . Initialized to a + no-op dummy implementation early. Similar + to GL (dl_rtld_lock_recursive) and GL (dl_rtld_unlock_recursive) + in !PTHREAD_IN_LIBC builds. */ +extern int (*___rtld_mutex_lock) (pthread_mutex_t *) attribute_hidden; +extern int (*___rtld_mutex_unlock) (pthread_mutex_t *lock) attribute_hidden; + +/* Called after libc has been loaded, but before RELRO is activated. + Used to initialize the function pointers to the actual + implementations. */ +void __rtld_mutex_init (void) attribute_hidden; +#else /* !PTHREAD_IN_LIBC */ +static inline void +__rtld_mutex_init (void) +{ + /* The initialization happens later (!PTHREAD_IN_LIBC) or is not + needed at all (!SHARED). */ +} +#endif /* !PTHREAD_IN_LIBC */ + #if THREAD_GSCOPE_IN_TCB void __thread_gscope_wait (void) attribute_hidden; # define THREAD_GSCOPE_WAIT() __thread_gscope_wait () diff --git a/sysdeps/nptl/libc-lockP.h b/sysdeps/nptl/libc-lockP.h index ae9691d40e..ec7b02bbdd 100644 --- a/sysdeps/nptl/libc-lockP.h +++ b/sysdeps/nptl/libc-lockP.h @@ -151,9 +151,6 @@ _Static_assert (LLL_LOCK_INITIALIZER == 0, "LLL_LOCK_INITIALIZER != 0"); __libc_maybe_call (__pthread_mutex_trylock, (&(NAME)), 0) #endif -#define __rtld_lock_trylock_recursive(NAME) \ - __libc_maybe_call (__pthread_mutex_trylock, (&(NAME).mutex), 0) - /* Unlock the named lock variable. */ #if IS_IN (libc) || IS_IN (libpthread) # define __libc_lock_unlock(NAME) \ @@ -163,19 +160,13 @@ _Static_assert (LLL_LOCK_INITIALIZER == 0, "LLL_LOCK_INITIALIZER != 0"); #endif #define __libc_rwlock_unlock(NAME) __pthread_rwlock_unlock (&(NAME)) -#ifdef SHARED -# define __rtld_lock_default_lock_recursive(lock) \ - ++((pthread_mutex_t *)(lock))->__data.__count; - -# define __rtld_lock_default_unlock_recursive(lock) \ - --((pthread_mutex_t *)(lock))->__data.__count; - +#if IS_IN (rtld) # define __rtld_lock_lock_recursive(NAME) \ - GL(dl_rtld_lock_recursive) (&(NAME).mutex) + ___rtld_mutex_lock (&(NAME).mutex) # define __rtld_lock_unlock_recursive(NAME) \ - GL(dl_rtld_unlock_recursive) (&(NAME).mutex) -#else + ___rtld_mutex_unlock (&(NAME).mutex) +#else /* Not in the dynamic loader. */ # define __rtld_lock_lock_recursive(NAME) \ __pthread_mutex_lock (&(NAME).mutex)