From patchwork Fri Jul 7 10:55:47 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Florian Weimer X-Patchwork-Id: 72292 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 A063B3A72CA0 for ; Fri, 7 Jul 2023 12:13:10 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org A063B3A72CA0 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=sourceware.org; s=default; t=1688731990; bh=R89q2c1AHRiGlX2iCiEtm+JU7Ma8f+TJLGf2Cd4wUxQ=; 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=BwUCRTSL3zz0taEUeZ4sDvU9lTRiq8u29OlSy0wNvFeZJ57qV+HjiIQwsABv9zcl0 56nWPOaYr/5uPXRZsQT/sw0T8nVeVT6IikftYatxY5BbrvlZyFKo2B8YiA7TF1Tupv beCjvlEGhT1o2D0fJfILNrVH8eyid7mDx/iW70sA= 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 [170.10.129.124]) by sourceware.org (Postfix) with ESMTPS id B0CFB394027F for ; Fri, 7 Jul 2023 10:55:51 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.2 sourceware.org B0CFB394027F Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-55-9pdBWAHJNGas1YqZcTW_Uw-1; Fri, 07 Jul 2023 06:55:50 -0400 X-MC-Unique: 9pdBWAHJNGas1YqZcTW_Uw-1 Received: from smtp.corp.redhat.com (int-mx09.intmail.prod.int.rdu2.redhat.com [10.11.54.9]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id C6F2585A58A for ; Fri, 7 Jul 2023 10:55:49 +0000 (UTC) Received: from oldenburg.str.redhat.com (unknown [10.2.16.31]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 0D4A0492B01 for ; Fri, 7 Jul 2023 10:55:48 +0000 (UTC) To: libc-alpha@sourceware.org Subject: [PATCH v5 2/3] elf: Introduce _dl_debug_change_state In-Reply-To: Message-ID: <559fd57392e89e3a7354511bb363f1f37de7764e.1688727287.git.fweimer@redhat.com> References: X-From-Line: 559fd57392e89e3a7354511bb363f1f37de7764e Mon Sep 17 00:00:00 2001 Date: Fri, 07 Jul 2023 12:55:47 +0200 User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/28.2 (gnu/linux) MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.1 on 10.11.54.9 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com X-Spam-Status: No, score=-10.6 required=5.0 tests=BAYES_00, DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, GIT_PATCH_0, RCVD_IN_DNSWL_NONE, RCVD_IN_MSPIKE_H4, RCVD_IN_MSPIKE_WL, SPF_HELO_NONE, SPF_NONE, TXREP, T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) 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+patchwork=sourceware.org@sourceware.org Sender: "Libc-alpha" It combines updating r_state with the debugger notification. The change to _dl_open introduces an additional debugger notification for dlmopen, but debuggers are expected to ignore it. --- elf/dl-close.c | 6 ++---- elf/dl-debug.c | 7 +++++++ elf/dl-load.c | 3 +-- elf/dl-open.c | 5 ++--- elf/rtld.c | 6 ++---- sysdeps/generic/ldsodefs.h | 14 ++++++++++++-- 6 files changed, 26 insertions(+), 15 deletions(-) diff --git a/elf/dl-close.c b/elf/dl-close.c index b887a44888..27fd187385 100644 --- a/elf/dl-close.c +++ b/elf/dl-close.c @@ -420,8 +420,7 @@ _dl_close_worker (struct link_map *map, bool force) /* Notify the debugger we are about to remove some loaded objects. */ struct r_debug *r = _dl_debug_update (nsid); - r->r_state = RT_DELETE; - _dl_debug_state (); + _dl_debug_change_state (r, RT_DELETE); LIBC_PROBE (unmap_start, 2, nsid, r); if (unload_global) @@ -725,8 +724,7 @@ _dl_close_worker (struct link_map *map, bool force) while (GL(dl_ns)[GL(dl_nns) - 1]._ns_loaded == NULL); /* Notify the debugger those objects are finalized and gone. */ - r->r_state = RT_CONSISTENT; - _dl_debug_state (); + _dl_debug_change_state (r, RT_CONSISTENT); LIBC_PROBE (unmap_complete, 2, nsid, r); /* Recheck if we need to retry, release the lock. */ diff --git a/elf/dl-debug.c b/elf/dl-debug.c index 88cccfa756..9d05e553d7 100644 --- a/elf/dl-debug.c +++ b/elf/dl-debug.c @@ -67,6 +67,13 @@ _dl_debug_update (Lmid_t ns) return &r->base; } +void +_dl_debug_change_state (struct r_debug *r, int state) +{ + atomic_store_release (&r->r_state, state); + _dl_debug_state (); +} + /* Initialize _r_debug_extended for the namespace NS. LDBASE is the run-time load address of the dynamic linker, to be put in _r_debug_extended.r_ldbase. Return the address of _r_debug. */ diff --git a/elf/dl-load.c b/elf/dl-load.c index 9a87fda9c9..4a5fd71f1a 100644 --- a/elf/dl-load.c +++ b/elf/dl-load.c @@ -1502,8 +1502,7 @@ cannot enable executable stack as shared object requires"); /* Notify the debugger we have added some objects. We need to call _dl_debug_initialize in a static program in case dynamic linking has not been used before. */ - r->r_state = RT_ADD; - _dl_debug_state (); + _dl_debug_change_state (r, RT_ADD); LIBC_PROBE (map_start, 2, nsid, r); } else diff --git a/elf/dl-open.c b/elf/dl-open.c index 2d985e21d8..02235f7e0b 100644 --- a/elf/dl-open.c +++ b/elf/dl-open.c @@ -619,8 +619,7 @@ dl_open_worker_begin (void *a) /* Notify the debugger all new objects are now ready to go. */ struct r_debug *r = _dl_debug_update (args->nsid); - r->r_state = RT_CONSISTENT; - _dl_debug_state (); + _dl_debug_change_state (r, RT_CONSISTENT); LIBC_PROBE (map_complete, 3, args->nsid, r, new); _dl_open_check (new); @@ -853,7 +852,7 @@ no more namespaces available for dlmopen()")); } GL(dl_ns)[nsid].libc_map = NULL; - _dl_debug_update (nsid)->r_state = RT_CONSISTENT; + _dl_debug_change_state (_dl_debug_update (nsid), RT_CONSISTENT); } /* Never allow loading a DSO in a namespace which is empty. Such direct placements is only causing problems. Also don't allow diff --git a/elf/rtld.c b/elf/rtld.c index a91e2a4471..77eea867c9 100644 --- a/elf/rtld.c +++ b/elf/rtld.c @@ -1826,8 +1826,7 @@ dl_main (const ElfW(Phdr) *phdr, elf_setup_debug_entry (main_map, r); /* We start adding objects. */ - r->r_state = RT_ADD; - _dl_debug_state (); + _dl_debug_change_state (r, RT_ADD); LIBC_PROBE (init_start, 2, LM_ID_BASE, r); /* Auditing checkpoint: we are ready to signal that the initial map @@ -2392,8 +2391,7 @@ dl_main (const ElfW(Phdr) *phdr, /* Notify the debugger all new objects are now ready to go. We must re-get the address since by now the variable might be in another object. */ r = _dl_debug_update (LM_ID_BASE); - r->r_state = RT_CONSISTENT; - _dl_debug_state (); + _dl_debug_change_state (r, RT_CONSISTENT); LIBC_PROBE (init_complete, 2, LM_ID_BASE, r); #if defined USE_LDCONFIG && !defined MAP_COPY diff --git a/sysdeps/generic/ldsodefs.h b/sysdeps/generic/ldsodefs.h index 55597a268e..99cc78b8e4 100644 --- a/sysdeps/generic/ldsodefs.h +++ b/sysdeps/generic/ldsodefs.h @@ -1058,8 +1058,14 @@ extern void _dl_debug_state (void); rtld_hidden_proto (_dl_debug_state) /* Initialize `struct r_debug_extended' for the namespace NS. LDBASE - is the run-time load address of the dynamic linker, to be put in the - `r_ldbase' member. Return the address of the structure. */ + is the run-time load address of the dynamic linker, to be put in + the `r_ldbase' member. + + This function returns the address of the r_debug structure for the + namespace. This is not merely a convenience or optimization, but + it is necessary for the LIBC_PROBE Systemtap/debugger probes to + work reliably: direct variable access can create probes that tools + cannot consume. */ extern struct r_debug *_dl_debug_initialize (ElfW(Addr) ldbase, Lmid_t ns) attribute_hidden; @@ -1067,6 +1073,10 @@ extern struct r_debug *_dl_debug_initialize (ElfW(Addr) ldbase, Lmid_t ns) of the namespace NS. */ extern struct r_debug *_dl_debug_update (Lmid_t ns) attribute_hidden; +/* Updates R->r_state to STATE and notifies the debugger by calling + _dl_debug_state. */ +void _dl_debug_change_state (struct r_debug *r, int state) attribute_hidden; + /* Initialize the basic data structure for the search paths. SOURCE is either "LD_LIBRARY_PATH" or "--library-path". GLIBC_HWCAPS_PREPEND adds additional glibc-hwcaps subdirectories to