From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by sourceware.org (Postfix) with ESMTPS id 0BAD13853825 for ; Tue, 6 Sep 2022 10:27:34 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org 0BAD13853825 Authentication-Results: sourceware.org; dmarc=pass (p=none dis=none) header.from=redhat.com Authentication-Results: sourceware.org; spf=pass smtp.mailfrom=redhat.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1662460053; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=VxYP2pSaazYZHY097Rcgb0a9uBcuiqYHWNszs+j4QxY=; b=IeR7QEgSouETs4Ku7VS4F6QM8sgOTWJwYNHO7eg7gjXo0w1NNRylcExWSDnARU2mwKwFbX Q/Mqz5D15cr9wLGFTJ2Hu+MSLcuywgKjvRW4wvmOEFVxWBfI7B7k8fhVre8RFeY9ZsR3WN Te8GPpJX3CQVp2kOCwJAHhTIBM5fSFw= 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-282-SWEiQCBxOWWG7WpgE1fWDA-1; Tue, 06 Sep 2022 06:27:32 -0400 X-MC-Unique: SWEiQCBxOWWG7WpgE1fWDA-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.rdu2.redhat.com [10.11.54.5]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 41325101A54E for ; Tue, 6 Sep 2022 10:27:32 +0000 (UTC) Received: from oldenburg.str.redhat.com (unknown [10.39.192.109]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 820024C816 for ; Tue, 6 Sep 2022 10:27:31 +0000 (UTC) From: Florian Weimer To: libc-alpha@sourceware.org Subject: [PATCH v2 2/3] elf: Introduce _dl_debug_change_state In-Reply-To: References: X-From-Line: e596eeb8df983d8259550e33180d66b937aa8dad Mon Sep 17 00:00:00 2001 Message-Id: Date: Tue, 06 Sep 2022 12:27:29 +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 10.11.54.5 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain X-Spam-Status: No, score=-10.7 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,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 List-Id: 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 | 6 ++---- elf/dl-open.c | 5 ++--- elf/rtld.c | 6 ++---- sysdeps/generic/ldsodefs.h | 14 ++++++++++++-- 6 files changed, 27 insertions(+), 17 deletions(-) diff --git a/elf/dl-close.c b/elf/dl-close.c index bcd6e206e9..c300999e5b 100644 --- a/elf/dl-close.c +++ b/elf/dl-close.c @@ -460,8 +460,7 @@ _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) @@ -765,8 +764,7 @@ _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 66f9ad375d..47961236cf 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 1ad0868dad..d23ad557fc 100644 --- a/elf/dl-load.c +++ b/elf/dl-load.c @@ -987,8 +987,7 @@ _dl_map_object_from_fd (const char *name, const char *origname, int fd, if (make_consistent && r != NULL) { - r->r_state = RT_CONSISTENT; - _dl_debug_state (); + _dl_debug_change_state (r, RT_CONSISTENT); LIBC_PROBE (map_failed, 2, nsid, r); } @@ -1507,8 +1506,7 @@ 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); make_consistent = true; } diff --git a/elf/dl-open.c b/elf/dl-open.c index 46e8066fd8..b67c2e099f 100644 --- a/elf/dl-open.c +++ b/elf/dl-open.c @@ -617,8 +617,7 @@ 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()")); memset (&GL(dl_ns)[nsid], 0, sizeof (GL(dl_ns)[nsid])); __rtld_lock_initialize (GL(dl_ns)[nsid]._ns_unique_sym_table.lock); - _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 3e771a93d8..ad67d7e4c5 100644 --- a/elf/rtld.c +++ b/elf/rtld.c @@ -1835,8 +1835,7 @@ 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 @@ -2409,8 +2408,7 @@ 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 b088f6b1ae..31fb19c871 100644 --- a/sysdeps/generic/ldsodefs.h +++ b/sysdeps/generic/ldsodefs.h @@ -1060,8 +1060,14 @@ 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; @@ -1069,6 +1075,10 @@ 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 -- 2.37.2