From patchwork Mon Jun 5 09:11:07 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andrew Burgess X-Patchwork-Id: 70588 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 C44CE385C6E7 for ; Mon, 5 Jun 2023 09:12:11 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org C44CE385C6E7 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=sourceware.org; s=default; t=1685956331; bh=UpXr3H3rgFySkm+NGuoDLvZDXdFE/6MNr+Jt9oR7W5g=; h=To:Cc:Subject:Date:In-Reply-To:References:List-Id: List-Unsubscribe:List-Archive:List-Post:List-Help:List-Subscribe: From:Reply-To:From; b=UA7AfJxAfHnUCeTjsTwEFDjmNMVWAGQVu3rzpfgdxuvlbseMtaWLIxwatiPTIoP3l cnfNUOGIviIqq6YCn7yi/A1C/oCEGN0EesEs0b3gbKHKDH52r3G1xIAA2/ESI485o6 5UgXQHAUx87io8xFF4dFAvn3nLhjtgNZ/pQibhUM= X-Original-To: gdb-patches@sourceware.org Delivered-To: gdb-patches@sourceware.org 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 3F8A93858C5E for ; Mon, 5 Jun 2023 09:11:17 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.2 sourceware.org 3F8A93858C5E Received: from mail-lf1-f69.google.com (mail-lf1-f69.google.com [209.85.167.69]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-592-Arw4-7DbPfeCIrJodtPCig-1; Mon, 05 Jun 2023 05:11:15 -0400 X-MC-Unique: Arw4-7DbPfeCIrJodtPCig-1 Received: by mail-lf1-f69.google.com with SMTP id 2adb3069b0e04-4f4c62e0c9eso2939990e87.3 for ; Mon, 05 Jun 2023 02:11:15 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1685956274; x=1688548274; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=UpXr3H3rgFySkm+NGuoDLvZDXdFE/6MNr+Jt9oR7W5g=; b=ewvf8WJIzwKf98dAsU9YBXsT9M8bQrKnsjKK7MsHUmFBNdPb7dKp1LHpeZWMDMYn8l Rhv3PMiA6Q9nVhBMlYrKjOfHxU7oDAldhhDZRUuIHf/D1Grn5jDkw9EDnYIDZSmwUW6A 3pqI+TEJbYImfbbioZ96agPgSyv3fnWb5ptzRgEpobz7aiqJSHSsVJun1+Hy+2cIS2GQ xk+q41S5ZXtLdv98KGJCI/Bpu0OSrW0OPNTGzQ9vX7/u3317+PUkEMivvN/yQpCXHZE6 GCeXxFabH78ohZ4yzFsjou1wUeDpb5TmxCxBz+NmGIvDfOiRxDtEG3LEQCEb7UGLh8Ba Xt7g== X-Gm-Message-State: AC+VfDzrjPjO337ne8In+nUNNMt0sP8B1rzNlroq55QkV7BotZtdGekA 32LuJvmS0KinSEhAjor0zg00cIGu9xBL6OXStQciBeliVXGIBQi8cj2AkmoKfbAWCQHA8ba/Fw2 ouI02R9x1yvmN6PN5/Ts8+kjgz2bZ5vf/q34vLYXHFwyM3ol1zjnTuwnV50U3k9cvYi5AfyGPe8 +QpEChqg== X-Received: by 2002:a19:ad41:0:b0:4f6:2e5c:de65 with SMTP id s1-20020a19ad41000000b004f62e5cde65mr313487lfd.28.1685956274162; Mon, 05 Jun 2023 02:11:14 -0700 (PDT) X-Google-Smtp-Source: ACHHUZ5wnIcSMtCVRWa9r6fvKJ5DFjPBDceAE/z1F4RM+Qo1b+d4Vf1MtPKQn3DipdmVVl52dCVJTw== X-Received: by 2002:a19:ad41:0:b0:4f6:2e5c:de65 with SMTP id s1-20020a19ad41000000b004f62e5cde65mr313474lfd.28.1685956273695; Mon, 05 Jun 2023 02:11:13 -0700 (PDT) Received: from localhost (11.72.115.87.dyn.plus.net. [87.115.72.11]) by smtp.gmail.com with ESMTPSA id w16-20020adfd4d0000000b0030aefa3a957sm9176556wrk.28.2023.06.05.02.11.13 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 05 Jun 2023 02:11:13 -0700 (PDT) To: gdb-patches@sourceware.org Cc: Andrew Burgess Subject: [PATCH 1/3] gdb: split inferior and thread setup when opening a core file Date: Mon, 5 Jun 2023 10:11:07 +0100 Message-Id: X-Mailer: git-send-email 2.25.4 In-Reply-To: References: MIME-Version: 1.0 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com X-Spam-Status: No, score=-11.7 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 X-BeenThere: gdb-patches@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Gdb-patches mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-Patchwork-Original-From: Andrew Burgess via Gdb-patches From: Andrew Burgess Reply-To: Andrew Burgess Errors-To: gdb-patches-bounces+patchwork=sourceware.org@sourceware.org Sender: "Gdb-patches" I noticed that in corelow.c, when a core file is opened, both the thread and inferior setup is done in add_to_thread_list. In this patch I propose hoisting the inferior setup out of add_to_thread_list into core_target_open. The only thing about this change that gave me cause for concern is that in add_to_thread_list, we only setup the inferior after finding the first section with a name like ".reg/NN". If we find no such section then the inferior will never be setup. Is this important? Well, I don't think so. Back in core_target_open, if there is no current thread (which there will not be if no ".reg/NN" section was found), then we look for a thread in the current inferior. If there are no threads (which there will not be if no ".reg/NN" is found), then we once again setup the current inferior. What I think this means, is that, in all cases, the current inferior will end up being setup. By moving the inferior setup code earlier in core_target_open and making it non-conditional, we can remove the later code that sets up the inferior, we now know this will always have been done. There should be no user visible changes after this commit. Reviewed-by: Kevin Buettner --- gdb/corelow.c | 62 ++++++++++++++++++++++++--------------------------- 1 file changed, 29 insertions(+), 33 deletions(-) diff --git a/gdb/corelow.c b/gdb/corelow.c index db489b4280e..7312d40374f 100644 --- a/gdb/corelow.c +++ b/gdb/corelow.c @@ -351,40 +351,24 @@ core_target::close () /* Look for sections whose names start with `.reg/' so that we can extract the list of threads in a core file. */ +/* If ASECT is a section whose name begins with '.reg/' then extract the + lwpid after the '/' and create a new thread in INF. + + If REG_SECT is not nullptr, and the both ASECT and REG_SECT point at the + same position in the parent bfd object then switch to the newly created + thread, otherwise, the selected thread is left unchanged. */ + static void -add_to_thread_list (asection *asect, asection *reg_sect) +add_to_thread_list (asection *asect, asection *reg_sect, inferior *inf) { - int core_tid; - int pid, lwpid; - bool fake_pid_p = false; - struct inferior *inf; - if (!startswith (bfd_section_name (asect), ".reg/")) return; - core_tid = atoi (bfd_section_name (asect) + 5); - - pid = bfd_core_file_pid (core_bfd); - if (pid == 0) - { - fake_pid_p = true; - pid = CORELOW_PID; - } - - lwpid = core_tid; - - inf = current_inferior (); - if (inf->pid == 0) - { - inferior_appeared (inf, pid); - inf->fake_pid_p = fake_pid_p; - } - - ptid_t ptid (pid, lwpid); - + int lwpid = atoi (bfd_section_name (asect) + 5); + ptid_t ptid (inf->pid, lwpid); thread_info *thr = add_thread (inf->process_target (), ptid); -/* Warning, Will Robinson, looking at BFD private data! */ + /* Warning, Will Robinson, looking at BFD private data! */ if (reg_sect != NULL && asect->filepos == reg_sect->filepos) /* Did we find .reg? */ @@ -541,12 +525,27 @@ core_target_open (const char *arg, int from_tty) previous session, and the frame cache being stale. */ registers_changed (); + /* Find (or fake) the pid for the process in this core file, and + initialise the current inferior with that pid. */ + bool fake_pid_p = false; + int pid = bfd_core_file_pid (core_bfd); + if (pid == 0) + { + fake_pid_p = true; + pid = CORELOW_PID; + } + + inferior *inf = current_inferior (); + gdb_assert (inf->pid == 0); + inferior_appeared (inf, pid); + inf->fake_pid_p = fake_pid_p; + /* Build up thread list from BFD sections, and possibly set the current thread to the .reg/NN section matching the .reg section. */ asection *reg_sect = bfd_get_section_by_name (core_bfd, ".reg"); for (asection *sect : gdb_bfd_sections (core_bfd)) - add_to_thread_list (sect, reg_sect); + add_to_thread_list (sect, reg_sect, inf); if (inferior_ptid == null_ptid) { @@ -556,13 +555,10 @@ core_target_open (const char *arg, int from_tty) which was the "main" thread. The latter case shouldn't usually happen, but we're dealing with input here, which can always be broken in different ways. */ - thread_info *thread = first_thread_of_inferior (current_inferior ()); + thread_info *thread = first_thread_of_inferior (inf); if (thread == NULL) - { - inferior_appeared (current_inferior (), CORELOW_PID); - thread = add_thread_silent (target, ptid_t (CORELOW_PID)); - } + thread = add_thread_silent (target, ptid_t (CORELOW_PID)); switch_to_thread (thread); } From patchwork Mon Jun 5 09:11:08 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andrew Burgess X-Patchwork-Id: 70589 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 B372E3854E58 for ; Mon, 5 Jun 2023 09:12:40 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org B372E3854E58 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=sourceware.org; s=default; t=1685956360; bh=+V7K0c+oiorWaplcB6ZpLCL816S2FPdh6WUbieIwUoA=; h=To:Cc:Subject:Date:In-Reply-To:References:List-Id: List-Unsubscribe:List-Archive:List-Post:List-Help:List-Subscribe: From:Reply-To:From; b=L9GcXpk+M5+HujnH0k35m4948w1fMKoTrDU+zBszmuQ4RhH2gPv/xAyb3rSgFXz6M nxRpVs2iiIMXodlTzyVQCmNjiQqxYI/vu7/ex/XcUHzKgqDHq7A5gD1/z+CTZAhiyM wKNIqxICruW9GU0gU+RVrNFBeN+FmTioCA/dri+o= X-Original-To: gdb-patches@sourceware.org Delivered-To: gdb-patches@sourceware.org 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 C355C38558A7 for ; Mon, 5 Jun 2023 09:11:18 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.2 sourceware.org C355C38558A7 Received: from mail-wm1-f72.google.com (mail-wm1-f72.google.com [209.85.128.72]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-228-hqYiB7m9OnWu87UMIYJ9Eg-1; Mon, 05 Jun 2023 05:11:17 -0400 X-MC-Unique: hqYiB7m9OnWu87UMIYJ9Eg-1 Received: by mail-wm1-f72.google.com with SMTP id 5b1f17b1804b1-3f6045853c1so22262875e9.3 for ; Mon, 05 Jun 2023 02:11:17 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1685956276; x=1688548276; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=+V7K0c+oiorWaplcB6ZpLCL816S2FPdh6WUbieIwUoA=; b=IcjuGTAE3gdw1htYNdLgBU9ZhhDISeHbHmB1BPrx4gWB7tRAYjK4h7aUj4ZT/PVxk5 LRbj6nBpQ4snW/8iE7phauxlNbAIw/03o8EnJZqDpVqIc2ikL3rkRAIOidrSuf/B+xBI 4U2wI/Odg6ksSLp13ZFj6u9RWTOc43RogFqXXN/Qz9yRKn8jIH6C3rcbCxv3RlGKlu7I 1zGrTDQ2HAVLaLN1wdxMgoYjqTvn5DtZii+zz/fSopBGTIVHbj3yIcGvsxsiTBUGgwTB 0oNZabSfjW7tHhQTHrgVrgdF8E7ZO2my5goknb+O/C3wSTCP2jQ0IeZ0dHmSDusmuywH +osg== X-Gm-Message-State: AC+VfDyoDbSEpnsPj15ygc0VUXpY87T6mKWSpCaN1+tPUzawxzgi1jo6 2/38EncNbPJmRh12Z1NszCqPmoCjEfnwtat1dkHIQIxbiVYx27ZVcsQJL5JbYALS5XUxVQYqhoM l6fpqSD2HeSQcqa0Gr784AetCj02xO9tUANde92cT3gdmm7EqDY4lUslJ8RkfpfpMEUq1tN+vNJ 5VMyH2nw== X-Received: by 2002:a05:600c:c9:b0:3f6:3497:aaaf with SMTP id u9-20020a05600c00c900b003f63497aaafmr6234848wmm.9.1685956275825; Mon, 05 Jun 2023 02:11:15 -0700 (PDT) X-Google-Smtp-Source: ACHHUZ4pDhpQ7c4D0q85vW56Fd3ZDG6SjrWexP2fg+bGsf+UHMUr+2mVifQ/3Rne4a6//qxh655fEA== X-Received: by 2002:a05:600c:c9:b0:3f6:3497:aaaf with SMTP id u9-20020a05600c00c900b003f63497aaafmr6234829wmm.9.1685956275405; Mon, 05 Jun 2023 02:11:15 -0700 (PDT) Received: from localhost (11.72.115.87.dyn.plus.net. [87.115.72.11]) by smtp.gmail.com with ESMTPSA id u4-20020a7bc044000000b003f70a7b4537sm13664342wmc.36.2023.06.05.02.11.14 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 05 Jun 2023 02:11:14 -0700 (PDT) To: gdb-patches@sourceware.org Cc: Andrew Burgess Subject: [PATCH 2/3] gdb/testsuite: add test for core file with a 0 pid Date: Mon, 5 Jun 2023 10:11:08 +0100 Message-Id: <6cb39b064b3e1c9ed57964b29fd980f3a6d30a25.1685956034.git.aburgess@redhat.com> X-Mailer: git-send-email 2.25.4 In-Reply-To: References: MIME-Version: 1.0 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com X-Spam-Status: No, score=-11.7 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_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 X-BeenThere: gdb-patches@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Gdb-patches mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-Patchwork-Original-From: Andrew Burgess via Gdb-patches From: Andrew Burgess Reply-To: Andrew Burgess Errors-To: gdb-patches-bounces+patchwork=sourceware.org@sourceware.org Sender: "Gdb-patches" This patch contains a test for this commit: commit c820c52a914cc9d7c63cb41ad396f4ddffff2196 Date: Fri Aug 6 19:45:58 2010 +0000 * thread.c (add_thread_silent): Use null_ptid instead of minus_one_ptid while getting rid of stale inferior_ptid. This is another test that has been carried in the Fedora GDB tree for some time, and I thought that it would be worth merging to master. I don't believe there is any test like this currently in the testsuite. The original issue was reported in this thread: https://inbox.sourceware.org/gdb-patches/AANLkTi=zuEDw6qiZ1jRatkdwHO99xF2Qu+WZ7i0EQjef@mail.gmail.com/ The problem was that when GDB was used to open a vmcore (core file) image generated by the Linux kernel GDB would (sometimes) crash with an assertion failure: thread.c:884: internal-error: switch_to_thread: Assertion `inf != NULL' failed. To understand what's going on we need some background; a vmcore file represents each processor core in the same way that a standard application core file represents threads. Thus, we might say, a vmcore file represents cores as threads. When writing a vmcore file, the kernel will store the pid of the process currently running on that core as the thread's lwpid. However, if a core is idle, with no process currently running on it, then the lwpid for that thread is stored as 0 in the vmcore file. If multiple cores are idle then multiple threads will have a lwpid of 0. Back in 2010, the original issue reported tried to change the kernel's behaviour in this thread: https://lkml.org/lkml/2010/8/3/75 This change was rejected by the kernel team, the current behaviour (lwpid of 0) was considered correct. I've checked the source of a recent kernel. The code mentioned in the lkml.org posting has moved, it's now in the function crash_save_cpu in the file kernel/kexec_core.c, but the general behaviour is unchanged, an idle core will have an lwpid of 0, so I think GDB still needs to be able to handle this case. When GDB loads a vmcore file (which is handled just like any other core file) the sections are processed in core_open to generate the threads for the core file. The processing is done by calling add_to_thread_list, a function which looks for sections named .reg/NN where NN is the lwpid of the thread, GDB then builds a ptid_t for the new thread and calls add_thread. Remember, in our case the lwpid is 0. Now for the first thread this is fine, if a little weird, 0 isn't usually a valid lwpid, but that's OK, GDB creates a thread with lwpid of 0 and carries on. When we find the next thread (core) with lwpid of 0, we attempt to create another thread with an lwpid of 0. This of course clashes with the previously created thread, they have the same ptid_t, so GDB tries to delete the first thread. And it was within this thread delete code that we triggered a bug which would then cause GDB to assert -- when deleting we tried to switch to a thread with minus_one_ptid, this resulted in a call to find_inferior_pid (passing in minus_one_ptid's pid, which is -1), the find_inferior_pid call fails and returns NULL, which then triggered an assert in switch_to_thread. The actual details of the why the assert triggered are really not important. What's important (I think) is that a vmcore file might have this interesting lwpid of 0 characteristic, which isn't something we see in "normal" application core files, and it is this that I think we should be testing. Now, you might be thinking: isn't deleting the first thread the wrong thing to do? If the vmcore file has two threads that represent two cores, and both have an lwpid of 0 (indicating both cores are idle), then surely GDB should still represent this as two threads? You're not wrong. This was mentioned by Pedro in the original GDB mailing list thread here: https://inbox.sourceware.org/gdb-patches/201008061057.03037.pedro@codesourcery.com/ This is indeed a problem, and this problem is still present in GDB today. I plan to try and address this in a later commit, however, this first commit is about getting a test in place to confirm that GDB at a minimum doesn't crash when loading such a vmcore file. And so, finally, what's in this commit? This commit contains a new test. The test doesn't actually contain a vmcore file. Instead I've created a standard application core file that contains two threads, and then manually edited the core file to set the lwpid of each thread to 0. To further reduce the size of the core file (as it will be stored in git), I've zeroed all of the LOAD-able segments in the core file. This test really doesn't care about that part of the core file, we only really care about loading the register's, this is enough to confirm that the GDB doesn't crash. Obviously as the core file is pre-generated, this test is architecture specific. There are already a few tests in gdb.arch/ that include pre-generate core files. Just as those existing tests do, I've compressed the core file with bzip2, which reduces it to just 750 bytes. I have structured the test so that if/when this patch is merged I can add some additional core files for other architectures, however, these are not included in this commit. The test simply expands the core file, and then loads it into GDB. One interesting thing to note is that GDB reports the core file loading like this: (gdb) core-file ./gdb/testsuite/outputs/gdb.arch/core-file-pid0/core-file-pid0.x86-64.core [New process 1] [New process 1] Failed to read a valid object file image from memory. Core was generated by `./segv-mt'. Program terminated with signal SIGSEGV, Segmentation fault. The current thread has terminated (gdb) There's two interesting things here: first, the repeated "New process 1" message. This is caused because linux_core_pid_to_str reports anything with an lwpid of 0 as a process, rather than an LWP. And second, the "The current thread has terminated" message. This is because the first thread in the core file is the current thread, but when GDB loads the second thread (which also has lwpid 0) this causes the first thread to be deleted, as a result GDB thinks that the current (first) thread has terminated. As I said previously, both of these problems are a result of the lwpid 0 aliasing, which is not being fixed in this commit -- this commit is just confirming that GDB doesn't crash when loading this core file. --- gdb/testsuite/gdb.arch/core-file-pid0.exp | 63 ++++++++++++++++++ .../gdb.arch/core-file-pid0.x86-64.core.bz2 | Bin 0 -> 750 bytes 2 files changed, 63 insertions(+) create mode 100644 gdb/testsuite/gdb.arch/core-file-pid0.exp create mode 100644 gdb/testsuite/gdb.arch/core-file-pid0.x86-64.core.bz2 diff --git a/gdb/testsuite/gdb.arch/core-file-pid0.exp b/gdb/testsuite/gdb.arch/core-file-pid0.exp new file mode 100644 index 00000000000..b960dfe095b --- /dev/null +++ b/gdb/testsuite/gdb.arch/core-file-pid0.exp @@ -0,0 +1,63 @@ +# This testcase is part of GDB, the GNU debugger. +# +# Copyright 2023 Free Software Foundation, Inc. +# +# This program is free software; you can redistribute it and/or modify +# it under the terms of the GNU General Public License as published by +# the Free Software Foundation; either version 2 of the License, or +# (at your option) any later version. +# +# This program 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 General Public License for more details. +# +# You should have received a copy of the GNU General Public License +# along with this program; if not, write to the Free Software +# Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. + +# Some kernel core files have PID 0 (for the idle task), check that +# GDB can handle such a core file. + +standard_testfile + +# Set CF_NAME, the name of the compressed core file within the source +# tree, and CF_SIZE, the size (in bytes) of the uncompressed core +# file. +if {[istarget "x86_64-*-linux*"]} { + set cf_name ${testfile}.x86-64.core.bz2 + set cf_size 8757248 +} else { + unsupported "no pre-generated core file for this target" +} + +# Decompress the core file. +set corebz2file ${srcdir}/${subdir}/${cf_name} +set corefile [decompress_bz2 $corebz2file] +if { $corefile eq "" } { + untested "failed to bunzip2 the core file" + return -1 +} + +# Check the size of the decompressed core file. Just for sanity. +file stat ${corefile} corestat +if { $corestat(size) != ${cf_size} } { + untested "uncompressed core file is the wrong size" + return -1 +} + +# Copy over the corefile if we are remote testing. +set corefile [gdb_remote_download host $corefile] + +clean_restart + +# Load the core file. At one point GDB would assert, complaining that +# the inferior was nullptr. For now we see a message about the +# current thread having terminated, this is because GDB gets confused +# and incorrectly deletes what should be the current thread. +gdb_test "core-file ${corefile}" \ + [multi_line \ + "Core was generated by \[^\r\n\]+\\." \ + "Program terminated with signal (?:11|SIGSEGV), Segmentation fault\\." \ + "The current thread has terminated"] \ + "check core file termination reason" diff --git a/gdb/testsuite/gdb.arch/core-file-pid0.x86-64.core.bz2 b/gdb/testsuite/gdb.arch/core-file-pid0.x86-64.core.bz2 new file mode 100644 index 0000000000000000000000000000000000000000..081a35250f1fbb9743aecc70723abc90ad2704e8 GIT binary patch literal 750 zcmVHzgLXaH~k4FC-QXaE4whyWS@0000Q0B`^e z01W_W007a502%-Q000^RIm5u!H4!vOi4u;~XXvv+_(4wTM27K9uvA#A$z8Re3k?Vx zg=D9NR?O2NX^{dvY9IV+DHS4>5kX7fxS%zD4RsCzh73;S*BC&GECiK?zCXv=Y z65o1Zd|ax6qtvPl(c_9KX5k85w|e}6l%`SES|O^nNNxR=)iL;!(m48t3>)nWv>L}odw_(LwYmfFnX^tXRS%I%0_gs2X0CMw)LAuUYge!* z*ho4d^b_t7!mr3Ox;W?}{mO+P*A-{+6zTs%^$`P2v5rXCxqZV4i%UXhQ~m4Hr~y%;=R2;=vk&8NAlooiprS>1{0SArS-sL;&Pz gX|25!i~Ev+81)1P_+g=)e((HU$rRy2Lt>?Ww9hY4asU7T literal 0 HcmV?d00001 -- 2.25.4 From patchwork Mon Jun 5 09:11:09 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andrew Burgess X-Patchwork-Id: 70587 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 B20C03854E65 for ; Mon, 5 Jun 2023 09:12:01 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org B20C03854E65 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=sourceware.org; s=default; t=1685956321; bh=W39x5Hy2ES1mkq0gyeVAkhyuGwW9bFpBB7hynkrp7ls=; h=To:Cc:Subject:Date:In-Reply-To:References:List-Id: List-Unsubscribe:List-Archive:List-Post:List-Help:List-Subscribe: From:Reply-To:From; b=NGfvjGT3tOqVkcn37hanbGzVI4d4YEnl4ekrxW3VcWl5MrdpbTDAyHWytYlHcTMM6 4kryF7Ec4LS+AbewtTZKjAGBhTSDX4nGgLCn482nNcR4dApsF683a9SLuc2IiU60JP dkid32QRdI9D7cpk5O9ajVhgMbMKC8lF+0wdDADg= X-Original-To: gdb-patches@sourceware.org Delivered-To: gdb-patches@sourceware.org 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 24D5F3858410 for ; Mon, 5 Jun 2023 09:11:20 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.2 sourceware.org 24D5F3858410 Received: from mail-wm1-f71.google.com (mail-wm1-f71.google.com [209.85.128.71]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-624-7Im7weoqOUCVLSHYH9yGEg-1; Mon, 05 Jun 2023 05:11:19 -0400 X-MC-Unique: 7Im7weoqOUCVLSHYH9yGEg-1 Received: by mail-wm1-f71.google.com with SMTP id 5b1f17b1804b1-3f613f5d290so80200415e9.2 for ; Mon, 05 Jun 2023 02:11:18 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1685956277; x=1688548277; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=W39x5Hy2ES1mkq0gyeVAkhyuGwW9bFpBB7hynkrp7ls=; b=Qz3HI6XMPnSV92Aa/8uNz0gdwSlJ5a//3Jg7R3ckd5eOltL/9DygTr7Li44WdQ8JMW Ie46KmQ7i0l/nRlu3T/0xVF1VYkoj96b/M7+QJDTuabj3AXFFBNe19vEcVUf40arLdFl ndMvkYEkZcUejWKoca+N9iaRJAimtqCkNTlFoFsDhILNmCBrzU7a5p9fOZ56E6Q1o3CW pGzLRjVm/mSnHu6BzF/yIysu8sKH6G2tSHIKs6DdGTUs0u8FVcVmeL5NtMqM17l0nivH KYbgvhKOalo/w607U0J26QGmYPfn8ZApXRsz0o8KkwkBoQ+yVGJqTwVED/NBivpn6FzT rSKQ== X-Gm-Message-State: AC+VfDygT20IaNgbUSMfH3So/SSTpgOInDr6KUdBRjtUBbTmA7BadFNU 0exX44iuwi701LID92EgoH582InbcPkvJwntyMtPZxIl8v/pZLm7M5Qd6SfuCLZtEOlDNNGgECv TqJgdHJYMwZTsR9SnOIuyjzj2bthMZWCmqA4ZBgw/5m0LHGHm8+Uqld0AB0ChNT2yCKst9mTMVc wv8VEJGA== X-Received: by 2002:a1c:720c:0:b0:3f5:ce2:9c82 with SMTP id n12-20020a1c720c000000b003f50ce29c82mr7701219wmc.32.1685956277305; Mon, 05 Jun 2023 02:11:17 -0700 (PDT) X-Google-Smtp-Source: ACHHUZ6dYuZHusD5B51wUGsiXmfyCw1X3BNOv3lFUDKtGzkitmlr8sYwU1g0a2ZY5BbKHWRTP/Jmgw== X-Received: by 2002:a1c:720c:0:b0:3f5:ce2:9c82 with SMTP id n12-20020a1c720c000000b003f50ce29c82mr7701188wmc.32.1685956276760; Mon, 05 Jun 2023 02:11:16 -0700 (PDT) Received: from localhost (11.72.115.87.dyn.plus.net. [87.115.72.11]) by smtp.gmail.com with ESMTPSA id q13-20020a05600c46cd00b003f1978bbcd6sm23919533wmo.3.2023.06.05.02.11.16 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 05 Jun 2023 02:11:16 -0700 (PDT) To: gdb-patches@sourceware.org Cc: Andrew Burgess Subject: [PATCH 3/3] gdb: handle core files with .reg/0 section names Date: Mon, 5 Jun 2023 10:11:09 +0100 Message-Id: <889bdea18153917a87db6425e78e1f13a218ee63.1685956034.git.aburgess@redhat.com> X-Mailer: git-send-email 2.25.4 In-Reply-To: References: MIME-Version: 1.0 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com X-Spam-Status: No, score=-11.7 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 X-BeenThere: gdb-patches@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Gdb-patches mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-Patchwork-Original-From: Andrew Burgess via Gdb-patches From: Andrew Burgess Reply-To: Andrew Burgess Errors-To: gdb-patches-bounces+patchwork=sourceware.org@sourceware.org Sender: "Gdb-patches" The previous commit added the test gdb.arch/core-file-pid0.exp which tests GDB's ability to load a core file containing threads with an lwpid of 0, which is something we GDB can encounter when loading a vmcore file -- a core file generated by the Linux kernel. The threads with an lwpid of 0 represents idle cores. While the previous commit added the test, which confirms GDB doesn't crash when confronted with such a core file, there are still some problems with GDB's handling of these core files. These problems all originate from the fact that the core file (once opened by bfd) contains multiple sections called .reg/0, these sections all represents different threads (cpu cores in the original vmcore dump), but GDB gets confused and thinks all of these .reg/0 sections are all referencing the same thread. Here is a GDB session on an x86-64 machine which loads the core file from the gdb.arch/core-file-pid0.exp, this core file contains two threads, both of which have a pid of 0: $ ./gdb/gdb --data-directory ./gdb/data-directory/ -q (gdb) core-file /tmp/x86_64-pid0-core.core [New process 1] [New process 1] Failed to read a valid object file image from memory. Core was generated by `./segv-mt'. Program terminated with signal SIGSEGV, Segmentation fault. The current thread has terminated (gdb) info threads Id Target Id Frame 2 process 1 0x00000000004017c2 in ?? () The current thread has terminated. See `help thread'. (gdb) maintenance info sections Core file: `/tmp/x86_64-pid0-core.core', file type elf64-x86-64. [0] 0x00000000->0x000012d4 at 0x00000318: note0 READONLY HAS_CONTENTS [1] 0x00000000->0x000000d8 at 0x0000039c: .reg/0 HAS_CONTENTS [2] 0x00000000->0x000000d8 at 0x0000039c: .reg HAS_CONTENTS [3] 0x00000000->0x00000080 at 0x0000052c: .note.linuxcore.siginfo/0 HAS_CONTENTS [4] 0x00000000->0x00000080 at 0x0000052c: .note.linuxcore.siginfo HAS_CONTENTS [5] 0x00000000->0x00000140 at 0x000005c0: .auxv HAS_CONTENTS [6] 0x00000000->0x000000a4 at 0x00000714: .note.linuxcore.file/0 HAS_CONTENTS [7] 0x00000000->0x000000a4 at 0x00000714: .note.linuxcore.file HAS_CONTENTS [8] 0x00000000->0x00000200 at 0x000007cc: .reg2/0 HAS_CONTENTS [9] 0x00000000->0x00000200 at 0x000007cc: .reg2 HAS_CONTENTS [10] 0x00000000->0x00000440 at 0x000009e0: .reg-xstate/0 HAS_CONTENTS [11] 0x00000000->0x00000440 at 0x000009e0: .reg-xstate HAS_CONTENTS [12] 0x00000000->0x000000d8 at 0x00000ea4: .reg/0 HAS_CONTENTS [13] 0x00000000->0x00000200 at 0x00000f98: .reg2/0 HAS_CONTENTS [14] 0x00000000->0x00000440 at 0x000011ac: .reg-xstate/0 HAS_CONTENTS [15] 0x00400000->0x00401000 at 0x00002000: load1 ALLOC LOAD READONLY HAS_CONTENTS [16] 0x00401000->0x004b9000 at 0x00003000: load2 ALLOC READONLY CODE [17] 0x004b9000->0x004e5000 at 0x00003000: load3 ALLOC READONLY [18] 0x004e6000->0x004ec000 at 0x00003000: load4 ALLOC LOAD HAS_CONTENTS [19] 0x004ec000->0x004f2000 at 0x00009000: load5 ALLOC LOAD HAS_CONTENTS [20] 0x012a8000->0x012cb000 at 0x0000f000: load6 ALLOC LOAD HAS_CONTENTS [21] 0x7fda77736000->0x7fda77737000 at 0x00032000: load7 ALLOC READONLY [22] 0x7fda77737000->0x7fda77f37000 at 0x00032000: load8 ALLOC LOAD HAS_CONTENTS [23] 0x7ffd55f65000->0x7ffd55f86000 at 0x00832000: load9 ALLOC LOAD HAS_CONTENTS [24] 0x7ffd55fc3000->0x7ffd55fc7000 at 0x00853000: load10 ALLOC LOAD READONLY HAS_CONTENTS [25] 0x7ffd55fc7000->0x7ffd55fc9000 at 0x00857000: load11 ALLOC LOAD READONLY CODE HAS_CONTENTS [26] 0xffffffffff600000->0xffffffffff601000 at 0x00859000: load12 ALLOC LOAD READONLY CODE HAS_CONTENTS (gdb) Notice when the core file is first loaded we see two lines like: [New process 1] And GDB reports: The current thread has terminated Which isn't what we'd expect from a core file -- the core file should only contain threads that are live at the point of the crash, one of which should be the current thread. The above message is reported because GDB has deleted what we think is the current thread! And in the 'info threads' output we are only seeing a single thread, again, this is because GDB has deleted one of the threads. Finally, the 'maintenance info sections' output shows the cause of all our problems, two sections named .reg/0. When GDB sees the first of these it creates a new thread. But, when we see the second .reg/0 GDB tries to create another new thread, but this thread has the same ptid_t as the first thread, so GDB deletes the first thread and creates the second thread in its place. Because both these threads are created with an lwpid of 0 GDB reports these are 'New process NN' rather than 'New LWP NN' which is what we would normally expect. The previous commit includes a little more of the history of GDB support in this area, but these problems were discussed on the mailing list a while ago in this thread: https://inbox.sourceware.org/gdb-patches/AANLkTi=zuEDw6qiZ1jRatkdwHO99xF2Qu+WZ7i0EQjef@mail.gmail.com/ In this commit I propose a solution to these problems. What I propose is that GDB should spot when we have .reg/0 sections and, when these are found, should rename these sections using some unique non-zero lwpid. Note in the above output we also have sections like .reg2/0 and .reg-xstate/0, these are additional register sets, this commit also renumbers these sections inline with their .reg section. The user is warned that some section renumbering has been performed. GDB takes care to ensure that the new numbers assigned are unique and don't clash with any of the pid's that might already be in use -- remember, in a real vmcore file, 0 is used to indicate an idle core, non-idle cores will have the pid of whichever process was running on that core, so we don't want GDB to assign an lwpid that clashes with an actual pid that is in use in the core file. After this commit here's the updated GDB session output: $ ./gdb/gdb --data-directory ./gdb/data-directory/ -q (gdb) core-file /tmp/x86_64-pid0-core.core warning: found threads with pid 0, assigned replacement Target Ids: LWP 1, LWP 2 [New LWP 1] [New LWP 2] Failed to read a valid object file image from memory. Core was generated by `./segv-mt'. Program terminated with signal SIGSEGV, Segmentation fault. #0 0x00000000004017c2 in ?? () [Current thread is 1 (LWP 1)] (gdb) info threads Id Target Id Frame * 1 LWP 1 0x00000000004017c2 in ?? () 2 LWP 2 0x000000000040dda5 in ?? () (gdb) maintenance info sections Core file: `/tmp/x86_64-pid0-core.core', file type elf64-x86-64. [0] 0x00000000->0x000012d4 at 0x00000318: note0 READONLY HAS_CONTENTS [1] 0x00000000->0x000000d8 at 0x0000039c: .reg/1 HAS_CONTENTS [2] 0x00000000->0x000000d8 at 0x0000039c: .reg HAS_CONTENTS [3] 0x00000000->0x00000080 at 0x0000052c: .note.linuxcore.siginfo/1 HAS_CONTENTS [4] 0x00000000->0x00000080 at 0x0000052c: .note.linuxcore.siginfo HAS_CONTENTS [5] 0x00000000->0x00000140 at 0x000005c0: .auxv HAS_CONTENTS [6] 0x00000000->0x000000a4 at 0x00000714: .note.linuxcore.file/1 HAS_CONTENTS [7] 0x00000000->0x000000a4 at 0x00000714: .note.linuxcore.file HAS_CONTENTS [8] 0x00000000->0x00000200 at 0x000007cc: .reg2/1 HAS_CONTENTS [9] 0x00000000->0x00000200 at 0x000007cc: .reg2 HAS_CONTENTS [10] 0x00000000->0x00000440 at 0x000009e0: .reg-xstate/1 HAS_CONTENTS [11] 0x00000000->0x00000440 at 0x000009e0: .reg-xstate HAS_CONTENTS [12] 0x00000000->0x000000d8 at 0x00000ea4: .reg/2 HAS_CONTENTS [13] 0x00000000->0x00000200 at 0x00000f98: .reg2/2 HAS_CONTENTS [14] 0x00000000->0x00000440 at 0x000011ac: .reg-xstate/2 HAS_CONTENTS [15] 0x00400000->0x00401000 at 0x00002000: load1 ALLOC LOAD READONLY HAS_CONTENTS [16] 0x00401000->0x004b9000 at 0x00003000: load2 ALLOC READONLY CODE [17] 0x004b9000->0x004e5000 at 0x00003000: load3 ALLOC READONLY [18] 0x004e6000->0x004ec000 at 0x00003000: load4 ALLOC LOAD HAS_CONTENTS [19] 0x004ec000->0x004f2000 at 0x00009000: load5 ALLOC LOAD HAS_CONTENTS [20] 0x012a8000->0x012cb000 at 0x0000f000: load6 ALLOC LOAD HAS_CONTENTS [21] 0x7fda77736000->0x7fda77737000 at 0x00032000: load7 ALLOC READONLY [22] 0x7fda77737000->0x7fda77f37000 at 0x00032000: load8 ALLOC LOAD HAS_CONTENTS [23] 0x7ffd55f65000->0x7ffd55f86000 at 0x00832000: load9 ALLOC LOAD HAS_CONTENTS [24] 0x7ffd55fc3000->0x7ffd55fc7000 at 0x00853000: load10 ALLOC LOAD READONLY HAS_CONTENTS [25] 0x7ffd55fc7000->0x7ffd55fc9000 at 0x00857000: load11 ALLOC LOAD READONLY CODE HAS_CONTENTS [26] 0xffffffffff600000->0xffffffffff601000 at 0x00859000: load12 ALLOC LOAD READONLY CODE HAS_CONTENTS (gdb) Notice the new warning which is issued when the core file is being loaded. The threads are announced as '[New LWP NN]', and we see two threads in the 'info threads' output. The 'maintenance info sections' output shows the result of the section renaming. The gdb.arch/core-file-pid0.exp test has been update to check for the improved GDB output. Reviewed-by: Kevin Buettner --- gdb/corelow.c | 150 ++++++++++++++++++++++ gdb/testsuite/gdb.arch/core-file-pid0.exp | 12 +- 2 files changed, 161 insertions(+), 1 deletion(-) diff --git a/gdb/corelow.c b/gdb/corelow.c index 7312d40374f..321b2454b5f 100644 --- a/gdb/corelow.c +++ b/gdb/corelow.c @@ -405,6 +405,153 @@ core_file_command (const char *filename, int from_tty) core_target_open (filename, from_tty); } +/* A vmcore file is a core file created by the Linux kernel at the point of + a crash. Each thread in the core file represents a real CPU core, and + the lwpid for each thread is the pid of the process that was running on + that core at the moment of the crash. + + However, not every CPU core will have been running a process, some cores + will be idle. For these idle cores the CPU writes an lwpid of 0. And + of course, multiple cores might be idle, so there could be multiple + threads with an lwpid of 0. + + The problem is GDB doesn't really like threads with an lwpid of 0; GDB + presents such a thread as a process rather than a thread. And GDB + certainly doesn't like multiple threads having the same lwpid, each time + a new thread is seen with the same lwpid the earlier thread (with the + same lwpid) will be deleted. + + This function addresses both of these problems by assigning a fake lwpid + to any thread with an lwpid of 0. + + GDB finds the lwpid information by looking at the bfd section names + which include the lwpid, e.g. .reg/NN where NN is the lwpid. This + function looks though all the section names looking for sections named + .reg/NN. If any sections are found where NN == 0, then we assign a new + unique value of NN. Then, in a second pass, any sections ending /0 are + assigned their new number. + + Remember, a core file may contain multiple register sections for + different register sets, but the sets are always grouped by thread, so + we can figure out which registers should be assigned the same new + lwpid. For example, consider a core file containing: + + .reg/0, .reg2/0, .reg/0, .reg2/0 + + This represents two threads, each thread contains a .reg and .reg2 + register set. The .reg represents the start of each thread. After + renaming the sections will now look like this: + + .reg/1, .reg2/1, .reg/2, .reg2/2 + + After calling this function the rest of the core file handling code can + treat this core file just like any other core file. */ + +static void +rename_vmcore_idle_reg_sections (bfd *abfd, inferior *inf) +{ + /* Map from the bfd section to its lwpid (the /NN number). */ + std::vector> sections_and_lwpids; + + /* The set of all /NN numbers found. Needed so we can easily find unused + numbers in the case that we need to rename some sections. */ + std::unordered_set all_lwpids; + + /* A count of how many sections called .reg/0 we have found. */ + unsigned zero_lwpid_count = 0; + + /* Look for all the .reg sections. Record the section object and the + lwpid which is extracted from the section name. Spot if any have an + lwpid of zero. */ + for (asection *sect : gdb_bfd_sections (core_bfd)) + { + if (startswith (bfd_section_name (sect), ".reg/")) + { + int lwpid = atoi (bfd_section_name (sect) + 5); + sections_and_lwpids.emplace_back (sect, lwpid); + all_lwpids.insert (lwpid); + if (lwpid == 0) + zero_lwpid_count++; + } + } + + /* If every ".reg/NN" section has a non-zero lwpid then we don't need to + do any renaming. */ + if (zero_lwpid_count == 0) + return; + + /* Assign a new number to any .reg sections with an lwpid of 0. */ + int new_lwpid = 1; + for (auto §_and_lwpid : sections_and_lwpids) + if (sect_and_lwpid.second == 0) + { + while (all_lwpids.find (new_lwpid) != all_lwpids.end ()) + new_lwpid++; + sect_and_lwpid.second = new_lwpid; + new_lwpid++; + } + + /* Now update the names of any sections with an lwpid of 0. This is + more than just the .reg sections we originally found. */ + std::string replacement_lwpid_str; + auto iter = sections_and_lwpids.begin (); + int replacement_lwpid = 0; + for (asection *sect : gdb_bfd_sections (core_bfd)) + { + if (iter != sections_and_lwpids.end () && sect == iter->first) + { + gdb_assert (startswith (bfd_section_name (sect), ".reg/")); + + int lwpid = atoi (bfd_section_name (sect) + 5); + if (lwpid == iter->second) + { + /* This section was not given a new number. */ + gdb_assert (lwpid != 0); + replacement_lwpid = 0; + } + else + { + replacement_lwpid = iter->second; + ptid_t ptid (inf->pid, replacement_lwpid); + if (!replacement_lwpid_str.empty ()) + replacement_lwpid_str += ", "; + replacement_lwpid_str += target_pid_to_str (ptid); + } + + iter++; + } + + if (replacement_lwpid != 0) + { + const char *name = bfd_section_name (sect); + size_t len = strlen (name); + + if (strncmp (name + len - 2, "/0", 2) == 0) + { + /* This section needs a new name. */ + std::string name_str + = string_printf ("%.*s/%d", + static_cast (len - 2), + name, replacement_lwpid); + char *name_buf + = static_cast (bfd_alloc (abfd, name_str.size () + 1)); + if (name_buf == nullptr) + error (_("failed to allocate space for section name '%s'"), + name_str.c_str ()); + memcpy (name_buf, name_str.c_str(), name_str.size () + 1); + bfd_rename_section (sect, name_buf); + } + } + } + + if (zero_lwpid_count == 1) + warning (_("found thread with pid 0, assigned replacement Target Id: %s"), + replacement_lwpid_str.c_str ()); + else + warning (_("found threads with pid 0, assigned replacement Target Ids: %s"), + replacement_lwpid_str.c_str ()); +} + /* Locate (and load) an executable file (and symbols) given the core file BFD ABFD. */ @@ -540,6 +687,9 @@ core_target_open (const char *arg, int from_tty) inferior_appeared (inf, pid); inf->fake_pid_p = fake_pid_p; + /* Rename any .reg/0 sections, giving them each a fake lwpid. */ + rename_vmcore_idle_reg_sections (core_bfd, inf); + /* Build up thread list from BFD sections, and possibly set the current thread to the .reg/NN section matching the .reg section. */ diff --git a/gdb/testsuite/gdb.arch/core-file-pid0.exp b/gdb/testsuite/gdb.arch/core-file-pid0.exp index b960dfe095b..6e91111b44b 100644 --- a/gdb/testsuite/gdb.arch/core-file-pid0.exp +++ b/gdb/testsuite/gdb.arch/core-file-pid0.exp @@ -57,7 +57,17 @@ clean_restart # and incorrectly deletes what should be the current thread. gdb_test "core-file ${corefile}" \ [multi_line \ + "warning: found threads with pid 0, assigned replacement Target Ids: LWP 1, LWP 2" \ + ".*" \ "Core was generated by \[^\r\n\]+\\." \ "Program terminated with signal (?:11|SIGSEGV), Segmentation fault\\." \ - "The current thread has terminated"] \ + "#0\\s+$hex in \[^\r\n\]+" \ + "\\\[Current thread is 1 \\(LWP 1\\)\\\]"] \ "check core file termination reason" + +# And check GDB has found both threads. +gdb_test "info threads" \ + [multi_line \ + "\\* 1\\s+LWP 1\\s+$hex in \[^\r\n\]+" \ + " 2\\s+LWP 2\\s+$hex in \[^\r\n\]+"] \ + "check both threads are visible"