From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from simark.ca by simark.ca with LMTP id bDBeFDbbk2BXIQAAWB0awg (envelope-from ) for ; Thu, 06 May 2021 08:04:06 -0400 Received: by simark.ca (Postfix, from userid 112) id 4CF141F11C; Thu, 6 May 2021 08:04:06 -0400 (EDT) X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on simark.ca X-Spam-Level: X-Spam-Status: No, score=-1.0 required=5.0 tests=MAILING_LIST_MULTI, URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.2 Received: from sourceware.org (server2.sourceware.org [8.43.85.97]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by simark.ca (Postfix) with ESMTPS id 52BD11E01F for ; Thu, 6 May 2021 08:04:05 -0400 (EDT) Received: from server2.sourceware.org (localhost [IPv6:::1]) by sourceware.org (Postfix) with ESMTP id 9710038515F4; Thu, 6 May 2021 12:04:04 +0000 (GMT) Received: from mx2.suse.de (mx2.suse.de [195.135.220.15]) by sourceware.org (Postfix) with ESMTPS id 70CCA38515F4 for ; Thu, 6 May 2021 12:04:01 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.3.2 sourceware.org 70CCA38515F4 Authentication-Results: sourceware.org; dmarc=none (p=none dis=none) header.from=suse.de Authentication-Results: sourceware.org; spf=pass smtp.mailfrom=tdevries@suse.de X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 5A0B8B1D6; Thu, 6 May 2021 12:04:00 +0000 (UTC) Date: Thu, 6 May 2021 14:02:49 +0200 From: Tom de Vries To: gdb-patches@sourceware.org Subject: [PATCH][gdb/symtab] Fix infinite recursion in dwarf2_cu::get_builder() Message-ID: <20210506120247.GA1559@delia.home> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.10.1 (2018-07-13) 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: , Cc: Tom Tromey Errors-To: gdb-patches-bounces@sourceware.org Sender: "Gdb-patches" Hi, With the test-case attached in PR26327, gdb aborts: ... $ gdb -q -batch 447.dealII -ex "b main" Aborted (core dumped) ... when running out of stack due to infinite recursion: ... #8 0x00000000006aaba6 in dwarf2_cu::get_builder (this=0x35e4b40) at src/gdb/dwarf2/read.c:700 #9 0x00000000006aaba6 in dwarf2_cu::get_builder (this=0x22ee2c0) at src/gdb/dwarf2/read.c:700 #10 0x00000000006aaba6 in dwarf2_cu::get_builder (this=0x35e4b40) at src/gdb/dwarf2/read.c:700 #11 0x00000000006aaba6 in dwarf2_cu::get_builder (this=0x22ee2c0) at src/gdb/dwarf2/read.c:700 ... We're recursing in this code in dwarf2_cu::get_builder(): ... /* Otherwise, search ancestors for a valid builder. */ if (ancestor != nullptr) return ancestor->get_builder (); ... due to the fact that the ancestor chain is a cycle. Higher up in the call stack, we find some code that is responsible for triggering this, in new_symbol: ... case DW_TAG_formal_parameter: { /* If we are inside a function, mark this as an argument. If not, we might be looking at an argument to an inlined function when we do not have enough information to show inlined frames; pretend it's a local variable in that case so that the user can still see it. */ struct context_stack *curr = cu->get_builder ()->get_current_context_stack (); if (curr != nullptr && curr->name != nullptr) SYMBOL_IS_ARGUMENT (sym) = 1; ... This is code that was added to support pre-4.1 gcc, to be able to show arguments of inlined functions as locals, in the absense of sufficiently correct debug information. Removing this code (that is, doing SYMBOL_IS_ARGUMENT (sym) = 1 unconditially), fixes the crash. The ancestor variable also seems to have been added specifically to deal with fallout from this code, so remove that as well. Tested on x86_64-linux: - openSUSE Leap 15.2 with gcc 7.5.0, and - openSUSE Tumbleweed with gcc 10.3.0. Any comments? Thanks, - Tom [gdb/symtab] Fix infinite recursion in dwarf2_cu::get_builder() gdb/ChangeLog: 2021-05-06 Tom de Vries PR symtab/26327 * dwarf2/read.c (struct dwarf2_cu): Remove ancestor. (dwarf2_cu::get_builder): Remove ancestor-related code. (new_symbol): Remove code supporting pre-4.1 gcc that show arguments of inlined functions as locals. (follow_die_offset, follow_die_sig_1): Remove setting of ancestor. --- gdb/doc/gdb.texinfo | 4 ++-- gdb/dwarf2/read.c | 25 ++----------------------- 2 files changed, 4 insertions(+), 25 deletions(-) diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo index 56f37eb2288..f4d7085da58 100644 --- a/gdb/doc/gdb.texinfo +++ b/gdb/doc/gdb.texinfo @@ -13842,8 +13842,8 @@ when using @sc{dwarf 2}. Versions of @value{NGCC} before 4.1 do not emit two required attributes (@samp{DW_AT_call_file} and @samp{DW_AT_call_line}); @value{GDBN} does not display inlined function calls with earlier versions of @value{NGCC}. It instead -displays the arguments and local variables of inlined functions as -local variables in the caller. +displays local variables of inlined functions as local variables in +the caller. The body of an inlined function is directly included at its call site; unlike a non-inlined function, there are no instructions devoted to diff --git a/gdb/dwarf2/read.c b/gdb/dwarf2/read.c index 5796cf1730b..b2f48f1f395 100644 --- a/gdb/dwarf2/read.c +++ b/gdb/dwarf2/read.c @@ -684,10 +684,6 @@ struct dwarf2_cu struct partial_die_info *find_partial_die (sect_offset sect_off); - /* If this CU was inherited by another CU (via specification, - abstract_origin, etc), this is the ancestor CU. */ - dwarf2_cu *ancestor; - /* Get the buildsym_compunit for this CU. */ buildsym_compunit *get_builder () { @@ -695,10 +691,6 @@ struct dwarf2_cu if (m_builder != nullptr) return m_builder.get (); - /* Otherwise, search ancestors for a valid builder. */ - if (ancestor != nullptr) - return ancestor->get_builder (); - return nullptr; } }; @@ -22045,15 +22037,7 @@ new_symbol (struct die_info *die, struct type *type, struct dwarf2_cu *cu, break; case DW_TAG_formal_parameter: { - /* If we are inside a function, mark this as an argument. If - not, we might be looking at an argument to an inlined function - when we do not have enough information to show inlined frames; - pretend it's a local variable in that case so that the user can - still see it. */ - struct context_stack *curr - = cu->get_builder ()->get_current_context_stack (); - if (curr != nullptr && curr->name != nullptr) - SYMBOL_IS_ARGUMENT (sym) = 1; + SYMBOL_IS_ARGUMENT (sym) = 1; attr = dwarf2_attr (die, DW_AT_location, cu); if (attr != nullptr) { @@ -23389,9 +23373,6 @@ follow_die_offset (sect_offset sect_off, int offset_in_dwz, *ref_cu = target_cu; temp_die.sect_off = sect_off; - if (target_cu != cu) - target_cu->ancestor = cu; - return (struct die_info *) htab_find_with_hash (target_cu->die_hash, &temp_die, to_underlying (sect_off)); @@ -23741,7 +23722,7 @@ follow_die_sig_1 (struct die_info *src_die, struct signatured_type *sig_type, struct dwarf2_cu **ref_cu) { struct die_info temp_die; - struct dwarf2_cu *sig_cu, *cu = *ref_cu; + struct dwarf2_cu *sig_cu; struct die_info *die; dwarf2_per_objfile *per_objfile = (*ref_cu)->per_objfile; @@ -23777,8 +23758,6 @@ follow_die_sig_1 (struct die_info *src_die, struct signatured_type *sig_type, } *ref_cu = sig_cu; - if (sig_cu != cu) - sig_cu->ancestor = cu; return die; }