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 [170.10.129.124]) by sourceware.org (Postfix) with ESMTPS id 362DC3858C78 for ; Wed, 6 Sep 2023 13:40:24 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.2 sourceware.org 362DC3858C78 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=1694007623; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding; bh=U0qn11nT+sZb03AcBS7pKl7Y9V0vIKrq0zqQ0S/hg4M=; b=iUBWDBEwTdlIzR8d1QYGOMLYH2LXWtpazgISvAVKBi/HRuwXAD8cU8bKJ3J/bfzLm0E7hT mEvxj5oH7DMVwr9TCSQNb4oN4xdEwWnQCpJpPNlzoLJAM6955FOrBHaDNY5hOwdu75NKnP i8bzpMpgjz4YnKxwwJURAU2MyRz0jgU= Received: from mimecast-mx02.redhat.com (mx-ext.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-41-JiPwX0krMTGjzzMlgMgFVg-1; Wed, 06 Sep 2023 09:40:20 -0400 X-MC-Unique: JiPwX0krMTGjzzMlgMgFVg-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.rdu2.redhat.com [10.11.54.8]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 4CC062999B34; Wed, 6 Sep 2023 13:40:20 +0000 (UTC) Received: from t14s.localdomain.com (unknown [10.22.34.57]) by smtp.corp.redhat.com (Postfix) with ESMTP id 0ED69C15BB8; Wed, 6 Sep 2023 13:40:20 +0000 (UTC) From: David Malcolm To: gcc-patches@gcc.gnu.org, jit@gcc.gnu.org Cc: antoyo@gcc.gnu.org, David Malcolm Subject: [PATCH] ggc, jit: forcibly clear GTY roots in jit Date: Wed, 6 Sep 2023 09:40:01 -0400 Message-Id: <20230906134001.681629-1-dmalcolm@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.1 on 10.11.54.8 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset="US-ASCII"; x-default=true X-Spam-Status: No, score=-10.9 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,THIS_AD,TXREP autolearn=unavailable autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org List-Id: As part of Antoyo's work on supporting LTO in rustc_codegen_gcc, he noticed an ICE inside libgccjit when compiling certain rust files. Debugging libgccjit showed that outdated information from a previous in-memory compile was referring to ad-hoc locations in the previous compile's line_table. The issue turned out to be the function decls in internal_fn_fnspec_array from the previous compile keeping alive the symtab nodes for these functions, and from this finding other functions in the previous compile, walking their CFGs, and finding ad-hoc data pointers in an edge with a location_t using ad-hoc data from the previous line_table instance, and thus a use-after-free ICE attempting to use this ad-hoc data. Previously in toplev::finalize we've fixed global state "piecemeal" by calling out to individual source_name_cc_finalize functions. However, it occurred to me that we have run-time information on where the GTY-marked pointers are. Hence this patch takes something of a "big hammer" approach by adding a new ggc_common_finalize that walks the GC roots, zeroing all of the pointers. I stepped through this in the debugger and observed that, in particular, this correctly zeroes the internal_fn_fnspec_array at the end of a libgccjit compile. Antoyo reports that this fixes the ICE for him. Doing so uncovered an ICE with libgccjit in dwarf2cfi.cc due to reuse of global variables from the previous compile, which this patch also fixes. I noticed that in ggc_mark_roots when clearing deletable roots we only clear the initial element in each gcc_root_tab_t. This looks like a latent bug to me, which the patch fixes. That said, there don't seem to be any deletable roots where the number of elements != 1. Successfully bootstrapped & regrtested on x86_64-pc-linux-gnu. OK for trunk? Thanks Dave gcc/ChangeLog: * dwarf2cfi.cc (dwarf2cfi_cc_finalize): New. * dwarf2out.h (dwarf2cfi_cc_finalize): New decl. * ggc-common.cc (ggc_mark_roots): Multiply by rti->nelt when clearing the deletable gcc_root_tab_t. (ggc_common_finalize): New. * ggc.h (ggc_common_finalize): New decl. * toplev.cc (toplev::finalize): Call dwarf2cfi_cc_finalize and ggc_common_finalize. --- gcc/dwarf2cfi.cc | 9 +++++++++ gcc/dwarf2out.h | 1 + gcc/ggc-common.cc | 23 ++++++++++++++++++++++- gcc/ggc.h | 2 ++ gcc/toplev.cc | 3 +++ 5 files changed, 37 insertions(+), 1 deletion(-) diff --git a/gcc/dwarf2cfi.cc b/gcc/dwarf2cfi.cc index ddc728f4ad00..f1777c0a4cf1 100644 --- a/gcc/dwarf2cfi.cc +++ b/gcc/dwarf2cfi.cc @@ -3822,4 +3822,13 @@ make_pass_dwarf2_frame (gcc::context *ctxt) return new pass_dwarf2_frame (ctxt); } +void dwarf2cfi_cc_finalize () +{ + add_cfi_insn = NULL; + add_cfi_vec = NULL; + cur_trace = NULL; + cur_row = NULL; + cur_cfa = NULL; +} + #include "gt-dwarf2cfi.h" diff --git a/gcc/dwarf2out.h b/gcc/dwarf2out.h index 870b56a6a372..61a996050ff9 100644 --- a/gcc/dwarf2out.h +++ b/gcc/dwarf2out.h @@ -419,6 +419,7 @@ struct fixed_point_type_info } scale_factor; }; +void dwarf2cfi_cc_finalize (void); void dwarf2out_cc_finalize (void); /* Some DWARF internals are exposed for the needs of DWARF-based debug diff --git a/gcc/ggc-common.cc b/gcc/ggc-common.cc index bed7a9d4d021..95803fa95a17 100644 --- a/gcc/ggc-common.cc +++ b/gcc/ggc-common.cc @@ -86,7 +86,7 @@ ggc_mark_roots (void) for (rt = gt_ggc_deletable_rtab; *rt; rt++) for (rti = *rt; rti->base != NULL; rti++) - memset (rti->base, 0, rti->stride); + memset (rti->base, 0, rti->stride * rti->nelt); for (rt = gt_ggc_rtab; *rt; rt++) ggc_mark_root_tab (*rt); @@ -1293,3 +1293,24 @@ report_heap_memory_use () SIZE_AMOUNT (MALLINFO_FN ().arena)); #endif } + +/* Forcibly clear all GTY roots. */ + +void +ggc_common_finalize () +{ + const struct ggc_root_tab *const *rt; + const_ggc_root_tab_t rti; + + for (rt = gt_ggc_deletable_rtab; *rt; rt++) + for (rti = *rt; rti->base != NULL; rti++) + memset (rti->base, 0, rti->stride * rti->nelt); + + for (rt = gt_ggc_rtab; *rt; rt++) + for (rti = *rt; rti->base != NULL; rti++) + memset (rti->base, 0, rti->stride * rti->nelt); + + for (rt = gt_pch_scalar_rtab; *rt; rt++) + for (rti = *rt; rti->base != NULL; rti++) + memset (rti->base, 0, rti->stride * rti->nelt); +} diff --git a/gcc/ggc.h b/gcc/ggc.h index 34108e2f0061..3280314f8481 100644 --- a/gcc/ggc.h +++ b/gcc/ggc.h @@ -368,4 +368,6 @@ inline void gt_ggc_mx (unsigned long int) { } inline void gt_ggc_mx (long long int) { } inline void gt_ggc_mx (unsigned long long int) { } +extern void ggc_common_finalize (); + #endif diff --git a/gcc/toplev.cc b/gcc/toplev.cc index 6c1a6f443c16..db62e3e995ec 100644 --- a/gcc/toplev.cc +++ b/gcc/toplev.cc @@ -2336,6 +2336,7 @@ toplev::finalize (void) cgraph_cc_finalize (); cgraphunit_cc_finalize (); symtab_thunks_cc_finalize (); + dwarf2cfi_cc_finalize (); dwarf2out_cc_finalize (); gcse_cc_finalize (); ipa_cp_cc_finalize (); @@ -2350,6 +2351,8 @@ toplev::finalize (void) save_decoded_options = NULL; save_decoded_options_count = 0; + ggc_common_finalize (); + /* Clean up the context (and pass_manager etc). */ delete g; g = NULL; -- 2.26.3