From patchwork Tue Sep 8 16:46:21 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ian Lance Taylor X-Patchwork-Id: 515448 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from sourceware.org (server1.sourceware.org [209.132.180.131]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id 843F4140187 for ; Wed, 9 Sep 2015 02:46:38 +1000 (AEST) Authentication-Results: ozlabs.org; dkim=pass (1024-bit key; unprotected) header.d=gcc.gnu.org header.i=@gcc.gnu.org header.b=yp2ITQ+z; dkim-atps=neutral DomainKey-Signature: a=rsa-sha1; c=nofws; d=gcc.gnu.org; h=list-id :list-unsubscribe:list-archive:list-post:list-help:sender :mime-version:date:message-id:subject:from:to:content-type; q= dns; s=default; b=yTfgzLIjWe+Au9tBmD0eryhOt5SQKytimEw0Chq4wg9Se4 a2GfQs/opuh3KLe7ueRADuBTs3YN6mDxa6nze7HfH69ZJwgngYHBvbiLPJ91RdjS oTE1qMdS6b5wvlJZQBCEHGPSG5PPkbNqyJm4ZuTygYNIGe+sN3buqcam0z+lg= DKIM-Signature: v=1; a=rsa-sha1; c=relaxed; d=gcc.gnu.org; h=list-id :list-unsubscribe:list-archive:list-post:list-help:sender :mime-version:date:message-id:subject:from:to:content-type; s= default; bh=NM8ZRVGeQWT2RXYnscmGGSxzeBU=; b=yp2ITQ+zNNQZevM8DoNX K6VJpIU144DYQsPQ4x4BjW4pri6pOF2zLIz2V16kszf9W1Z2KJeJGkhuaxJY+0qt NjtR/bkPxLHTdERkQzz7klN013hNy+jR1r/AujlmR8qrPio22QaV3DvG7Xy0jIB5 gyulIA3FqPlmpwXEtPCRTNY= Received: (qmail 75710 invoked by alias); 8 Sep 2015 16:46:26 -0000 Mailing-List: contact gcc-patches-help@gcc.gnu.org; run by ezmlm Precedence: bulk List-Id: List-Unsubscribe: List-Archive: List-Post: List-Help: Sender: gcc-patches-owner@gcc.gnu.org Delivered-To: mailing list gcc-patches@gcc.gnu.org Received: (qmail 75620 invoked by uid 89); 8 Sep 2015 16:46:26 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-1.7 required=5.0 tests=AWL, BAYES_00, KAM_ASCII_DIVIDERS, RCVD_IN_DNSWL_LOW, SPF_PASS, T_RP_MATCHES_RCVD autolearn=ham version=3.3.2 X-HELO: mail-ob0-f178.google.com Received: from mail-ob0-f178.google.com (HELO mail-ob0-f178.google.com) (209.85.214.178) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with (AES128-GCM-SHA256 encrypted) ESMTPS; Tue, 08 Sep 2015 16:46:23 +0000 Received: by obbda8 with SMTP id da8so60037502obb.1 for ; Tue, 08 Sep 2015 09:46:21 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:mime-version:date:message-id:subject:from:to :content-type; bh=cDiyAQN3bApezFw4kIccBauQx+oM1X7rIMFwRWwM1PI=; b=G505m3rO4zH7pf84eszEJu/dkN8QmcRinVY/9alXpw8aEL/xfbJv2HbOQIFipnIifw ftjX+vTNEiQn5QF53ut3LrWhyQKcFrByRUl+GKbT4PjGEinrzSbrLRnWfWTQ/AkZsafA J9uW/18w4Zb98s+DmTWT3RA2l9+E2bS+0F93s0Kk1AVlqkc9NvYLNIlAXTlPTi/YUFTP /Crl7UIQWEn0IZsMlC2xrB2G42Y0nvoYC/T8BcyuXp61WpAKB3Nkqiv/cE5gCI+5VzID V2zmPGy6tqgPCZVtZvMI+jY2HgALJczoHk1AoaZ1Fs/7vEO2ZCIQRyeb3+nXJlvE9cYD /Itw== X-Gm-Message-State: ALoCoQkNpb4Wc87gsei29qmmheLYzR3qMKEEAD9IP1EOS7fLQOsH+8zCvmRVOfmSwckLMXN6RIqx MIME-Version: 1.0 X-Received: by 10.60.131.74 with SMTP id ok10mr21542782oeb.83.1441730781629; Tue, 08 Sep 2015 09:46:21 -0700 (PDT) Received: by 10.60.160.67 with HTTP; Tue, 8 Sep 2015 09:46:21 -0700 (PDT) Date: Tue, 8 Sep 2015 09:46:21 -0700 Message-ID: Subject: libbacktrace patch committed: Graceful fallback if out of memory From: Ian Lance Taylor To: gcc-patches X-IsSubscribed: yes I've committed this libbacktrace patch to mainline to do a graceful fallback if no memory can be allocated. In that case we print out the PC addresses without trying to resolve file/line information. This is imperfect but better than the earlier behaviour of producing a series of error messages. Tested with libbacktrace and Go testsuites. Committed to mainline. Ian 2015-09-08 Ian Lance Taylor PR other/67457 * backtrace.c: #include "internal.h". (struct backtrace_data): Add can_alloc field. (unwind): If can_alloc is false, don't try to get file/line information. (backtrace_full): Set can_alloc field in bdata. * alloc.c (backtrace_alloc): Don't call error_callback if it is NULL. * mmap.c (backtrace_alloc): Likewise. * internal.h: Update comments for backtrace_alloc and backtrace_free. Index: alloc.c =================================================================== --- alloc.c (revision 227528) +++ alloc.c (working copy) @@ -44,7 +44,8 @@ POSSIBILITY OF SUCH DAMAGE. */ backtrace functions may not be safely invoked from a signal handler. */ -/* Allocate memory like malloc. */ +/* Allocate memory like malloc. If ERROR_CALLBACK is NULL, don't + report an error. */ void * backtrace_alloc (struct backtrace_state *state ATTRIBUTE_UNUSED, @@ -55,7 +56,10 @@ backtrace_alloc (struct backtrace_state ret = malloc (size); if (ret == NULL) - error_callback (data, "malloc", errno); + { + if (error_callback) + error_callback (data, "malloc", errno); + } return ret; } Index: backtrace.c =================================================================== --- backtrace.c (revision 227528) +++ backtrace.c (working copy) @@ -34,6 +34,7 @@ POSSIBILITY OF SUCH DAMAGE. */ #include "unwind.h" #include "backtrace.h" +#include "internal.h" /* The main backtrace_full routine. */ @@ -53,6 +54,8 @@ struct backtrace_data void *data; /* Value to return from backtrace_full. */ int ret; + /* Whether there is any memory available. */ + int can_alloc; }; /* Unwind library callback routine. This is passed to @@ -80,8 +83,11 @@ unwind (struct _Unwind_Context *context, if (!ip_before_insn) --pc; - bdata->ret = backtrace_pcinfo (bdata->state, pc, bdata->callback, - bdata->error_callback, bdata->data); + if (!bdata->can_alloc) + bdata->ret = bdata->callback (bdata->data, pc, NULL, 0, NULL); + else + bdata->ret = backtrace_pcinfo (bdata->state, pc, bdata->callback, + bdata->error_callback, bdata->data); if (bdata->ret != 0) return _URC_END_OF_STACK; @@ -96,6 +102,7 @@ backtrace_full (struct backtrace_state * backtrace_error_callback error_callback, void *data) { struct backtrace_data bdata; + void *p; bdata.skip = skip + 1; bdata.state = state; @@ -103,6 +110,18 @@ backtrace_full (struct backtrace_state * bdata.error_callback = error_callback; bdata.data = data; bdata.ret = 0; + + /* If we can't allocate any memory at all, don't try to produce + file/line information. */ + p = backtrace_alloc (state, 4096, NULL, NULL); + if (p == NULL) + bdata.can_alloc = 0; + else + { + backtrace_free (state, p, 4096, NULL, NULL); + bdata.can_alloc = 1; + } + _Unwind_Backtrace (unwind, &bdata); return bdata.ret; } Index: internal.h =================================================================== --- internal.h (revision 227528) +++ internal.h (working copy) @@ -201,13 +201,15 @@ extern int backtrace_close (int descript extern void backtrace_qsort (void *base, size_t count, size_t size, int (*compar) (const void *, const void *)); -/* Allocate memory. This is like malloc. */ +/* Allocate memory. This is like malloc. If ERROR_CALLBACK is NULL, + this does not report an error, it just returns NULL. */ extern void *backtrace_alloc (struct backtrace_state *state, size_t size, backtrace_error_callback error_callback, void *data) ATTRIBUTE_MALLOC; -/* Free memory allocated by backtrace_alloc. */ +/* Free memory allocated by backtrace_alloc. If ERROR_CALLBACK is + NULL, this does not report an error. */ extern void backtrace_free (struct backtrace_state *state, void *mem, size_t size, Index: mmap.c =================================================================== --- mmap.c (revision 227529) +++ mmap.c (working copy) @@ -77,7 +77,8 @@ backtrace_free_locked (struct backtrace_ } } -/* Allocate memory like malloc. */ +/* Allocate memory like malloc. If ERROR_CALLBACK is NULL, don't + report an error. */ void * backtrace_alloc (struct backtrace_state *state, @@ -140,7 +141,10 @@ backtrace_alloc (struct backtrace_state page = mmap (NULL, asksize, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0); if (page == MAP_FAILED) - error_callback (data, "mmap", errno); + { + if (error_callback) + error_callback (data, "mmap", errno); + } else { size = (size + 7) & ~ (size_t) 7;