From patchwork Wed Mar 4 15:03:30 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Stefan Liebler X-Patchwork-Id: 1249061 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=sourceware.org (client-ip=209.132.180.131; helo=sourceware.org; envelope-from=libc-alpha-return-110263-incoming=patchwork.ozlabs.org@sourceware.org; receiver=) Authentication-Results: ozlabs.org; dmarc=none (p=none dis=none) header.from=linux.ibm.com Authentication-Results: ozlabs.org; dkim=pass (1024-bit key; secure) header.d=sourceware.org header.i=@sourceware.org header.a=rsa-sha1 header.s=default header.b=CFpcnl1p; dkim-atps=neutral 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 48XcbM110Lz9sP7 for ; Thu, 5 Mar 2020 02:03:58 +1100 (AEDT) DomainKey-Signature: a=rsa-sha1; c=nofws; d=sourceware.org; h=list-id :list-unsubscribe:list-subscribe:list-archive:list-post :list-help:sender:from:to:cc:subject:date:mime-version :content-transfer-encoding:message-id; q=dns; s=default; b=V7zwr /8X9bR8yY5qxbcZqEWTTspSgB32Sppo/cHmUopO8OCnoF4NFLa1Fm35C07u0UJWl w7Sq3+8q6yzXqVi2wNVmpguGzpxeQEce7oJHl71ag3pEZTj6zjvlWxlDJTON4nnQ wrc9HAN4AMyEKDik9jePcfieXb5IhAqLtzh+h8= DKIM-Signature: v=1; a=rsa-sha1; c=relaxed; d=sourceware.org; h=list-id :list-unsubscribe:list-subscribe:list-archive:list-post :list-help:sender:from:to:cc:subject:date:mime-version :content-transfer-encoding:message-id; s=default; bh=Q+cgi5sXm+v /noN90hFMN6WCdps=; b=CFpcnl1pAAqQmt4ICjIQhqL7n1hNGHvrWut4Uss8kHn tTnmPT2tdkQSMTMf7FUKahWX9rmv1KyLEkV+c+M1K62WFinoiqddLZosUWUkLoNP 26tOa7MDdk1hqQWngHK7APpLX5QlkTbz+Qg/freGewFUvIm9gw5DjMC9ps0a+5P0 = Received: (qmail 22953 invoked by alias); 4 Mar 2020 15:03:52 -0000 Mailing-List: contact libc-alpha-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Unsubscribe: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: libc-alpha-owner@sourceware.org Delivered-To: mailing list libc-alpha@sourceware.org Received: (qmail 22945 invoked by uid 89); 4 Mar 2020 15:03:52 -0000 Authentication-Results: sourceware.org; auth=none X-Spam-SWARE-Status: No, score=-22.4 required=5.0 tests=AWL, BAYES_00, GIT_PATCH_0, GIT_PATCH_1, GIT_PATCH_2, GIT_PATCH_3, KAM_SHORT, RCVD_IN_DNSWL_LOW, SPF_PASS autolearn=ham version=3.3.1 spammy=wwwsourcewareorg, www.sourceware.org, sk:__libc_, sk:wwwsou X-HELO: mx0a-001b2d01.pphosted.com From: Stefan Liebler To: libc-alpha@sourceware.org Cc: Stefan Liebler Subject: [PATCH] S390: Remove backchain-based fallback and use generic backtrace.c. Date: Wed, 4 Mar 2020 16:03:30 +0100 MIME-Version: 1.0 x-cbid: 20030415-0012-0000-0000-0000038D251B X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 20030415-0013-0000-0000-000021C9E0FF Message-Id: <20200304150330.3054553-1-stli@linux.ibm.com> After recent discussions: - "[PATCH] s390: Remove backchain-based fallback from backtrace" https://www.sourceware.org/ml/libc-alpha/2020-02/msg00287.html - "Re: [PATCH 07/11] s390: Implement backtrace on top of " https://www.sourceware.org/ml/libc-alpha/2020-02/msg00637.html We've checked and decided to remove the backchain: We don't know of any environments without libgcc. Thus the backchain unwinder is not used. If somebody builds with -mbackchain and without fasynchronous-unwind-tables and has libgcc installed, then the libgcc unwinder is called but not the backchain-based fallback. This step allows to get rid of the s390x specific backtrace.c files at all. Furthermore the now used debug/backtrace.c version has some more advantages: - Free all resources if necessary. (libc_freeres_fn) - Remove NULL address above _start. - Check whether we make any progress while getting addresses. --- sysdeps/s390/s390-32/backtrace.c | 148 ------------------------------- sysdeps/s390/s390-64/backtrace.c | 147 ------------------------------ 2 files changed, 295 deletions(-) delete mode 100644 sysdeps/s390/s390-32/backtrace.c delete mode 100644 sysdeps/s390/s390-64/backtrace.c diff --git a/sysdeps/s390/s390-32/backtrace.c b/sysdeps/s390/s390-32/backtrace.c deleted file mode 100644 index 497e4f8875..0000000000 --- a/sysdeps/s390/s390-32/backtrace.c +++ /dev/null @@ -1,148 +0,0 @@ -/* Return backtrace of current program state. - Copyright (C) 2000-2020 Free Software Foundation, Inc. - Contributed by Martin Schwidefsky . - This file is part of the GNU C Library. - - The GNU C Library is free software; you can redistribute it and/or - modify it under the terms of the GNU Lesser General Public - License as published by the Free Software Foundation; either - version 2.1 of the License, or (at your option) any later version. - - The GNU C Library 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 - Lesser General Public License for more details. - - You should have received a copy of the GNU Lesser General Public - License along with the GNU C Library; if not, see - . */ - -#include -#include -#include -#include -#include -#include - -/* This is a global variable set at program start time. It marks the - highest used stack address. */ -extern void *__libc_stack_end; - - -/* This is the stack layout we see for every non-leaf function. - size offset - %r15 -> +------------------+ - 4 | back chain | 0 - 4 | end of stack | 4 - 8 | glue | 8 - 8 | scratch | 16 - 40 | save area r6-r15 | 24 - 16 | save area f4,f6 | 64 - 16 | empty | 80 - +------------------+ - r14 in the save area holds the return address. -*/ - -struct layout -{ - int back_chain; - int end_of_stack; - int glue[2]; - int scratch[2]; - int save_grps[10]; - int save_fp[4]; - int empty[2]; -}; - -struct trace_arg -{ - void **array; - int cnt, size; -}; - -#ifdef SHARED -static _Unwind_Reason_Code (*unwind_backtrace) (_Unwind_Trace_Fn, void *); -static _Unwind_Ptr (*unwind_getip) (struct _Unwind_Context *); - -static void -init (void) -{ - void *handle = __libc_dlopen ("libgcc_s.so.1"); - - if (handle == NULL) - return; - - unwind_backtrace = __libc_dlsym (handle, "_Unwind_Backtrace"); - unwind_getip = __libc_dlsym (handle, "_Unwind_GetIP"); - if (unwind_getip == NULL) - unwind_backtrace = NULL; -} - -static int -__backchain_backtrace (void **array, int size) -{ - /* We assume that all the code is generated with frame pointers set. */ - struct layout *stack; - int cnt = 0; - - __asm__ ("LR %0,%%r15" : "=d" (stack) ); - /* We skip the call to this function, it makes no sense to record it. */ - stack = (struct layout *) stack->back_chain; - while (cnt < size) - { - if (stack == NULL || (void *) stack > __libc_stack_end) - /* This means the address is out of range. Note that for the - toplevel we see a frame pointer with value NULL which clearly is - out of range. */ - break; - - array[cnt++] = (void *) (stack->save_grps[8] & 0x7fffffff); - - stack = (struct layout *) stack->back_chain; - } - - return cnt; -} -#else -# define unwind_backtrace _Unwind_Backtrace -# define unwind_getip _Unwind_GetIP -#endif - -static _Unwind_Reason_Code -backtrace_helper (struct _Unwind_Context *ctx, void *a) -{ - struct trace_arg *arg = a; - - /* We are first called with address in the __backtrace function. - Skip it. */ - if (arg->cnt != -1) - arg->array[arg->cnt] = (void *) unwind_getip (ctx); - if (++arg->cnt == arg->size) - return _URC_END_OF_STACK; - return _URC_NO_REASON; -} - -int -__backtrace (void **array, int size) -{ - struct trace_arg arg = { .array = array, .size = size, .cnt = -1 }; - - if (size <= 0) - return 0; - -#ifdef SHARED - __libc_once_define (static, once); - - __libc_once (once, init); - - if (unwind_backtrace == NULL) - return __backchain_backtrace (array, size); -#endif - - unwind_backtrace (backtrace_helper, &arg); - - return arg.cnt != -1 ? arg.cnt : 0; -} - -weak_alias (__backtrace, backtrace) -libc_hidden_def (__backtrace) diff --git a/sysdeps/s390/s390-64/backtrace.c b/sysdeps/s390/s390-64/backtrace.c deleted file mode 100644 index 5d14e01280..0000000000 --- a/sysdeps/s390/s390-64/backtrace.c +++ /dev/null @@ -1,147 +0,0 @@ -/* Return backtrace of current program state. 64 bit S/390 version. - Copyright (C) 2001-2020 Free Software Foundation, Inc. - Contributed by Martin Schwidefsky . - This file is part of the GNU C Library. - - The GNU C Library is free software; you can redistribute it and/or - modify it under the terms of the GNU Lesser General Public - License as published by the Free Software Foundation; either - version 2.1 of the License, or (at your option) any later version. - - The GNU C Library 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 - Lesser General Public License for more details. - - You should have received a copy of the GNU Lesser General Public - License along with the GNU C Library; if not, see - . */ - -#include -#include -#include -#include -#include -#include - - -/* This is a global variable set at program start time. It marks the - highest used stack address. */ -extern void *__libc_stack_end; - - -/* This is the stack layout we see for every non-leaf function. - size offset - %r15 -> +------------------+ - 8 | back chain | 0 - 8 | end of stack | 8 - 32 | scratch | 16 - 80 | save area r6-r15 | 48 - 16 | save area f4,f6 | 128 - 16 | empty | 144 - +------------------+ - r14 in the save area holds the return address. -*/ - -struct layout -{ - long back_chain; - long end_of_stack; - long scratch[4]; - long save_grps[10]; - long save_fp[2]; - long empty[2]; -}; - -struct trace_arg -{ - void **array; - int cnt, size; -}; - -#ifdef SHARED -static _Unwind_Reason_Code (*unwind_backtrace) (_Unwind_Trace_Fn, void *); -static _Unwind_Ptr (*unwind_getip) (struct _Unwind_Context *); - -static void -init (void) -{ - void *handle = __libc_dlopen ("libgcc_s.so.1"); - - if (handle == NULL) - return; - - unwind_backtrace = __libc_dlsym (handle, "_Unwind_Backtrace"); - unwind_getip = __libc_dlsym (handle, "_Unwind_GetIP"); - if (unwind_getip == NULL) - unwind_backtrace = NULL; -} - -static int -__backchain_backtrace (void **array, int size) -{ - /* We assume that all the code is generated with frame pointers set. */ - struct layout *stack; - int cnt = 0; - - __asm__ ("LGR %0,%%r15" : "=d" (stack) ); - /* We skip the call to this function, it makes no sense to record it. */ - stack = (struct layout *) stack->back_chain; - while (cnt < size) - { - if (stack == NULL || (void *) stack > __libc_stack_end) - /* This means the address is out of range. Note that for the - toplevel we see a frame pointer with value NULL which clearly is - out of range. */ - break; - - array[cnt++] = (void *) stack->save_grps[8]; - - stack = (struct layout *) stack->back_chain; - } - - return cnt; -} -#else -# define unwind_backtrace _Unwind_Backtrace -# define unwind_getip _Unwind_GetIP -#endif - -static _Unwind_Reason_Code -backtrace_helper (struct _Unwind_Context *ctx, void *a) -{ - struct trace_arg *arg = a; - - /* We are first called with address in the __backtrace function. - Skip it. */ - if (arg->cnt != -1) - arg->array[arg->cnt] = (void *) unwind_getip (ctx); - if (++arg->cnt == arg->size) - return _URC_END_OF_STACK; - return _URC_NO_REASON; -} - -int -__backtrace (void **array, int size) -{ - struct trace_arg arg = { .array = array, .size = size, .cnt = -1 }; - - if (size <= 0) - return 0; - -#ifdef SHARED - __libc_once_define (static, once); - - __libc_once (once, init); - - if (unwind_backtrace == NULL) - return __backchain_backtrace (array, size); -#endif - - unwind_backtrace (backtrace_helper, &arg); - - return arg.cnt != -1 ? arg.cnt : 0; -} - -weak_alias (__backtrace, backtrace) -libc_hidden_def (__backtrace)