From patchwork Mon Feb 10 18:04:55 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Florian Weimer X-Patchwork-Id: 1235950 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-109381-incoming=patchwork.ozlabs.org@sourceware.org; receiver=) Authentication-Results: ozlabs.org; dmarc=pass (p=none dis=none) header.from=redhat.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=CUOxud6D; dkim=pass (1024-bit key; unprotected) header.d=redhat.com header.i=@redhat.com header.a=rsa-sha256 header.s=mimecast20190719 header.b=TK0NpK18; 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 48GYjT2ywwz9sPJ for ; Tue, 11 Feb 2020 05:05:33 +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:message-id :mime-version:content-type:content-transfer-encoding; q=dns; s= default; b=oUPXQKECZnRt9D8l74BgH9GFYYfxdkqmBE2rrK9SLNuj1bdKyCtbp wTVOoFQi+imTyvZpJo9YdxGShtDe4VYKqlyXOf+QyQQ+K0Eo9AWFkRF6w1cLhEL8 eqRGZnZ+aeqdINrQ+TO4EXc554frAv6MAPUp9eMfyAOKCfvkfRP7QU= 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:message-id :mime-version:content-type:content-transfer-encoding; s=default; bh=QD3VTfYSQ3FXBbAVnUncK9KexBo=; b=CUOxud6DaP1hKpKm7kXhRntiBHl4 tLDduqW8VqpGxLyV77MIXxUAb6WJ4WnIB87G3u8iIiQPc0cgXihxPr76IBSWGwz9 XEvk55h4Cr1znvs10qmpPhBt0Gtgm5ZJPfrI7V1xpkPNNBknWe+yS/BhvGk1LgI+ x1mW81w93fwzAa0= Received: (qmail 63801 invoked by alias); 10 Feb 2020 18:05:27 -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 63792 invoked by uid 89); 10 Feb 2020 18:05:26 -0000 Authentication-Results: sourceware.org; auth=none X-Spam-SWARE-Status: No, score=-18.5 required=5.0 tests=AWL, BAYES_00, GIT_PATCH_0, GIT_PATCH_1, GIT_PATCH_2, GIT_PATCH_3, KAM_ASCII_DIVIDERS, KAM_SHORT, RCVD_IN_DNSWL_NONE autolearn=ham version=3.3.1 spammy=limitations, 20012020, 2001-2020 X-HELO: us-smtp-1.mimecast.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1581357923; 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=Tes+Y4jQzQIlrH3fDOdxenMIK+O6bf3PjcqA1hvxPJ0=; b=TK0NpK18aB40Ztv5it/x4pVXEdR+MApzbLgIGdj/6XIfAqR+DfUpZzvu+M1hxxeM+REl6X BUioXo19TYmc6oSySEP4EBgQ/ysW6qmmY7zKQXUpHR6mhbzL/UKnyd5wb3KfgcqW8oLKn3 rCM0S0F1UwbVxZG2eTkr371Q8KWyPzs= From: Florian Weimer To: Stefan Liebler Cc: libc-alpha@sourceware.org Subject: [PATCH] s390: Remove backchain-based fallback from backtrace Date: Mon, 10 Feb 2020 19:04:55 +0100 Message-ID: <878slatj20.fsf@oldenburg2.str.redhat.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/26.3 (gnu/linux) MIME-Version: 1.0 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Stefan, do you agree this change is correct? It's not really clear to me how the fallback unwinder can work given its dependency on _Unwind_GetIP. I tested this on s390-linux-gnu and s390x-linux-gnu (but couldn't run the C++ tests on s390 due to test environment limitations). Thanks, Florian 8<------------------------------------------------------------------8< This backtrace variant is used when _Unwind_Backtrace is not found in libgcc_s. It still depends on _Unwind_GetIP from libgcc_s, so it does not work if loading libgcc_s fails. Therefore, as long as libgcc_s provides a definition of _Unwind_Backtrace, the fallback is not useful. After this change, the implementation is the same on s390 and s390x and can be shared. ----- sysdeps/s390/{s390-32 => }/backtrace.c | 58 +------------ sysdeps/s390/s390-64/backtrace.c | 147 --------------------------------- 2 files changed, 1 insertion(+), 204 deletions(-) diff --git a/sysdeps/s390/s390-32/backtrace.c b/sysdeps/s390/backtrace.c similarity index 60% rename from sysdeps/s390/s390-32/backtrace.c rename to sysdeps/s390/backtrace.c index 497e4f8875..5801e5e211 100644 --- a/sysdeps/s390/s390-32/backtrace.c +++ b/sysdeps/s390/backtrace.c @@ -24,36 +24,6 @@ #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; @@ -77,32 +47,6 @@ init (void) 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 @@ -136,7 +80,7 @@ __backtrace (void **array, int size) __libc_once (once, init); if (unwind_backtrace == NULL) - return __backchain_backtrace (array, size); + return 0; #endif unwind_backtrace (backtrace_helper, &arg); 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)