From 13010976653675db489292dd4e253af2b5be2557 Mon Sep 17 00:00:00 2001 From: Stefan Liebler Date: Thu, 5 Mar 2020 12:52:19 +0100 Subject: S390: Remove backchain-based fallback and use generic backtrace.c. 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 --------------------------------------- 1 file changed, 148 deletions(-) delete mode 100644 sysdeps/s390/s390-32/backtrace.c (limited to 'sysdeps/s390/s390-32') 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) -- cgit 1.4.1