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118 lines
3.3 KiB
C
118 lines
3.3 KiB
C
/* Return backtrace of current program state.
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Copyright (C) 1998-2021 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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Contributed by Ulrich Drepper <drepper@cygnus.com>, 1998.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<https://www.gnu.org/licenses/>. */
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#include <execinfo.h>
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#include <stdlib.h>
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#include <unwind-link.h>
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struct trace_arg
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{
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void **array;
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struct unwind_link *unwind_link;
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int cnt, size;
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void *lastebp, *lastesp;
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};
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static _Unwind_Reason_Code
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backtrace_helper (struct _Unwind_Context *ctx, void *a)
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{
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struct trace_arg *arg = a;
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/* We are first called with address in the __backtrace function.
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Skip it. */
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if (arg->cnt != -1)
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arg->array[arg->cnt]
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= (void *) UNWIND_LINK_PTR (arg->unwind_link, _Unwind_GetIP) (ctx);
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if (++arg->cnt == arg->size)
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return _URC_END_OF_STACK;
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/* %ebp is DWARF2 register 5 on IA-32. */
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arg->lastebp
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= (void *) UNWIND_LINK_PTR (arg->unwind_link, _Unwind_GetGR) (ctx, 5);
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arg->lastesp
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= (void *) UNWIND_LINK_PTR (arg->unwind_link, _Unwind_GetCFA) (ctx);
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return _URC_NO_REASON;
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}
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/* This is a global variable set at program start time. It marks the
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highest used stack address. */
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extern void *__libc_stack_end;
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/* This is the stack layout we see with every stack frame
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if not compiled without frame pointer.
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+-----------------+ +-----------------+
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%ebp -> | %ebp last frame--------> | %ebp last frame--->...
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| | | |
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| return address | | return address |
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+-----------------+ +-----------------+
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First try as far to get as far as possible using
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_Unwind_Backtrace which handles -fomit-frame-pointer
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as well, but requires .eh_frame info. Then fall back to
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walking the stack manually. */
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struct layout
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{
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struct layout *ebp;
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void *ret;
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};
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int
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__backtrace (void **array, int size)
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{
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struct trace_arg arg =
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{
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.array = array,
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.unwind_link = __libc_unwind_link_get (),
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.size = size,
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.cnt = -1,
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};
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if (size <= 0 || arg.unwind_link == NULL)
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return 0;
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UNWIND_LINK_PTR (arg.unwind_link, _Unwind_Backtrace)
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(backtrace_helper, &arg);
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if (arg.cnt > 1 && arg.array[arg.cnt - 1] == NULL)
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--arg.cnt;
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else if (arg.cnt < size)
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{
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struct layout *ebp = (struct layout *) arg.lastebp;
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while (arg.cnt < size)
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{
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/* Check for out of range. */
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if ((void *) ebp < arg.lastesp || (void *) ebp > __libc_stack_end
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|| ((long) ebp & 3))
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break;
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array[arg.cnt++] = ebp->ret;
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ebp = ebp->ebp;
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}
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}
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return arg.cnt != -1 ? arg.cnt : 0;
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}
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weak_alias (__backtrace, backtrace)
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libc_hidden_def (__backtrace)
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