160 lines
4.1 KiB
C
160 lines
4.1 KiB
C
/* Return backtrace of current program state.
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Copyright (C) 2013 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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Contributed by David S. Miller <davem@davemloft.net>
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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 Library General Public License as
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published by the Free Software Foundation; either version 2 of the
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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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Library General Public License for more details.
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You should have received a copy of the GNU Library General Public
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License along with the GNU C Library; see the file COPYING.LIB. If
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not, see <http://www.gnu.org/licenses/>. */
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#include <execinfo.h>
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#include <stddef.h>
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#include <sysdep.h>
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#include <sys/trap.h>
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#include <dlfcn.h>
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#include <unwind.h>
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#include <backtrace.h>
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struct layout
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{
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unsigned long locals[8];
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unsigned long ins[6];
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unsigned long next;
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void *return_address;
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};
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struct trace_arg
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{
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void **array;
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_Unwind_Word cfa;
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int cnt;
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int size;
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};
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#ifdef SHARED
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static _Unwind_Reason_Code (*unwind_backtrace) (_Unwind_Trace_Fn, void *);
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static _Unwind_Ptr (*unwind_getip) (struct _Unwind_Context *);
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static _Unwind_Word (*unwind_getcfa) (struct _Unwind_Context *);
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static void *libgcc_handle;
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/* Dummy version in case libgcc_s does not contain the real code. */
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static _Unwind_Word
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dummy_getcfa (struct _Unwind_Context *ctx __attribute__ ((unused)))
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{
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return 0;
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}
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static void
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init (void)
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{
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libgcc_handle = __libc_dlopen ("libgcc_s.so.1");
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if (libgcc_handle == NULL)
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return;
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unwind_backtrace = __libc_dlsym (libgcc_handle, "_Unwind_Backtrace");
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unwind_getip = __libc_dlsym (libgcc_handle, "_Unwind_GetIP");
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if (unwind_getip == NULL)
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unwind_backtrace = NULL;
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unwind_getcfa = (__libc_dlsym (libgcc_handle, "_Unwind_GetCFA")
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?: dummy_getcfa);
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}
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#else
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# define unwind_backtrace _Unwind_Backtrace
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# define unwind_getip _Unwind_GetIP
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# define unwind_getcfa _Unwind_GetCFA
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#endif
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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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_Unwind_Ptr ip;
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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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{
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ip = unwind_getip (ctx);
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arg->array[arg->cnt] = (void *) ip;
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/* Check whether we make any progress. */
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_Unwind_Word cfa = unwind_getcfa (ctx);
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if (arg->cnt > 0 && arg->array[arg->cnt - 1] == arg->array[arg->cnt]
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&& cfa == arg->cfa)
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return _URC_END_OF_STACK;
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arg->cfa = cfa;
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}
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if (++arg->cnt == arg->size)
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return _URC_END_OF_STACK;
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return _URC_NO_REASON;
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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 = { .array = array, .cfa = 0, .size = size, .cnt = -1 };
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bool use_unwinder;
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int count;
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if (!size)
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return 0;
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use_unwinder = true;
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#ifdef SHARED
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__libc_once_define (static, once);
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__libc_once (once, init);
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if (unwind_backtrace == NULL)
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use_unwinder = false;
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#endif
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if (use_unwinder == false)
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{
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struct layout *current;
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unsigned long fp, i7;
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asm volatile ("mov %%fp, %0" : "=r"(fp));
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asm volatile ("mov %%i7, %0" : "=r"(i7));
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current = (struct layout *) (fp + BACKTRACE_STACK_BIAS);
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array[0] = (void *) i7;
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if (size == 1)
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return 1;
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backtrace_flush_register_windows();
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for (count = 1; count < size; count++)
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{
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array[count] = current->return_address;
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if (!current->next)
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break;
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current = (struct layout *) (current->next + BACKTRACE_STACK_BIAS);
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}
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}
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else
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{
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unwind_backtrace (backtrace_helper, &arg);
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/* _Unwind_Backtrace seems to put NULL address above
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_start. Fix it up here. */
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if (arg.cnt > 1 && arg.array[arg.cnt - 1] == NULL)
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--arg.cnt;
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count = arg.cnt != -1 ? arg.cnt : 0;
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}
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return count;
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}
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weak_alias (__backtrace, backtrace)
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libc_hidden_def (__backtrace)
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