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6e05978f0c
MIPS fallback code handle a frame where its FDE can not be obtained (for instance a signal frame) by reading the kernel allocated signal frame and adding '2' to the value of 'sc_pc' [1]. The added value is used to recognize an end of an EH region on mips16 [2]. The fix adjust the obtained signal frame value and remove the libgcc added value by checking if the previous frame is a signal frame one. Checked with backtrace and tst-sigcontext-get_pc tests on mips-linux-gnu and mips64-linux-gnu. [1] libgcc/config/mips/linux-unwind.h from gcc code. [2] gcc/config/mips/mips.h from gcc code. */
140 lines
3.6 KiB
C
140 lines
3.6 KiB
C
/* Return backtrace of current program state.
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Copyright (C) 2003-2020 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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Contributed by Jakub Jelinek <jakub@redhat.com>, 2003.
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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 <libc-lock.h>
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#include <dlfcn.h>
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#include <execinfo.h>
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#include <gnu/lib-names.h>
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#include <stdlib.h>
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#include <unwind.h>
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#include <unwind-arch.h>
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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);
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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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/* 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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arg->array[arg->cnt] = (void *) unwind_getip (ctx);
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if (arg->cnt > 0)
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arg->array[arg->cnt]
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= unwind_arch_adjustment (arg->array[arg->cnt - 1],
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arg->array[arg->cnt]);
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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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if (size <= 0)
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return 0;
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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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return 0;
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#endif
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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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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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#ifdef SHARED
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/* Free all resources if necessary. */
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libc_freeres_fn (free_mem)
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{
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unwind_backtrace = NULL;
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if (libgcc_handle != NULL)
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{
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__libc_dlclose (libgcc_handle);
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libgcc_handle = NULL;
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}
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}
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#endif
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