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87 lines
2.5 KiB
C
87 lines
2.5 KiB
C
/* Get previous frame state for an existing frame state.
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Copyright (C) 2016 The Qt Company Ltd.
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This file is part of elfutils.
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This file is free software; you can redistribute it and/or modify
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it under the terms of either
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* the GNU Lesser General Public License as published by the Free
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Software Foundation; either version 3 of the License, or (at
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your option) any later version
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or
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* the GNU General Public License as published by the Free
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Software Foundation; either version 2 of the License, or (at
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your option) any later version
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or both in parallel, as here.
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elfutils is distributed in the hope that it will be useful, but
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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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General Public License for more details.
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You should have received copies of the GNU General Public License and
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the GNU Lesser General Public License along with this program. If
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not, see <http://www.gnu.org/licenses/>. */
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#ifdef HAVE_CONFIG_H
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# include <config.h>
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#endif
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#include <stdlib.h>
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#include <assert.h>
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#define BACKEND x86_64_
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#include "libebl_CPU.h"
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/* There was no CFI. Maybe we happen to have a frame pointer and can unwind from that? */
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bool
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x86_64_unwind (Ebl *ebl __attribute__ ((unused)),
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Dwarf_Addr pc __attribute__ ((unused)),
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ebl_tid_registers_t *setfunc, ebl_tid_registers_get_t *getfunc,
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ebl_pid_memory_read_t *readfunc, void *arg,
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bool *signal_framep __attribute__ ((unused)))
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{
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// Register 6 is supposed to be rbp, thus the conventional frame pointer
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const int fpReg = 6;
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const int spReg = 7;
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Dwarf_Word fp;
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if (!getfunc(fpReg, 1, &fp, arg) || fp == 0)
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return false;
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// Try to read old sp, so that we can avoid infinite loops below
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Dwarf_Word sp;
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if (!getfunc(spReg, 1, &sp, arg))
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sp = 0;
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Dwarf_Word prev_fp;
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if (!readfunc(fp, &prev_fp, arg))
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prev_fp = 0;
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Dwarf_Word ret;
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if (!readfunc(fp + 8, &ret, arg))
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return false;
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if (!setfunc(fpReg, 1, &prev_fp, arg))
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return false;
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fp += 16; // Pop fp and return address and write result to sp
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if (!setfunc(spReg, 1, &fp, arg))
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return false;
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if (!setfunc(-1, 1, &ret, arg))
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return false;
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// If the sp didn't move up we don't actually have a new stack
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// frame but rather some random data that doesn't include frame
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// pointers. Break the unwinding then.
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if (sp >= fp)
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return false;
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return true;
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}
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