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85 lines
2.5 KiB
85 lines
2.5 KiB
4 months ago
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/* Get previous frame state for an existing frame state using frame pointers.
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Copyright (C) 2017 Red Hat, Inc.
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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 i386_
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#include "libebl_CPU.h"
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/* Register numbers for frame and stack pointers. We take advantage of
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them being next to each other when calling getfunc and setfunc. */
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#define ESP 4
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#define EBP (ESP + 1)
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/* Most basic frame pointer chasing with EBP as frame pointer.
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PC = *(FP + 4), SP = FP + 8, FP = *FP. */
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bool
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i386_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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/* sp = 0, fp = 1 */
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Dwarf_Word regs[2];
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/* Get current stack and frame pointers. */
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if (! getfunc (ESP, 2, regs, arg))
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return false;
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Dwarf_Word sp = regs[0];
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Dwarf_Word fp = regs[1];
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/* Sanity check. We only support traditional stack frames. */
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if (fp == 0 || sp == 0 || fp < sp)
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return false;
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/* Get the return address from the stack, it is our new pc. */
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Dwarf_Word ret_addr;
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if (! readfunc (fp + 4, &ret_addr, arg) || ret_addr == 0)
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return false;
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/* Get new sp and fp. Sanity check again. */
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sp = fp + 8;
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if (! readfunc (fp, &fp, arg) || fp == 0 || sp >= fp)
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return false;
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/* Set new sp, fp and pc. */
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regs[0] = sp;
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regs[1] = fp;
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if (! setfunc (ESP, 2, regs, arg) || ! setfunc (-1, 1, &ret_addr, arg))
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return false;
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return true;
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}
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