1 /* Get previous frame state for an existing frame state. 2 Copyright (C) 2017 Red Hat, Inc. 3 This file is part of elfutils. 4 5 This file is free software; you can redistribute it and/or modify 6 it under the terms of either 7 8 * the GNU Lesser General Public License as published by the Free 9 Software Foundation; either version 3 of the License, or (at 10 your option) any later version 11 12 or 13 14 * the GNU General Public License as published by the Free 15 Software Foundation; either version 2 of the License, or (at 16 your option) any later version 17 18 or both in parallel, as here. 19 20 elfutils is distributed in the hope that it will be useful, but 21 WITHOUT ANY WARRANTY; without even the implied warranty of 22 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 23 General Public License for more details. 24 25 You should have received copies of the GNU General Public License and 26 the GNU Lesser General Public License along with this program. If 27 not, see <http://www.gnu.org/licenses/>. */ 28 29 #ifdef HAVE_CONFIG_H 30 # include <config.h> 31 #endif 32 33 #define BACKEND ppc64_ 34 35 #define LR_REG 65 /* Not 108, see ppc_dwarf_to_regno. */ 36 #define SP_REG 1 37 38 #define LR_OFFSET 16 39 40 #include "libebl_CPU.h" 41 42 /* Simplistic fallback frame unwinder. SP points to the backchain (contains 43 address of previous stack pointer). At SP offset 16 is the LR save area 44 (contains the value of the previous LR). */ 45 46 bool 47 EBLHOOK(unwind) (Ebl *ebl __attribute__ ((unused)), 48 Dwarf_Addr pc __attribute__ ((unused)), 49 ebl_tid_registers_t *setfunc, ebl_tid_registers_get_t *getfunc, 50 ebl_pid_memory_read_t *readfunc, void *arg, 51 bool *signal_framep __attribute__ ((unused))) 52 { 53 Dwarf_Word sp, newSp, lr, newLr; 54 55 /* Stack pointer points to the backchain which contains the previous sp. */ 56 if (! getfunc (SP_REG, 1, &sp, arg)) 57 sp = 0; 58 59 /* Link register contains previous program counter. */ 60 if (! getfunc (LR_REG, 1, &lr, arg) 61 || lr == 0 62 || ! setfunc (-1, 1, &lr, arg)) 63 return false; 64 65 if (! readfunc(sp, &newSp, arg)) 66 newSp = 0; 67 68 if (! readfunc(newSp + LR_OFFSET, &newLr, arg)) 69 newLr = 0; 70 71 setfunc(SP_REG, 1, &newSp, arg); 72 setfunc(LR_REG, 1, &newLr, arg); 73 74 /* Sanity check the stack grows down. */ 75 return newSp > sp; 76 } 77
