1/* DWARF2 EH unwinding support for PowerPC64 FreeBSD. 2 Copyright (C) 2012-2015 Free Software Foundation, Inc. 3 4 This file is part of GCC. 5 6 GCC is free software; you can redistribute it and/or modify it 7 under the terms of the GNU General Public License as published 8 by the Free Software Foundation; either version 3, or (at your 9 option) any later version. 10 11 GCC is distributed in the hope that it will be useful, but WITHOUT 12 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY 13 or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public 14 License for more details. 15 16 Under Section 7 of GPL version 3, you are granted additional 17 permissions described in the GCC Runtime Library Exception, version 18 3.1, as published by the Free Software Foundation. 19 20 You should have received a copy of the GNU General Public License and 21 a copy of the GCC Runtime Library Exception along with this program; 22 see the files COPYING3 and COPYING.RUNTIME respectively. If not, see 23 <http://www.gnu.org/licenses/>. */ 24 25#define R_LR 65 26 27#define MD_FROB_UPDATE_CONTEXT frob_update_context 28 29static void 30frob_update_context (struct _Unwind_Context *context, 31 _Unwind_FrameState *fs ATTRIBUTE_UNUSED) 32{ 33 const unsigned int *pc = (const unsigned int *) context->ra; 34 35#ifdef __powerpc64__ 36 if (fs->regs.reg[2].how == REG_UNSAVED) 37 { 38 /* If the current unwind info (FS) does not contain explicit info 39 saving R2, then we have to do a minor amount of code reading to 40 figure out if it was saved. The big problem here is that the 41 code that does the save/restore is generated by the linker, so 42 we have no good way to determine at compile time what to do. */ 43 if (pc[0] == 0xF8410028 44 || ((pc[0] & 0xFFFF0000) == 0x3D820000 45 && pc[1] == 0xF8410028)) 46 { 47 /* We are in a plt call stub or r2 adjusting long branch stub, 48 before r2 has been saved. Keep REG_UNSAVED. */ 49 } 50 else 51 { 52 unsigned int *insn 53 = (unsigned int *) _Unwind_GetGR (context, R_LR); 54 if (insn && *insn == 0xE8410028) 55 _Unwind_SetGRPtr (context, 2, context->cfa + 40); 56 else if (pc[0] == 0x4E800421 57 && pc[1] == 0xE8410028) 58 { 59 /* We are at the bctrl instruction in a call via function 60 pointer. gcc always emits the load of the new R2 just 61 before the bctrl so this is the first and only place 62 we need to use the stored R2. */ 63 _Unwind_Word sp = _Unwind_GetGR (context, 1); 64 _Unwind_SetGRPtr (context, 2, (void *)(sp + 40)); 65 } 66 } 67 } 68#endif 69} 70