1 /* Get previous frame state for an existing frame state. 2 Copyright (C) 2013 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 #include <stdlib.h> 34 #include <assert.h> 35 36 #define BACKEND s390_ 37 #include "libebl_CPU.h" 38 39 /* s390/s390x do not annotate signal handler frame by CFI. It would be also 40 difficult as PC points into a stub built on stack. Function below is called 41 only if unwinder could not find CFI. Function then verifies the register 42 state for this frame really belongs to a signal frame. In such case it 43 fetches original registers saved by the signal frame. */ 44 45 bool 46 s390_unwind (Ebl *ebl, Dwarf_Addr pc, ebl_tid_registers_t *setfunc, 47 ebl_tid_registers_get_t *getfunc, ebl_pid_memory_read_t *readfunc, 48 void *arg, bool *signal_framep) 49 { 50 /* Caller already assumed caller adjustment but S390 instructions are 4 bytes 51 long. Undo it. */ 52 if ((pc & 0x3) != 0x3) 53 return false; 54 pc++; 55 /* We can assume big-endian read here. */ 56 Dwarf_Word instr; 57 if (! readfunc (pc, &instr, arg)) 58 return false; 59 /* Fetch only the very first two bytes. */ 60 instr = (instr >> (ebl->class == ELFCLASS64 ? 48 : 16)) & 0xffff; 61 /* See GDB s390_sigtramp_frame_sniffer. */ 62 /* Check for 'svc' as the first instruction. */ 63 if (((instr >> 8) & 0xff) != 0x0a) 64 return false; 65 /* Check for 'sigreturn' or 'rt_sigreturn' as the second instruction. */ 66 if ((instr & 0xff) != 119 && (instr & 0xff) != 173) 67 return false; 68 /* See GDB s390_sigtramp_frame_unwind_cache. */ 69 Dwarf_Word this_sp; 70 if (! getfunc (0 + 15, 1, &this_sp, arg)) 71 return false; 72 unsigned word_size = ebl->class == ELFCLASS64 ? 8 : 4; 73 Dwarf_Addr next_cfa = this_sp + 16 * word_size + 32; 74 /* "New-style RT frame" is not supported, 75 assuming "Old-style RT frame and all non-RT frames". 76 Pointer to the array of saved registers is at NEXT_CFA + 8. */ 77 Dwarf_Word sigreg_ptr; 78 if (! readfunc (next_cfa + 8, &sigreg_ptr, arg)) 79 return false; 80 /* Skip PSW mask. */ 81 sigreg_ptr += word_size; 82 /* Read PSW address. */ 83 Dwarf_Word val; 84 if (! readfunc (sigreg_ptr, &val, arg)) 85 return false; 86 if (! setfunc (-1, 1, &val, arg)) 87 return false; 88 sigreg_ptr += word_size; 89 /* Then the GPRs. */ 90 Dwarf_Word gprs[16]; 91 for (int i = 0; i < 16; i++) 92 { 93 if (! readfunc (sigreg_ptr, &gprs[i], arg)) 94 return false; 95 sigreg_ptr += word_size; 96 } 97 /* Then the ACRs. Skip them, they are not used in CFI. */ 98 for (int i = 0; i < 16; i++) 99 sigreg_ptr += 4; 100 /* The floating-point control word. */ 101 sigreg_ptr += 8; 102 /* And finally the FPRs. */ 103 Dwarf_Word fprs[16]; 104 for (int i = 0; i < 16; i++) 105 { 106 if (! readfunc (sigreg_ptr, &val, arg)) 107 return false; 108 if (ebl->class == ELFCLASS32) 109 { 110 Dwarf_Addr val_low; 111 if (! readfunc (sigreg_ptr + 4, &val_low, arg)) 112 return false; 113 val = (val << 32) | val_low; 114 } 115 fprs[i] = val; 116 sigreg_ptr += 8; 117 } 118 /* If we have them, the GPR upper halves are appended at the end. */ 119 if (ebl->class == ELFCLASS32) 120 { 121 /* Skip signal number. */ 122 sigreg_ptr += 4; 123 for (int i = 0; i < 16; i++) 124 { 125 if (! readfunc (sigreg_ptr, &val, arg)) 126 return false; 127 Dwarf_Word val_low = gprs[i]; 128 val = (val << 32) | val_low; 129 gprs[i] = val; 130 sigreg_ptr += 4; 131 } 132 } 133 if (! setfunc (0, 16, gprs, arg)) 134 return false; 135 if (! setfunc (16, 16, fprs, arg)) 136 return false; 137 *signal_framep = true; 138 return true; 139 } 140
