1 /* libunwind - a platform-independent unwind library 2 Copyright (C) 2006-2007 IBM 3 Contributed by 4 Corey Ashford <cjashfor (at) us.ibm.com> 5 Jose Flavio Aguilar Paulino <jflavio (at) br.ibm.com> <joseflavio (at) gmail.com> 6 7 This file is part of libunwind. 8 9 Permission is hereby granted, free of charge, to any person obtaining 10 a copy of this software and associated documentation files (the 11 "Software"), to deal in the Software without restriction, including 12 without limitation the rights to use, copy, modify, merge, publish, 13 distribute, sublicense, and/or sell copies of the Software, and to 14 permit persons to whom the Software is furnished to do so, subject to 15 the following conditions: 16 17 The above copyright notice and this permission notice shall be 18 included in all copies or substantial portions of the Software. 19 20 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, 21 EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF 22 MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND 23 NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE 24 LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION 25 OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION 26 WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. */ 27 28 #include <libunwind_i.h> 29 30 PROTECTED int 31 unw_is_signal_frame (unw_cursor_t * cursor) 32 { 33 struct cursor *c = (struct cursor *) cursor; 34 unw_word_t w0, w1, ip; 35 unw_addr_space_t as; 36 unw_accessors_t *a; 37 void *arg; 38 int ret; 39 40 as = c->dwarf.as; 41 as->validate = 1; /* Don't trust the ip */ 42 arg = c->dwarf.as_arg; 43 44 /* Check if return address points at sigreturn sequence. 45 on ppc64 Linux that is (see libc.so): 46 0x38210080 addi r1, r1, 128 // pop the stack 47 0x380000ac li r0, 172 // invoke system service 172 48 0x44000002 sc 49 */ 50 51 ip = c->dwarf.ip; 52 if (ip == 0) 53 return 0; 54 55 /* Read up two 8-byte words at the IP. We are only looking at 3 56 consecutive 32-bit words, so the second 8-byte word needs to be 57 shifted right by 32 bits (think big-endian) */ 58 59 a = unw_get_accessors (as); 60 if ((ret = (*a->access_mem) (as, ip, &w0, 0, arg)) < 0 61 || (ret = (*a->access_mem) (as, ip + 8, &w1, 0, arg)) < 0) 62 return 0; 63 w1 >>= 32; 64 return (w0 == 0x38210080380000ac && w1 == 0x44000002); 65 66 } 67
