1 /* libunwind - a platform-independent unwind library 2 Copyright (C) 2008 CodeSourcery 3 Copyright 2011 Linaro Limited 4 Copyright (C) 2012 Tommi Rantala <tt.rantala (at) gmail.com> 5 6 This file is part of libunwind. 7 8 Permission is hereby granted, free of charge, to any person obtaining 9 a copy of this software and associated documentation files (the 10 "Software"), to deal in the Software without restriction, including 11 without limitation the rights to use, copy, modify, merge, publish, 12 distribute, sublicense, and/or sell copies of the Software, and to 13 permit persons to whom the Software is furnished to do so, subject to 14 the following conditions: 15 16 The above copyright notice and this permission notice shall be 17 included in all copies or substantial portions of the Software. 18 19 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, 20 EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF 21 MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND 22 NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE 23 LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION 24 OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION 25 WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. */ 26 27 #include "unwind_i.h" 28 #include "offsets.h" 29 #include "ex_tables.h" 30 31 #include <signal.h> 32 33 #define arm_exidx_step UNW_OBJ(arm_exidx_step) 34 35 static inline int 36 arm_exidx_step (struct cursor *c) 37 { 38 uint8_t buf[32]; 39 int ret; 40 41 /* mark PC unsaved */ 42 c->dwarf.loc[UNW_ARM_R15] = DWARF_NULL_LOC; 43 44 if ((ret = tdep_find_proc_info (&c->dwarf, c->dwarf.ip, 1)) < 0) 45 return ret; 46 47 if (c->dwarf.pi.format != UNW_INFO_FORMAT_ARM_EXIDX) 48 return -UNW_ENOINFO; 49 50 ret = arm_exidx_extract (&c->dwarf, buf); 51 if (ret == -UNW_ESTOPUNWIND) 52 return 0; 53 else if (ret < 0) 54 return ret; 55 56 ret = arm_exidx_decode (buf, ret, &c->dwarf); 57 if (ret < 0) 58 return ret; 59 60 c->dwarf.pi_valid = 0; 61 62 return (c->dwarf.ip == 0) ? 0 : 1; 63 } 64 65 /* ANDROID support update. */ 66 67 /* When taking a step back up the stack, the pc will point to the next 68 * instruction to execute, not the currently executing instruction. This 69 * function adjusts the pc to the currently executing instruction. 70 */ 71 static void adjust_ip(struct cursor *c) 72 { 73 unw_word_t ip, value; 74 ip = c->dwarf.ip; 75 76 if (ip) 77 { 78 int adjust = 4; 79 if (ip & 1) 80 { 81 /* Thumb instructions, the currently executing instruction could be 82 * 2 or 4 bytes, so adjust appropriately. 83 */ 84 unw_addr_space_t as; 85 unw_accessors_t *a; 86 void *arg; 87 88 as = c->dwarf.as; 89 a = unw_get_accessors (as); 90 arg = c->dwarf.as_arg; 91 92 if (ip < 5 || (*a->access_mem) (as, ip-5, &value, 0, arg) < 0 || 93 (value & 0xe000f000) != 0xe000f000) 94 adjust = 2; 95 } 96 c->dwarf.ip -= adjust; 97 } 98 } 99 /* End of ANDROID update. */ 100 101 PROTECTED int 102 unw_handle_signal_frame (unw_cursor_t *cursor) 103 { 104 struct cursor *c = (struct cursor *) cursor; 105 int ret; 106 unw_word_t sc_addr, sp, sp_addr = c->dwarf.cfa; 107 struct dwarf_loc sp_loc = DWARF_LOC (sp_addr, 0); 108 109 if ((ret = dwarf_get (&c->dwarf, sp_loc, &sp)) < 0) 110 return -UNW_EUNSPEC; 111 112 /* Obtain signal frame type (non-RT or RT). */ 113 ret = unw_is_signal_frame (cursor); 114 115 /* Save the SP and PC to be able to return execution at this point 116 later in time (unw_resume). */ 117 c->sigcontext_sp = c->dwarf.cfa; 118 c->sigcontext_pc = c->dwarf.ip; 119 120 /* Since kernel version 2.6.18 the non-RT signal frame starts with a 121 ucontext while the RT signal frame starts with a siginfo, followed 122 by a sigframe whose first element is an ucontext. 123 Prior 2.6.18 the non-RT signal frame starts with a sigcontext while 124 the RT signal frame starts with two pointers followed by a siginfo 125 and an ucontext. The first pointer points to the start of the siginfo 126 structure and the second one to the ucontext structure. */ 127 128 if (ret == 1) 129 { 130 /* Handle non-RT signal frames. Check if the first word on the stack 131 is the magic number. */ 132 if (sp == 0x5ac3c35a) 133 { 134 c->sigcontext_format = ARM_SCF_LINUX_SIGFRAME; 135 sc_addr = sp_addr + LINUX_UC_MCONTEXT_OFF; 136 } 137 else 138 { 139 c->sigcontext_format = ARM_SCF_LINUX_OLD_SIGFRAME; 140 sc_addr = sp_addr; 141 } 142 } 143 else if (ret == 2) 144 { 145 /* Handle RT signal frames. Check if the first word on the stack is a 146 pointer to the siginfo structure. */ 147 if (sp == sp_addr + 8) 148 { 149 c->sigcontext_format = ARM_SCF_LINUX_OLD_RT_SIGFRAME; 150 sc_addr = sp_addr + 8 + sizeof (siginfo_t) + LINUX_UC_MCONTEXT_OFF; 151 } 152 else 153 { 154 c->sigcontext_format = ARM_SCF_LINUX_RT_SIGFRAME; 155 sc_addr = sp_addr + sizeof (siginfo_t) + LINUX_UC_MCONTEXT_OFF; 156 } 157 } 158 else 159 return -UNW_EUNSPEC; 160 161 c->sigcontext_addr = sc_addr; 162 163 /* Update the dwarf cursor. 164 Set the location of the registers to the corresponding addresses of the 165 uc_mcontext / sigcontext structure contents. */ 166 c->dwarf.loc[UNW_ARM_R0] = DWARF_LOC (sc_addr + LINUX_SC_R0_OFF, 0); 167 c->dwarf.loc[UNW_ARM_R1] = DWARF_LOC (sc_addr + LINUX_SC_R1_OFF, 0); 168 c->dwarf.loc[UNW_ARM_R2] = DWARF_LOC (sc_addr + LINUX_SC_R2_OFF, 0); 169 c->dwarf.loc[UNW_ARM_R3] = DWARF_LOC (sc_addr + LINUX_SC_R3_OFF, 0); 170 c->dwarf.loc[UNW_ARM_R4] = DWARF_LOC (sc_addr + LINUX_SC_R4_OFF, 0); 171 c->dwarf.loc[UNW_ARM_R5] = DWARF_LOC (sc_addr + LINUX_SC_R5_OFF, 0); 172 c->dwarf.loc[UNW_ARM_R6] = DWARF_LOC (sc_addr + LINUX_SC_R6_OFF, 0); 173 c->dwarf.loc[UNW_ARM_R7] = DWARF_LOC (sc_addr + LINUX_SC_R7_OFF, 0); 174 c->dwarf.loc[UNW_ARM_R8] = DWARF_LOC (sc_addr + LINUX_SC_R8_OFF, 0); 175 c->dwarf.loc[UNW_ARM_R9] = DWARF_LOC (sc_addr + LINUX_SC_R9_OFF, 0); 176 c->dwarf.loc[UNW_ARM_R10] = DWARF_LOC (sc_addr + LINUX_SC_R10_OFF, 0); 177 c->dwarf.loc[UNW_ARM_R11] = DWARF_LOC (sc_addr + LINUX_SC_FP_OFF, 0); 178 c->dwarf.loc[UNW_ARM_R12] = DWARF_LOC (sc_addr + LINUX_SC_IP_OFF, 0); 179 c->dwarf.loc[UNW_ARM_R13] = DWARF_LOC (sc_addr + LINUX_SC_SP_OFF, 0); 180 c->dwarf.loc[UNW_ARM_R14] = DWARF_LOC (sc_addr + LINUX_SC_LR_OFF, 0); 181 c->dwarf.loc[UNW_ARM_R15] = DWARF_LOC (sc_addr + LINUX_SC_PC_OFF, 0); 182 183 /* Set SP/CFA and PC/IP. */ 184 dwarf_get (&c->dwarf, c->dwarf.loc[UNW_ARM_R13], &c->dwarf.cfa); 185 dwarf_get (&c->dwarf, c->dwarf.loc[UNW_ARM_R15], &c->dwarf.ip); 186 187 c->dwarf.pi_valid = 0; 188 189 return 1; 190 } 191 192 PROTECTED int 193 unw_step (unw_cursor_t *cursor) 194 { 195 struct cursor *c = (struct cursor *) cursor; 196 int ret = -UNW_EUNSPEC; 197 198 Debug (1, "(cursor=%p)\n", c); 199 200 unw_word_t old_ip = c->dwarf.ip; 201 unw_word_t old_cfa = c->dwarf.cfa; 202 203 /* Check if this is a signal frame. */ 204 if (unw_is_signal_frame (cursor)) 205 { 206 ret = unw_handle_signal_frame (cursor); 207 } 208 209 #ifdef CONFIG_DEBUG_FRAME 210 /* First, try DWARF-based unwinding. */ 211 if (ret < 0 && UNW_TRY_METHOD(UNW_ARM_METHOD_DWARF)) 212 { 213 ret = dwarf_step (&c->dwarf); 214 Debug(1, "dwarf_step()=%d\n", ret); 215 216 if (likely (ret > 0)) 217 ret = 1; 218 else if (unlikely (ret == -UNW_ESTOPUNWIND)) 219 ret = 0; 220 } 221 #endif /* CONFIG_DEBUG_FRAME */ 222 223 /* Next, try extbl-based unwinding. */ 224 if (ret < 0 && UNW_TRY_METHOD (UNW_ARM_METHOD_EXIDX)) 225 { 226 ret = arm_exidx_step (c); 227 if (ret > 0) 228 ret = 1; 229 if (ret == -UNW_ESTOPUNWIND || ret == 0) 230 ret = 0; 231 } 232 233 /* Fall back on APCS frame parsing. 234 Note: This won't work in case the ARM EABI is used. */ 235 if (unlikely (ret < 0)) 236 { 237 if (UNW_TRY_METHOD(UNW_ARM_METHOD_FRAME)) 238 { 239 ret = UNW_ESUCCESS; 240 /* DWARF unwinding failed, try to follow APCS/optimized APCS frame chain */ 241 unw_word_t instr, i; 242 Debug (13, "dwarf_step() failed (ret=%d), trying frame-chain\n", ret); 243 dwarf_loc_t ip_loc, fp_loc; 244 unw_word_t frame; 245 /* Mark all registers unsaved, since we don't know where 246 they are saved (if at all), except for the EBP and 247 EIP. */ 248 if (dwarf_get(&c->dwarf, c->dwarf.loc[UNW_ARM_R11], &frame) < 0) 249 { 250 return 0; 251 } 252 for (i = 0; i < DWARF_NUM_PRESERVED_REGS; ++i) { 253 c->dwarf.loc[i] = DWARF_NULL_LOC; 254 } 255 if (frame) 256 { 257 if (dwarf_get(&c->dwarf, DWARF_LOC(frame, 0), &instr) < 0) 258 { 259 return 0; 260 } 261 instr -= 8; 262 if (dwarf_get(&c->dwarf, DWARF_LOC(instr, 0), &instr) < 0) 263 { 264 return 0; 265 } 266 if ((instr & 0xFFFFD800) == 0xE92DD800) 267 { 268 /* Standard APCS frame. */ 269 ip_loc = DWARF_LOC(frame - 4, 0); 270 fp_loc = DWARF_LOC(frame - 12, 0); 271 } 272 else 273 { 274 /* Codesourcery optimized normal frame. */ 275 ip_loc = DWARF_LOC(frame, 0); 276 fp_loc = DWARF_LOC(frame - 4, 0); 277 } 278 if (dwarf_get(&c->dwarf, ip_loc, &c->dwarf.ip) < 0) 279 { 280 return 0; 281 } 282 c->dwarf.loc[UNW_ARM_R12] = ip_loc; 283 c->dwarf.loc[UNW_ARM_R11] = fp_loc; 284 c->dwarf.pi_valid = 0; 285 Debug(15, "ip=%x\n", c->dwarf.ip); 286 } 287 else 288 { 289 ret = -UNW_ENOINFO; 290 } 291 } 292 } 293 294 /* ANDROID support update. */ 295 if (ret < 0 && UNW_TRY_METHOD(UNW_ARM_METHOD_LR) && c->dwarf.frame == 0) 296 { 297 /* If this is the first frame, the code may be executing garbage 298 * in the middle of nowhere. In this case, try using the lr as 299 * the pc. 300 */ 301 unw_word_t lr; 302 if (dwarf_get(&c->dwarf, c->dwarf.loc[UNW_ARM_R14], &lr) >= 0) 303 { 304 if (lr != c->dwarf.ip) 305 { 306 ret = 1; 307 c->dwarf.ip = lr; 308 } 309 } 310 } 311 /* End of ANDROID update. */ 312 313 if (ret >= 0) 314 { 315 adjust_ip(c); 316 if (c->dwarf.ip == old_ip && c->dwarf.cfa == old_cfa) 317 { 318 Dprintf ("%s: ip and cfa unchanged; stopping here (ip=0x%lx)\n", 319 __FUNCTION__, (long) c->dwarf.ip); 320 return -UNW_EBADFRAME; 321 } 322 c->dwarf.frame++; 323 } 324 return ret == -UNW_ENOINFO ? 0 : ret; 325 } 326
