1 /* 2 * CDDL HEADER START 3 * 4 * The contents of this file are subject to the terms of the 5 * Common Development and Distribution License (the "License"). 6 * You may not use this file except in compliance with the License. 7 * 8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE 9 * or http://www.opensolaris.org/os/licensing. 10 * See the License for the specific language governing permissions 11 * and limitations under the License. 12 * 13 * When distributing Covered Code, include this CDDL HEADER in each 14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE. 15 * If applicable, add the following below this CDDL HEADER, with the 16 * fields enclosed by brackets "[]" replaced with your own identifying 17 * information: Portions Copyright [yyyy] [name of copyright owner] 18 * 19 * CDDL HEADER END 20 */ 21 /* 22 * Copyright 2007 Sun Microsystems, Inc. All rights reserved. 23 * Use is subject to license terms. 24 */ 25 /* 26 * Copyright (c) 2012, Joyent, Inc. All rights reserved. 27 */ 28 29 #include <sys/types.h> 30 #include <sys/reg.h> 31 #include <sys/privregs.h> 32 #include <sys/stack.h> 33 #include <sys/frame.h> 34 35 #include <mdb/mdb_ia32util.h> 36 #include <mdb/mdb_target_impl.h> 37 #include <mdb/mdb_kreg_impl.h> 38 #include <mdb/mdb_debug.h> 39 #include <mdb/mdb_modapi.h> 40 #include <mdb/mdb_err.h> 41 #include <mdb/mdb.h> 42 43 /* 44 * We also define an array of register names and their corresponding 45 * array indices. This is used by the getareg and putareg entry points, 46 * and also by our register variable discipline. 47 */ 48 const mdb_tgt_regdesc_t mdb_ia32_kregs[] = { 49 { "savfp", KREG_SAVFP, MDB_TGT_R_EXPORT }, 50 { "savpc", KREG_SAVPC, MDB_TGT_R_EXPORT }, 51 { "eax", KREG_EAX, MDB_TGT_R_EXPORT }, 52 { "ax", KREG_EAX, MDB_TGT_R_EXPORT | MDB_TGT_R_16 }, 53 { "ah", KREG_EAX, MDB_TGT_R_EXPORT | MDB_TGT_R_8H }, 54 { "al", KREG_EAX, MDB_TGT_R_EXPORT | MDB_TGT_R_8L }, 55 { "ebx", KREG_EBX, MDB_TGT_R_EXPORT }, 56 { "bx", KREG_EBX, MDB_TGT_R_EXPORT | MDB_TGT_R_16 }, 57 { "bh", KREG_EBX, MDB_TGT_R_EXPORT | MDB_TGT_R_8H }, 58 { "bl", KREG_EBX, MDB_TGT_R_EXPORT | MDB_TGT_R_8L }, 59 { "ecx", KREG_ECX, MDB_TGT_R_EXPORT }, 60 { "cx", KREG_ECX, MDB_TGT_R_EXPORT | MDB_TGT_R_16 }, 61 { "ch", KREG_ECX, MDB_TGT_R_EXPORT | MDB_TGT_R_8H }, 62 { "cl", KREG_ECX, MDB_TGT_R_EXPORT | MDB_TGT_R_8L }, 63 { "edx", KREG_EDX, MDB_TGT_R_EXPORT }, 64 { "dx", KREG_EDX, MDB_TGT_R_EXPORT | MDB_TGT_R_16 }, 65 { "dh", KREG_EDX, MDB_TGT_R_EXPORT | MDB_TGT_R_8H }, 66 { "dl", KREG_EDX, MDB_TGT_R_EXPORT | MDB_TGT_R_8L }, 67 { "esi", KREG_ESI, MDB_TGT_R_EXPORT }, 68 { "si", KREG_ESI, MDB_TGT_R_EXPORT | MDB_TGT_R_16 }, 69 { "edi", KREG_EDI, MDB_TGT_R_EXPORT }, 70 { "di", EDI, MDB_TGT_R_EXPORT | MDB_TGT_R_16 }, 71 { "ebp", KREG_EBP, MDB_TGT_R_EXPORT }, 72 { "bp", KREG_EBP, MDB_TGT_R_EXPORT | MDB_TGT_R_16 }, 73 { "esp", KREG_ESP, MDB_TGT_R_EXPORT }, 74 { "sp", KREG_ESP, MDB_TGT_R_EXPORT | MDB_TGT_R_16 }, 75 { "cs", KREG_CS, MDB_TGT_R_EXPORT }, 76 { "ds", KREG_DS, MDB_TGT_R_EXPORT }, 77 { "ss", KREG_SS, MDB_TGT_R_EXPORT }, 78 { "es", KREG_ES, MDB_TGT_R_EXPORT }, 79 { "fs", KREG_FS, MDB_TGT_R_EXPORT }, 80 { "gs", KREG_GS, MDB_TGT_R_EXPORT }, 81 { "eflags", KREG_EFLAGS, MDB_TGT_R_EXPORT }, 82 { "eip", KREG_EIP, MDB_TGT_R_EXPORT }, 83 { "uesp", KREG_UESP, MDB_TGT_R_EXPORT | MDB_TGT_R_PRIV }, 84 { "usp", KREG_UESP, MDB_TGT_R_EXPORT | MDB_TGT_R_16 }, 85 { "trapno", KREG_TRAPNO, MDB_TGT_R_EXPORT | MDB_TGT_R_PRIV }, 86 { "err", KREG_ERR, MDB_TGT_R_EXPORT | MDB_TGT_R_PRIV }, 87 { NULL, 0, 0 } 88 }; 89 90 void 91 mdb_ia32_printregs(const mdb_tgt_gregset_t *gregs) 92 { 93 const kreg_t *kregs = &gregs->kregs[0]; 94 kreg_t eflags = kregs[KREG_EFLAGS]; 95 96 mdb_printf("%%cs = 0x%04x\t\t%%eax = 0x%0?p %A\n", 97 kregs[KREG_CS], kregs[KREG_EAX], kregs[KREG_EAX]); 98 99 mdb_printf("%%ds = 0x%04x\t\t%%ebx = 0x%0?p %A\n", 100 kregs[KREG_DS], kregs[KREG_EBX], kregs[KREG_EBX]); 101 102 mdb_printf("%%ss = 0x%04x\t\t%%ecx = 0x%0?p %A\n", 103 kregs[KREG_SS], kregs[KREG_ECX], kregs[KREG_ECX]); 104 105 mdb_printf("%%es = 0x%04x\t\t%%edx = 0x%0?p %A\n", 106 kregs[KREG_ES], kregs[KREG_EDX], kregs[KREG_EDX]); 107 108 mdb_printf("%%fs = 0x%04x\t\t%%esi = 0x%0?p %A\n", 109 kregs[KREG_FS], kregs[KREG_ESI], kregs[KREG_ESI]); 110 111 mdb_printf("%%gs = 0x%04x\t\t%%edi = 0x%0?p %A\n\n", 112 kregs[KREG_GS], kregs[KREG_EDI], kregs[KREG_EDI]); 113 114 mdb_printf("%%eip = 0x%0?p %A\n", kregs[KREG_EIP], kregs[KREG_EIP]); 115 mdb_printf("%%ebp = 0x%0?p\n", kregs[KREG_EBP]); 116 mdb_printf("%%esp = 0x%0?p\n\n", kregs[KREG_ESP]); 117 mdb_printf("%%eflags = 0x%08x\n", eflags); 118 119 mdb_printf(" id=%u vip=%u vif=%u ac=%u vm=%u rf=%u nt=%u iopl=0x%x\n", 120 (eflags & KREG_EFLAGS_ID_MASK) >> KREG_EFLAGS_ID_SHIFT, 121 (eflags & KREG_EFLAGS_VIP_MASK) >> KREG_EFLAGS_VIP_SHIFT, 122 (eflags & KREG_EFLAGS_VIF_MASK) >> KREG_EFLAGS_VIF_SHIFT, 123 (eflags & KREG_EFLAGS_AC_MASK) >> KREG_EFLAGS_AC_SHIFT, 124 (eflags & KREG_EFLAGS_VM_MASK) >> KREG_EFLAGS_VM_SHIFT, 125 (eflags & KREG_EFLAGS_RF_MASK) >> KREG_EFLAGS_RF_SHIFT, 126 (eflags & KREG_EFLAGS_NT_MASK) >> KREG_EFLAGS_NT_SHIFT, 127 (eflags & KREG_EFLAGS_IOPL_MASK) >> KREG_EFLAGS_IOPL_SHIFT); 128 129 mdb_printf(" status=<%s,%s,%s,%s,%s,%s,%s,%s,%s>\n\n", 130 (eflags & KREG_EFLAGS_OF_MASK) ? "OF" : "of", 131 (eflags & KREG_EFLAGS_DF_MASK) ? "DF" : "df", 132 (eflags & KREG_EFLAGS_IF_MASK) ? "IF" : "if", 133 (eflags & KREG_EFLAGS_TF_MASK) ? "TF" : "tf", 134 (eflags & KREG_EFLAGS_SF_MASK) ? "SF" : "sf", 135 (eflags & KREG_EFLAGS_ZF_MASK) ? "ZF" : "zf", 136 (eflags & KREG_EFLAGS_AF_MASK) ? "AF" : "af", 137 (eflags & KREG_EFLAGS_PF_MASK) ? "PF" : "pf", 138 (eflags & KREG_EFLAGS_CF_MASK) ? "CF" : "cf"); 139 140 #ifndef _KMDB 141 mdb_printf(" %%uesp = 0x%0?x\n", kregs[KREG_UESP]); 142 #endif 143 mdb_printf("%%trapno = 0x%x\n", kregs[KREG_TRAPNO]); 144 mdb_printf(" %%err = 0x%x\n", kregs[KREG_ERR]); 145 } 146 147 /* 148 * Given a return address (%eip), determine the likely number of arguments 149 * that were pushed on the stack prior to its execution. We do this by 150 * expecting that a typical call sequence consists of pushing arguments on 151 * the stack, executing a call instruction, and then performing an add 152 * on %esp to restore it to the value prior to pushing the arguments for 153 * the call. We attempt to detect such an add, and divide the addend 154 * by the size of a word to determine the number of pushed arguments. 155 */ 156 static uint_t 157 kvm_argcount(mdb_tgt_t *t, uintptr_t eip, ssize_t size) 158 { 159 uint8_t ins[6]; 160 ulong_t n; 161 162 enum { 163 M_MODRM_ESP = 0xc4, /* Mod/RM byte indicates %esp */ 164 M_ADD_IMM32 = 0x81, /* ADD imm32 to r/m32 */ 165 M_ADD_IMM8 = 0x83 /* ADD imm8 to r/m32 */ 166 }; 167 168 if (mdb_tgt_vread(t, ins, sizeof (ins), eip) != sizeof (ins)) 169 return (0); 170 171 if (ins[1] != M_MODRM_ESP) 172 return (0); 173 174 switch (ins[0]) { 175 case M_ADD_IMM32: 176 n = ins[2] + (ins[3] << 8) + (ins[4] << 16) + (ins[5] << 24); 177 break; 178 179 case M_ADD_IMM8: 180 n = ins[2]; 181 break; 182 183 default: 184 n = 0; 185 } 186 187 return (MIN((ssize_t)n, size) / sizeof (long)); 188 } 189 190 int 191 mdb_ia32_kvm_stack_iter(mdb_tgt_t *t, const mdb_tgt_gregset_t *gsp, 192 mdb_tgt_stack_f *func, void *arg) 193 { 194 mdb_tgt_gregset_t gregs; 195 kreg_t *kregs = &gregs.kregs[0]; 196 int got_pc = (gsp->kregs[KREG_EIP] != 0); 197 198 struct { 199 uintptr_t fr_savfp; 200 uintptr_t fr_savpc; 201 long fr_argv[32]; 202 } fr; 203 204 uintptr_t fp = gsp->kregs[KREG_EBP]; 205 uintptr_t pc = gsp->kregs[KREG_EIP]; 206 uintptr_t lastfp; 207 208 ssize_t size; 209 uint_t argc; 210 int detect_exception_frames = 0; 211 #ifndef _KMDB 212 int xp; 213 214 if ((mdb_readsym(&xp, sizeof (xp), "xpv_panicking") != -1) && (xp > 0)) 215 detect_exception_frames = 1; 216 #endif 217 218 bcopy(gsp, &gregs, sizeof (gregs)); 219 220 while (fp != 0) { 221 222 if (fp & (STACK_ALIGN - 1)) 223 return (set_errno(EMDB_STKALIGN)); 224 225 if ((size = mdb_tgt_vread(t, &fr, sizeof (fr), fp)) >= 226 (ssize_t)(2 * sizeof (uintptr_t))) { 227 size -= (ssize_t)(2 * sizeof (uintptr_t)); 228 argc = kvm_argcount(t, fr.fr_savpc, size); 229 } else { 230 bzero(&fr, sizeof (fr)); 231 argc = 0; 232 } 233 234 if (got_pc && func(arg, pc, argc, fr.fr_argv, &gregs) != 0) 235 break; 236 237 kregs[KREG_ESP] = kregs[KREG_EBP]; 238 239 lastfp = fp; 240 fp = fr.fr_savfp; 241 /* 242 * The Xen hypervisor marks a stack frame as belonging to 243 * an exception by inverting the bits of the pointer to 244 * that frame. We attempt to identify these frames by 245 * inverting the pointer and seeing if it is within 0xfff 246 * bytes of the last frame. 247 */ 248 if (detect_exception_frames) 249 if ((fp != 0) && (fp < lastfp) && 250 ((lastfp ^ ~fp) < 0xfff)) 251 fp = ~fp; 252 253 kregs[KREG_EBP] = fp; 254 kregs[KREG_EIP] = pc = fr.fr_savpc; 255 256 got_pc = (pc != 0); 257 } 258 259 return (0); 260 } 261 262 /* 263 * Determine the return address for the current frame. Typically this is the 264 * fr_savpc value from the current frame, but we also perform some special 265 * handling to see if we are stopped on one of the first two instructions of a 266 * typical function prologue, in which case %ebp will not be set up yet. 267 */ 268 int 269 mdb_ia32_step_out(mdb_tgt_t *t, uintptr_t *p, kreg_t pc, kreg_t fp, kreg_t sp, 270 mdb_instr_t curinstr) 271 { 272 struct frame fr; 273 GElf_Sym s; 274 char buf[1]; 275 276 enum { 277 M_PUSHL_EBP = 0x55, /* pushl %ebp */ 278 M_MOVL_EBP = 0x8b /* movl %esp, %ebp */ 279 }; 280 281 if (mdb_tgt_lookup_by_addr(t, pc, MDB_TGT_SYM_FUZZY, 282 buf, 0, &s, NULL) == 0) { 283 if (pc == s.st_value && curinstr == M_PUSHL_EBP) 284 fp = sp - 4; 285 else if (pc == s.st_value + 1 && curinstr == M_MOVL_EBP) 286 fp = sp; 287 } 288 289 if (mdb_tgt_vread(t, &fr, sizeof (fr), fp) == sizeof (fr)) { 290 *p = fr.fr_savpc; 291 return (0); 292 } 293 294 return (-1); /* errno is set for us */ 295 } 296 297 /* 298 * Return the address of the next instruction following a call, or return -1 299 * and set errno to EAGAIN if the target should just single-step. We perform 300 * a bit of disassembly on the current instruction in order to determine if it 301 * is a call and how many bytes should be skipped, depending on the exact form 302 * of the call instruction that is being used. 303 */ 304 int 305 mdb_ia32_next(mdb_tgt_t *t, uintptr_t *p, kreg_t pc, mdb_instr_t curinstr) 306 { 307 uint8_t m; 308 309 enum { 310 M_CALL_REL = 0xe8, /* call near with relative displacement */ 311 M_CALL_REG = 0xff, /* call near indirect or call far register */ 312 313 M_MODRM_MD = 0xc0, /* mask for Mod/RM byte Mod field */ 314 M_MODRM_OP = 0x38, /* mask for Mod/RM byte opcode field */ 315 M_MODRM_RM = 0x07, /* mask for Mod/RM byte R/M field */ 316 317 M_MD_IND = 0x00, /* Mod code for [REG] */ 318 M_MD_DSP8 = 0x40, /* Mod code for disp8[REG] */ 319 M_MD_DSP32 = 0x80, /* Mod code for disp32[REG] */ 320 M_MD_REG = 0xc0, /* Mod code for REG */ 321 322 M_OP_IND = 0x10, /* Opcode for call near indirect */ 323 M_RM_DSP32 = 0x05 /* R/M code for disp32 */ 324 }; 325 326 /* 327 * If the opcode is a near call with relative displacement, assume the 328 * displacement is a rel32 from the next instruction. 329 */ 330 if (curinstr == M_CALL_REL) { 331 *p = pc + sizeof (mdb_instr_t) + sizeof (uint32_t); 332 return (0); 333 } 334 335 /* 336 * If the opcode is a call near indirect or call far register opcode, 337 * read the subsequent Mod/RM byte to perform additional decoding. 338 */ 339 if (curinstr == M_CALL_REG) { 340 if (mdb_tgt_vread(t, &m, sizeof (m), pc + 1) != sizeof (m)) 341 return (-1); /* errno is set for us */ 342 343 /* 344 * If the Mod/RM opcode extension indicates a near indirect 345 * call, then skip the appropriate number of additional 346 * bytes depending on the addressing form that is used. 347 */ 348 if ((m & M_MODRM_OP) == M_OP_IND) { 349 switch (m & M_MODRM_MD) { 350 case M_MD_DSP8: 351 *p = pc + 3; /* skip pr_instr, m, disp8 */ 352 break; 353 case M_MD_DSP32: 354 *p = pc + 6; /* skip pr_instr, m, disp32 */ 355 break; 356 case M_MD_IND: 357 if ((m & M_MODRM_RM) == M_RM_DSP32) { 358 *p = pc + 6; 359 break; /* skip pr_instr, m, disp32 */ 360 } 361 /* FALLTHRU */ 362 case M_MD_REG: 363 *p = pc + 2; /* skip pr_instr, m */ 364 break; 365 } 366 return (0); 367 } 368 } 369 370 return (set_errno(EAGAIN)); 371 } 372 373 /*ARGSUSED*/ 374 int 375 mdb_ia32_kvm_frame(void *arglim, uintptr_t pc, uint_t argc, const long *argv, 376 const mdb_tgt_gregset_t *gregs) 377 { 378 argc = MIN(argc, (uint_t)arglim); 379 mdb_printf("%a(", pc); 380 381 if (argc != 0) { 382 mdb_printf("%lr", *argv++); 383 for (argc--; argc != 0; argc--) 384 mdb_printf(", %lr", *argv++); 385 } 386 387 mdb_printf(")\n"); 388 return (0); 389 } 390 391 int 392 mdb_ia32_kvm_framev(void *arglim, uintptr_t pc, uint_t argc, const long *argv, 393 const mdb_tgt_gregset_t *gregs) 394 { 395 argc = MIN(argc, (uint_t)arglim); 396 mdb_printf("%0?lr %a(", gregs->kregs[KREG_EBP], pc); 397 398 if (argc != 0) { 399 mdb_printf("%lr", *argv++); 400 for (argc--; argc != 0; argc--) 401 mdb_printf(", %lr", *argv++); 402 } 403 404 mdb_printf(")\n"); 405 return (0); 406 } 407