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 * Copyright 2014 Nexenta Systems, Inc. All rights reserved. 28 */ 29 30 #include <sys/types.h> 31 #include <sys/reg.h> 32 #include <sys/privregs.h> 33 #include <sys/stack.h> 34 #include <sys/frame.h> 35 36 #include <mdb/mdb_ia32util.h> 37 #include <mdb/mdb_target_impl.h> 38 #include <mdb/mdb_kreg_impl.h> 39 #include <mdb/mdb_debug.h> 40 #include <mdb/mdb_modapi.h> 41 #include <mdb/mdb_err.h> 42 #include <mdb/mdb.h> 43 44 /* 45 * We also define an array of register names and their corresponding 46 * array indices. This is used by the getareg and putareg entry points, 47 * and also by our register variable discipline. 48 */ 49 const mdb_tgt_regdesc_t mdb_ia32_kregs[] = { 50 { "savfp", KREG_SAVFP, MDB_TGT_R_EXPORT }, 51 { "savpc", KREG_SAVPC, MDB_TGT_R_EXPORT }, 52 { "eax", KREG_EAX, MDB_TGT_R_EXPORT }, 53 { "ax", KREG_EAX, MDB_TGT_R_EXPORT | MDB_TGT_R_16 }, 54 { "ah", KREG_EAX, MDB_TGT_R_EXPORT | MDB_TGT_R_8H }, 55 { "al", KREG_EAX, MDB_TGT_R_EXPORT | MDB_TGT_R_8L }, 56 { "ebx", KREG_EBX, MDB_TGT_R_EXPORT }, 57 { "bx", KREG_EBX, MDB_TGT_R_EXPORT | MDB_TGT_R_16 }, 58 { "bh", KREG_EBX, MDB_TGT_R_EXPORT | MDB_TGT_R_8H }, 59 { "bl", KREG_EBX, MDB_TGT_R_EXPORT | MDB_TGT_R_8L }, 60 { "ecx", KREG_ECX, MDB_TGT_R_EXPORT }, 61 { "cx", KREG_ECX, MDB_TGT_R_EXPORT | MDB_TGT_R_16 }, 62 { "ch", KREG_ECX, MDB_TGT_R_EXPORT | MDB_TGT_R_8H }, 63 { "cl", KREG_ECX, MDB_TGT_R_EXPORT | MDB_TGT_R_8L }, 64 { "edx", KREG_EDX, MDB_TGT_R_EXPORT }, 65 { "dx", KREG_EDX, MDB_TGT_R_EXPORT | MDB_TGT_R_16 }, 66 { "dh", KREG_EDX, MDB_TGT_R_EXPORT | MDB_TGT_R_8H }, 67 { "dl", KREG_EDX, MDB_TGT_R_EXPORT | MDB_TGT_R_8L }, 68 { "esi", KREG_ESI, MDB_TGT_R_EXPORT }, 69 { "si", KREG_ESI, MDB_TGT_R_EXPORT | MDB_TGT_R_16 }, 70 { "edi", KREG_EDI, MDB_TGT_R_EXPORT }, 71 { "di", EDI, MDB_TGT_R_EXPORT | MDB_TGT_R_16 }, 72 { "ebp", KREG_EBP, MDB_TGT_R_EXPORT }, 73 { "bp", KREG_EBP, MDB_TGT_R_EXPORT | MDB_TGT_R_16 }, 74 { "esp", KREG_ESP, MDB_TGT_R_EXPORT }, 75 { "sp", KREG_ESP, MDB_TGT_R_EXPORT | MDB_TGT_R_16 }, 76 { "cs", KREG_CS, MDB_TGT_R_EXPORT }, 77 { "ds", KREG_DS, MDB_TGT_R_EXPORT }, 78 { "ss", KREG_SS, MDB_TGT_R_EXPORT }, 79 { "es", KREG_ES, MDB_TGT_R_EXPORT }, 80 { "fs", KREG_FS, MDB_TGT_R_EXPORT }, 81 { "gs", KREG_GS, MDB_TGT_R_EXPORT }, 82 { "eflags", KREG_EFLAGS, MDB_TGT_R_EXPORT }, 83 { "eip", KREG_EIP, MDB_TGT_R_EXPORT }, 84 { "uesp", KREG_UESP, MDB_TGT_R_EXPORT | MDB_TGT_R_PRIV }, 85 { "usp", KREG_UESP, MDB_TGT_R_EXPORT | MDB_TGT_R_16 }, 86 { "trapno", KREG_TRAPNO, MDB_TGT_R_EXPORT | MDB_TGT_R_PRIV }, 87 { "err", KREG_ERR, MDB_TGT_R_EXPORT | MDB_TGT_R_PRIV }, 88 { NULL, 0, 0 } 89 }; 90 91 void 92 mdb_ia32_printregs(const mdb_tgt_gregset_t *gregs) 93 { 94 const kreg_t *kregs = &gregs->kregs[0]; 95 kreg_t eflags = kregs[KREG_EFLAGS]; 96 97 mdb_printf("%%cs = 0x%04x\t\t%%eax = 0x%0?p %A\n", 98 kregs[KREG_CS], kregs[KREG_EAX], kregs[KREG_EAX]); 99 100 mdb_printf("%%ds = 0x%04x\t\t%%ebx = 0x%0?p %A\n", 101 kregs[KREG_DS], kregs[KREG_EBX], kregs[KREG_EBX]); 102 103 mdb_printf("%%ss = 0x%04x\t\t%%ecx = 0x%0?p %A\n", 104 kregs[KREG_SS], kregs[KREG_ECX], kregs[KREG_ECX]); 105 106 mdb_printf("%%es = 0x%04x\t\t%%edx = 0x%0?p %A\n", 107 kregs[KREG_ES], kregs[KREG_EDX], kregs[KREG_EDX]); 108 109 mdb_printf("%%fs = 0x%04x\t\t%%esi = 0x%0?p %A\n", 110 kregs[KREG_FS], kregs[KREG_ESI], kregs[KREG_ESI]); 111 112 mdb_printf("%%gs = 0x%04x\t\t%%edi = 0x%0?p %A\n\n", 113 kregs[KREG_GS], kregs[KREG_EDI], kregs[KREG_EDI]); 114 115 mdb_printf("%%eip = 0x%0?p %A\n", kregs[KREG_EIP], kregs[KREG_EIP]); 116 mdb_printf("%%ebp = 0x%0?p\n", kregs[KREG_EBP]); 117 mdb_printf("%%esp = 0x%0?p\n\n", kregs[KREG_ESP]); 118 mdb_printf("%%eflags = 0x%08x\n", eflags); 119 120 mdb_printf(" id=%u vip=%u vif=%u ac=%u vm=%u rf=%u nt=%u iopl=0x%x\n", 121 (eflags & KREG_EFLAGS_ID_MASK) >> KREG_EFLAGS_ID_SHIFT, 122 (eflags & KREG_EFLAGS_VIP_MASK) >> KREG_EFLAGS_VIP_SHIFT, 123 (eflags & KREG_EFLAGS_VIF_MASK) >> KREG_EFLAGS_VIF_SHIFT, 124 (eflags & KREG_EFLAGS_AC_MASK) >> KREG_EFLAGS_AC_SHIFT, 125 (eflags & KREG_EFLAGS_VM_MASK) >> KREG_EFLAGS_VM_SHIFT, 126 (eflags & KREG_EFLAGS_RF_MASK) >> KREG_EFLAGS_RF_SHIFT, 127 (eflags & KREG_EFLAGS_NT_MASK) >> KREG_EFLAGS_NT_SHIFT, 128 (eflags & KREG_EFLAGS_IOPL_MASK) >> KREG_EFLAGS_IOPL_SHIFT); 129 130 mdb_printf(" status=<%s,%s,%s,%s,%s,%s,%s,%s,%s>\n\n", 131 (eflags & KREG_EFLAGS_OF_MASK) ? "OF" : "of", 132 (eflags & KREG_EFLAGS_DF_MASK) ? "DF" : "df", 133 (eflags & KREG_EFLAGS_IF_MASK) ? "IF" : "if", 134 (eflags & KREG_EFLAGS_TF_MASK) ? "TF" : "tf", 135 (eflags & KREG_EFLAGS_SF_MASK) ? "SF" : "sf", 136 (eflags & KREG_EFLAGS_ZF_MASK) ? "ZF" : "zf", 137 (eflags & KREG_EFLAGS_AF_MASK) ? "AF" : "af", 138 (eflags & KREG_EFLAGS_PF_MASK) ? "PF" : "pf", 139 (eflags & KREG_EFLAGS_CF_MASK) ? "CF" : "cf"); 140 141 #ifndef _KMDB 142 mdb_printf(" %%uesp = 0x%0?x\n", kregs[KREG_UESP]); 143 #endif 144 mdb_printf("%%trapno = 0x%x\n", kregs[KREG_TRAPNO]); 145 mdb_printf(" %%err = 0x%x\n", kregs[KREG_ERR]); 146 } 147 148 /* 149 * Given a return address (%eip), determine the likely number of arguments 150 * that were pushed on the stack prior to its execution. We do this by 151 * expecting that a typical call sequence consists of pushing arguments on 152 * the stack, executing a call instruction, and then performing an add 153 * on %esp to restore it to the value prior to pushing the arguments for 154 * the call. We attempt to detect such an add, and divide the addend 155 * by the size of a word to determine the number of pushed arguments. 156 */ 157 static uint_t 158 kvm_argcount(mdb_tgt_t *t, uintptr_t eip, ssize_t size) 159 { 160 uint8_t ins[6]; 161 ulong_t n; 162 163 enum { 164 M_MODRM_ESP = 0xc4, /* Mod/RM byte indicates %esp */ 165 M_ADD_IMM32 = 0x81, /* ADD imm32 to r/m32 */ 166 M_ADD_IMM8 = 0x83 /* ADD imm8 to r/m32 */ 167 }; 168 169 if (mdb_tgt_vread(t, ins, sizeof (ins), eip) != sizeof (ins)) 170 return (0); 171 172 if (ins[1] != M_MODRM_ESP) 173 return (0); 174 175 switch (ins[0]) { 176 case M_ADD_IMM32: 177 n = ins[2] + (ins[3] << 8) + (ins[4] << 16) + (ins[5] << 24); 178 break; 179 180 case M_ADD_IMM8: 181 n = ins[2]; 182 break; 183 184 default: 185 n = 0; 186 } 187 188 return (MIN((ssize_t)n, size) / sizeof (long)); 189 } 190 191 int 192 mdb_ia32_kvm_stack_iter(mdb_tgt_t *t, const mdb_tgt_gregset_t *gsp, 193 mdb_tgt_stack_f *func, void *arg) 194 { 195 mdb_tgt_gregset_t gregs; 196 kreg_t *kregs = &gregs.kregs[0]; 197 int got_pc = (gsp->kregs[KREG_EIP] != 0); 198 int err; 199 200 struct fr { 201 uintptr_t fr_savfp; 202 uintptr_t fr_savpc; 203 long fr_argv[32]; 204 } fr; 205 206 uintptr_t fp = gsp->kregs[KREG_EBP]; 207 uintptr_t pc = gsp->kregs[KREG_EIP]; 208 uintptr_t lastfp = 0; 209 210 ssize_t size; 211 uint_t argc; 212 int detect_exception_frames = 0; 213 int advance_tortoise = 1; 214 uintptr_t tortoise_fp = 0; 215 #ifndef _KMDB 216 int xp; 217 218 if ((mdb_readsym(&xp, sizeof (xp), "xpv_panicking") != -1) && (xp > 0)) 219 detect_exception_frames = 1; 220 #endif 221 222 bcopy(gsp, &gregs, sizeof (gregs)); 223 224 while (fp != 0) { 225 if (fp & (STACK_ALIGN - 1)) { 226 err = EMDB_STKALIGN; 227 goto badfp; 228 } 229 if ((size = mdb_tgt_vread(t, &fr, sizeof (fr), fp)) >= 230 (ssize_t)(2 * sizeof (uintptr_t))) { 231 size -= (ssize_t)(2 * sizeof (uintptr_t)); 232 argc = kvm_argcount(t, fr.fr_savpc, size); 233 } else { 234 err = EMDB_NOMAP; 235 goto badfp; 236 } 237 238 if (tortoise_fp == 0) { 239 tortoise_fp = fp; 240 } else { 241 /* 242 * Advance tortoise_fp every other frame, so we detect 243 * cycles with Floyd's tortoise/hare. 244 */ 245 if (advance_tortoise != 0) { 246 struct fr tfr; 247 248 if (mdb_tgt_vread(t, &tfr, sizeof (tfr), 249 tortoise_fp) != sizeof (tfr)) { 250 err = EMDB_NOMAP; 251 goto badfp; 252 } 253 254 tortoise_fp = tfr.fr_savfp; 255 } 256 257 if (fp == tortoise_fp) { 258 err = EMDB_STKFRAME; 259 goto badfp; 260 } 261 } 262 263 advance_tortoise = !advance_tortoise; 264 265 if (got_pc && func(arg, pc, argc, fr.fr_argv, &gregs) != 0) 266 break; 267 268 kregs[KREG_ESP] = kregs[KREG_EBP]; 269 270 lastfp = fp; 271 fp = fr.fr_savfp; 272 /* 273 * The Xen hypervisor marks a stack frame as belonging to 274 * an exception by inverting the bits of the pointer to 275 * that frame. We attempt to identify these frames by 276 * inverting the pointer and seeing if it is within 0xfff 277 * bytes of the last frame. 278 */ 279 if (detect_exception_frames) 280 if ((fp != 0) && (fp < lastfp) && 281 ((lastfp ^ ~fp) < 0xfff)) 282 fp = ~fp; 283 284 kregs[KREG_EBP] = fp; 285 kregs[KREG_EIP] = pc = fr.fr_savpc; 286 287 got_pc = (pc != 0); 288 } 289 290 return (0); 291 292 badfp: 293 mdb_printf("%p [%s]", fp, mdb_strerror(err)); 294 return (set_errno(err)); 295 } 296 297 /* 298 * Determine the return address for the current frame. Typically this is the 299 * fr_savpc value from the current frame, but we also perform some special 300 * handling to see if we are stopped on one of the first two instructions of a 301 * typical function prologue, in which case %ebp will not be set up yet. 302 */ 303 int 304 mdb_ia32_step_out(mdb_tgt_t *t, uintptr_t *p, kreg_t pc, kreg_t fp, kreg_t sp, 305 mdb_instr_t curinstr) 306 { 307 struct frame fr; 308 GElf_Sym s; 309 char buf[1]; 310 311 enum { 312 M_PUSHL_EBP = 0x55, /* pushl %ebp */ 313 M_MOVL_EBP = 0x8b /* movl %esp, %ebp */ 314 }; 315 316 if (mdb_tgt_lookup_by_addr(t, pc, MDB_TGT_SYM_FUZZY, 317 buf, 0, &s, NULL) == 0) { 318 if (pc == s.st_value && curinstr == M_PUSHL_EBP) 319 fp = sp - 4; 320 else if (pc == s.st_value + 1 && curinstr == M_MOVL_EBP) 321 fp = sp; 322 } 323 324 if (mdb_tgt_vread(t, &fr, sizeof (fr), fp) == sizeof (fr)) { 325 *p = fr.fr_savpc; 326 return (0); 327 } 328 329 return (-1); /* errno is set for us */ 330 } 331 332 /* 333 * Return the address of the next instruction following a call, or return -1 334 * and set errno to EAGAIN if the target should just single-step. We perform 335 * a bit of disassembly on the current instruction in order to determine if it 336 * is a call and how many bytes should be skipped, depending on the exact form 337 * of the call instruction that is being used. 338 */ 339 int 340 mdb_ia32_next(mdb_tgt_t *t, uintptr_t *p, kreg_t pc, mdb_instr_t curinstr) 341 { 342 uint8_t m; 343 344 enum { 345 M_CALL_REL = 0xe8, /* call near with relative displacement */ 346 M_CALL_REG = 0xff, /* call near indirect or call far register */ 347 348 M_MODRM_MD = 0xc0, /* mask for Mod/RM byte Mod field */ 349 M_MODRM_OP = 0x38, /* mask for Mod/RM byte opcode field */ 350 M_MODRM_RM = 0x07, /* mask for Mod/RM byte R/M field */ 351 352 M_MD_IND = 0x00, /* Mod code for [REG] */ 353 M_MD_DSP8 = 0x40, /* Mod code for disp8[REG] */ 354 M_MD_DSP32 = 0x80, /* Mod code for disp32[REG] */ 355 M_MD_REG = 0xc0, /* Mod code for REG */ 356 357 M_OP_IND = 0x10, /* Opcode for call near indirect */ 358 M_RM_DSP32 = 0x05 /* R/M code for disp32 */ 359 }; 360 361 /* 362 * If the opcode is a near call with relative displacement, assume the 363 * displacement is a rel32 from the next instruction. 364 */ 365 if (curinstr == M_CALL_REL) { 366 *p = pc + sizeof (mdb_instr_t) + sizeof (uint32_t); 367 return (0); 368 } 369 370 /* 371 * If the opcode is a call near indirect or call far register opcode, 372 * read the subsequent Mod/RM byte to perform additional decoding. 373 */ 374 if (curinstr == M_CALL_REG) { 375 if (mdb_tgt_vread(t, &m, sizeof (m), pc + 1) != sizeof (m)) 376 return (-1); /* errno is set for us */ 377 378 /* 379 * If the Mod/RM opcode extension indicates a near indirect 380 * call, then skip the appropriate number of additional 381 * bytes depending on the addressing form that is used. 382 */ 383 if ((m & M_MODRM_OP) == M_OP_IND) { 384 switch (m & M_MODRM_MD) { 385 case M_MD_DSP8: 386 *p = pc + 3; /* skip pr_instr, m, disp8 */ 387 break; 388 case M_MD_DSP32: 389 *p = pc + 6; /* skip pr_instr, m, disp32 */ 390 break; 391 case M_MD_IND: 392 if ((m & M_MODRM_RM) == M_RM_DSP32) { 393 *p = pc + 6; 394 break; /* skip pr_instr, m, disp32 */ 395 } 396 /* FALLTHRU */ 397 case M_MD_REG: 398 *p = pc + 2; /* skip pr_instr, m */ 399 break; 400 } 401 return (0); 402 } 403 } 404 405 return (set_errno(EAGAIN)); 406 } 407 408 /*ARGSUSED*/ 409 int 410 mdb_ia32_kvm_frame(void *arglim, uintptr_t pc, uint_t argc, const long *argv, 411 const mdb_tgt_gregset_t *gregs) 412 { 413 argc = MIN(argc, (uint_t)arglim); 414 mdb_printf("%a(", pc); 415 416 if (argc != 0) { 417 mdb_printf("%lr", *argv++); 418 for (argc--; argc != 0; argc--) 419 mdb_printf(", %lr", *argv++); 420 } 421 422 mdb_printf(")\n"); 423 return (0); 424 } 425 426 int 427 mdb_ia32_kvm_framev(void *arglim, uintptr_t pc, uint_t argc, const long *argv, 428 const mdb_tgt_gregset_t *gregs) 429 { 430 argc = MIN(argc, (uint_t)arglim); 431 mdb_printf("%0?lr %a(", gregs->kregs[KREG_EBP], pc); 432 433 if (argc != 0) { 434 mdb_printf("%lr", *argv++); 435 for (argc--; argc != 0; argc--) 436 mdb_printf(", %lr", *argv++); 437 } 438 439 mdb_printf(")\n"); 440 return (0); 441 } 442