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) 2018, Joyent, Inc. All rights reserved.
27 * Copyright 2014 Nexenta Systems, Inc. All rights reserved.
28 */
29
30 #include <sys/types.h>
31 #include <sys/types32.h>
32 #include <sys/reg.h>
33 #include <sys/privregs.h>
34 #include <sys/stack.h>
35 #include <sys/frame.h>
36
37 #include <mdb/mdb_isautil.h>
38 #include <mdb/mdb_ia32util.h>
39 #include <mdb/mdb_target_impl.h>
40 #include <mdb/mdb_kreg_impl.h>
41 #include <mdb/mdb_debug.h>
42 #include <mdb/mdb_modapi.h>
43 #include <mdb/mdb_err.h>
44 #include <mdb/mdb.h>
45
46 #ifndef __amd64
47 /*
48 * We also define an array of register names and their corresponding
49 * array indices. This is used by the getareg and putareg entry points,
50 * and also by our register variable discipline.
51 *
52 * When built into an amd64 mdb this won't be used as it's only a subset of
53 * mdb_amd64_kregs, hence the #ifdef.
54 */
55 const mdb_tgt_regdesc_t mdb_ia32_kregs[] = {
56 { "savfp", KREG_SAVFP, MDB_TGT_R_EXPORT },
57 { "savpc", KREG_SAVPC, MDB_TGT_R_EXPORT },
58 { "eax", KREG_EAX, MDB_TGT_R_EXPORT },
59 { "ax", KREG_EAX, MDB_TGT_R_EXPORT | MDB_TGT_R_16 },
60 { "ah", KREG_EAX, MDB_TGT_R_EXPORT | MDB_TGT_R_8H },
61 { "al", KREG_EAX, MDB_TGT_R_EXPORT | MDB_TGT_R_8L },
62 { "ebx", KREG_EBX, MDB_TGT_R_EXPORT },
63 { "bx", KREG_EBX, MDB_TGT_R_EXPORT | MDB_TGT_R_16 },
64 { "bh", KREG_EBX, MDB_TGT_R_EXPORT | MDB_TGT_R_8H },
65 { "bl", KREG_EBX, MDB_TGT_R_EXPORT | MDB_TGT_R_8L },
66 { "ecx", KREG_ECX, MDB_TGT_R_EXPORT },
67 { "cx", KREG_ECX, MDB_TGT_R_EXPORT | MDB_TGT_R_16 },
68 { "ch", KREG_ECX, MDB_TGT_R_EXPORT | MDB_TGT_R_8H },
69 { "cl", KREG_ECX, MDB_TGT_R_EXPORT | MDB_TGT_R_8L },
70 { "edx", KREG_EDX, MDB_TGT_R_EXPORT },
71 { "dx", KREG_EDX, MDB_TGT_R_EXPORT | MDB_TGT_R_16 },
72 { "dh", KREG_EDX, MDB_TGT_R_EXPORT | MDB_TGT_R_8H },
73 { "dl", KREG_EDX, MDB_TGT_R_EXPORT | MDB_TGT_R_8L },
74 { "esi", KREG_ESI, MDB_TGT_R_EXPORT },
75 { "si", KREG_ESI, MDB_TGT_R_EXPORT | MDB_TGT_R_16 },
76 { "edi", KREG_EDI, MDB_TGT_R_EXPORT },
77 { "di", EDI, MDB_TGT_R_EXPORT | MDB_TGT_R_16 },
78 { "ebp", KREG_EBP, MDB_TGT_R_EXPORT },
79 { "bp", KREG_EBP, MDB_TGT_R_EXPORT | MDB_TGT_R_16 },
80 { "esp", KREG_ESP, MDB_TGT_R_EXPORT },
81 { "sp", KREG_ESP, MDB_TGT_R_EXPORT | MDB_TGT_R_16 },
82 { "cs", KREG_CS, MDB_TGT_R_EXPORT },
83 { "ds", KREG_DS, MDB_TGT_R_EXPORT },
84 { "ss", KREG_SS, MDB_TGT_R_EXPORT },
85 { "es", KREG_ES, MDB_TGT_R_EXPORT },
86 { "fs", KREG_FS, MDB_TGT_R_EXPORT },
87 { "gs", KREG_GS, MDB_TGT_R_EXPORT },
88 { "eflags", KREG_EFLAGS, MDB_TGT_R_EXPORT },
89 { "eip", KREG_EIP, MDB_TGT_R_EXPORT },
90 { "uesp", KREG_UESP, MDB_TGT_R_EXPORT | MDB_TGT_R_PRIV },
91 { "usp", KREG_UESP, MDB_TGT_R_EXPORT | MDB_TGT_R_16 },
92 { "trapno", KREG_TRAPNO, MDB_TGT_R_EXPORT | MDB_TGT_R_PRIV },
93 { "err", KREG_ERR, MDB_TGT_R_EXPORT | MDB_TGT_R_PRIV },
94 { NULL, 0, 0 }
95 };
96 #endif
97
98 void
mdb_ia32_printregs(const mdb_tgt_gregset_t * gregs)99 mdb_ia32_printregs(const mdb_tgt_gregset_t *gregs)
100 {
101 const kreg_t *kregs = &gregs->kregs[0];
102 kreg_t eflags = kregs[KREG_EFLAGS];
103
104 mdb_printf("%%cs = 0x%04x\t\t%%eax = 0x%08p %A\n",
105 kregs[KREG_CS], kregs[KREG_EAX], kregs[KREG_EAX]);
106
107 mdb_printf("%%ds = 0x%04x\t\t%%ebx = 0x%08p %A\n",
108 kregs[KREG_DS], kregs[KREG_EBX], kregs[KREG_EBX]);
109
110 mdb_printf("%%ss = 0x%04x\t\t%%ecx = 0x%08p %A\n",
111 kregs[KREG_SS], kregs[KREG_ECX], kregs[KREG_ECX]);
112
113 mdb_printf("%%es = 0x%04x\t\t%%edx = 0x%08p %A\n",
114 kregs[KREG_ES], kregs[KREG_EDX], kregs[KREG_EDX]);
115
116 mdb_printf("%%fs = 0x%04x\t\t%%esi = 0x%08p %A\n",
117 kregs[KREG_FS], kregs[KREG_ESI], kregs[KREG_ESI]);
118
119 mdb_printf("%%gs = 0x%04x\t\t%%edi = 0x%08p %A\n\n",
120 kregs[KREG_GS], kregs[KREG_EDI], kregs[KREG_EDI]);
121
122 mdb_printf("%%eip = 0x%08p %A\n", kregs[KREG_EIP], kregs[KREG_EIP]);
123 mdb_printf("%%ebp = 0x%08p\n", kregs[KREG_EBP]);
124 mdb_printf("%%esp = 0x%08p\n\n", kregs[KREG_ESP]);
125 mdb_printf("%%eflags = 0x%08x\n", eflags);
126
127 mdb_printf(" id=%u vip=%u vif=%u ac=%u vm=%u rf=%u nt=%u iopl=0x%x\n",
128 (eflags & KREG_EFLAGS_ID_MASK) >> KREG_EFLAGS_ID_SHIFT,
129 (eflags & KREG_EFLAGS_VIP_MASK) >> KREG_EFLAGS_VIP_SHIFT,
130 (eflags & KREG_EFLAGS_VIF_MASK) >> KREG_EFLAGS_VIF_SHIFT,
131 (eflags & KREG_EFLAGS_AC_MASK) >> KREG_EFLAGS_AC_SHIFT,
132 (eflags & KREG_EFLAGS_VM_MASK) >> KREG_EFLAGS_VM_SHIFT,
133 (eflags & KREG_EFLAGS_RF_MASK) >> KREG_EFLAGS_RF_SHIFT,
134 (eflags & KREG_EFLAGS_NT_MASK) >> KREG_EFLAGS_NT_SHIFT,
135 (eflags & KREG_EFLAGS_IOPL_MASK) >> KREG_EFLAGS_IOPL_SHIFT);
136
137 mdb_printf(" status=<%s,%s,%s,%s,%s,%s,%s,%s,%s>\n\n",
138 (eflags & KREG_EFLAGS_OF_MASK) ? "OF" : "of",
139 (eflags & KREG_EFLAGS_DF_MASK) ? "DF" : "df",
140 (eflags & KREG_EFLAGS_IF_MASK) ? "IF" : "if",
141 (eflags & KREG_EFLAGS_TF_MASK) ? "TF" : "tf",
142 (eflags & KREG_EFLAGS_SF_MASK) ? "SF" : "sf",
143 (eflags & KREG_EFLAGS_ZF_MASK) ? "ZF" : "zf",
144 (eflags & KREG_EFLAGS_AF_MASK) ? "AF" : "af",
145 (eflags & KREG_EFLAGS_PF_MASK) ? "PF" : "pf",
146 (eflags & KREG_EFLAGS_CF_MASK) ? "CF" : "cf");
147
148 #if !defined(__amd64) && !defined(_KMDB)
149 mdb_printf(" %%uesp = 0x%08x\n", kregs[KREG_UESP]);
150 #endif
151 mdb_printf("%%trapno = 0x%x\n", kregs[KREG_TRAPNO]);
152 mdb_printf(" %%err = 0x%x\n", kregs[KREG_ERR]);
153 }
154
155 /*
156 * Given a return address (%eip), determine the likely number of arguments
157 * that were pushed on the stack prior to its execution. We do this by
158 * expecting that a typical call sequence consists of pushing arguments on
159 * the stack, executing a call instruction, and then performing an add
160 * on %esp to restore it to the value prior to pushing the arguments for
161 * the call. We attempt to detect such an add, and divide the addend
162 * by the size of a word to determine the number of pushed arguments.
163 */
164 static uint_t
kvm_argcount(mdb_tgt_t * t,uintptr_t eip,ssize_t size)165 kvm_argcount(mdb_tgt_t *t, uintptr_t eip, ssize_t size)
166 {
167 uint8_t ins[6];
168 ulong_t n;
169
170 enum {
171 M_MODRM_ESP = 0xc4, /* Mod/RM byte indicates %esp */
172 M_ADD_IMM32 = 0x81, /* ADD imm32 to r/m32 */
173 M_ADD_IMM8 = 0x83 /* ADD imm8 to r/m32 */
174 };
175
176 if (mdb_tgt_aread(t, MDB_TGT_AS_VIRT_I, ins, sizeof (ins), eip) !=
177 sizeof (ins))
178 return (0);
179
180 if (ins[1] != M_MODRM_ESP)
181 return (0);
182
183 switch (ins[0]) {
184 case M_ADD_IMM32:
185 n = ins[2] + (ins[3] << 8) + (ins[4] << 16) + (ins[5] << 24);
186 break;
187
188 case M_ADD_IMM8:
189 n = ins[2];
190 break;
191
192 default:
193 n = 0;
194 }
195
196 return (MIN((ssize_t)n, size) / sizeof (uint32_t));
197 }
198
199 int
mdb_ia32_kvm_stack_iter(mdb_tgt_t * t,const mdb_tgt_gregset_t * gsp,mdb_tgt_stack_f * func,void * arg)200 mdb_ia32_kvm_stack_iter(mdb_tgt_t *t, const mdb_tgt_gregset_t *gsp,
201 mdb_tgt_stack_f *func, void *arg)
202 {
203 mdb_tgt_gregset_t gregs;
204 kreg_t *kregs = &gregs.kregs[0];
205 int got_pc = (gsp->kregs[KREG_EIP] != 0);
206 int err;
207
208 struct fr {
209 uintptr32_t fr_savfp;
210 uintptr32_t fr_savpc;
211 uint32_t fr_argv[32];
212 } fr;
213
214 uintptr_t fp = gsp->kregs[KREG_EBP];
215 uintptr_t pc = gsp->kregs[KREG_EIP];
216 uintptr_t lastfp = 0;
217
218 ssize_t size;
219 uint_t argc;
220 int detect_exception_frames = 0;
221 int advance_tortoise = 1;
222 uintptr_t tortoise_fp = 0;
223 #ifndef _KMDB
224 int xp;
225
226 if ((mdb_readsym(&xp, sizeof (xp), "xpv_panicking") != -1) && (xp > 0))
227 detect_exception_frames = 1;
228 #endif
229
230 bcopy(gsp, &gregs, sizeof (gregs));
231
232 while (fp != 0) {
233 if (fp & (STACK_ALIGN - 1)) {
234 err = EMDB_STKALIGN;
235 goto badfp;
236 }
237 if ((size = mdb_tgt_aread(t, MDB_TGT_AS_VIRT_S, &fr,
238 sizeof (fr), fp)) >= (ssize_t)(2 * sizeof (uintptr32_t))) {
239 size -= (ssize_t)(2 * sizeof (uintptr32_t));
240 argc = kvm_argcount(t, fr.fr_savpc, size);
241 } else {
242 err = EMDB_NOMAP;
243 goto badfp;
244 }
245
246 if (tortoise_fp == 0) {
247 tortoise_fp = fp;
248 } else {
249 /*
250 * Advance tortoise_fp every other frame, so we detect
251 * cycles with Floyd's tortoise/hare.
252 */
253 if (advance_tortoise != 0) {
254 struct fr tfr;
255
256 if (mdb_tgt_aread(t, MDB_TGT_AS_VIRT_S, &tfr,
257 sizeof (tfr), tortoise_fp) !=
258 sizeof (tfr)) {
259 err = EMDB_NOMAP;
260 goto badfp;
261 }
262
263 tortoise_fp = tfr.fr_savfp;
264 }
265
266 if (fp == tortoise_fp) {
267 err = EMDB_STKFRAME;
268 goto badfp;
269 }
270 }
271
272 advance_tortoise = !advance_tortoise;
273
274 if (got_pc &&
275 func(arg, pc, argc, (const long *)fr.fr_argv, &gregs) != 0)
276 break;
277
278 kregs[KREG_ESP] = kregs[KREG_EBP];
279
280 lastfp = fp;
281 fp = fr.fr_savfp;
282 /*
283 * The Xen hypervisor marks a stack frame as belonging to
284 * an exception by inverting the bits of the pointer to
285 * that frame. We attempt to identify these frames by
286 * inverting the pointer and seeing if it is within 0xfff
287 * bytes of the last frame.
288 */
289 if (detect_exception_frames)
290 if ((fp != 0) && (fp < lastfp) &&
291 ((lastfp ^ ~fp) < 0xfff))
292 fp = ~fp;
293
294 kregs[KREG_EBP] = fp;
295 kregs[KREG_EIP] = pc = fr.fr_savpc;
296
297 got_pc = (pc != 0);
298 }
299
300 return (0);
301
302 badfp:
303 mdb_printf("%p [%s]", fp, mdb_strerror(err));
304 return (set_errno(err));
305 }
306
307 #ifndef __amd64
308 /*
309 * The functions mdb_ia32_step_out and mdb_ia32_next haven't yet been adapted
310 * to work when built for an amd64 mdb. They are unused by the amd64-only bhyve
311 * target, hence the #ifdef.
312 */
313 /*
314 * Determine the return address for the current frame. Typically this is the
315 * fr_savpc value from the current frame, but we also perform some special
316 * handling to see if we are stopped on one of the first two instructions of a
317 * typical function prologue, in which case %ebp will not be set up yet.
318 */
319 int
mdb_ia32_step_out(mdb_tgt_t * t,uintptr_t * p,kreg_t pc,kreg_t fp,kreg_t sp,mdb_instr_t curinstr)320 mdb_ia32_step_out(mdb_tgt_t *t, uintptr_t *p, kreg_t pc, kreg_t fp, kreg_t sp,
321 mdb_instr_t curinstr)
322 {
323 struct frame fr;
324 GElf_Sym s;
325 char buf[1];
326
327 enum {
328 M_PUSHL_EBP = 0x55, /* pushl %ebp */
329 M_MOVL_EBP = 0x8b /* movl %esp, %ebp */
330 };
331
332 if (mdb_tgt_lookup_by_addr(t, pc, MDB_TGT_SYM_FUZZY,
333 buf, 0, &s, NULL) == 0) {
334 if (pc == s.st_value && curinstr == M_PUSHL_EBP)
335 fp = sp - 4;
336 else if (pc == s.st_value + 1 && curinstr == M_MOVL_EBP)
337 fp = sp;
338 }
339
340 if (mdb_tgt_aread(t, MDB_TGT_AS_VIRT_S, &fr, sizeof (fr), fp) ==
341 sizeof (fr)) {
342 *p = fr.fr_savpc;
343 return (0);
344 }
345
346 return (-1); /* errno is set for us */
347 }
348
349 /*
350 * Return the address of the next instruction following a call, or return -1
351 * and set errno to EAGAIN if the target should just single-step. We perform
352 * a bit of disassembly on the current instruction in order to determine if it
353 * is a call and how many bytes should be skipped, depending on the exact form
354 * of the call instruction that is being used.
355 */
356 int
mdb_ia32_next(mdb_tgt_t * t,uintptr_t * p,kreg_t pc,mdb_instr_t curinstr)357 mdb_ia32_next(mdb_tgt_t *t, uintptr_t *p, kreg_t pc, mdb_instr_t curinstr)
358 {
359 uint8_t m;
360
361 enum {
362 M_CALL_REL = 0xe8, /* call near with relative displacement */
363 M_CALL_REG = 0xff, /* call near indirect or call far register */
364
365 M_MODRM_MD = 0xc0, /* mask for Mod/RM byte Mod field */
366 M_MODRM_OP = 0x38, /* mask for Mod/RM byte opcode field */
367 M_MODRM_RM = 0x07, /* mask for Mod/RM byte R/M field */
368
369 M_MD_IND = 0x00, /* Mod code for [REG] */
370 M_MD_DSP8 = 0x40, /* Mod code for disp8[REG] */
371 M_MD_DSP32 = 0x80, /* Mod code for disp32[REG] */
372 M_MD_REG = 0xc0, /* Mod code for REG */
373
374 M_OP_IND = 0x10, /* Opcode for call near indirect */
375 M_RM_DSP32 = 0x05 /* R/M code for disp32 */
376 };
377
378 /*
379 * If the opcode is a near call with relative displacement, assume the
380 * displacement is a rel32 from the next instruction.
381 */
382 if (curinstr == M_CALL_REL) {
383 *p = pc + sizeof (mdb_instr_t) + sizeof (uint32_t);
384 return (0);
385 }
386
387 /*
388 * If the opcode is a call near indirect or call far register opcode,
389 * read the subsequent Mod/RM byte to perform additional decoding.
390 */
391 if (curinstr == M_CALL_REG) {
392 if (mdb_tgt_aread(t, MDB_TGT_AS_VIRT_I, &m, sizeof (m), pc + 1)
393 != sizeof (m))
394 return (-1); /* errno is set for us */
395
396 /*
397 * If the Mod/RM opcode extension indicates a near indirect
398 * call, then skip the appropriate number of additional
399 * bytes depending on the addressing form that is used.
400 */
401 if ((m & M_MODRM_OP) == M_OP_IND) {
402 switch (m & M_MODRM_MD) {
403 case M_MD_DSP8:
404 *p = pc + 3; /* skip pr_instr, m, disp8 */
405 break;
406 case M_MD_DSP32:
407 *p = pc + 6; /* skip pr_instr, m, disp32 */
408 break;
409 case M_MD_IND:
410 if ((m & M_MODRM_RM) == M_RM_DSP32) {
411 *p = pc + 6;
412 break; /* skip pr_instr, m, disp32 */
413 }
414 /* FALLTHRU */
415 case M_MD_REG:
416 *p = pc + 2; /* skip pr_instr, m */
417 break;
418 }
419 return (0);
420 }
421 }
422
423 return (set_errno(EAGAIN));
424 }
425 #endif
426
427 /*ARGSUSED*/
428 int
mdb_ia32_kvm_frame(void * arglim,uintptr_t pc,uint_t argc,const long * largv,const mdb_tgt_gregset_t * gregs)429 mdb_ia32_kvm_frame(void *arglim, uintptr_t pc, uint_t argc, const long *largv,
430 const mdb_tgt_gregset_t *gregs)
431 {
432 const uint32_t *argv = (const uint32_t *)largv;
433
434 argc = MIN(argc, (uintptr_t)arglim);
435 mdb_printf("%a(", pc);
436
437 if (argc != 0) {
438 mdb_printf("%lr", *argv++);
439 for (argc--; argc != 0; argc--)
440 mdb_printf(", %lr", *argv++);
441 }
442
443 mdb_printf(")\n");
444 return (0);
445 }
446
447 int
mdb_ia32_kvm_framev(void * arglim,uintptr_t pc,uint_t argc,const long * largv,const mdb_tgt_gregset_t * gregs)448 mdb_ia32_kvm_framev(void *arglim, uintptr_t pc, uint_t argc, const long *largv,
449 const mdb_tgt_gregset_t *gregs)
450 {
451 const uint32_t *argv = (const uint32_t *)largv;
452
453 argc = MIN(argc, (uintptr_t)arglim);
454 mdb_printf("%08lr %a(", gregs->kregs[KREG_EBP], pc);
455
456 if (argc != 0) {
457 mdb_printf("%lr", *argv++);
458 for (argc--; argc != 0; argc--)
459 mdb_printf(", %lr", *argv++);
460 }
461
462 mdb_printf(")\n");
463 return (0);
464 }
465