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
mdb_ia32_printregs(const mdb_tgt_gregset_t * gregs)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
kvm_argcount(mdb_tgt_t * t,uintptr_t eip,ssize_t size)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
mdb_ia32_kvm_stack_iter(mdb_tgt_t * t,const mdb_tgt_gregset_t * gsp,mdb_tgt_stack_f * func,void * arg)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
mdb_ia32_step_out(mdb_tgt_t * t,uintptr_t * p,kreg_t pc,kreg_t fp,kreg_t sp,mdb_instr_t curinstr)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
mdb_ia32_next(mdb_tgt_t * t,uintptr_t * p,kreg_t pc,mdb_instr_t curinstr)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
mdb_ia32_kvm_frame(void * arglim,uintptr_t pc,uint_t argc,const long * argv,const mdb_tgt_gregset_t * gregs)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
mdb_ia32_kvm_framev(void * arglim,uintptr_t pc,uint_t argc,const long * argv,const mdb_tgt_gregset_t * gregs)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