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 {
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 #ifndef _KMDB
214 int xp;
215
216 if ((mdb_readsym(&xp, sizeof (xp), "xpv_panicking") != -1) && (xp > 0))
217 detect_exception_frames = 1;
218 #endif
219
220 bcopy(gsp, &gregs, sizeof (gregs));
221
222 while (fp != 0) {
223
224 /*
225 * Ensure progress (increasing fp), and prevent
226 * endless loop with the same FP.
227 */
228 if (fp <= lastfp) {
229 err = EMDB_STKFRAME;
230 goto badfp;
231 }
232 if (fp & (STACK_ALIGN - 1)) {
233 err = EMDB_STKALIGN;
234 goto badfp;
235 }
236 if ((size = mdb_tgt_vread(t, &fr, sizeof (fr), fp)) >=
237 (ssize_t)(2 * sizeof (uintptr_t))) {
238 size -= (ssize_t)(2 * sizeof (uintptr_t));
239 argc = kvm_argcount(t, fr.fr_savpc, size);
240 } else {
241 err = EMDB_NOMAP;
242 goto badfp;
243 }
244
245 if (got_pc && func(arg, pc, argc, fr.fr_argv, &gregs) != 0)
246 break;
247
248 kregs[KREG_ESP] = kregs[KREG_EBP];
249
250 lastfp = fp;
251 fp = fr.fr_savfp;
252 /*
253 * The Xen hypervisor marks a stack frame as belonging to
254 * an exception by inverting the bits of the pointer to
255 * that frame. We attempt to identify these frames by
256 * inverting the pointer and seeing if it is within 0xfff
257 * bytes of the last frame.
258 */
259 if (detect_exception_frames)
260 if ((fp != 0) && (fp < lastfp) &&
261 ((lastfp ^ ~fp) < 0xfff))
262 fp = ~fp;
263
264 kregs[KREG_EBP] = fp;
265 kregs[KREG_EIP] = pc = fr.fr_savpc;
266
267 got_pc = (pc != 0);
268 }
269
270 return (0);
271
272 badfp:
273 mdb_printf("%p [%s]", fp, mdb_strerror(err));
274 return (set_errno(err));
275 }
276
277 /*
278 * Determine the return address for the current frame. Typically this is the
279 * fr_savpc value from the current frame, but we also perform some special
280 * handling to see if we are stopped on one of the first two instructions of a
281 * typical function prologue, in which case %ebp will not be set up yet.
282 */
283 int
284 mdb_ia32_step_out(mdb_tgt_t *t, uintptr_t *p, kreg_t pc, kreg_t fp, kreg_t sp,
285 mdb_instr_t curinstr)
286 {
287 struct frame fr;
288 GElf_Sym s;
289 char buf[1];
290
291 enum {
292 M_PUSHL_EBP = 0x55, /* pushl %ebp */
293 M_MOVL_EBP = 0x8b /* movl %esp, %ebp */
294 };
295
296 if (mdb_tgt_lookup_by_addr(t, pc, MDB_TGT_SYM_FUZZY,
297 buf, 0, &s, NULL) == 0) {
298 if (pc == s.st_value && curinstr == M_PUSHL_EBP)
299 fp = sp - 4;
300 else if (pc == s.st_value + 1 && curinstr == M_MOVL_EBP)
301 fp = sp;
302 }
303
304 if (mdb_tgt_vread(t, &fr, sizeof (fr), fp) == sizeof (fr)) {
305 *p = fr.fr_savpc;
306 return (0);
307 }
308
309 return (-1); /* errno is set for us */
310 }
311
312 /*
313 * Return the address of the next instruction following a call, or return -1
314 * and set errno to EAGAIN if the target should just single-step. We perform
315 * a bit of disassembly on the current instruction in order to determine if it
316 * is a call and how many bytes should be skipped, depending on the exact form
317 * of the call instruction that is being used.
318 */
319 int
320 mdb_ia32_next(mdb_tgt_t *t, uintptr_t *p, kreg_t pc, mdb_instr_t curinstr)
321 {
322 uint8_t m;
323
324 enum {
325 M_CALL_REL = 0xe8, /* call near with relative displacement */
326 M_CALL_REG = 0xff, /* call near indirect or call far register */
327
328 M_MODRM_MD = 0xc0, /* mask for Mod/RM byte Mod field */
329 M_MODRM_OP = 0x38, /* mask for Mod/RM byte opcode field */
330 M_MODRM_RM = 0x07, /* mask for Mod/RM byte R/M field */
331
332 M_MD_IND = 0x00, /* Mod code for [REG] */
333 M_MD_DSP8 = 0x40, /* Mod code for disp8[REG] */
334 M_MD_DSP32 = 0x80, /* Mod code for disp32[REG] */
335 M_MD_REG = 0xc0, /* Mod code for REG */
336
337 M_OP_IND = 0x10, /* Opcode for call near indirect */
338 M_RM_DSP32 = 0x05 /* R/M code for disp32 */
339 };
340
341 /*
342 * If the opcode is a near call with relative displacement, assume the
343 * displacement is a rel32 from the next instruction.
344 */
345 if (curinstr == M_CALL_REL) {
346 *p = pc + sizeof (mdb_instr_t) + sizeof (uint32_t);
347 return (0);
348 }
349
350 /*
351 * If the opcode is a call near indirect or call far register opcode,
352 * read the subsequent Mod/RM byte to perform additional decoding.
353 */
354 if (curinstr == M_CALL_REG) {
355 if (mdb_tgt_vread(t, &m, sizeof (m), pc + 1) != sizeof (m))
356 return (-1); /* errno is set for us */
357
358 /*
359 * If the Mod/RM opcode extension indicates a near indirect
360 * call, then skip the appropriate number of additional
361 * bytes depending on the addressing form that is used.
362 */
363 if ((m & M_MODRM_OP) == M_OP_IND) {
364 switch (m & M_MODRM_MD) {
365 case M_MD_DSP8:
366 *p = pc + 3; /* skip pr_instr, m, disp8 */
367 break;
368 case M_MD_DSP32:
369 *p = pc + 6; /* skip pr_instr, m, disp32 */
370 break;
371 case M_MD_IND:
372 if ((m & M_MODRM_RM) == M_RM_DSP32) {
373 *p = pc + 6;
374 break; /* skip pr_instr, m, disp32 */
375 }
376 /* FALLTHRU */
377 case M_MD_REG:
378 *p = pc + 2; /* skip pr_instr, m */
379 break;
380 }
381 return (0);
382 }
383 }
384
385 return (set_errno(EAGAIN));
386 }
387
388 /*ARGSUSED*/
389 int
390 mdb_ia32_kvm_frame(void *arglim, uintptr_t pc, uint_t argc, const long *argv,
391 const mdb_tgt_gregset_t *gregs)
392 {
393 argc = MIN(argc, (uint_t)arglim);
394 mdb_printf("%a(", pc);
395
396 if (argc != 0) {
397 mdb_printf("%lr", *argv++);
398 for (argc--; argc != 0; argc--)
399 mdb_printf(", %lr", *argv++);
400 }
401
402 mdb_printf(")\n");
403 return (0);
404 }
405
406 int
407 mdb_ia32_kvm_framev(void *arglim, uintptr_t pc, uint_t argc, const long *argv,
408 const mdb_tgt_gregset_t *gregs)
409 {
410 argc = MIN(argc, (uint_t)arglim);
411 mdb_printf("%0?lr %a(", gregs->kregs[KREG_EBP], pc);
412
413 if (argc != 0) {
414 mdb_printf("%lr", *argv++);
415 for (argc--; argc != 0; argc--)
416 mdb_printf(", %lr", *argv++);
417 }
418
419 mdb_printf(")\n");
420 return (0);
421 }