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