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      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
     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
    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
    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
    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
    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
    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
    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