1 2 /*---------------------------------------------------------------*/ 3 /*--- begin libvex_guest_x86.h ---*/ 4 /*---------------------------------------------------------------*/ 5 6 /* 7 This file is part of Valgrind, a dynamic binary instrumentation 8 framework. 9 10 Copyright (C) 2004-2011 OpenWorks LLP 11 info (at) open-works.net 12 13 This program is free software; you can redistribute it and/or 14 modify it under the terms of the GNU General Public License as 15 published by the Free Software Foundation; either version 2 of the 16 License, or (at your option) any later version. 17 18 This program is distributed in the hope that it will be useful, but 19 WITHOUT ANY WARRANTY; without even the implied warranty of 20 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 21 General Public License for more details. 22 23 You should have received a copy of the GNU General Public License 24 along with this program; if not, write to the Free Software 25 Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 26 02110-1301, USA. 27 28 The GNU General Public License is contained in the file COPYING. 29 30 Neither the names of the U.S. Department of Energy nor the 31 University of California nor the names of its contributors may be 32 used to endorse or promote products derived from this software 33 without prior written permission. 34 */ 35 36 #ifndef __LIBVEX_PUB_GUEST_X86_H 37 #define __LIBVEX_PUB_GUEST_X86_H 38 39 #include "libvex_basictypes.h" 40 #include "libvex_emwarn.h" 41 42 43 /*---------------------------------------------------------------*/ 44 /*--- Vex's representation of the x86 CPU state. ---*/ 45 /*---------------------------------------------------------------*/ 46 47 /* The integer parts should be pretty straightforward. */ 48 49 /* Hmm, subregisters. The simulated state is stored in memory in the 50 host's byte ordering, so we can't say here what the offsets of %ax, 51 %al, %ah etc are since that depends on the host's byte ordering, 52 which we don't know. */ 53 54 /* FPU. For now, just simulate 8 64-bit registers, their tags, and 55 the reg-stack top pointer, of which only the least significant 56 three bits are relevant. 57 58 The model is: 59 F0 .. F7 are the 8 registers. FTOP[2:0] contains the 60 index of the current 'stack top' -- pretty meaningless, but 61 still. FTOP is a 32-bit value. FTOP[31:3] can be anything 62 (not guaranteed to be zero). 63 64 When a value is pushed onto the stack, ftop is first replaced by 65 (ftop-1) & 7, and then F[ftop] is assigned the value. 66 67 When a value is popped off the stack, the value is read from 68 F[ftop], and then ftop is replaced by (ftop+1) & 7. 69 70 In general, a reference to a register ST(i) actually references 71 F[ (ftop+i) & 7 ]. 72 73 FTAG0 .. FTAG0+7 are the tags. Each is a byte, zero means empty, 74 non-zero means non-empty. 75 76 The general rule appears to be that a read or modify of a register 77 gets a stack underflow fault if the register is empty. A write of 78 a register (only a write, not a modify) gets a stack overflow fault 79 if the register is full. Note that "over" vs "under" is pretty 80 meaningless since the FP stack pointer can move around arbitrarily, 81 so it's really just two different kinds of exceptions: 82 register-empty and register full. 83 84 Naturally Intel (in its infinite wisdom) has seen fit to throw in 85 some ad-hoc inconsistencies to the fault-generation rules of the 86 above para, just to complicate everything. Known inconsistencies: 87 88 * fxam can read a register in any state without taking an underflow 89 fault. 90 91 * fst from st(0) to st(i) does not take an overflow fault even if the 92 destination is already full. 93 94 FPROUND[1:0] is the FPU's notional rounding mode, encoded as per 95 the IRRoundingMode type (see libvex_ir.h). This just happens to be 96 the Intel encoding. Note carefully, the rounding mode is only 97 observed on float-to-int conversions, and on float-to-float 98 rounding, but not for general float-to-float operations, which are 99 always rounded-to-nearest. 100 101 Loads/stores of the FPU control word are faked accordingly -- on 102 loads, everything except the rounding mode is ignored, and on 103 stores, you get a vanilla control world (0x037F) with the rounding 104 mode patched in. Hence the only values you can get are 0x037F, 105 0x077F, 0x0B7F or 0x0F7F. Vex will emit an emulation warning if 106 you try and load a control word which either (1) unmasks FP 107 exceptions, or (2) changes the default (80-bit) precision. 108 109 FC3210 contains the C3, C2, C1 and C0 bits in the same place they 110 are in the FPU's status word. (bits 14, 10, 9, 8 respectively). 111 All other bits should be zero. The relevant mask to select just 112 those bits is 0x4700. To select C3, C2 and C0 only, the mask is 113 0x4500. 114 115 SSEROUND[1:0] is the SSE unit's notional rounding mode, encoded as 116 per the IRRoundingMode type. As with the FPU control word, the 117 rounding mode is the only part of %MXCSR that Vex observes. On 118 storing %MXCSR, you will get a vanilla word (0x1F80) with the 119 rounding mode patched in. Hence the only values you will get are 120 0x1F80, 0x3F80, 0x5F80 or 0x7F80. Vex will emit an emulation 121 warning if you try and load a control word which either (1) unmasks 122 any exceptions, (2) sets FZ (flush-to-zero) to 1, or (3) sets DAZ 123 (denormals-are-zeroes) to 1. 124 125 Segments: initial prefixes of local and global segment descriptor 126 tables are modelled. guest_LDT is either zero (NULL) or points in 127 the host address space to an array of VEX_GUEST_X86_LDT_NENT 128 descriptors, which have the type VexGuestX86SegDescr, defined 129 below. Similarly, guest_GDT is either zero or points in the host 130 address space to an array of VEX_GUEST_X86_GDT_NENT descriptors. 131 The only place where these are used are in the helper function 132 x86g_use_seg(). LibVEX's client is responsible for pointing 133 guest_LDT and guest_GDT at suitable tables. The contents of these 134 tables are expected not to change during the execution of any given 135 superblock, but they may validly be changed by LibVEX's client in 136 between superblock executions. 137 138 Since x86g_use_seg() only expects these tables to have 139 VEX_GUEST_X86_{LDT,GDT}_NENT entries, LibVEX's client should not 140 attempt to write entries beyond those limits. 141 */ 142 typedef 143 struct { 144 UInt guest_EAX; /* 0 */ 145 UInt guest_ECX; 146 UInt guest_EDX; 147 UInt guest_EBX; 148 UInt guest_ESP; 149 UInt guest_EBP; 150 UInt guest_ESI; 151 UInt guest_EDI; /* 28 */ 152 153 /* 4-word thunk used to calculate O S Z A C P flags. */ 154 UInt guest_CC_OP; /* 32 */ 155 UInt guest_CC_DEP1; 156 UInt guest_CC_DEP2; 157 UInt guest_CC_NDEP; /* 44 */ 158 /* The D flag is stored here, encoded as either -1 or +1 */ 159 UInt guest_DFLAG; /* 48 */ 160 /* Bit 21 (ID) of eflags stored here, as either 0 or 1. */ 161 UInt guest_IDFLAG; /* 52 */ 162 /* Bit 18 (AC) of eflags stored here, as either 0 or 1. */ 163 UInt guest_ACFLAG; /* 56 */ 164 165 /* EIP */ 166 UInt guest_EIP; /* 60 */ 167 168 /* FPU */ 169 ULong guest_FPREG[8]; /* 64 */ 170 UChar guest_FPTAG[8]; /* 128 */ 171 UInt guest_FPROUND; /* 136 */ 172 UInt guest_FC3210; /* 140 */ 173 UInt guest_FTOP; /* 144 */ 174 175 /* SSE */ 176 UInt guest_SSEROUND; /* 148 */ 177 U128 guest_XMM0; /* 152 */ 178 U128 guest_XMM1; 179 U128 guest_XMM2; 180 U128 guest_XMM3; 181 U128 guest_XMM4; 182 U128 guest_XMM5; 183 U128 guest_XMM6; 184 U128 guest_XMM7; 185 186 /* Segment registers. */ 187 UShort guest_CS; 188 UShort guest_DS; 189 UShort guest_ES; 190 UShort guest_FS; 191 UShort guest_GS; 192 UShort guest_SS; 193 /* LDT/GDT stuff. */ 194 HWord guest_LDT; /* host addr, a VexGuestX86SegDescr* */ 195 HWord guest_GDT; /* host addr, a VexGuestX86SegDescr* */ 196 197 /* Emulation warnings */ 198 UInt guest_EMWARN; 199 200 /* For clflush: record start and length of area to invalidate */ 201 UInt guest_TISTART; 202 UInt guest_TILEN; 203 204 /* Used to record the unredirected guest address at the start of 205 a translation whose start has been redirected. By reading 206 this pseudo-register shortly afterwards, the translation can 207 find out what the corresponding no-redirection address was. 208 Note, this is only set for wrap-style redirects, not for 209 replace-style ones. */ 210 UInt guest_NRADDR; 211 212 /* Used for Darwin syscall dispatching. */ 213 UInt guest_SC_CLASS; 214 215 /* Needed for Darwin (but mandated for all guest architectures): 216 EIP at the last syscall insn (int 0x80/81/82, sysenter, 217 syscall). Used when backing up to restart a syscall that has 218 been interrupted by a signal. */ 219 UInt guest_IP_AT_SYSCALL; 220 221 /* Padding to make it have an 16-aligned size */ 222 UInt padding1; 223 UInt padding2; 224 UInt padding3; 225 } 226 VexGuestX86State; 227 228 #define VEX_GUEST_X86_LDT_NENT /*64*/ 8192 /* use complete LDT */ 229 #define VEX_GUEST_X86_GDT_NENT /*16*/ 8192 /* use complete GDT */ 230 231 232 /*---------------------------------------------------------------*/ 233 /*--- Types for x86 guest stuff. ---*/ 234 /*---------------------------------------------------------------*/ 235 236 /* VISIBLE TO LIBRARY CLIENT */ 237 238 /* This is the hardware-format for a segment descriptor, ie what the 239 x86 actually deals with. It is 8 bytes long. It's ugly. */ 240 241 typedef struct { 242 union { 243 struct { 244 UShort LimitLow; 245 UShort BaseLow; 246 UInt BaseMid : 8; 247 UInt Type : 5; 248 UInt Dpl : 2; 249 UInt Pres : 1; 250 UInt LimitHi : 4; 251 UInt Sys : 1; 252 UInt Reserved_0 : 1; 253 UInt Default_Big : 1; 254 UInt Granularity : 1; 255 UInt BaseHi : 8; 256 } Bits; 257 struct { 258 UInt word1; 259 UInt word2; 260 } Words; 261 } 262 LdtEnt; 263 } VexGuestX86SegDescr; 264 265 266 /*---------------------------------------------------------------*/ 267 /*--- Utility functions for x86 guest stuff. ---*/ 268 /*---------------------------------------------------------------*/ 269 270 /* ALL THE FOLLOWING ARE VISIBLE TO LIBRARY CLIENT */ 271 272 /* Initialise all guest x86 state. The FPU is put in default mode. */ 273 extern 274 void LibVEX_GuestX86_initialise ( /*OUT*/VexGuestX86State* vex_state ); 275 276 277 /* Extract from the supplied VexGuestX86State structure the 278 corresponding native %eflags value. */ 279 extern 280 UInt LibVEX_GuestX86_get_eflags ( /*IN*/VexGuestX86State* vex_state ); 281 282 /* Set the carry flag in the given state to 'new_carry_flag', which 283 should be zero or one. */ 284 extern 285 void 286 LibVEX_GuestX86_put_eflag_c ( UInt new_carry_flag, 287 /*MOD*/VexGuestX86State* vex_state ); 288 289 #endif /* ndef __LIBVEX_PUB_GUEST_X86_H */ 290 291 /*---------------------------------------------------------------*/ 292 /*--- libvex_guest_x86.h ---*/ 293 /*---------------------------------------------------------------*/ 294
