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/*--- begin libvex_guest_x86.h ---*/
This file is part of Valgrind, a dynamic binary instrumentation
Copyright (C) 2004-2013 OpenWorks LLP
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#ifndef __LIBVEX_PUB_GUEST_X86_H
#define __LIBVEX_PUB_GUEST_X86_H
#include "libvex_basictypes.h"
/*--- Vex's representation of the x86 CPU state. ---*/
/* The integer parts should be pretty straightforward. */
/* Hmm, subregisters. The simulated state is stored in memory in the
host's byte ordering, so we can't say here what the offsets of %ax,
%al, %ah etc are since that depends on the host's byte ordering,
which we don't know. */
/* FPU. For now, just simulate 8 64-bit registers, their tags, and
the reg-stack top pointer, of which only the least significant
three bits are relevant.
The model is:
F0 .. F7 are the 8 registers. FTOP[2:0] contains the
index of the current 'stack top' -- pretty meaningless, but
still. FTOP is a 32-bit value. FTOP[31:3] can be anything
(not guaranteed to be zero).
When a value is pushed onto the stack, ftop is first replaced by
(ftop-1) & 7, and then F[ftop] is assigned the value.
When a value is popped off the stack, the value is read from
F[ftop], and then ftop is replaced by (ftop+1) & 7.
In general, a reference to a register ST(i) actually references
F[ (ftop+i) & 7 ].
FTAG0 .. FTAG0+7 are the tags. Each is a byte, zero means empty,
non-zero means non-empty.
The general rule appears to be that a read or modify of a register
gets a stack underflow fault if the register is empty. A write of
a register (only a write, not a modify) gets a stack overflow fault
if the register is full. Note that "over" vs "under" is pretty
meaningless since the FP stack pointer can move around arbitrarily,
so it's really just two different kinds of exceptions:
register-empty and register full.
Naturally Intel (in its infinite wisdom) has seen fit to throw in
some ad-hoc inconsistencies to the fault-generation rules of the
above para, just to complicate everything. Known inconsistencies:
* fxam can read a register in any state without taking an underflow
* fst from st(0) to st(i) does not take an overflow fault even if the
destination is already full.
FPROUND[1:0] is the FPU's notional rounding mode, encoded as per
the IRRoundingMode type (see libvex_ir.h). This just happens to be
the Intel encoding. Note carefully, the rounding mode is only
observed on float-to-int conversions, and on float-to-float
rounding, but not for general float-to-float operations, which are
always rounded-to-nearest.
Loads/stores of the FPU control word are faked accordingly -- on
loads, everything except the rounding mode is ignored, and on
stores, you get a vanilla control world (0x037F) with the rounding
mode patched in. Hence the only values you can get are 0x037F,
0x077F, 0x0B7F or 0x0F7F. Vex will emit an emulation warning if
you try and load a control word which either (1) unmasks FP
exceptions, or (2) changes the default (80-bit) precision.
FC3210 contains the C3, C2, C1 and C0 bits in the same place they
are in the FPU's status word. (bits 14, 10, 9, 8 respectively).
All other bits should be zero. The relevant mask to select just
those bits is 0x4700. To select C3, C2 and C0 only, the mask is
SSEROUND[1:0] is the SSE unit's notional rounding mode, encoded as
per the IRRoundingMode type. As with the FPU control word, the
rounding mode is the only part of %MXCSR that Vex observes. On
storing %MXCSR, you will get a vanilla word (0x1F80) with the
rounding mode patched in. Hence the only values you will get are
0x1F80, 0x3F80, 0x5F80 or 0x7F80. Vex will emit an emulation
warning if you try and load a control word which either (1) unmasks
any exceptions, (2) sets FZ (flush-to-zero) to 1, or (3) sets DAZ
(denormals-are-zeroes) to 1.
Segments: initial prefixes of local and global segment descriptor
tables are modelled. guest_LDT is either zero (NULL) or points in
the host address space to an array of VEX_GUEST_X86_LDT_NENT
descriptors, which have the type VexGuestX86SegDescr, defined
below. Similarly, guest_GDT is either zero or points in the host
address space to an array of VEX_GUEST_X86_GDT_NENT descriptors.
The only place where these are used are in the helper function
x86g_use_seg(). LibVEX's client is responsible for pointing
guest_LDT and guest_GDT at suitable tables. The contents of these
tables are expected not to change during the execution of any given
superblock, but they may validly be changed by LibVEX's client in
between superblock executions.
Since x86g_use_seg() only expects these tables to have
VEX_GUEST_X86_{LDT,GDT}_NENT entries, LibVEX's client should not
attempt to write entries beyond those limits.
struct {
/* Event check fail addr and counter. */
UInt host_EvC_FAILADDR; /* 0 */
UInt host_EvC_COUNTER; /* 4 */
UInt guest_EAX; /* 8 */
UInt guest_ECX;
UInt guest_EDX;
UInt guest_EBX;
UInt guest_ESP;
UInt guest_EBP;
UInt guest_ESI;
UInt guest_EDI; /* 36 */
/* 4-word thunk used to calculate O S Z A C P flags. */
UInt guest_CC_OP; /* 40 */
UInt guest_CC_DEP1;
UInt guest_CC_DEP2;
UInt guest_CC_NDEP; /* 52 */
/* The D flag is stored here, encoded as either -1 or +1 */
UInt guest_DFLAG; /* 56 */
/* Bit 21 (ID) of eflags stored here, as either 0 or 1. */
UInt guest_IDFLAG; /* 60 */
/* Bit 18 (AC) of eflags stored here, as either 0 or 1. */
UInt guest_ACFLAG; /* 64 */
/* EIP */
UInt guest_EIP; /* 68 */
/* FPU */
ULong guest_FPREG[8]; /* 72 */
UChar guest_FPTAG[8]; /* 136 */
UInt guest_FPROUND; /* 144 */
UInt guest_FC3210; /* 148 */
UInt guest_FTOP; /* 152 */
/* SSE */
UInt guest_SSEROUND; /* 156 */
U128 guest_XMM0; /* 160 */
U128 guest_XMM1;
U128 guest_XMM2;
U128 guest_XMM3;
U128 guest_XMM4;
U128 guest_XMM5;
U128 guest_XMM6;
U128 guest_XMM7;
/* Segment registers. */
UShort guest_CS;
UShort guest_DS;
UShort guest_ES;
UShort guest_FS;
UShort guest_GS;
UShort guest_SS;
/* LDT/GDT stuff. */
HWord guest_LDT; /* host addr, a VexGuestX86SegDescr* */
HWord guest_GDT; /* host addr, a VexGuestX86SegDescr* */
/* Emulation notes */
UInt guest_EMNOTE;
/* For clflush/clinval: record start and length of area */
UInt guest_CMSTART;
UInt guest_CMLEN;
/* Used to record the unredirected guest address at the start of
a translation whose start has been redirected. By reading
this pseudo-register shortly afterwards, the translation can
find out what the corresponding no-redirection address was.
Note, this is only set for wrap-style redirects, not for
replace-style ones. */
UInt guest_NRADDR;
/* Used for Darwin syscall dispatching. */
UInt guest_SC_CLASS;
/* Needed for Darwin (but mandated for all guest architectures):
EIP at the last syscall insn (int 0x80/81/82, sysenter,
syscall). Used when backing up to restart a syscall that has
been interrupted by a signal. */
/* Padding to make it have an 16-aligned size */
UInt padding1;
#define VEX_GUEST_X86_LDT_NENT /*64*/ 8192 /* use complete LDT */
#define VEX_GUEST_X86_GDT_NENT /*16*/ 8192 /* use complete GDT */
/*--- Types for x86 guest stuff. ---*/
/* This is the hardware-format for a segment descriptor, ie what the
x86 actually deals with. It is 8 bytes long. It's ugly. */
typedef struct {
union {
struct {
UShort LimitLow;
UShort BaseLow;
UInt BaseMid : 8;
UInt Type : 5;
UInt Dpl : 2;
UInt Pres : 1;
UInt LimitHi : 4;
UInt Sys : 1;
UInt Reserved_0 : 1;
UInt Default_Big : 1;
UInt Granularity : 1;
UInt BaseHi : 8;
} Bits;
struct {
UInt word1;
UInt word2;
} Words;
} VexGuestX86SegDescr;
/*--- Utility functions for x86 guest stuff. ---*/
/* Initialise all guest x86 state. The FPU is put in default mode. */
void LibVEX_GuestX86_initialise ( /*OUT*/VexGuestX86State* vex_state );
/* Extract from the supplied VexGuestX86State structure the
corresponding native %eflags value. */
UInt LibVEX_GuestX86_get_eflags ( /*IN*/const VexGuestX86State* vex_state );
/* Set the carry flag in the given state to 'new_carry_flag', which
should be zero or one. */
LibVEX_GuestX86_put_eflag_c ( UInt new_carry_flag,
/*MOD*/VexGuestX86State* vex_state );
#endif /* ndef __LIBVEX_PUB_GUEST_X86_H */
/*--- libvex_guest_x86.h ---*/