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tme-0.8
/* $Id: rc-x86-rws.c,v 1.1.1.1 2018/04/24 16:43:07 root Exp $ */
/* libtme/host/x86/rc-x86-rws.c - x86 host recode reads and writes support: */
/*
* Copyright (c) 2008 Matt Fredette
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by Matt Fredette.
* 4. The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT,
* INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
_TME_RCSID("$Id: rc-x86-rws.c,v 1.1.1.1 2018/04/24 16:43:07 root Exp $");
/* this emits instructions to do a byte swap in a host register: */
static tme_uint8_t *
_tme_recode_x86_rw_bswap(tme_uint8_t *thunk_bytes,
unsigned int size,
unsigned int reg_x86)
{
unsigned int rex;
/* NB: we don't have to worry about zero-truncation on an x86-64
host; if this register is supposed to be sign-extended, we do
that after all byte swapping: */
/* if this is an eight-bit byte swap: */
if (size == TME_RECODE_SIZE_8) {
/* nothing to do */
}
/* otherwise, if this is a 16-bit byte swap: */
else if (size == TME_RECODE_SIZE_16) {
/* if this register has a high 8-bit encoding: */
if (reg_x86 < TME_RECODE_X86_REG_SP) {
/* emit an xchgb %regh, %regl: */
thunk_bytes[0]
= (TME_RECODE_X86_OPCODE_BINOP_XCHG
+ TME_RECODE_X86_OPCODE_BINOP_Gb_Eb);
thunk_bytes[1]
= TME_RECODE_X86_MOD_OPREG_RM(TME_RECODE_X86_MOD_RM_REG(reg_x86),
TME_RECODE_X86_REG((TME_RECODE_X86_REG_SP + reg_x86)));
thunk_bytes += 2;
}
/* otherwise, this register doesn't have a high 8-bit encoding: */
else {
/* emit a rorw $8, %reg: */
thunk_bytes[0] = TME_RECODE_X86_PREFIX_OPSIZ;
thunk_bytes[1] = TME_RECODE_X86_OPCODE_GRP2_Ib_Ev;
thunk_bytes[2]
= TME_RECODE_X86_MOD_OPREG_RM(TME_RECODE_X86_MOD_RM_REG(reg_x86),
TME_RECODE_X86_OPCODE_GRP2_ROR);
thunk_bytes[3] = 8;
thunk_bytes += 4;
}
}
/* otherwise, this is a 32-bit swap, and/or a host-sized byte
swap: */
else {
/* if the bswap instruction is available: */
if (1) {
/* emit a bswap %reg: */
rex = TME_RECODE_X86_REX_R(size, reg_x86);
if (rex != 0) {
*(thunk_bytes++) = rex;
}
thunk_bytes[0] = TME_RECODE_X86_OPCODE_ESC_0F;
thunk_bytes[1] = TME_RECODE_X86_OPCODE0F_BSWAP(reg_x86);
thunk_bytes += 2;
}
/* otherwise, the bswap instruction is not available: */
else {
/* this must be a 32-bit swap: */
assert (size == TME_RECODE_SIZE_32);
/* emit:
rorw $8, %reg
rorl $16, %reg
rorw $8, %reg
*/
thunk_bytes[0] = TME_RECODE_X86_PREFIX_OPSIZ;
thunk_bytes[1] = TME_RECODE_X86_OPCODE_GRP2_Ib_Ev;
thunk_bytes[2]
= TME_RECODE_X86_MOD_OPREG_RM(TME_RECODE_X86_MOD_RM_REG(reg_x86),
TME_RECODE_X86_OPCODE_GRP2_ROR);
thunk_bytes[3] = 8;
thunk_bytes += 4;
thunk_bytes[0] = TME_RECODE_X86_OPCODE_GRP2_Ib_Ev;
thunk_bytes[1]
= TME_RECODE_X86_MOD_OPREG_RM(TME_RECODE_X86_MOD_RM_REG(reg_x86),
TME_RECODE_X86_OPCODE_GRP2_ROR);
thunk_bytes[2] = 16;
thunk_bytes += 3;
thunk_bytes[0] = TME_RECODE_X86_PREFIX_OPSIZ;
thunk_bytes[1] = TME_RECODE_X86_OPCODE_GRP2_Ib_Ev;
thunk_bytes[2]
= TME_RECODE_X86_MOD_OPREG_RM(TME_RECODE_X86_MOD_RM_REG(reg_x86),
TME_RECODE_X86_OPCODE_GRP2_ROR);
thunk_bytes[3] = 8;
thunk_bytes += 4;
}
}
return (thunk_bytes);
}
/* this host function returns a new read/write thunk: */
struct tme_recode_rw_thunk *
tme_recode_host_rw_thunk_new(struct tme_recode_ic *ic,
const struct tme_recode_rw *rw)
{
struct tme_recode_rw_thunk *rw_thunk;
unsigned int max_boundaries_guest;
unsigned int max_boundaries_host;
struct tme_recode_x86_tlb_type x86_tlb_type;
unsigned int reg_x86_address;
unsigned int reg_host_value_0;
unsigned int reg_host_value_1;
struct tme_recode_insn insn_buffer;
tme_uint8_t *thunk_bytes;
unsigned int rex;
unsigned int reg_host_value_orig;
int stack_adjust;
unsigned int reg_size;
int memory_signed;
/* start the new read/write thunk: */
if (!tme_recode_host_thunk_start(ic)) {
abort();
}
rw_thunk = tme_new(struct tme_recode_rw_thunk, 1);
rw_thunk->tme_recode_x86_rw_thunk_subs
= tme_recode_build_to_thunk_off(ic, ic->tme_recode_ic_thunk_build_next);
/* assume that we will always need to assist: */
x86_tlb_type.tme_recode_x86_tlb_type_assist_jmp_address_ok = (tme_uint8_t *) NULL;
x86_tlb_type.tme_recode_x86_tlb_type_assist_jmp = (tme_uint8_t *) NULL;
/* get the worst-case maximum number of guest bus boundaries this
read/write could cross: */
max_boundaries_guest
= (rw->tme_recode_rw_bus_boundary == 0
? 0
: (((TME_MAX(rw->tme_recode_rw_bus_boundary,
rw->tme_recode_rw_address_type.tme_recode_address_type_align_min)
- rw->tme_recode_rw_address_type.tme_recode_address_type_align_min)
+ (TME_BIT(rw->tme_recode_rw_memory_size - TME_RECODE_SIZE_8)
- 1))
/ rw->tme_recode_rw_bus_boundary));
/* get the worst-case maximum number of host bus boundaries this
read/write could cross: */
max_boundaries_host
= (((TME_MAX(TME_MEMORY_BUS_BOUNDARY,
rw->tme_recode_rw_address_type.tme_recode_address_type_align_min)
- rw->tme_recode_rw_address_type.tme_recode_address_type_align_min)
+ (TME_BIT(rw->tme_recode_rw_memory_size - TME_RECODE_SIZE_8)
- 1))
/ TME_MEMORY_BUS_BOUNDARY);
/* NB: as of 20080906, Intel's "Intel 64 Architecture Memory
Ordering White Paper" (Order number 318147-001, from August 2007)
only guarantees that size-aligned reads and writes up to 64 bits
are atomic; we assume that non-Intel processors are similar.
until this guarantee is extended to cover size-aligned 128-bit
reads and writes, TME_MEMORY_BUS_BOUNDARY shouldn't be more than
sizeof(tme_uint64_t).
this means that we will always assist guest 128-bit reads
and writes that might be atomic for the guest (since we will
detect above that we might cross more bus boundaries than the
guest might): */
/* if threads are cooperative, or if common atomic operations aren't
being done under software lock and we can't cross more boundaries
than the guest would: */
if (TME_THREADS_COOPERATIVE
|| (TME_MEMORY_ALIGNMENT_ATOMIC(TME_MEMORY_TYPE_COMMON) != 0
&& max_boundaries_host <= max_boundaries_guest)) {
/* get the TLB type for the address type: */
tme_recode_address_type_tlb_type(ic,
&rw->tme_recode_rw_address_type,
&x86_tlb_type.tme_recode_tlb_type);
/* XXX FIXME - document read/write thunk calling convention, how
it differs from normal subs */
/* for a double-host-size guest, the guest address is in the a:bp
register pair, otherwise it's in the a register. NB that we
primarily deal with only a host-sized part: */
reg_x86_address
= tme_recode_x86_reg_from_host[_tme_recode_x86_tlb_reg_host_address(ic)];
/* for a write, the value to write is in the first host register
(pair). for a read, the value read is returned in the same
host register (pair) that was used for the address: */
if (rw->tme_recode_rw_write) {
reg_host_value_0 = TME_RECODE_REG_HOST(0);
}
else {
reg_host_value_0
= _tme_recode_x86_tlb_reg_host_address(ic);
assert (tme_recode_x86_reg_from_host[reg_host_value_0] == reg_x86_address);
}
reg_host_value_1 = reg_host_value_0 + 1;
/* find, busy, and check a data TLB entry: */
_tme_recode_x86_tlb_busy(ic,
&rw->tme_recode_rw_address_type,
&x86_tlb_type);
/* start more instructions: */
tme_recode_x86_insns_start(ic, thunk_bytes);
/* if this is a write, and we need to byte-swap the value to
write: */
if (rw->tme_recode_rw_write
&& rw->tme_recode_rw_memory_size > TME_RECODE_SIZE_8
&& rw->tme_recode_rw_memory_endian != TME_ENDIAN_NATIVE) {
/* we will byte-swap the value to write into (at least) the
TLB scratch register: */
reg_host_value_orig = reg_host_value_0;
assert (reg_host_value_1 == reg_host_value_0 + 1);
reg_host_value_0 = TME_RECODE_REG_HOST_UNDEF;
assert (tme_recode_x86_reg_from_host[reg_host_value_0] == TME_RECODE_X86_REG_TLB_SCRATCH);
/* if this is a double-host-size write: */
if (TME_RECODE_SIZE_IS_DOUBLE_HOST(rw->tme_recode_rw_memory_size)) {
/* we will use the most-significant half of the guest register
that held the address for the higher-in-memory (i.e., the
guest least-significant) part of the value. NB that we are
swapping guest register halves here, too: */
reg_host_value_1 = TME_RECODE_X86_REG_HOST_SUBS_SRC1 + 1;
assert (tme_recode_x86_reg_from_host[reg_host_value_1 - 1] == reg_x86_address);
_tme_recode_x86_emit_reg_copy(thunk_bytes,
tme_recode_x86_reg_from_host[reg_host_value_orig + 0],
tme_recode_x86_reg_from_host[reg_host_value_1]);
thunk_bytes
= _tme_recode_x86_rw_bswap(thunk_bytes,
TME_RECODE_SIZE_HOST,
tme_recode_x86_reg_from_host[reg_host_value_1]);
reg_host_value_orig += 1;
}
/* copy and swap the lower-in-memory (i.e., the guest
most-significant) part of the value: */
_tme_recode_x86_emit_reg_copy(thunk_bytes,
tme_recode_x86_reg_from_host[reg_host_value_orig],
tme_recode_x86_reg_from_host[reg_host_value_0]);
thunk_bytes
= _tme_recode_x86_rw_bswap(thunk_bytes,
TME_MIN(rw->tme_recode_rw_memory_size,
TME_RECODE_SIZE_HOST),
tme_recode_x86_reg_from_host[reg_host_value_0]);
}
/* if threads aren't cooperative, and this is a double-host-size
access: */
if (!TME_THREADS_COOPERATIVE
&& TME_RECODE_SIZE_IS_DOUBLE_HOST(rw->tme_recode_rw_memory_size)) {
/* NB: in this case, we assume that the host is capable of SSE2
instructions. this seems reasonable: */
/* the x86-64 ABI requires that the stack pointer be 16-byte
aligned immediately before a call instruction. inside an
insn thunk, the stack pointer is 16-byte aligned immediately
before a call to a read/write thunk, which means at the
beginning of a read/write thunk it is only 8-byte aligned
(because of the return address for the read/write thunk).
on x86-64, we want to use at least one movdqa, which requires
us to align the stack pointer: */
stack_adjust
= (TME_RECODE_SIZE_HOST == TME_RECODE_SIZE_32
? 0
: TME_BIT(TME_RECODE_SIZE_HOST - TME_RECODE_SIZE_8));
/* if this is a write: */
if (rw->tme_recode_rw_write) {
/* do any stack pointer alignment: */
if (stack_adjust) {
thunk_bytes = _tme_recode_x86_emit_adjust_sp(thunk_bytes, -stack_adjust);
}
/* push the double-host-size value to write: */
_tme_recode_x86_emit_reg_push(thunk_bytes, tme_recode_x86_reg_from_host[reg_host_value_1]);
_tme_recode_x86_emit_reg_push(thunk_bytes, tme_recode_x86_reg_from_host[reg_host_value_0]);
/* after the write, we will need to discard the value: */
stack_adjust += TME_BIT(rw->tme_recode_rw_memory_size - TME_RECODE_SIZE_8);
}
/* otherwise, this is a read: */
else {
/* do any stack pointer alignment, and make space for the
double-host-size value to read: */
thunk_bytes
= _tme_recode_x86_emit_adjust_sp(thunk_bytes,
-(stack_adjust
+ TME_BIT(rw->tme_recode_rw_memory_size
- TME_RECODE_SIZE_8)));
}
/* emit one of:
movq (%esp), %xmm0
movdqa (%esp), %xmm0
movq (%address), %xmm0
movdqa (%address), %xmm0
to read the value to read or write into %xmm0:
*/
thunk_bytes[0]
= ((TME_RECODE_SIZE_HOST == TME_RECODE_SIZE_32
|| (!rw->tme_recode_rw_write
&& (rw->tme_recode_rw_address_type.tme_recode_address_type_align_min
< TME_BIT(rw->tme_recode_rw_memory_size - TME_RECODE_SIZE_8))))
? TME_RECODE_X86_PREFIX_REP
: TME_RECODE_X86_PREFIX_OPSIZ);
thunk_bytes[1] = TME_RECODE_X86_OPCODE_ESC_0F;
thunk_bytes[2]
= (TME_RECODE_SIZE_HOST == TME_RECODE_SIZE_32
? TME_RECODE_X86_OPCODEF30F_MOVQ_Wq_Vq
: thunk_bytes[0] == TME_RECODE_X86_PREFIX_REP
? TME_RECODE_X86_OPCODEF30F_MOVDQU_Wdq_Vdq
: TME_RECODE_X86_OPCODE660F_MOVDQA_Wdq_Vdq);
if (rw->tme_recode_rw_write) {
thunk_bytes[3]
= TME_RECODE_X86_MOD_OPREG_RM(TME_RECODE_X86_MOD_RM_EA(TME_RECODE_X86_EA_BASE_SIB),
TME_RECODE_X86_REG(TME_RECODE_X86_REG_XMM(0)));
thunk_bytes[4]
= TME_RECODE_X86_SIB(TME_RECODE_X86_REG_SP, TME_RECODE_X86_SIB_INDEX_NONE, 1);
thunk_bytes += 5;
}
else {
thunk_bytes[3]
= TME_RECODE_X86_MOD_OPREG_RM(TME_RECODE_X86_MOD_RM_EA(reg_x86_address),
TME_RECODE_X86_REG(TME_RECODE_X86_REG_XMM(0)));
thunk_bytes += 4;
}
/* emit one of:
movq %xmm0, (%address)
movdqu %xmm0, (%address)
movdqa %xmm0, (%address)
movq %xmm0, (%esp)
movdqa %xmm0, (%esp)
to write the value to read or write in %xmm0:
*/
thunk_bytes[0]
= ((TME_RECODE_SIZE_HOST == TME_RECODE_SIZE_32
|| (rw->tme_recode_rw_write
&& (rw->tme_recode_rw_address_type.tme_recode_address_type_align_min
>= TME_BIT(rw->tme_recode_rw_memory_size - TME_RECODE_SIZE_8))))
? TME_RECODE_X86_PREFIX_OPSIZ
: TME_RECODE_X86_PREFIX_REP);
thunk_bytes[1] = TME_RECODE_X86_OPCODE_ESC_0F;
thunk_bytes[2]
= (TME_RECODE_SIZE_HOST == TME_RECODE_SIZE_32
? TME_RECODE_X86_OPCODE660F_MOVQ_Vq_Wq
: thunk_bytes[0] == TME_RECODE_X86_PREFIX_REP
? TME_RECODE_X86_OPCODEF30F_MOVDQU_Vdq_Wdq
: TME_RECODE_X86_OPCODE660F_MOVDQA_Vdq_Wdq);
if (rw->tme_recode_rw_write) {
thunk_bytes[3]
= TME_RECODE_X86_MOD_OPREG_RM(TME_RECODE_X86_MOD_RM_EA(reg_x86_address),
TME_RECODE_X86_REG(TME_RECODE_X86_REG_XMM(0)));
thunk_bytes += 4;
}
else {
thunk_bytes[3]
= TME_RECODE_X86_MOD_OPREG_RM(TME_RECODE_X86_MOD_RM_EA(TME_RECODE_X86_EA_BASE_SIB),
TME_RECODE_X86_REG(TME_RECODE_X86_REG_XMM(0)));
thunk_bytes[4]
= TME_RECODE_X86_SIB(TME_RECODE_X86_REG_SP, TME_RECODE_X86_SIB_INDEX_NONE, 1);
thunk_bytes += 5;
}
/* if this was a read: */
if (!rw->tme_recode_rw_write) {
/* pop the double-host-size value we read: */
_tme_recode_x86_emit_reg_pop(thunk_bytes, tme_recode_x86_reg_from_host[reg_host_value_0]);
_tme_recode_x86_emit_reg_pop(thunk_bytes, tme_recode_x86_reg_from_host[reg_host_value_1]);
}
/* discard any double-host-size value we wrote, and any stack
pointer alignment: */
if (stack_adjust) {
thunk_bytes = _tme_recode_x86_emit_adjust_sp(thunk_bytes, -stack_adjust);
}
}
/* otherwise, either threads are cooperative, or this isn't a
double-host-size access: */
/* if this is a write: */
else if (rw->tme_recode_rw_write) {
/* if this is an ia32 host, and an 8-bit store of a register
that doesn't have an 8-bit encoding: */
if (TME_RECODE_SIZE_HOST <= TME_RECODE_SIZE_32
&& rw->tme_recode_rw_memory_size == TME_RECODE_SIZE_8
&& tme_recode_x86_reg_from_host[reg_host_value_0] >= TME_RECODE_X86_REG_SP) {
/* we will copy the value to write into the TLB scratch
register, which has an 8-bit encoding: */
reg_host_value_orig = reg_host_value_0;
reg_host_value_0 = TME_RECODE_REG_HOST_UNDEF;
assert (tme_recode_x86_reg_from_host[reg_host_value_0] < TME_RECODE_X86_REG_SP);
assert (tme_recode_x86_reg_from_host[reg_host_value_0] == TME_RECODE_X86_REG_TLB_SCRATCH);
_tme_recode_x86_emit_reg_copy(thunk_bytes,
tme_recode_x86_reg_from_host[reg_host_value_orig],
tme_recode_x86_reg_from_host[reg_host_value_0]);
}
/* emit one of:
movb %reg, (%address)
movw %reg, (%address)
movl %reg, (%address)
movq %reg, (%address)
*/
if (rw->tme_recode_rw_memory_size == TME_RECODE_SIZE_16) {
*(thunk_bytes++) = TME_RECODE_X86_PREFIX_OPSIZ;
}
rex
= (TME_RECODE_X86_REX_R(TME_MIN(rw->tme_recode_rw_memory_size,
TME_RECODE_SIZE_HOST),
tme_recode_x86_reg_from_host[reg_host_value_0])
| TME_RECODE_X86_REX_B(0, reg_x86_address));
if (rex != 0) {
*(thunk_bytes++) = rex;
}
thunk_bytes[0]
= (rw->tme_recode_rw_memory_size >= TME_RECODE_SIZE_16
? (TME_RECODE_X86_OPCODE_BINOP_MOV + TME_RECODE_X86_OPCODE_BINOP_Gv_Ev)
: (TME_RECODE_X86_OPCODE_BINOP_MOV + TME_RECODE_X86_OPCODE_BINOP_Gb_Eb));
/* NB: a disp8 EA must be used when the base register is bp or r13: */
if (TME_RECODE_X86_REG(reg_x86_address) == TME_RECODE_X86_REG_BP) {
thunk_bytes[1]
= TME_RECODE_X86_MOD_OPREG_RM(TME_RECODE_X86_MOD_RM_EA_DISP8(reg_x86_address),
TME_RECODE_X86_REG(tme_recode_x86_reg_from_host[reg_host_value_0]));
thunk_bytes[2] = 0;
thunk_bytes += 3;
}
else {
thunk_bytes[1]
= TME_RECODE_X86_MOD_OPREG_RM(TME_RECODE_X86_MOD_RM_EA(reg_x86_address),
TME_RECODE_X86_REG(tme_recode_x86_reg_from_host[reg_host_value_0]));
thunk_bytes += 2;
}
/* if this is a double-host-size write: */
if (TME_RECODE_SIZE_IS_DOUBLE_HOST(rw->tme_recode_rw_memory_size)) {
/* emit one of:
movl %reg, 4(%address)
movq %reg, 8(%address)
*/
rex
= (TME_RECODE_X86_REX_R(TME_RECODE_SIZE_HOST,
tme_recode_x86_reg_from_host[reg_host_value_1])
| TME_RECODE_X86_REX_B(0, reg_x86_address));
if (rex != 0) {
*(thunk_bytes++) = rex;
}
thunk_bytes[0] = TME_RECODE_X86_OPCODE_BINOP_MOV + TME_RECODE_X86_OPCODE_BINOP_Gv_Ev;
thunk_bytes[1]
= TME_RECODE_X86_MOD_OPREG_RM(TME_RECODE_X86_MOD_RM_EA_DISP8(reg_x86_address),
TME_RECODE_X86_REG(tme_recode_x86_reg_from_host[reg_host_value_1]));
thunk_bytes[2] = TME_BIT(TME_RECODE_SIZE_HOST - TME_RECODE_SIZE_8);
thunk_bytes += 3;
}
}
/* otherwise, this is a read: */
else {
/* if this is a double-host-size read: */
if (TME_RECODE_SIZE_IS_DOUBLE_HOST(rw->tme_recode_rw_memory_size)) {
/* emit one of:
movl 4(%address), %reg
movq 8(%address), %reg
*/
rex
= (TME_RECODE_X86_REX_R(TME_RECODE_SIZE_HOST,
tme_recode_x86_reg_from_host[reg_host_value_1])
| TME_RECODE_X86_REX_B(0, reg_x86_address));
if (rex != 0) {
*(thunk_bytes++) = rex;
}
thunk_bytes[0] = TME_RECODE_X86_OPCODE_BINOP_MOV + TME_RECODE_X86_OPCODE_BINOP_Ev_Gv;
thunk_bytes[1]
= TME_RECODE_X86_MOD_OPREG_RM(TME_RECODE_X86_MOD_RM_EA_DISP8(reg_x86_address),
TME_RECODE_X86_REG(tme_recode_x86_reg_from_host[reg_host_value_1]));
thunk_bytes[2] = TME_BIT(TME_RECODE_SIZE_HOST - TME_RECODE_SIZE_8);
thunk_bytes += 3;
}
/* assume that we we will read into all of a host register: */
reg_size = TME_MAX(rw->tme_recode_rw_reg_size, TME_RECODE_SIZE_HOST);
/* by default, in the read instruction itself we zero-extend the
value into all of a host register. the only time we will
sign-extend in the read instruction itself is when the
register size is greater than the memory size, memory is
signed, and we're only reading a byte or the guest's byte
order matches the host. if the first two are true, but we're
reading more than a byte and the guest's byte order doesn't
match the host, we have to wait to do the sign extension
after we've byte swapped the value read: */
memory_signed
= (rw->tme_recode_rw_reg_size > rw->tme_recode_rw_memory_size
&& rw->tme_recode_rw_memory_signed
&& (rw->tme_recode_rw_memory_size == TME_RECODE_SIZE_8
|| rw->tme_recode_rw_memory_endian == TME_ENDIAN_NATIVE));
/* if this is an x86-64 host and a 32-bit sign- or zero-extended load: */
if (TME_RECODE_SIZE_HOST > TME_RECODE_SIZE_32
&& rw->tme_recode_rw_memory_size == TME_RECODE_SIZE_32
&& rw->tme_recode_rw_reg_size > rw->tme_recode_rw_memory_size) {
/* if this is a zero-extended load, or if the guest's byte
order doesn't match the host: */
if (!memory_signed) {
/* read into only the least-significant 32 bits of the
register. this will zero-extend the read to all 64
bits. this should prevent a rex prefix: */
reg_size = TME_RECODE_SIZE_32;
}
}
/* emit any rex prefix: */
rex
= (TME_RECODE_X86_REX_B(0, reg_x86_address)
| TME_RECODE_X86_REX_R(TME_MIN(reg_size,
TME_RECODE_SIZE_HOST),
tme_recode_x86_reg_from_host[reg_host_value_0]));
if (rex != 0) {
*(thunk_bytes++) = rex;
}
/* if this is an x86-64 host and a 32-bit sign-extended load: */
if (TME_RECODE_SIZE_HOST > TME_RECODE_SIZE_32
&& rw->tme_recode_rw_memory_size == TME_RECODE_SIZE_32
&& reg_size > TME_RECODE_SIZE_32) {
/* emit the opcode part of a movslq (%address), %reg: */
thunk_bytes[0] = TME_RECODE_X86_OPCODE_MOVS_El_Gv;
}
/* otherwise, if this is an 8- or 16-bit load: */
else if (rw->tme_recode_rw_memory_size <= TME_RECODE_SIZE_16) {
/* emit the opcode part of one of:
movsb (%address), %reg
movzb (%address), %reg
movsw (%address), %reg
movzw (%address), %reg
*/
*(thunk_bytes++) = TME_RECODE_X86_OPCODE_ESC_0F;
thunk_bytes[0]
= (rw->tme_recode_rw_memory_size == TME_RECODE_SIZE_8
? (memory_signed
? TME_RECODE_X86_OPCODE0F_MOVS_Eb_Gv
: TME_RECODE_X86_OPCODE0F_MOVZ_Eb_Gv)
: (memory_signed
? TME_RECODE_X86_OPCODE0F_MOVS_Ew_Gv
: TME_RECODE_X86_OPCODE0F_MOVZ_Ew_Gv));
}
/* otherwise, this load is double-host-size, or host-size, or a
32-bit zero-extended load on an x86-64 host: */
else {
/* emit the opcode part of a movl (%address), %reg or a movq (%address), %reg: */
thunk_bytes[0]
= (TME_RECODE_X86_OPCODE_BINOP_MOV
+ TME_RECODE_X86_OPCODE_BINOP_Ev_Gv);
}
/* emit the modR/M byte for this instruction: */
/* NB: a disp8 EA must be used when the base register is bp or r13: */
if (TME_RECODE_X86_REG(reg_x86_address) == TME_RECODE_X86_REG_BP) {
thunk_bytes[1]
= TME_RECODE_X86_MOD_OPREG_RM(TME_RECODE_X86_MOD_RM_EA_DISP8(reg_x86_address),
TME_RECODE_X86_REG(tme_recode_x86_reg_from_host[reg_host_value_0]));
thunk_bytes[2] = 0;
thunk_bytes += 3;
}
else {
thunk_bytes[1]
= TME_RECODE_X86_MOD_OPREG_RM(TME_RECODE_X86_MOD_RM_EA(reg_x86_address),
TME_RECODE_X86_REG(tme_recode_x86_reg_from_host[reg_host_value_0]));
thunk_bytes += 2;
}
}
/* if this is a read: */
if (!rw->tme_recode_rw_write) {
/* if we need to byte-swap the value read: */
if (rw->tme_recode_rw_memory_size > TME_RECODE_SIZE_8
&& rw->tme_recode_rw_memory_endian != TME_ENDIAN_NATIVE) {
/* if this is a double-host-size read: */
if (TME_RECODE_SIZE_IS_DOUBLE_HOST(rw->tme_recode_rw_memory_size)) {
/* swap the guest register halves: */
_tme_recode_x86_emit_reg_binop(thunk_bytes,
TME_RECODE_X86_OPCODE_BINOP_XCHG,
tme_recode_x86_reg_from_host[reg_host_value_0],
tme_recode_x86_reg_from_host[reg_host_value_1]);
/* byte-swap the most-significant half of the guest register: */
thunk_bytes
= _tme_recode_x86_rw_bswap(thunk_bytes,
TME_RECODE_SIZE_HOST,
tme_recode_x86_reg_from_host[reg_host_value_1]);
}
/* byte-swap the (least-significant half of the) guest register: */
thunk_bytes
= _tme_recode_x86_rw_bswap(thunk_bytes,
TME_MIN(rw->tme_recode_rw_memory_size,
TME_RECODE_SIZE_HOST),
tme_recode_x86_reg_from_host[reg_host_value_0]);
/* if the read is sign-extended from smaller than host-sized: */
if (rw->tme_recode_rw_reg_size > rw->tme_recode_rw_memory_size
&& rw->tme_recode_rw_memory_signed
&& rw->tme_recode_rw_memory_size < TME_RECODE_SIZE_HOST) {
/* sign-extend the value read to host size: */
tme_recode_x86_insns_finish(ic, thunk_bytes);
insn_buffer.tme_recode_insn_opcode = TME_RECODE_OPCODE_EXTS;
insn_buffer.tme_recode_insn_operand_src[0] = reg_host_value_0;
insn_buffer.tme_recode_insn_operand_src[1] = rw->tme_recode_rw_memory_size;
insn_buffer.tme_recode_insn_operand_dst = reg_host_value_0;
_tme_recode_x86_insn_ext(ic, &insn_buffer);
tme_recode_x86_insns_start(ic, thunk_bytes);
}
}
/* if this is a double-host-size read that needs zero- or sign-extension: */
if (TME_RECODE_SIZE_IS_DOUBLE_HOST(rw->tme_recode_rw_reg_size)
&& rw->tme_recode_rw_reg_size > rw->tme_recode_rw_memory_size) {
/* if memory is signed: */
if (rw->tme_recode_rw_memory_signed) {
/* sign-extend the value read: */
_tme_recode_x86_emit_reg_binop(thunk_bytes,
TME_RECODE_X86_OPCODE_BINOP_MOV,
tme_recode_x86_reg_from_host[reg_host_value_0],
tme_recode_x86_reg_from_host[reg_host_value_1]);
_tme_recode_x86_emit_reg_binop(thunk_bytes,
TME_RECODE_X86_OPCODE_BINOP_ADD,
tme_recode_x86_reg_from_host[reg_host_value_0],
tme_recode_x86_reg_from_host[reg_host_value_1]);
_tme_recode_x86_emit_reg_binop(thunk_bytes,
TME_RECODE_X86_OPCODE_BINOP_SBB,
tme_recode_x86_reg_from_host[reg_host_value_1],
tme_recode_x86_reg_from_host[reg_host_value_1]);
}
/* otherwise, memory is unsigned: */
else {
/* zero-extend the value read: */
/* NB: we always make this a 32-bit operation, to try to
prevent a rex prefix: */
rex = (TME_RECODE_X86_REX_R(TME_RECODE_SIZE_32,
tme_recode_x86_reg_from_host[reg_host_value_1])
| TME_RECODE_X86_REX_B(TME_RECODE_SIZE_32,
tme_recode_x86_reg_from_host[reg_host_value_1]));
if (rex != 0) {
*(thunk_bytes++) = rex;
}
thunk_bytes[0]
= (TME_RECODE_X86_OPCODE_BINOP_XOR
+ TME_RECODE_X86_OPCODE_BINOP_Gv_Ev);
thunk_bytes[1]
= TME_RECODE_X86_MOD_OPREG_RM(TME_RECODE_X86_MOD_RM_REG(tme_recode_x86_reg_from_host[reg_host_value_1]),
TME_RECODE_X86_REG(tme_recode_x86_reg_from_host[reg_host_value_1]));
thunk_bytes += 2;
}
}
}
/* finish these instructions: */
tme_recode_x86_insns_finish(ic, thunk_bytes);
/* unbusy the TLB entry: */
_tme_recode_x86_tlb_unbusy(ic,
x86_tlb_type.tme_recode_tlb_type.tme_recode_tlb_type_offset_token);
/* start more instructions: */
tme_recode_x86_insns_start(ic, thunk_bytes);
/* return to the instructions thunk: */
*(thunk_bytes++) = TME_RECODE_X86_OPCODE_RET;
/* finish these instructions: */
tme_recode_x86_insns_finish(ic, thunk_bytes);
}
if (x86_tlb_type.tme_recode_x86_tlb_type_assist_jmp != NULL) {
/* finish the assist conditional jump above, now
that we are at the target: */
_tme_recode_x86_fixup_jmp(x86_tlb_type.tme_recode_x86_tlb_type_assist_jmp,
ic->tme_recode_ic_thunk_build_next);
/* start more instructions: */
tme_recode_x86_insns_start(ic, thunk_bytes);
/* exclusive-or the TLB entry page offset with the
(least-significant half of the) TLB entry page, to convert the
TLB entry page offset back into the (least-significant half of
the) guest address: */
thunk_bytes
= _tme_recode_x86_tlb_ref(thunk_bytes,
TME_RECODE_SIZE_HOST,
(TME_RECODE_X86_OPCODE_BINOP_XOR
+ TME_RECODE_X86_OPCODE_BINOP_Ev_Gv),
TME_RECODE_X86_REG_TLB,
x86_tlb_type.tme_recode_tlb_type.tme_recode_tlb_type_offset_page,
TME_RECODE_X86_REG(reg_x86_address));
/* finish these instructions: */
tme_recode_x86_insns_finish(ic, thunk_bytes);
}
/* fix up any double-host-size address assist: */
if (x86_tlb_type.tme_recode_x86_tlb_type_assist_jmp_address_ok != NULL) {
_tme_recode_x86_fixup_jmp(x86_tlb_type.tme_recode_x86_tlb_type_assist_jmp_address_ok,
ic->tme_recode_ic_thunk_build_next);
}
if (x86_tlb_type.tme_recode_x86_tlb_type_assist_jmp_address_ok != NULL
|| x86_tlb_type.tme_recode_x86_tlb_type_assist_jmp != NULL) {
/* unbusy the TLB entry: */
_tme_recode_x86_tlb_unbusy(ic,
x86_tlb_type.tme_recode_tlb_type.tme_recode_tlb_type_offset_token);
}
/* start more instructions: */
tme_recode_x86_insns_start(ic, thunk_bytes);
/* if this is an ia32 host: */
if (TME_RECODE_SIZE_HOST == TME_RECODE_SIZE_32) {
/* if this is a write: */
if (rw->tme_recode_rw_write) {
/* push the value argument for the guest function. NB that if
double-host-size guests are supported, but this isn't a
double-host-size guest, we use a garbage word on the stack as
the most-significant half of this argument (which is okay
since the guest functions are supposed to truncate their
arguments to the expected size): */
if (TME_RECODE_SIZE_GUEST_MAX > TME_RECODE_SIZE_HOST) {
_tme_recode_x86_emit_reg_push(thunk_bytes, tme_recode_x86_reg_from_host[TME_RECODE_REG_HOST(0) + 1]);
}
_tme_recode_x86_emit_reg_push(thunk_bytes, tme_recode_x86_reg_from_host[TME_RECODE_REG_HOST(0)]);
}
/* push the address argument for the guest function. NB that if
double-host-size guests are supported, but this isn't a
double-host-size guest, we use a garbage word on the stack as
the most-significant half of this argument (which is okay since
the guest functions are supposed to truncate their arguments to
the expected size): */
if (TME_RECODE_SIZE_GUEST_MAX > TME_RECODE_SIZE_HOST) {
_tme_recode_x86_emit_reg_push(thunk_bytes, TME_RECODE_X86_REG_A);
}
_tme_recode_x86_emit_reg_push(thunk_bytes, reg_x86_address);
/* emit the instruction to push the struct tme_ic * argument for
the guest function, and then the call instruction to the guest
function: */
*((tme_uint16_t *) thunk_bytes)
= (TME_RECODE_X86_OPCODE_PUSH_Gv(TME_RECODE_X86_REG_IC)
+ (TME_RECODE_X86_OPCODE_CALL_RELz << 8));
thunk_bytes += 2 + sizeof(tme_uint32_t);
((tme_int32_t *) thunk_bytes)[-1]
= (tme_recode_function_to_thunk_off(ic, rw->tme_recode_rw_guest_func_read)
- tme_recode_build_to_thunk_off(ic, thunk_bytes));
/* remove the guest function arguments from the stack: */
thunk_bytes
= _tme_recode_x86_emit_adjust_sp(thunk_bytes,
(sizeof(struct tme_ic *)
+ sizeof(tme_recode_uguest_t)
+ (sizeof(tme_recode_uguest_t)
* !!rw->tme_recode_rw_write)));
}
/* otherwise, this is an x86-64 host: */
else {
/* push the caller-saved registers that aren't normally destroyed
by a read/write thunk: */
_tme_recode_x86_emit_reg_push(thunk_bytes, TME_RECODE_X86_REG_N(10));
_tme_recode_x86_emit_reg_push(thunk_bytes, TME_RECODE_X86_REG_N(11));
_tme_recode_x86_emit_reg_push(thunk_bytes, TME_RECODE_X86_REG_DI);
_tme_recode_x86_emit_reg_push(thunk_bytes, TME_RECODE_X86_REG_SI);
_tme_recode_x86_emit_reg_push(thunk_bytes, TME_RECODE_X86_REG_N(8));
_tme_recode_x86_emit_reg_push(thunk_bytes, TME_RECODE_X86_REG_N(9));
/* make the struct tme_ic * argument for the guest function: */
_tme_recode_x86_emit_reg_copy(thunk_bytes, TME_RECODE_X86_REG_IC, TME_RECODE_X86_REG_DI);
/* make the address argument for the guest function. NB that if
double-host-size guests are supported, but this isn't a
double-host-size guest, we use a garbage word as the
most-significant half of this argument (which is okay since the
guest functions are supposed to truncate their arguments to the
expected size): */
_tme_recode_x86_emit_reg_copy(thunk_bytes, reg_x86_address, TME_RECODE_X86_REG_SI);
if (TME_RECODE_SIZE_IS_DOUBLE_HOST(ic->tme_recode_ic_reg_size)) {
_tme_recode_x86_emit_reg_copy(thunk_bytes, TME_RECODE_X86_REG_A, TME_RECODE_X86_REG_D);
}
/* if this is a write: */
if (rw->tme_recode_rw_write) {
/* make the value argument for the guest function. NB that if
double-host-size guests are supported, but this isn't a
double-host-size guest, we use a garbage word as the
most-significant half of this argument (which is okay since
the guest functions are supposed to truncate their arguments
to the expected size): */
_tme_recode_x86_emit_reg_copy(thunk_bytes,
tme_recode_x86_reg_from_host[TME_RECODE_REG_HOST(0)],
(TME_RECODE_SIZE_GUEST_MAX <= TME_RECODE_SIZE_HOST
? TME_RECODE_X86_REG_D
: TME_RECODE_X86_REG_C));
if (TME_RECODE_SIZE_IS_DOUBLE_HOST(ic->tme_recode_ic_reg_size)) {
_tme_recode_x86_emit_reg_copy(thunk_bytes,
tme_recode_x86_reg_from_host[TME_RECODE_REG_HOST(0)],
TME_RECODE_X86_REG_N(8));
}
}
/* we must assume that we can't reach the guest function from the
instruction thunk with a 32-bit displacement. emit a direct
call to the guest function using %rax: */
*((tme_uint16_t *) thunk_bytes)
= (TME_RECODE_X86_REX_B(TME_RECODE_SIZE_HOST, TME_RECODE_X86_REG_A)
+ (TME_RECODE_X86_OPCODE_MOV_Iv_Gv(TME_RECODE_X86_REG_A)
<< 8));
memcpy(thunk_bytes + 2,
&rw->tme_recode_rw_guest_func_write,
TME_BIT(TME_RECODE_SIZE_HOST - TME_RECODE_SIZE_8));
thunk_bytes += 2 + TME_BIT(TME_RECODE_SIZE_HOST - TME_RECODE_SIZE_8);
*((tme_uint16_t *) thunk_bytes)
= (TME_RECODE_X86_OPCODE_GRP5
+ (TME_RECODE_X86_MOD_OPREG_RM(TME_RECODE_X86_MOD_RM_REG(TME_RECODE_X86_REG_A),
TME_RECODE_X86_OPCODE_GRP5_CALL)
<< 8));
thunk_bytes += 2;
/* pop the caller-saved registers that aren't normally destroyed
by a read/write thunk: */
_tme_recode_x86_emit_reg_pop(thunk_bytes, TME_RECODE_X86_REG_N(9));
_tme_recode_x86_emit_reg_pop(thunk_bytes, TME_RECODE_X86_REG_N(8));
_tme_recode_x86_emit_reg_pop(thunk_bytes, TME_RECODE_X86_REG_SI);
_tme_recode_x86_emit_reg_pop(thunk_bytes, TME_RECODE_X86_REG_DI);
_tme_recode_x86_emit_reg_pop(thunk_bytes, TME_RECODE_X86_REG_N(11));
_tme_recode_x86_emit_reg_pop(thunk_bytes, TME_RECODE_X86_REG_N(10));
}
/* if this is a read: */
if (!rw->tme_recode_rw_write) {
/* if this is a double-host-size guest: */
if (TME_RECODE_SIZE_IS_DOUBLE_HOST(ic->tme_recode_ic_reg_size)) {
/* move the value read into the expected return registers: */
_tme_recode_x86_emit_reg_copy(thunk_bytes,
TME_RECODE_X86_REG_A,
tme_recode_x86_reg_from_host[reg_host_value_0]);
_tme_recode_x86_emit_reg_copy(thunk_bytes,
TME_RECODE_X86_REG_D,
tme_recode_x86_reg_from_host[reg_host_value_1]);
}
/* otherwise, this is not a double-host-size guest: */
else {
/* the value read should already be in the expected register: */
assert (tme_recode_x86_reg_from_host[reg_host_value_0] == TME_RECODE_X86_REG_A);
}
}
/* return to the instructions thunk: */
*(thunk_bytes++) = TME_RECODE_X86_OPCODE_RET;
/* finish these instructions: */
tme_recode_x86_insns_finish(ic, thunk_bytes);
/* finish this read/write thunk: */
tme_recode_host_thunk_finish(ic);
/* no further extension is needed for this read/write thunk: */
rw_thunk->tme_recode_x86_rw_thunk_extend_size = 0;
return (rw_thunk);
}
/* this host function tries to duplicate a read/write thunk: */
struct tme_recode_rw_thunk *
tme_recode_host_rw_thunk_dup(struct tme_recode_ic *ic,
const struct tme_recode_rw *rw,
const struct tme_recode_rw *rw_other)
{
tme_uint8_t *thunk_bytes_0;
struct tme_recode_insn insn_buffer;
tme_uint8_t *thunk_bytes_1;
struct tme_recode_rw_thunk *rw_thunk;
/* start more instructions, so if we use _tme_recode_x86_insn_ext()
to emit an extension instruction, we can discard it from the
thunk build memory: */
tme_recode_x86_insns_start(ic, thunk_bytes_0);
/* if our register size is the same as the memory size, or
if the existing read/write thunk will do the extension that
we need to at least our register size: */
/* NB: a read/write thunk always extends to at least host size, and
when no particular extension is explicitly required,
zero-extension is the default: */
if ((rw->tme_recode_rw_reg_size
== rw_other->tme_recode_rw_memory_size)
|| ((((rw_other->tme_recode_rw_reg_size
> rw_other->tme_recode_rw_memory_size)
&& rw_other->tme_recode_rw_memory_signed)
== !!rw->tme_recode_rw_memory_signed)
&& (TME_MAX(rw_other->tme_recode_rw_reg_size, TME_RECODE_SIZE_HOST)
>= rw->tme_recode_rw_reg_size))) {
/* we can reuse the existing read/write thunk, and we don't need
to do any extension: */
/* nothing to do */
}
/* otherwise, if this is a double-host-size read: */
else if (TME_RECODE_SIZE_IS_DOUBLE_HOST(rw->tme_recode_rw_reg_size)) {
/* we won't reuse the existing read/write thunk: */
return (NULL);
}
/* otherwise, we will reuse this read/write thunk, with a single
zero- or sign-extension instruction after each call: */
else {
/* use _tme_recode_x86_insn_ext() to emit the extension
instruction: */
insn_buffer.tme_recode_insn_opcode
= (rw->tme_recode_rw_memory_signed
? TME_RECODE_OPCODE_EXTS
: TME_RECODE_OPCODE_EXTZ);
insn_buffer.tme_recode_insn_operand_src[0] = TME_RECODE_X86_REG_HOST_FREE_CALL;
insn_buffer.tme_recode_insn_operand_src[1] = rw->tme_recode_rw_memory_size;
insn_buffer.tme_recode_insn_operand_dst = insn_buffer.tme_recode_insn_operand_src[0];
_tme_recode_x86_insn_ext(ic, &insn_buffer);
}
/* duplicate the read/write thunk: */
rw_thunk = tme_dup(struct tme_recode_rw_thunk, rw_other->tme_recode_rw_thunk, 1);
/* get any extension instruction from the thunk build memory, and
then discard it: */
tme_recode_x86_insns_start(ic, thunk_bytes_1);
rw_thunk->tme_recode_x86_rw_thunk_extend = *((tme_uint32_t *) thunk_bytes_0);
rw_thunk->tme_recode_x86_rw_thunk_extend_size = (thunk_bytes_1 - thunk_bytes_0);
assert (rw_thunk->tme_recode_x86_rw_thunk_extend_size <= sizeof(tme_uint32_t));
tme_recode_x86_insns_finish(ic, thunk_bytes_0);
/* return the duplicated read/write thunk: */
return (rw_thunk);
}
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