Add a transaction attribute indicating that a memory access is being
done from user-mode (unprivileged). This corresponds to an equivalent
signal in ARM AMBA buses.
Backports commit 0995bf8cd91b81ec9c1078e37b808794080dc5c0 from qemu
Factor out the page table walk memory accesses into their own function,
so that we can specify the correct S/NS memory attributes for them.
This will also provide a place to use the correct endianness and
handle the need for a stage-2 translation when virtualization is
supported.
Backports commit ebca90e4c3aaaae5ed1ee7c569dea00d5d6ed476 from qemu
Honour the NS bit in ARM page tables:
* when adding entries to the TLB, include the Secure/NonSecure
transaction attribute
* set the NS bit in the PAR when doing ATS operations
Note that we don't yet correctly use the NSTable bit to
cause the page table walk itself to use the right attributes.
Backports commit 8bf5b6a9c1911d2c8473385fc0cebfaaeef42dbc from qem
This patch makes the following changes to the determination of
whether an address is executable, when translating addresses
using LPAE.
1. No longer assumes that PL0 can't execute when it can't read.
It can in AArch64, a difference from AArch32.
2. Use va_size == 64 to determine we're in AArch64, rather than
arm_feature(env, ARM_FEATURE_V8), which is insufficient.
3. Add additional XN determinants
- NS && is_secure && (SCR & SCR_SIF)
- WXN && (prot & PAGE_WRITE)
- AArch64: (prot_PL0 & PAGE_WRITE)
- AArch32: UWXN && (prot_PL0 & PAGE_WRITE)
- XN determination should also work in secure mode (untested)
- XN may even work in EL2 (currently impossible to test)
4. Cleans up the bloated PAGE_EXEC condition - by removing it.
The helper get_S1prot is introduced. It may even work in EL2,
when support for that comes, but, as the function name implies,
it only works for stage 1 translations.
Backports commit d8e052b387635639a6ba4a09a7874fd2f113b218 from qemu
Introduce simple_ap_to_rw_prot(), which has the same behavior as
ap_to_rw_prot(), but takes the 2-bit simple AP[2:1] instead of
the 3-bit AP[2:0]. Use this in get_phys_addr_v6 when SCTLR_AFE
is set, as that bit indicates we should be using the simple AP
format.
It's unlikely this path is getting used. I don't see CR_AFE
getting used by Linux, so possibly not. If it had been, then
the check would have been wrong for all but AP[2:1] = 0b11.
Anyway, this should fix it up, in case it ever does get used.
Backports commit d76951b65dfb1be4e41cfae6abebf8db7a1243a3 from qemu
Instead of mixing access permission checking with access permissions
to page protection flags translation, just do the translation, and
leave it to the caller to check the protection flags against the access
type. Also rename to ap_to_rw_prot to better describe the new behavior.
Backports commit 0fbf5238203041f734c51b49778223686f14366b from qemu
A LDRD or STRD where rd is not an even number is UNPREDICTABLE.
We were letting this fall through, which is OK unless rd is 15,
in which case we would attempt to do a load_reg or store_reg
to a nonexistent r16 for the second half of the double-word.
Catch the odd-numbered-rd cases and UNDEF them instead.
To do this we rearrange the structure of the code a little
so we can put the UNDEF catches at the top before we've
allocated TCG temporaries.
Backports commit a4bb522ee51087af61998f290d12ba2e14c7910e from qemu
The AArch64 SPSR_EL1 register is architecturally mandated to
be mapped to the AArch32 SPSR_svc register. This means its
state should live in QEMU's env->banked_spsr[1] field.
Correct the various places in the code that incorrectly
put it in banked_spsr[0].
Backports commit 7847f9ea9fce15a9ecfb62ab72c1e84ff516b0db from qemu
For the ARM M-profile cores, exception return pops various registers
including the PC from the stack. The architecture defines that if the
lowest bit in the new PC value is set (ie the PC is not halfword
aligned) then behaviour is UNPREDICTABLE. In practice hardware
implementations seem to simply ignore the low bit, and some buggy
RTOSes incorrectly rely on this. QEMU's behaviour was architecturally
permitted, but bringing QEMU into line with the hardware behaviour
allows more guest code to run. We log the situation as a guest error.
This was reported as LP:1428657.
Backports commit fcf83ab103dce6d2951f24f48e30820e7dbb3622 from qemu
The A32 encoding of LDM distinguishes LDM (user) from LDM (exception
return) based on whether r15 is in the register list. However for
STM (user) there is no equivalent distinction. We were incorrectly
treating "r15 in list" as indicating exception return for both LDM
and STM, with the result that an STM (user) involving r15 went into
an infinite loop. Fix this; note that the value stored for r15
in this case is the current PC regardless of our current mode.
Backports commit da3e53ddcb0ca924da97ca5a35605fc554aa3e05 from qemu
Avoid shifting potentially negative signed offset values in
disas_ldst_pair() by keeping the offset in a uint64_t rather
than an int64_t.
Backports commit c2ebd862a54b7e12175d65c03ba259926cb2237a from qemu
Shifting a negative integer left is undefined behaviour in C.
Avoid it by assembling and shifting the offset fields as
unsigned values and then sign extending as the final action.
Backports commit 037e1d009e2fcb80784d37f0e12aa999787d46d4 from qemu
The code in logic_imm_decode_wmask attempts to rotate a mask
value within the bottom 'e' bits of the value with
mask = (mask >> r) | (mask << (e - r));
This has two issues:
* if the element size is 64 then a rotate by zero results
in a shift left by 64, which is undefined behaviour
* if the element size is smaller than 64 then this will
leave junk in the value at bit 'e' and above, which is
not valid input to bitfield_replicate(). As it happens,
the bits at bit 'e' to '2e - r' are exactly the ones
which bitfield_replicate is going to copy in there,
so this isn't a "wrong code generated" bug, but it's
confusing and if we ever put an assert in
bitfield_replicate it would fire on valid guest code.
Fix the former by not doing anything if r is zero, and
the latter by masking with bitmask64(e).
Backports commit e167adc9d9f5df4f8109aecd4552c407fdce094a from qemu
Fix attempts to shift into the sign bit of an int, which is undefined
behaviour in C and warned about by the clang sanitizer.
Backports commit 1743d55c8b38bcee632cf6eb2de81131635bb3d2 from qemu
Add AArch32 to AArch64 register sychronization functions.
Replace manual register synchronization with new functions in
aarch64_cpu_do_interrupt() and HELPER(exception_return)().
Backports commit ce02049dbf1828b4bc77d921b108a9d84246e5aa from qemu
Adds registration and get/set functions for enabling/disabling the AArch64
execution state on AArch64 CPUs. By default AArch64 execution state is enabled
on AArch64 CPUs, setting the property to off, will disable the execution state.
The below QEMU invocation would have AArch64 execution state disabled.
$ ./qemu-system-aarch64 -machine virt -cpu cortex-a57,aarch64=off
Also adds stripping of features from CPU model string in acquiring the ARM CPU
by name.
Backports part of commit fb8d6c24b095c426151b9bba8c8b0e58b03d6503 from qemu
f64 exponent in HELPER(recpe_f64) should be compared to 2045 rather than 1023
(FPRecipEstimate in ARMV8 spec). This fixes incorrect underflow handling when
flushing denormals to zero in the FRECPE instructions operating on 64-bit
values.
Backports commit fc1792e9aa36227ee9994757974f9397684e1a48 from qemu
This patch implements a fucntion pointer "virtio_is_big_endian"
from "CPUClass" structure for arm/arm64.
Function arm_cpu_is_big_endian() is added to determine and
return the guest cpu endianness to virtio.
This is required for running cross endian guests with virtio on ARM/ARM64.
Backports commit 84f2bed3cf505f90b7918e2de32e11da27160563 from qemu
A few of the oldest parts of the page-table-walk code have broken indent
(either hardcoded tabs or two-spaces). Reindent these sections.
For ease of review, this patch does not touch the brace style and
so is a whitespace-only change.
Backports commit 554b0b09aec4579c8164f363b18a263150e91a2c from qemu
Now we have the mmu_idx in get_phys_addr(), use it correctly to
determine the behaviour of virtual to physical address translations,
rather than using just an is_user flag and the current CPU state.
Some TODO comments have been added to indicate where changes will
need to be made to add EL2 and 64-bit EL3 support.
Backports commit 0480f69abf849ca0d48928cc6c669c1c7264239b from qemu
Make all the callers of get_phys_addr() pass it the correct
mmu_idx rather than just a simple "is_user" flag. This includes
properly decoding the AT/ATS system instructions; we include the
logic for handling all the opc1/opc2 cases because we'll need
them later for supporting EL2/EL3, even if we don't have the
regdef stanzas yet.
Backports commit d364970287c0ba68979711928c15e5d37414f87f from qemu
Instead of simply reusing ats_write() as the handler for both AArch32
and AArch64 address translation operations, use a different function
for each with the common code in a third function. This is necessary
because the semantics for selecting the right translation regime are
different; we are only getting away with sharing currently because
we don't support EL2 and only support EL3 in AArch32.
Backports commit 060e8a48cb84d41d4ac36e4bb29d9c14ed7168b6 from qemu
target-arm doesn't use any of the MMU-mode specific cpu ldst
accessor functions. Suppress their generation by not defining
any of the MMU_MODE*_SUFFIX macros. ("user" and "kernel" are
too simplistic as descriptions of indexes 0 and 1 anyway.)
Backports commit 0dfef7b58f0c24b463e36630f08a45e93012b33a from qemu
The MMU index to use for unprivileged loads and stores is more
complicated than we currently implement:
* for A64, it should be "if at EL1, access as if EL0; otherwise
access at current EL"
* for A32/T32, it should be "if EL2, UNPREDICTABLE; otherwise
access as if at EL0".
In both cases, if we want to make the access for Secure EL0
this is not the same mmu_idx as for Non-Secure EL0.
Backports commit 579d21cce63f3dd2f6ee49c0b02a14e92cb4a836 from qemu
We currently claim that for ARM the mmu_idx should simply be the current
exception level. However this isn't actually correct -- secure EL0 and EL1
should have separate indexes from non-secure EL0 and EL1 since their
VA->PA mappings may differ. We also will want an index for stage 2
translations when we properly support EL2.
Define and document all seven mmu index values that we require, and
pass the mmu index in the TB flags rather than exception level or
priv/user bit.
This change doesn't update the get_phys_addr() code, so our page
table walking still assumes a simplistic "user or priv?" model for
the moment.
Backports commit c1e3781090b9d36c60e1a254ba297cb34011d3d4 from qemu
Although M profile doesn't have the same concept of exception level
as A profile, it does have a notion of privileged versus not, which
we currently track in the privmode TB flag. Support returning this
information if arm_current_el() is called on an M profile core, so
that we can identify the correct MMU index to use (and put the MMU
index in the TB flags) without having to special-case M profile.
Backports commit 6d54ed3c93f1e05a483201b087142998381c9be8 from qemu
The documentation states that if LSB > MSB in BFI instruction behaviour
is unpredictable. Currently QEMU crashes because of assertion failure in
this case:
tcg/tcg-op.h:2061: tcg_gen_deposit_i32: Assertion `len <= 32' failed.
While assertion failure may meet the "unpredictable" definition this
behaviour is undesirable because it allows an unprivileged guest program
to crash the emulator with the OS and other programs.
This patch addresses the issue by throwing illegal instruction exception
if LSB > MSB. Only ARM decoder is affected because Thumb decoder already
has this check in place.
To reproduce issue run the following program
int main(void) {
asm volatile (".long 0x07c00c12" :: );
return 0;
}
compiled with
gcc -marm -static badop_arm.c -o badop_arm
Backports commit 45140a57675ecb4b0daee71bf145c24dbdf9429c from qemu
The helper functions for FRECPS and FRSQRTS have special case
handling that includes checks for zero inputs, so squash input
denormals if necessary before those checks. This fixes incorrect
output when the FPCR DZ bit is set to enable squashing of input
denormals.
Backports commit a8eb6e19991d1a7a6a7b04ac447548d30d75eb4a from qemu
Add assertion checking when cpreg structures are registered that they
either forbid raw-access attempts or at least make an attempt at
handling them. Also add an assert in the raw-accessor-of-last-resort,
to avoid silently doing a read or write from offset zero, which is
actually AArch32 CPU register r0.
Backports commit 375421ccaeebae8212eb8f9a36835ad4d9dc60a8 from qemu
We currently mark ARM coprocessor/system register definitions with
the flag ARM_CP_NO_MIGRATE for two different reasons:
1) register is an alias on to state that's also visible via
some other register, and that other register is the one
responsible for migrating the state
2) register is not actually state at all (for instance the TLB
or cache maintenance operation "registers") and it makes no
sense to attempt to migrate it or otherwise access the raw state
This works fine for identifying which registers should be ignored
when performing migration, but we also use the same functions for
synchronizing system register state between QEMU and the kernel
when using KVM. In this case we don't want to try to sync state
into registers in category 2, but we do want to sync into registers
in category 1, because the kernel might have picked a different
one of the aliases as its choice for which one to expose for
migration. (In particular, on 32 bit hosts the kernel will
expose the state in the AArch32 version of the register, but
TCG's convention is to mark the AArch64 version as the version
to migrate, even if the CPU being emulated happens to be 32 bit,
so almost all system registers will hit this issue now that we've
added AArch64 system emulation.)
Fix this by splitting the NO_MIGRATE flag in two (ALIAS and NO_RAW)
corresponding to the two different reasons we might not want to
migrate a register. When setting up the TCG list of registers to
migrate we honour both flags; when populating the list from KVM,
only ignore registers which are NO_RAW.
Backports commit 7a0e58fa648736a75f2a6943afd2ab08ea15b8e0 from qemu
Update to arm_cpu_reset() to reset into the highest available exception level
based on the set ARM features.
Backports commit 5097227c15aa89baec1123aac25dd9500a62684d from qemu
Added RVBAR_EL2 and RVBAR_EL3 CP register support. All RVBAR_EL# registers
point to the same location and only the highest EL version exists at any one
time.
Backports commit be8e8128595b41b9f609c1507e67d121e65e7173 from qemu
The crypto emulation code in target-arm/crypto_helper.c never worked
correctly on big endian hosts, due to the fact that it uses a union
of array types to convert between the native VFP register size (64
bits) and the types used in the algorithms (bytes and 32 bit words)
We cannot just swab between LE and BE when reading and writing the
registers, as the SHA code performs word additions, so instead, add
array accessors for the CRYPTO_STATE type whose LE and BE specific
implementations ensure that the correct array elements are referenced.
Backports commit b449ca3c1874418d948878d5417a32fc0dbf9fea from qemu
Added a "has_el3" state property to the ARMCPU descriptor. This property
indicates whether the ARMCPU has security extensions enabled (EL3) or not.
By default it is disabled at this time.
Backports commit 51942aee3c51ca23b0dd78f95534a57e8dc1e582 from qemu
Add an unset_feature() function to compliment the set_feature() function. This
will be used to disable functions after they have been enabled during
initialization.
Backports commit 08828484a5c1ec55a6cbb4b4d377bfcf41199b5c from qemu
Merge of the v8_el2_cp_reginfo and el3_cp_reginfo ARMCPRegInfo lists.
Previously, some EL3 registers were restricted to the ARMv8 list under the
impression that they were not needed on ARMv7. However, this is not the case
as the ARMv7/32-bit variants rely on the ARMv8/64-bit variants to handle
migration and reset. For this reason they must always exist.
Backports commit 60fb1a87b47b14e4ea67043aa56f353e77fbd70a from qemu
When EL3 is running in AArch32 (or ARMv7 with Security Extensions)
FCSEIDR, CONTEXTIDR, TPIDRURW, TPIDRURO and TPIDRPRW have a secure
and a non-secure instance.
Backports commit 54bf36ed351c526cde0c853079f9ff1ab7e2ff89 from qemu
When EL3 is running in Aarch32 (or ARMv7 with Security Extensions)
VBAR has a secure and a non-secure instance, which are mapped to
VBAR_EL1 and VBAR_EL3.
Backports commit fb6c91ba2bb0b1c1b8662ceeeeb9474a025f9a6b from qemu
When EL3 is running in AArch32 (or ARMv7 with Security Extensions)
PAR has a secure and a non-secure instance.
Backports commit 01c097f7960b330c4bf038d34bae17ad6c1ba499 from qemu
When EL3 is running in AArch32 (or ARMv7 with Security Extensions)
IFAR and DFAR have a secure and a non-secure instance.
Backports commit b848ce2b9cbd38da3f2530fd93dba76dba0621c0 from qemu
When EL3 is running in AArch32 (or ARMv7 with Security Extensions)
DFSR has a secure and a non-secure instance.
Backports commit 4a7e2d7315bd2ce28e49ccd0bde73eabdfd7437b from qemu
When EL3 is running in AArch32 (or ARMv7 with Security Extensions)
IFSR has a secure and a non-secure instance. Adds IFSR32_EL2 definition and
storage.
Backports commit 88ca1c2d70523486a952065f3ed7b8fc823b5863 from qemu
When EL3 is running in AArch32 (or ARMv7 with Security Extensions)
DACR has a secure and a non-secure instance. Adds definition for DACR32_EL2.
Backports commit 0c17d68c1d3d6c35f37f5692042d2edb65c8bcc0 from qemu
Adds secure and non-secure bank register suport for TTBCR.
Added new struct to compartmentalize the TCR data and masks. Removed old
tcr/ttbcr data and added a 4 element array of the new structs in cp15. This
allows for one entry per EL. Added a CP register definition for TCR_EL3.
Backports commit 11f136ee25232a00f433cefe98ee33cd614ecccc from qemu
Adds secure and non-secure bank register suport for TTBR0 and TTBR1.
Changes include adding secure and non-secure instances of ttbr0 and ttbr1 as
well as a CP register definition for TTBR0_EL3. Added a union containing
both EL based array fields and secure and non-secure fields mapped to them.
Updated accesses to use A32_BANKED_CURRENT_REG_GET macro.
Backports commit 7dd8c9af0d9d18fb3e54a4843b3bb1398bd330bc to qemu
Add checks of SCR AW/FW bits when performing writes of CPSR. These SCR bits
are used to control whether the CPSR masking bits can be adjusted from
non-secure state.
Backports commit 6e8801f9dea9e10449f4fd7d85dbe8cab708a686 from qemu
Use MVBAR register as exception vector base address for
exceptions taken to CPU monitor mode.
Backports commit e89e51a17ea0d8aef9bf9b766c98f963e835fbf2 from qemu
Added CP register defintions for SDER and SDER32_EL3 as well as cp15.sder for
register storage.
Backports commit 144634ae6c1618dcee6aced9c0d4427844154091 from qemu
Implements NSACR register with corresponding read/write functions
for ARMv7 and ARMv8.
Backports commit 770225764f831031d2e1453f69c365eb1b647d87 from qemu
SCR.{IRQ/FIQ} bits allow to route IRQ/FIQ exceptions to monitor CPU
mode. When taking IRQ exception to monitor mode FIQ exception is
additionally masked.
Backports commit de38d23b542efca54108ef28bcc0efe96f378d2e from qemu
Define a new ARM CP register info list for the ARMv7 Security Extension
feature. Register that list only for ARM cores with Security Extension/EL3
support. Moving AArch32 SCR into Security Extension register group.
Backports commit 0f1a3b2470d798ad5335eb9d6236f02ff64e31a8 from qemu
Prepare for cp register banking by inserting every cp register twice,
once for secure world and once for non-secure world.
Backports commit 3f3c82a57d128aa3ec823aa8032867c3a6e2e795 from qemu
Added additional NS-bit to CPREG hash encoding. Updated hash lookup
locations to specify hash bit currently set to non-secure.
Backports commit 51a79b039728277e35fd19f7a7b4bc6cb323697f from qemu
Prepare ARMCPRegInfo to support specifying two fieldoffsets per
register definition. This will allow us to keep one register
definition for banked registers (different offsets for secure/
non-secure world).
Also added secure state tracking field and flags. This allows for
identification of the register info secure state.
Backports commit c3e302606253a17568dc3ef30238f102468f7ee1 from qemu
This patch is based on idea found in patch at
git://github.com/jowinter/qemu-trustzone.git
f3d955c6c0ed8c46bc0eb10b634201032a651dd2 by
Johannes Winter <johannes.winter@iaik.tugraz.at>.
The TBFLAG captures the SCR NS secure state at the time when a TB is created so
the correct bank is accessed on system register accesses.
Backports commit 3f342b9e0e64ad681cd39840bfa75ef12d2807c1 from qemu
If EL3 is in AArch32 state certain cp registers are banked (secure and
non-secure instance). When reading or writing to coprocessor registers
the following macros can be used.
- A32_BANKED macros are used for choosing the banked register based on provided
input security argument. This macro is used to choose the bank during
translation of MRC/MCR instructions that are dependent on something other
than the current secure state.
- A32_BANKED_CURRENT macros are used for choosing the banked register based on
current secure state. This is NOT to be used for choosing the bank used
during translation as it breaks monitor mode.
If EL3 is operating in AArch64 state coprocessor registers are not
banked anymore. The macros use the non-secure instance (_ns) in this
case, which is architecturally mapped to the AArch64 EL register.
Backports commit ea30a4b824ecc3c829b70eb9999ac5457dc5790f from qemu
Adds a dedicated function and a lookup table for determining the target
exception level of IRQ and FIQ exceptions. The lookup table is taken from the
ARMv7 and ARMv8 specification exception routing tables.
Backports commit 0eeb17d618361a0f4faddc160e33598b23da6dd5 from qemu
This patch extends arm_excp_unmasked() to use lookup tables for determining
whether IRQ and FIQ exceptions are masked. The lookup tables are based on the
ARMv8 and ARMv7 specification physical interrupt masking tables.
If EL3 is using AArch64 IRQ/FIQ masking is ignored in all exception levels
other than EL3 if SCR.{FIQ|IRQ} is set to 1 (routed to EL3).
Backports commit 57e3a0c7cb0ac2f0288890482e0a463adce2080a from qemu
While we're at it, emit the opcode adjacent to where we currently
record data for search_pc. This puts gen_io_start et al on the
"correct" side of the marker.
Backports commit 667b8e29c5b1d8c5b4e6ad5f780ca60914eb6e96 from qemu
Usually, eliminate an operation from the translator by combining
a shift with an extract.
In the case of gen_set_NZ64, we don't need a boolean value for cpu_ZF,
merely a non-zero value. Given that we can extract both halves of a
64-bit input in one call, this simplifies the code.
Backports commit 7cb36e18b2f1c1f971ebdc2121de22a8c2e94fd6 from qemu
For !SF, this initial ext32u can't be optimized away by the
current TCG code generator. (It would require backward bit
liveness propagation.)
Backports commit d3a77b42decd0cbfa62a5526e67d1d6d380c83a9 from qemu
This can allow much of a ccmp to be elided when particular
flags are subsequently dead.
Backports commit 7dd03d773e0dafae9271318fc8d6b2b14de74403 from qemu
Handling this with TCG_COND_ALWAYS will allow these unlikely
cases to be handled without special cases in the rest of the
translator. The TCG optimizer ought to be able to reduce
these ALWAYS conditions completely.
Backports commit 9305eac09e61d857c9cc11e20db754dfc25a82db from qemu
Split arm_gen_test_cc into 3 functions, so that it can be reused
for non-branch TCG comparisons.
Backports commit 6c2c63d3a02c79e9035ca0370cc549d0f938a4dd from qemu
The extra information is not yet used but it is now available.
This requires minor changes through all of the tcg backends.
Backports commit 3972ef6f830d65e9bacbd31257abedc055fd6dc8 from qemu
This is improved type checking for the translators -- it's no longer
possible to accidentally swap arguments to the branch functions.
Note that the code generating backends still manipulate labels as int.
With notable exceptions, the scope of the change is just a few lines
for each target, so it's not worth building extra machinery to do this
change in per-target increments.
Backports commit 42a268c241183877192c376d03bd9b6d527407c7 from qemu
The method by which we count the number of ops emitted
is going to change. Abstract that away into some inlines.
Backports commit fe700adb3db5b028b504423b946d4ee5200a8f2f from qemu.
Thus, use cpu_env as the parameter, not TCG_AREG0 directly.
Update all uses in the translators.
Backports commit e1ccc05444676b92c63708096e36582be27fbee1 from qemu
* arm64eb: arm64 big endian also using little endian instructions.
* arm64: using another example that depends on endians.
example:
1. store a word: 0x12345678
2. load a byte:
* little endian : 0x78
* big endian : 0x12
* uc_reg_read & uc_reg_write now support ARM64 Neon registers
* Do not reuse uc_x86_xmm for uc_arm64_neon128. TODO: refactor both classes to use the same parent.
* reg_read and reg_write now work with registers W0 through W30 in Aarch64 emulaton
* Added a regress test for the ARM64 reg_read and reg_write on 32-bit registers (W0-W30)
Added a new macro in uc_priv.h (WRITE_DWORD_TO_QWORD), in order to write to the lower 32 bits of a 64 bit value without overwriting the whole value when using reg_write
* Fixed WRITE_DWORD macro
reg_write would zero out the high order bits when writing to 32 bit registers
e.g. uc.reg_write(UC_X86_REG_EAX, 0) would also set register RAX to zero
