These instructions shift left or right depending on the sign
of the input, and 7 bits are significant to the shift. This
requires several masks and selects in addition to the actual
shifts to form the complete answer.
That said, the operation is still a small improvement even for
two 64-bit elements -- 13 vector operations instead of 2 * 7
integer operations.
Backports commit 87b74e8b6edd287ea2160caa0ebea725fa8f1ca1 from qemu
Implement emulation of GINVT instruction. As QEMU doesn't support
caches and virtualization, this implementation covers only one
instruction (GINVT - Global Invalidate TLB) among all TLB-related
MIPS instructions.
Backports commit 99029be1c2875cd857614397674bbf563ddb6f91 from qemu
WatchHi is extended by the field MemoryMapID with the GINVT instruction.
The field is accessible by MTHC0/MFHC0 in 32-bit architectures and DMTC0/
DMFC0 in 64-bit architectures.
Backports commit feafe82cc2289a31b3e3f11dc76f3539ea22d670 from qemu
Add an option to trigger memory writeback to sync given memory region
with the corresponding backing store, case one is available.
This extends the support for persistent memory, allowing syncing on-demand.
Backports commit 61c490e25e081af39ff40556f6c1229b8b011585 from qemu
The raising of exceptions from check_watchpoint, buried inside
of the I/O subsystem, is fundamentally broken. We do not have
the helper return address with which we can unwind guest state.
Replace PHYS_SECTION_WATCH and io_mem_watch with TLB_WATCHPOINT.
Move the call to cpu_check_watchpoint into the cputlb helpers
where we do have the helper return address.
This allows watchpoints on RAM to bypass the full i/o access path.
Backports commit 50b107c5d617eaf93301cef20221312e7a986701 from qemu
Preparation for collapsing the two byte swaps adjust_endianness and
handle_bswap into the former.
Call memory_region_dispatch_{read|write} with endianness encoded into
the "MemOp op" operand.
This patch does not change any behaviour as
memory_region_dispatch_{read|write} is yet to handle the endianness.
Once it does handle endianness, callers with byte swaps can collapse
them into adjust_endianness.
Backports commit d5d680cacc66ef7e3c02c81dc8f3a34eabce6dfe from qemu
HCR_EL2.TID3 requires that AArch32 reads of MVFR[012] are trapped to
EL2, and HCR_EL2.TID0 does the same for reads of FPSID.
In order to handle this, introduce a new TCG helper function that
checks for these control bits before executing the VMRC instruction.
Tested with a hacked-up version of KVM/arm64 that sets the control
bits for 32bit guests.
Backports commit 9ca1d776cb49c09b09579d9edd0447542970c834 from qemu
Switch the MIPS target from the old unassigned_access hook to the new
do_transaction_failed hook.
Unlike the old hook, do_transaction_failed is only ever called from
the TCG memory access paths, so there is no need for the "ignore this
if we're using KVM" hack that we were previously using to work around
the way unassigned_access was called for all kinds of memory accesses
to unassigned physical addresses.
The MIPS target does not ever do direct memory reads by physical
address (via either ldl_phys etc or address_space_ldl etc), so the
only memory accesses this affects are the 'normal' guest loads and
stores, which will be handled by the new hook; their behaviour is
unchanged.
Backports commit 4f02a06d50ef0081089ed8cb3ec7c7986e3c95f8 from qemu
Replace x = double_saturate(y) with x = add_saturate(y, y).
There is no need for a separate more specialized helper.
Backports commit 640581a06d14e2d0d3c3ba79b916de6bc43578b0 from qemu
The old version of the helper for the INSERT.<B|H|W|D> MSA instructions
has been replaced with four helpers that don't use switch, and change
the endianness of the given index, when executed on a big endian host.
Backports commit c1c9a10fb1f7a6782711817c167a2c20b000fc12 from qemu
The old version of the helper for the COPY_U.<B|H|W> MSA instructions
has been replaced with four helpers that don't use switch, and change
the endianness of the given index, when executed on a big endian host.
Backports commit 41d288582782cf8d63241ecb6efa1e4160fe78f7 from qemu
The old version of the helper for the COPY_S.<B|H|W|D> MSA instructions
has been replaced with four helpers that don't use switch, and change
the endianness of the given index, when executed on a big endian host.
Backports commit 631c467461496dcf6d6a3e4c3d27a1433e96868e from qemu
Perform a per-element conditional move. This combination operation is
easier to implement on some host vector units than plain cmp+bitsel.
Omit the usual gvec interface, as this is intended to be used by
target-specific gvec expansion call-backs.
Backports commit f75da2988eb2457fa23d006d573220c5c680ec4e from qemu
This operation performs d = (b & a) | (c & ~a), and is present
on a majority of host vector units. Include gvec expanders.
Backports commit 38dc12947ec9106237f9cdbd428792c985cd86ae from qemu
We can now use the CPUClass hook instead of a named function.
Create a static tlb_fill function to avoid other changes within
cputlb.c. This also isolates the asserts within. Remove the
named tlb_fill function from all of the targets.
Backports commit c319dc13579a92937bffe02ad2c9f1a550e73973 from qemu
Note that env->active_tc.PC is removed from the qemu_log as that value
is garbage. The PC isn't recovered until cpu_restore_state, called from
cpu_loop_exit_restore, called from do_raise_exception_err.
Backports commit 931d019f5b2e7bbacb162869497123be402ddd86 from qemu
Remove a function of the same name from target/arm/.
Use a branchless implementation of abs gleaned from gcc.
Backports commit ff1f11f7f8710a768f9313f24bd7f509d3db27e5 from qemu
Allow expansion either via shift by scalar or by replicating
the scalar for shift by vector.
Backports commit b4578cd91cda4cef1c413304353ca6dc5b957b60 from qemu
The gvec expanders perform a modulo on the shift count. If the target
requires alternate behaviour, then it cannot use the generic gvec
expanders anyway, and will have to have its own custom code.
Backports commit 5ee5c14cacda27e904cd6b0d9e7ffe1acff42838 from qemu
Allow the backend to expand dup from memory directly, instead of
forcing the value into a temp first. This is especially important
if integer/vector register moves do not exist.
Note that officially tcg_out_dupm_vec is allowed to fail.
If it did, we could fix this up relatively easily:
VECE == 32/64:
Load the value into a vector register, then dup.
Both of these must work.
VECE == 8/16:
If the value happens to be at an offset such that an aligned
load would place the desired value in the least significant
end of the register, go ahead and load w/garbage in high bits.
Load the value w/INDEX_op_ld{8,16}_i32.
Attempt a move directly to vector reg, which may fail.
Store the value into the backing store for OTS.
Load the value into the vector reg w/TCG_TYPE_I32, which must work.
Duplicate from the vector reg into itself, which must work.
All of which is well and good, except that all supported
hosts can support dupm for all vece, so all of the failure
paths would be dead code and untestable.
Backports commit 37ee55a081b7863ffab2151068dd1b2f11376914 from qemu
Replace the single opcode in .opc with a null-terminated
array in .opt_opc. We still require that all opcodes be
used with the same .vece.
Validate the contents of this list with CONFIG_DEBUG_TCG.
All tcg_gen_*_vec functions will check any list active
during .fniv expansion. Swap the active list in and out
as we expand other opcodes, or take control away from the
front-end function.
Convert all existing vector aware front ends.
Backports commit 53229a7703eeb2bbe101a19a33ef22aaf960c65b from qemu
Let's add tcg_gen_gvec_3i(), similar to tcg_gen_gvec_2i(), however
without introducing "gen_helper_gvec_3i *fnoi", as it isn't needed
for now.
Backports commit e1227bb6e59173117f094a6a13b998587b45c928 from qemu
The M-profile architecture floating point system supports
lazy FP state preservation, where FP registers are not
pushed to the stack when an exception occurs but are instead
only saved if and when the first FP instruction in the exception
handler is executed. Implement this in QEMU, corresponding
to the check of LSPACT in the pseudocode ExecuteFPCheck().
Backports commit e33cf0f8d8c9998a7616684f9d6aa0d181b88803 from qemu
Will be helpful for s390x. Input 128 bit and output 64 bit only,
which is sufficient for now.
Backports commit 2089fcc9e7b4174d1c351eaa7d277c02188a6dd2 from qemu
This ports over the RISC-V architecture from Qemu. This is currently a
very barebones transition. No code hooking or any fancy stuff.
Currently, you can feed it instructions and query the CPU state itself.
This also allows choosing whether or not RISC-V 32-bit or RISC-V 64-bit
is desirable through Unicorn's interface as well.
Extremely basic examples of executing a single instruction have been
added to the samples directory to help demonstrate how to use the basic
functionality.
We do not need an out-of-line helper for manipulating bits in pstate.
While changing things, share the implementation of gen_ss_advance.
Backports commit 22ac3c49641f6eed93dca5b852030b4d3eacf6c4 from qemu
The EL0+UMA check is unique to DAIF. While SPSel had avoided the
check by nature of already checking EL >= 1, the other post v8.0
extensions to MSR (imm) allow EL0 and do not require UMA. Avoid
the unconditional write to pc and use raise_exception_ra to unwind.
Backports commit ff730e9666a716b669ac4a8ca7c521177d1d2b15 from qemu
Note that float16_to_float32 rightly squashes SNaN to QNaN.
But of course pickNaNMulAdd, for ARM, selects SNaNs first.
So we have to preserve SNaN long enough for the correct NaN
to be selected. Thus float16_to_float32_by_bits.
Backports commit a4e943a716d5fac923d82df3eabc65d1e3624019 from qemu
For same-sign saturation, we have tcg vector operations. We can
compute the QC bit by comparing the saturated value against the
unsaturated value.
Backports commit 89e68b575e138d0af1435f11a8ffcd8779c237bd from qemu
A number of CPUID registers are exposed to userspace by modern Linux
kernels thanks to the "ARM64 CPU Feature Registers" ABI. For QEMU's
user-mode emulation we don't need to emulate the kernels trap but just
return the value the trap would have done. To avoid too much #ifdef
hackery we process ARMCPRegInfo with a new helper (modify_arm_cp_regs)
before defining the registers. The modify routine is driven by a
simple data structure which describes which bits are exported and
which are fixed.
Backports commit 6c5c0fec29bbfe36c64eca1edfd8455be46b77c6 from qemu
pmccntr_read and pmccntr_write contained duplicate code that was already
being handled by pmccntr_sync. Consolidate the duplicated code into two
functions: pmccntr_op_start and pmccntr_op_finish. Add a companion to
c15_ccnt in CPUARMState so that we can simultaneously save both the
architectural register value and the last underlying cycle count - this
ensures time isn't lost and will also allow us to access the 'old'
architectural register value in order to detect overflows in later
patches.
Backports commit 5d05b9d462666ed21b7fef61aa45dec9aaa9f0ff from qemu
In commit 8a0fc3a29fc2315325400 we tried to implement HCR_EL2.{VI,VF},
but we got it wrong and had to revert it.
In that commit we implemented them as simply tracking whether there
is a pending virtual IRQ or virtual FIQ. This is not correct -- these
bits cause a software-generated VIRQ/VFIQ, which is distinct from
whether there is a hardware-generated VIRQ/VFIQ caused by the
external interrupt controller. So we need to track separately
the HCR_EL2 bit state and the external virq/vfiq line state, and
OR the two together to get the actual pending VIRQ/VFIQ state.
Fixes: 8a0fc3a29fc2315325400c738f807d0d4ae0ab7f
Backports commit 89430fc6f80a5aef1d4cbd6fc26b40c30793786c from qemu
Add a new flag to mark memory region that are used as non-volatile, by
NVDIMM for example. That bit is propagated down to the flat view, and
reflected in HMP info mtree with a "nv-" prefix on the memory type.
This way, guest_phys_blocks_region_add() can skip the NV memory
regions for dumps and TCG memory clear in a following patch.
Backports commit c26763f8ec70b1011098cab0da9178666d8256a5 from qemu
Implement hardware page table walker. This implementation is
limiter only to MIPS32.
Backports commit 074cfcb4daedf59ccbbbc83c24eee80e0e8f4c71 from qemu
Add PWCtl register (CP0 Register 5, Select 6).
The PWCtl register configures hardware page table walking for TLB
refills.
This register is required for the hardware page walker feature. It
exists only if Config3 PW bit is set to 1. It contains following
fields:
PWEn (31) - Hardware Page Table walker enable
PWDirExt (30) - If 1, 4-th level implemented (MIPS64 only)
XK (28) - If 1, walker handles xkseg (MIPS64 only)
XS (27) - If 1, walker handles xsseg (MIPS64 only)
XU (26) - If 1, walker handles xuseg (MIPS64 only)
DPH (7) - Dual Page format of Huge Page support
HugePg (6) - Huge Page PTE supported in Directory levels
PSn (5..0) - Bit position of PTEvld in Huge Page PTE
Backports commit 103be64c26c166f12b3e1308edadef3443723ff1 from qemu
Add PWSize register (CP0 Register 5, Select 7).
The PWSize register configures hardware page table walking for TLB
refills.
This register is required for the hardware page walker feature. It
exists only if Config3 PW bit is set to 1. It contains following
fields:
BDW (37..32) Base Directory index width (MIPS64 only)
GDW (29..24) Global Directory index width
UDW (23..18) Upper Directory index width
MDW (17..12) Middle Directory index width
PTW (11..6 ) Page Table index width
PTEW ( 5..0 ) Left shift applied to the Page Table index
Backports commit 20b28ebc49945583d7191b57755cfd92433de9ff from qemu
Add PWField register (CP0 Register 5, Select 6).
The PWField register configures hardware page table walking for TLB
refills.
This register is required for the hardware page walker feature. It
exists only if Config3 PW bit is set to 1. It contains following
fields:
MIPS64:
BDI (37..32) - Base Directory index
GDI (29..24) - Global Directory index
UDI (23..18) - Upper Directory index
MDI (17..12) - Middle Directory index
PTI (11..6 ) - Page Table index
PTEI ( 5..0 ) - Page Table Entry shift
MIPS32:
GDW (29..24) - Global Directory index
UDW (23..18) - Upper Directory index
MDW (17..12) - Middle Directory index
PTW (11..6 ) - Page Table index
PTEW ( 5..0 ) - Page Table Entry shift
Backports commit fa75ad1459f4f6abbeb6d375a812dfad61320f58 from qemu
Add code to insert calls to a helper function to do the stack
limit checking when we handle these forms of instruction
that write to SP:
* ADD (SP plus immediate)
* ADD (SP plus register)
* SUB (SP minus immediate)
* SUB (SP minus register)
* MOV (register)
Backports commit 5520318939fea5d659bf808157cd726cb967b761 from qemu
It has not had users since f83311e476 ("target-m68k: use floatx80
internally", 2017-06-21).
Note that no other bit-width has floatX_trunc_to_int.
Backports commit c953da8f0be5e026d1c9128660736d72294feb3e from qemu
if MemoryRegion intialization fails it's left in semi-initialized state,
where it's size is not 0 and attached as child to owner object.
And this leds to crash in following use-case:
(monitor) object_add memory-backend-file,id=mem1,size=99999G,mem-path=/tmp/foo,discard-data=yes
memory.c:2083: memory_region_get_ram_ptr: Assertion `mr->ram_block' failed
Aborted (core dumped)
it happens due to assumption that memory region is intialized when
memory_region_size() != 0
and therefore it's ok to access it in
file_backend_unparent()
if (memory_region_size() != 0)
memory_region_get_ram_ptr()
which happens when object_add fails and unparents failed backend making
file_backend_unparent() access invalid memory region.
Fix it by making sure that memory_region_init_foo() APIs cleanup externally
visible side effects on failure (like set size to 0 and unparenting object)
Added a helper for ROTX based on the pseudocode from the
architecture spec. This instraction was not present in previous
MIPS instruction sets.
Backports commit e222f5067269392af489731221750976d0cf3c05 from qemu
The API for cpu_transaction_failed() says that it takes the physical
address for the failed transaction. However we were actually passing
it the offset within the target MemoryRegion. We don't currently
have any target CPU implementations of this hook that require the
physical address; fix this bug so we don't get confused if we ever
do add one.
Backports commit 2d54f19401bc54b3b56d1cc44c96e4087b604b97 from qemu
Instead of passing env and leaving it up to the helper to get the
right fpstatus we pass it explicitly. There was already a get_fpstatus
helper for neon for the 32 bit code. We also add an get_ahp_flag() for
passing the state of the alternative FP16 format flag. This leaves
scope for later tracking the AHP state in translation flags.
Backports commit 486624fcd3eaca6165ab8401d73bbae6c0fb81c1 from qemu
The instruction "ucvtf v0.4h, v04h, #2", with input 0x8000u,
overflows the intermediate float16 to infinity before we have a
chance to scale the output. Use float64 as the intermediate type
so that no input argument (uint32_t in this case) can overflow
or round before scaling. Given the declared argument, the signed
int32_t function has the same problem.
When converting from float16 to integer, using u/int32_t instead
of u/int16_t means that the bounding is incorrect.
Backports commit 88808a022c06f98d81cd3f2d105a5734c5614839 from qemu
Given that this atomic operation will be used by both risc-v
and aarch64, let's not duplicate code across the two targets.
Backports commit 5507c2bf35aa6b4705939349184e71afd5e058b2 from qemu
These operations are re-invented by several targets so far.
Several supported hosts have insns for these, so place the
expanders out-of-line for a future introduction of tcg opcodes.
Backports commit b87fb8cd9f9a0ba599ff79e7bf03222da02e5724 from qemu
Drop TCGV_PTR_TO_NAT and TCGV_NAT_TO_PTR internal macros.
Add tcg_temp_local_new_ptr, tcg_gen_brcondi_ptr, tcg_gen_ext_i32_ptr,
tcg_gen_trunc_i64_ptr, tcg_gen_extu_ptr_i64, tcg_gen_trunc_ptr_i32.
Use inlines instead of macros where possible.
Backports commit 5bfa803448638a45542441fd6b7cc1241403ea72 from qemu
The MDCR_EL2.TDE bit allows the exception level targeted by debug
exceptions to be set to EL2 for code executing at EL0. We handle
this in the arm_debug_target_el() function, but this is only used for
hardware breakpoint and watchpoint exceptions, not for the exception
generated when the guest executes an AArch32 BKPT or AArch64 BRK
instruction. We don't have enough information for a translate-time
equivalent of arm_debug_target_el(), so instead make BKPT and BRK
call a special purpose helper which can do the routing, rather than
the generic exception_with_syndrome helper.
Backports commit c900a2e62dd6dde11c8f5249b638caad05bb15be from qemu
Currently CPUState::cpu_index is monotonically increasing and a newly
created CPU always gets the next higher index. The next available
index is calculated by counting the existing number of CPUs. This is
fine as long as we only add CPUs, but there are architectures which
are starting to support CPU removal, too. For an architecture like PowerPC
which derives its CPU identifier (device tree ID) from cpu_index, the
existing logic of generating cpu_index values causes problems.
With the currently proposed method of handling vCPU removal by parking
the vCPU fd in QEMU
(Ref: http://lists.gnu.org/archive/html/qemu-devel/2015-02/msg02604.html),
generating cpu_index this way will not work for PowerPC.
This patch changes the way cpu_index is handed out by maintaining
a bit map of the CPUs that tracks both addition and removal of CPUs.
The CPU bitmap allocation logic is part of cpu_exec_init(), which is
called by instance_init routines of various CPU targets. Newly added
cpu_exec_exit() API handles the deallocation part and this routine is
called from generic CPU instance_finalize.
Note: This new CPU enumeration is for !CONFIG_USER_ONLY only.
CONFIG_USER_ONLY continues to have the old enumeration logic.
Backports commit b7bca7333411bd19c449147e8202ae6b0e4a8e09 from qemu
With all targets defining CPU_RESOLVING_TYPE, refactor
cpu_parse_cpu_model(type, cpu_model) to parse_cpu_model(cpu_model)
so that callers won't have to know internal resolving cpu
type. Place it in exec.c so it could be called from both
target independed vl.c and *-user/main.c.
That allows us to stop abusing cpu type from
MachineClass::default_cpu_type
as resolver class in vl.c which were confusing part of
cpu_parse_cpu_model().
Also with new parse_cpu_model(), the last users of cpu_init()
in null-machine.c and bsd/linux-user targets could be switched
to cpu_create() API and cpu_init() API will be removed by
follow up patch.
With no longer users left remove MachineState::cpu_model field,
new code should use MachineState::cpu_type instead and
leave cpu_model parsing to generic code in vl.c.
Backports commit 2278b93941d42c30e2950d4b8dff4943d064e7de from qemu
The only difference from qstring_get_str() is that it allows the qstring
to be NULL. If so, NULL is returned.
Backports commit 775932020dd6bd7e9c1acc0d7779677d8b4c094c from qemu
Instantiate a QObject* from a literal QLitObject.
LitObject only supports int64_t for now. uint64_t and double aren't
implemented.
Backports commit 3cf42b8b3af1bd61e736a9ca0f94806c7931ae56 from qemu
Backports commits 2994fd96d986578a342f2342501b4ad30f6d0a85,
701e3c78ce45fa630ffc6826c4b9a4218954bc7f, and
d1853231c60d16af78cf4d1608d043614bfbac0b from qemuu
This function needs to be converted to QOM hook and virtualised for
multi-arch. This rename interferes, as cpu-qom will not have access
to the renaming causing name divergence. This rename doesn't really do
anything anyway so just delete it.
Backports commit 8642c1b81e0418df066a7960a7426d85a923a253 from qemu
Unify half a dozen copies of very similar code (the only difference being
whether comparisons were case-sensitive) and use it also in Tricore,
which did not do any sorting of CPU model names.
Backports commit 47c66009ab793241e8210b3018c77a9ce9506aa8 from qemu
A few block drivers will need to rename .bdrv_create options for their
QAPIfication, so let's have a helper function for that.
Backports commit bcebf102ccc3c6db327f341adc379fdf0673ca6b from qemu
This shares an cached empty FlatView among address spaces. The empty
FV is used every time when a root MR renders into a FV without memory
sections which happens when MR or its children are not enabled or
zero-sized. The empty_view is not NULL to keep the rest of memory
API intact; it also has a dispatch tree for the same reason.
On POWER8 with 255 CPUs, 255 virtio-net, 40 PCI bridges guest this halves
the amount of FlatView's in use (557 -> 260) and dispatch tables
(~800000 -> ~370000). In an unrelated experiment with 112 non-virtio
devices on x86 ("-M pc"), only 4 FlatViews are alive, and about ~2000
are created at startup.
Backports commit 092aa2fc65b7a35121616aad8f39d47b8f921618 from qemu
Since FlatViews are shared now and ASes not, this gets rid of
address_space_init_shareable().
This should cause no behavioural change.
Backports commit b516572f31c0ea0937cd9d11d9bd72dd83809886 from qemu
This renames some helpers to reflect better what they do.
This should cause no behavioural change.
Backports commit 8629d3fcb77e9775e44d9051bad0fb5187925eae from qemu
FlatView's will be shared between AddressSpace's and subpage_t
and MemoryRegionSection cannot store AS anymore, hence this change.
In particular, for:
typedef struct subpage_t {
MemoryRegion iomem;
- AddressSpace *as;
+ FlatView *fv;
hwaddr base;
uint16_t sub_section[];
} subpage_t;
struct MemoryRegionSection {
MemoryRegion *mr;
- AddressSpace *address_space;
+ FlatView *fv;
hwaddr offset_within_region;
Int128 size;
hwaddr offset_within_address_space;
bool readonly;
};
This should cause no behavioural change.
Backports commit 166206845f7fd75e720e6feea0bb01957c8da07f from qemu
As we are going to share FlatView's between AddressSpace's,
and AddressSpaceDispatch is a structure to perform quick lookup
in FlatView, this moves ASD to FlatView.
After previosly open coded ASD rendering, we can also remove
as->next_dispatch as the new FlatView pointer is stored
on a stack and set to an AS atomically.
flatview_destroy() is executed under RCU instead of
address_space_dispatch_free() now.
This makes mem_begin/mem_commit to work with ASD and mem_add with FV
as later on mem_add will be taking FV as an argument anyway.
This should cause no behavioural change.
Backports commit 66a6df1dc6d5b28cc3e65db0d71683fbdddc6b62 from qemu
Convert all machines to use DEFINE_MACHINE() instead of QEMUMachine
automatically using a script.
Backports commit e264d29de28c5b0be3d063307ce9fb613b427cc3 from qemu
Since f3218a8 ("softfloat: add floatx80 constants")
floatx80_infinity is defined but never used.
This patch updates floatx80 functions to use
this definition.
This allows to define a different default Infinity
value on m68k: the m68k FPU defines infinity with
all bits set to zero in the mantissa.
Backports commit 0f605c889ca3fe9744166ad4149d0dff6dacb696 from qemu
Much like recpe the ARM ARM has simplified the pseudo code for the
calculation which is done on a fixed point 9 bit integer maths. So
while adding f16 we can also clean this up to be a little less heavy
on the floating point and just return the fractional part and leave
the calle's to do the final packing of the result.
Backports commit d719cbc7641991d16b891ffbbfc3a16a04e37b9a from qemu
Also removes a load of symbols that seem unnecessary from the header_gen script
It looks like the ARM ARM has simplified the pseudo code for the
calculation which is done on a fixed point 9 bit integer maths. So
while adding f16 we can also clean this up to be a little less heavy
on the floating point and just return the fractional part and leave
the calle's to do the final packing of the result.
Backports commit 5eb70735af1c0b607bf2671a53aff3710cc1672f from qemu
