In commit a3494d4671 we reworked the M-profile handling of its
checks for when the NOCP exception should be raised because the FPU
is disabled, so that (in line with the architecture) the NOCP check
is done early over a large range of the encoding space, and takes
precedence over UNDEF exceptions. As part of this, we removed the
code from full_vfp_access_check() which raised an exception there for
M-profile with the FPU disabled, because it was no longer reachable.
For MVE, some instructions which are outside the "coprocessor space"
region of the encoding space must nonetheless do "is the FPU enabled"
checks and possibly raise a NOCP exception. (In particular this
covers the MVE-specific low-overhead branch insns LCTP, DLSTP and
WLSTP.) To support these insns, reinstate the code in
full_vfp_access_check(), so that their trans functions can call
vfp_access_check() and get the correct behaviour.
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20210614151007.4545-6-peter.maydell@linaro.org
On A-profile, PSR bits [15:10][26:25] are always the IT state bits.
On M-profile, some of the reserved encodings of the IT state are used
to instead indicate partial progress through instructions that were
interrupted partway through by an exception and can be resumed.
These resumable instructions fall into two categories:
(1) load/store multiple instructions, where these bits are called
"ICI" and specify the register in the ldm/stm list where execution
should resume. (Specifically: LDM, STM, VLDM, VSTM, VLLDM, VLSTM,
CLRM, VSCCLRM.)
(2) MVE instructions subject to beatwise execution, where these bits
are called "ECI" and specify which beats in this and possibly also
the following MVE insn have been executed.
There are also a few insns (LE, LETP, and BKPT) which do not use the
ICI/ECI bits but must leave them alone.
Otherwise, we should raise an INVSTATE UsageFault for any attempt to
execute an insn with non-zero ICI/ECI bits.
So far we have been able to ignore ECI/ICI, because the architecture
allows the IMPDEF choice of "always restart load/store multiple from
the beginning regardless of ICI state", so the only thing we have
been missing is that we don't raise the INVSTATE fault for bad guest
code. However, MVE requires that we honour ECI bits and do not
rexecute beats of an insn that have already been executed.
Add the support in the decoder for handling ECI/ICI:
* identify the ECI/ICI case in the CONDEXEC TB flags
* when a load/store multiple insn succeeds, it updates the ECI/ICI
state (both in DisasContext and in the CPU state), and sets a flag
to say that the ECI/ICI state was handled
* if we find that the insn we just decoded did not handle the
ECI/ICI state, we delete all the code that we just generated for
it and instead emit the code to raise the INVFAULT. This allows
us to avoid having to update every non-MVE non-LDM/STM insn to
make it check for "is ECI/ICI set?".
We continue with our existing IMPDEF choice of not caring about the
ICI state for the load/store multiples and simply restarting them
from the beginning. Because we don't allow interrupts in the middle
of an insn, the only way we would see this state is if the guest set
ICI manually on return from an exception handler, so it's a corner
case which doesn't merit optimisation.
ICI update for LDM/STM is simple -- it always zeroes the state. ECI
update for MVE beatwise insns will be a little more complex, since
the ECI state may include information for the following insn.
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20210614151007.4545-5-peter.maydell@linaro.org
When MVE is supported, the VPR register has a place on the exception
stack frame in a previously reserved slot just above the FPSCR.
It must also be zeroed in various situations when we invalidate
FPU context.
Update the code which handles the stack frames (exception entry and
exit code, VLLDM, and VLSTM) to save/restore VPR.
Update code which invalidates FP registers (mostly also exception
entry and exit code, but also VSCCLRM and the code in
full_vfp_access_check() that corresponds to the ExecuteFPCheck()
pseudocode) to zero VPR.
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20210614151007.4545-4-peter.maydell@linaro.org
MVE has an FPSCR.QC bit similar to the A-profile Neon one; when MVE
is implemented make the bit writeable, both in the generic "load and
store FPSCR" helper functions and in the code for handling the NZCVQC
sysreg which we had previously left as "TODO when we implement MVE".
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20210614151007.4545-3-peter.maydell@linaro.org
This is the 64-bit BFCVT and the 32-bit VCVT{B,T}.BF16.F32.
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20210525225817.400336-4-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
If MVE is implemented for an M-profile CPU then it has a VPR
register, which tracks predication information.
Implement the read and write handling of this register, and
the migration of its state.
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20210520152840.24453-7-peter.maydell@linaro.org
The fp_sysreg_checks() function is supposed to be returning an
FPSysRegCheckResult, which is an enum with three possible values.
However, three places in the function "return false" (a hangover from
a previous iteration of the design where the function just returned a
bool). Make these return FPSysRegCheckFailed instead (for no
functional change, since both false and FPSysRegCheckFailed are
zero).
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20210520152840.24453-6-peter.maydell@linaro.org
Split out the handling of VMOV_reg_sp and VMOV_reg_dp so that we can
permit the insns if either FP or MVE are present.
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20210520152840.24453-5-peter.maydell@linaro.org
The do_vfp_2op_sp() and do_vfp_2op_dp() functions currently check
whether floating point is supported via the aa32_fpdp_v2 and
aa32_fpsp_v2 isar checks. For v8.1M MVE support, the VMOV_reg trans
functions (but not any of the others) need to update this to also
allow the insn if MVE is implemented. Move the check out of the do_
function and into its callsites (which are all implemented via the
DO_VFP_2OP macro), so we have a place to change the check for the
VMOV insns.
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20210520152840.24453-4-peter.maydell@linaro.org
Some v8M instructions are present if either the floating point
extension or MVE is implemented. Update our implementation of them
to check for MVE as well as for FP.
This is all the insns which use CheckDecodeFaults(ExtType_MveOrFp) or
CheckDecodeFaults(ExtType_MveOrDpFp) in their pseudocode, which are
essentially the loads and stores, moves and sysreg accesses, except
for VMOV_reg_sp and VMOV_reg_dp, which we handle in subsequent
patches because they need a refactor to provide a place to put the
new MVE check.
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20210520152840.24453-3-peter.maydell@linaro.org
Switch translate-vfp.c.inc from being #included into translate.c
to being its own compilation unit.
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20210430132740.10391-9-peter.maydell@linaro.org
Peter Maydell