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
In the v7M architecture, if an exception is generated in the process
of doing the lazy stacking of FP registers, the handling of
possible escalation to HardFault is treated differently to the normal
approach: it works based on the saved information about exception
readiness that was stored in the FPCCR when the stack frame was
created. Provide a new function armv7m_nvic_set_pending_lazyfp()
which pends exceptions during lazy stacking, and implements
this logic.
This corresponds to the pseudocode TakePreserveFPException().
Backports the relevant parts of commit
a99ba8ab1601904e0fa20325192fc850362ce80e from qemu
Add a new helper function which returns the MMU index to use
for v7M, where the caller specifies all of the security
state, privilege level and whether the execution priority
is negative, and reimplement the existing
arm_v7m_mmu_idx_for_secstate_and_priv() in terms of it.
We are going to need this for the lazy-FP-stacking code.
Backports commit fa6252a988dbe440cd6087bf93cbe0887f0c401b from qemu
The M-profile FPCCR.ASPEN bit indicates that automatic floating-point
context preservation is enabled. Before executing any floating-point
instruction, if FPCCR.ASPEN is set and the CONTROL FPCA/SFPA bits
indicate that there is no active floating point context then we
must create a new context (by initializing FPSCR and setting
FPCA/SFPA to indicate that the context is now active). In the
pseudocode this is handled by ExecuteFPCheck().
Implement this with a new TB flag which tracks whether we
need to create a new FP context.
Backports commit 6000531e19964756673a5f4b694a649ef883605a from qemu
The M-profile FPCCR.S bit indicates the security status of
the floating point context. In the pseudocode ExecuteFPCheck()
function it is unconditionally set to match the current
security state whenever a floating point instruction is
executed.
Implement this by adding a new TB flag which tracks whether
FPCCR.S is different from the current security state, so
that we only need to emit the code to update it in the
less-common case when it is not already set correctly.
Note that we will add the handling for the other work done
by ExecuteFPCheck() in later commits.
Backports commit 6d60c67a1a03be32c3342aff6604cdc5095088d1 from qemu
We are close to running out of TB flags for AArch32; we could
start using the cs_base word, but before we do that we can
economise on our usage by sharing the same bits for the VFP
VECSTRIDE field and the XScale XSCALE_CPAR field. This
works because no XScale CPU ever had VFP.
Backports commit ea7ac69d124c94c6e5579145e727adec9ccbefef from qemu
Move the NS TBFLAG down from bit 19 to bit 6, which has not
been used since commit c1e3781090b9d36c60 in 2015, when we
started passing the entire MMU index in the TB flags rather
than just a 'privilege level' bit.
This rearrangement is not strictly necessary, but means that
we can put M-profile-only bits next to each other rather
than scattered across the flag word.
Backports commit 7fbb535f7aeb22896fedfcf18a1eeff48165f1d7 from qemu
Implement the code which updates the FPCCR register on an
exception entry where we are going to use lazy FP stacking.
We have to defer to the NVIC to determine whether the
various exceptions are currently ready or not.
Backports commit b593c2b81287040ab6f452afec6281e2f7ee487b from qemu
The M-profile floating point support has three associated config
registers: FPCAR, FPCCR and FPDSCR. It also makes the registers
CPACR and NSACR have behaviour other than reads-as-zero.
Add support for all of these as simple reads-as-written registers.
We will hook up actual functionality later.
The main complexity here is handling the FPCCR register, which
has a mix of banked and unbanked bits.
Note that we don't share storage with the A-profile
cpu->cp15.nsacr and cpu->cp15.cpacr_el1, though the behaviour
is quite similar, for two reasons:
* the M profile CPACR is banked between security states
* it preserves the invariant that M profile uses no state
inside the cp15 substruct
Backports commit d33abe82c7c9847284a23e575e1078cccab540b5 from qemu
Minimize the number of places that will need updating when
the virtual host extensions are added.
Backports commit 64e40755cd41fbe8cd266cf387e42ddc57a449ef from qemu
There is a set of VFP instructions which we implement in
disas_vfp_v8_insn() and gate on the ARM_FEATURE_V8 bit.
These were all first introduced in v8 for A-profile, but in
M-profile they appeared in v7M. Gate them on the MVFR2
FPMisc field instead, and rename the function appropriately.
Backports commit c0c760afe800b60b48c80ddf3509fec413594778 from qemu
Instead of gating the A32/T32 FP16 conversion instructions on
the ARM_FEATURE_VFP_FP16 flag, switch to our new approach of
looking at ID register bits. In this case MVFR1 fields FPHP
and SIMDHP indicate the presence of these insns.
This change doesn't alter behaviour for any of our CPUs.
Backports commit 602f6e42cfbfe9278be34e9b91d2ceb695837e02 from qemu
Change the representation of this field such that it is easy
to set from vector code.
Backports commit a4d5846245c5e029e5aa3945a9bda1de1c3fedbf from qemu
There are a whole bunch more registers in the CPUID space which are
currently not used but are exposed as RAZ. To avoid too much
duplication we expand ARMCPRegUserSpaceInfo to understand glob
patterns so we only need one entry to tweak whole ranges of registers.
Backports commit d040242effe47850060d2ef1c461ff637d88a84d 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
Although technically not visible to userspace the kernel does make
them visible via a trap and emulate ABI. We provide a new permission
mask (PL0U_R) which maps to PL0_R for CONFIG_USER builds and adjust
the minimum permission check accordingly.
Backports commit b5bd7440422bb66deaceb812bb9287a6a3cdf10c from qemu
The {IOE, DZE, OFE, UFE, IXE, IDE} bits in the FPSCR/FPCR are for
enabling trapped IEEE floating point exceptions (where IEEE exception
conditions cause a CPU exception rather than updating the FPSR status
bits). QEMU doesn't implement this (and nor does the hardware we're
modelling), but for implementations which don't implement trapped
exception handling these control bits are supposed to be RAZ/WI.
This allows guest code to test for whether the feature is present
by trying to write to the bit and checking whether it sticks.
QEMU is incorrectly making these bits read as written. Make them
RAZ/WI as the architecture requires.
In particular this was causing problems for the NetBSD automatic
test suite.
Backports commit a15945d98d3a3390c3da344d1b47218e91e49d8b from qemu
Split out gen_top_byte_ignore in preparation of handling these
data accesses; the new tbflags field is not yet honored.
Backports commit 4a9ee99db38ba513bf1e8f43665b79c60accd017 from qemu
Place this in its own field within ENV, as that will
make it easier to reset from within TCG generated code.
With the change to pstate_read/write, exception entry
and return are automatically handled.
Backports commit f6e52eaac13b6947f4406c127e3090c898e439c9 from qemu
Since QEMU does not support the ARMv8.2-LVA, Large Virtual Address,
extension (yet), the VA address space is 48-bits plus a sign bit. User
mode can only handle the positive half of the address space, so that
makes a limit of 48 bits.
(With LVA, it would be 53 and 52 bits respectively.)
The incorrectly large address space conflicts with PAuth instructions,
which use bits 48-54 and 56-63 for the pointer authentication code. This
also conflicts with (as yet unsupported by QEMU) data tagging and with
the ARMv8.5-MTE extension.
Backports commit f6768aa1b4c6a80448eabd22bb9b4123c709caea from qemu
A bug was introduced during a respin of:
commit 57a4a11b2b281bb548b419ca81bfafb214e4c77a
target/arm: Add array for supported PMU events, generate PMCEID[01]_EL0
This patch introduced two calls to get_pmceid() during CPU
initialization - one each for PMCEID0 and PMCEID1. In addition to
building the register values, get_pmceid() clears an internal array
mapping event numbers to their implementations (supported_event_map)
before rebuilding it. This is an optimization since much of the logic is
shared. However, since it was called twice, the contents of
supported_event_map reflect only the events in PMCEID1 (the second call
to get_pmceid()).
Fix this bug by moving the initialization of PMCEID0 and PMCEID1 back
into a single function call, and name it more appropriately since it is
doing more than simply generating the contents of the PMCEID[01]
registers.
Backports commit bf8d09694ccc07487cd73d7562081fdaec3370c8 from qemu
The instruction event is only enabled when icount is used, cycles are
always supported. Always defining get_cycle_count (but altering its
behavior depending on CONFIG_USER_ONLY) allows us to remove some
CONFIG_USER_ONLY #defines throughout the rest of the code.
Backports commit b2e2372511946fae86fbb8709edec7a41c6f3167 from qemu
Add arrays to hold the registers, the definitions themselves, access
functions, and logic to reset counters when PMCR.P is set. Update
filtering code to support counters other than PMCCNTR. Support migration
with raw read/write functions.
Backports commit 5ecdd3e47cadae83a62dc92b472f1fe163b56f59 from qemu
This commit doesn't add any supported events, but provides the framework
for adding them. We store the pm_event structs in a simple array, and
provide the mapping from the event numbers to array indexes in the
supported_event_map array. Because the value of PMCEID[01] depends upon
which events are supported at runtime, generate it dynamically.
Backports commit 57a4a11b2b281bb548b419ca81bfafb214e4c77a from qemu
This is immediately necessary for the PMUv3 implementation to check
ID_DFR0.PerfMon to enable/disable specific features, but defines the
full complement of fields for possible future use elsewhere.
Backports commit beceb99c0c1218d0b55cc04ce6ef77579d3416cb from qemu
Rename arm_ccnt_enabled to pmu_counter_enabled, and add logic to only
return 'true' if the specified counter is enabled and neither prohibited
or filtered.
Backports commit 033614c47de78409ad3fb39bb7bd1483b71c6789 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
The arm_regime_tbi{0,1} functions are replacable with the new function
by giving the lowest and highest address.
Backports commit 5d8634f5a3a8474525edcfd581a659830e9e97c0 from qemu
We will shortly want to talk about TBI as it relates to data.
Passing around a pair of variables is less convenient than a
single variable.
Backports commit 476a4692f06e381117fb7ad0d04d37c9c2612198 from qemu
The pattern
ARMMMUIdx mmu_idx = core_to_arm_mmu_idx(env, cpu_mmu_index(env, false));
is computing the full ARMMMUIdx, stripping off the ARM bits,
and then putting them back.
Avoid the extra two steps with the appropriate helper function.
Backports commit 50494a279dab22a015aba9501a94fcc3cd52140e from qemu
There are 5 bits of state that could be added, but to save
space within tbflags, add only a single enable bit.
Helpers will determine the rest of the state at runtime.
Backports commit 0816ef1bfcd3ac53e7454b62ca436727887f6056 from qemu
Use "register" TBFLAG_ANY to indicate shared state between
A32 and A64, and "registers" TBFLAG_A32 & TBFLAG_A64 for
fields that are specific to the given cpu state.
Move ARM_TBFLAG_BE_DATA to shared state, instead of its current
placement within "Bit usage when in AArch32 state".
Backports commit aad821ac4faad369fad8941d25e59edf2514246b from qemu
