Per the SDM, when returning to outer privilege level, for segment
registers (ES, FS, GS, and DS) if the check fails, the segment
selector becomes null, but QEMU clears the base/limit/flags as well
as nullifying the segment selector, which should be a spec violation.
Real hardware seems to be compliant with the spec, at least on one
Coffee Lake board I tested.
Backports c2ba0515f2df58a661fcb5d6485139877d92ab1b
For PDEP and PEXT, the mask is provided in the memory (mod+r/m)
operand, and therefore is loaded in s->T0 by gen_ldst_modrm.
The source is provided in the second source operand (VEX.vvvv)
and therefore is loaded in s->T1. Fix the order in which
they are passed to the helpers.
Backports 75b208c28316095c4685e8596ceb9e3f656592e2
For v8.1M the architecture mandates that CPUs must provide at
least the "minimal RAS implementation" from the Reliability,
Availability and Serviceability extension. This consists of:
* an ESB instruction which is a NOP
-- since it is in the HINT space we need only add a comment
* an RFSR register which will RAZ/WI
* a RAZ/WI AIRCR.IESB bit
-- the code which handles writes to AIRCR does not allow setting
of RES0 bits, so we already treat this as RAZ/WI; add a comment
noting that this is deliberate
* minimal implementation of the RAS register block at 0xe0005000
-- this will be in a subsequent commit
* setting the ID_PFR0.RAS field to 0b0010
-- we will do this when we add the Cortex-M55 CPU model
Backports 46f4976f22a4549322307b34272e053d38653243
v8.1M introduces a new TRD flag in the CCR register, which enables
checking for stack frame integrity signatures on SG instructions.
Add the code in the SG insn implementation for the new behaviour.
Backports 7f484147369080d36c411c4ba969f90d025aed55
v8.1M adds new encodings of VLLDM and VLSTM (where bit 7 is set).
The only difference is that:
* the old T1 encodings UNDEF if the implementation implements 32
Dregs (this is currently architecturally impossible for M-profile)
* the new T2 encodings have the implementation-defined option to
read from memory (discarding the data) or write UNKNOWN values to
memory for the stack slots that would be D16-D31
We choose not to make those accesses, so for us the two
instructions behave identically assuming they don't UNDEF.
Backports fe6fa228a71f0eb8b8ee315452e6a7736c537b1f
In v8.1M a new exception return check is added which may cause a NOCP
UsageFault (see rule R_XLTP): before we clear s0..s15 and the FPSCR
we must check whether access to CP10 from the Security state of the
returning exception is disabled; if it is then we must take a fault.
(Note that for our implementation CPPWR is always RAZ/WI and so can
never cause CP10 accesses to fail.)
The other v8.1M change to this register-clearing code is that if MVE
is implemented VPR must also be cleared, so add a TODO comment to
that effect.
Backports 3423fbf10427db7680d3237d4f62d8370052fca0
In v8.0M, on exception entry the registers R0-R3, R12, APSR and EPSR
are zeroed for an exception taken to Non-secure state; for an
exception taken to Secure state they become UNKNOWN, and we chose to
leave them at their previous values.
In v8.1M the behaviour is specified more tightly and these registers
are always zeroed regardless of the security state that the exception
targets (see rule R_KPZV). Implement this.
Backports a59b1ed618415212c5f0f05abc1192e14ad5fdbb
Implement the new-in-v8.1M FPCXT_S floating point system register.
This is for saving and restoring the secure floating point context,
and it reads and writes bits [27:0] from the FPSCR and the
CONTROL.SFPA bit in bit [31].
Backports 64f863baeedc86590a608e2f1722dd8640aa9431
Factor out the code which handles M-profile lazy FP state preservation
from full_vfp_access_check(); accesses to the FPCXT_NS register are
a special case which need to do just this part (corresponding in the
pseudocode to the PreserveFPState() function), and not the full
set of actions matching the pseudocode ExecuteFPCheck() which
normal FP instructions need to do.
Backports 96dfae686628fc14ba4f993824322b93395e221b
We defined a constant name for the mask of NZCV bits in the FPCR/FPSCR
in the previous commit; use it in a couple of places in existing code,
where we're masking out everything except NZCV for the "load to Rt=15
sets CPSR.NZCV" special case.
Backports 6a017acdf83e3bb6bd5e85289ca90b2ea3282b7e
v8.1M defines a new FP system register FPSCR_nzcvqc; this behaves
like the existing FPSCR, except that it reads and writes only bits
[31:27] of the FPSCR (the N, Z, C, V and QC flag bits). (Unlike the
FPSCR, the special case for Rt=15 of writing the CPSR.NZCV is not
permitted.)
Implement the register. Since we don't yet implement MVE, we handle
the QC bit as RES0, with todo comments for where we will need to add
support later.
Backports 9542c30bcf13c495400d63616dd8dfa825b04685
Implement the new-in-v8.1M VLDR/VSTR variants which directly
read or write FP system registers to memory.
Backports 0bf0dd4dcbd9fab324700ac6e0cd061cd043de0d
The constant-expander functions like negate, plus_2, etc, are
generally useful; move them up in translate.c so we can use them in
the VFP/Neon decoders as well as in the A32/T32/T16 decoders.
Backports f7ed0c9433e7c5c157d2e6235eb5c8b93234a71a
Currently M-profile borrows the A-profile code for VMSR and VMRS
(access to the FP system registers), because all it needs to support
is the FPSCR. In v8.1M things become significantly more complicated
in two ways:
* there are several new FP system registers; some have side effects
on read, and one (FPCXT_NS) needs to avoid the usual
vfp_access_check() and the "only if FPU implemented" check
* all sysregs are now accessible both by VMRS/VMSR (which
reads/writes a general purpose register) and also by VLDR/VSTR
(which reads/writes them directly to memory)
Refactor the structure of how we handle VMSR/VMRS to cope with this:
* keep the M-profile code entirely separate from the A-profile code
* abstract out the "read or write the general purpose register" part
of the code into a loadfn or storefn function pointer, so we can
reuse it for VLDR/VSTR.
Backports 32a290b8c3c2dc85cd88bd8983baf900d575cab
For M-profile before v8.1M, the only valid register for VMSR/VMRS is
the FPSCR. We have a comment that states this, but the actual logic
to forbid accesses for any other register value is missing, so we
would end up with A-profile style behaviour. Add the missing check.
Backports ede97c9d71110821738a48f88ff9f10d6bec017f
In v8.1M the new CLRM instruction allows zeroing an arbitrary set of
the general-purpose registers and APSR. Implement this.
The encoding is a subset of the LDMIA T2 encoding, using what would
be Rn=0b1111 (which UNDEFs for LDMIA).
Backports 6e21a013fbdf54960a079dccc90772bb622e28e8
Implement the v8.1M VSCCLRM insn, which zeros floating point
registers if there is an active floating point context.
This requires support in write_neon_element32() for the MO_32
element size, so add it.
Because we want to use arm_gen_condlabel(), we need to move
the definition of that function up in translate.c so it is
before the #include of translate-vfp.c.inc.
Backports 83ff3d6add965c9752324de11eac5687121ea826
In arm_cpu_realizefn() we check whether the board code disabled EL3
via the has_el3 CPU object property, which we create if the CPU
starts with the ARM_FEATURE_EL3 feature bit. If it is disabled, then
we turn off ARM_FEATURE_EL3 and also zero out the relevant fields in
the ID_PFR1 and ID_AA64PFR0 registers.
This codepath was incorrectly being taken for M-profile CPUs, which
do not have an EL3 and don't set ARM_FEATURE_EL3, but which may have
the M-profile Security extension and so should have non-zero values
in the ID_PFR1.Security field.
Restrict the handling of the feature flag to A/R-profile cores.
Backports 4018818840f499d0a478508aedbb6802c8eae928
In v8.1M the PXN architecture extension adds a new PXN bit to the
MPU_RLAR registers, which forbids execution of code in the region
from a privileged mode.
This is another feature which is just in the generic "in v8.1M" set
and has no ID register field indicating its presence.
Backports cad8e2e3160dd10371552fce6cd8c6e171503e13
Using a target unsigned long would limit the Input Address to a LPAE
page-walk to 32 bits on AArch32 and 64 bits on AArch64. This is okay
for stage 1 or on AArch64, but it is insufficient for stage 2 on
AArch32. In that later case, the Input Address can have up to 40 bits.
Backports commit 98e8779770c40901ed585745aacc9a8e2b934a28
There is no "version 2" of the "Lesser" General Public License.
It is either "GPL version 2.0" or "Lesser GPL version 2.1".
This patch replaces all occurrences of "Lesser GPL version 2" with
"Lesser GPL version 2.1" in comment section.
Backport d9ff33ada7f32ca59f99b270a2d0eb223b3c9c8f
There is no "version 2" of the "Lesser" General Public License.
It is either "GPL version 2.0" or "Lesser GPL version 2.1".
This patch replaces all occurrences of "Lesser GPL version 2" with
"Lesser GPL version 2.1" in comment section.
Backports 50f57e09fda4b7ffbc5ba62aad6cebf660824023
Checks for UNDEF cases should go before the "is VFP enabled?" access
check, except in special cases. Move a stray UNDEF check in the VTBL
trans function up above the access check.
Backports b6c56c8a9a4064ea783f352f43c5df6231a110fa
The helper function did not get updated when we reorganized
the vector register file for SVE. Since then, the neon dregs
are non-sequential and cannot be simply indexed.
At the same time, make the helper function operate on 64-bit
quantities so that we do not have to call it twice.
Backports 604cef3e57eaeeef77074d78f6cf2eca1be11c62
Fix code style. Don't use '#' flag of printf format ('%#') in
format strings, use '0x' prefix instead
Backports 6eb55edbabb9eed1e4c7dfb233e7d738e8b5fa89
In arm_v7m_mmu_idx_for_secstate() we get the 'priv' level to pass to
armv7m_mmu_idx_for_secstate_and_priv() by calling arm_current_el().
This is incorrect when the security state being queried is not the
current one, because arm_current_el() uses the current security state
to determine which of the banked CONTROL.nPRIV bits to look at.
The effect was that if (for instance) Secure state was in privileged
mode but Non-Secure was not then we would return the wrong MMU index.
The only places where we are using this function in a way that could
trigger this bug are for the stack loads during a v8M function-return
and for the instruction fetch of a v8M SG insn.
Fix the bug by expanding out the M-profile version of the
arm_current_el() logic inline so it can use the passed in secstate
rather than env->v7m.secure.
Backports 7142eb9e24b4aa5118cd67038057f15694d782aa
Secure mode is not exempted from checking SCR_EL3.TLOR, and in the
future HCR_EL2.TLOR when S-EL2 is enabled.
Backports 9bd268bae5c4760870522292fb1d46e7da7e372a
The helper functions for performing the udot/sdot operations against
a scalar were not using an address-swizzling macro when converting
the index of the scalar element into a pointer into the vm array.
This had no effect on little-endian hosts but meant we generated
incorrect results on big-endian hosts.
For these insns, the index is indexing over group of 4 8-bit values,
so 32 bits per indexed entity, and H4() is therefore what we want.
(For Neon the only possible input indexes are 0 and 1.)
Backports d1a9254be5cc93afb15be19f7543da6ff4806256
In the neon_padd/pmax/pmin helpers for float16, a cut-and-paste error
meant we were using the H4() address swizzler macro rather than the
H2() which is required for 2-byte data. This had no effect on
little-endian hosts but meant we put the result data into the
destination Dreg in the wrong order on big-endian hosts.
Backports 552714c0812a10e5cff239bd29928e5fcb8d8b3b
In both cases, we can sink the write-back and perform
the accumulate into the normal destination temps
Backports 9f1a5f93c2dd345dc6c8fe86ed14bf1485056f6e
The only uses of this function are for loading VFP
double-precision values, and nothing to do with NEON.
Backports b38b96ca90827012ab8eb045c1337cea83a54c4b
The only uses of this function are for loading VFP
single-precision values, and nothing to do with NEON.
Backports 21c1c0e50b73c580c6bfc8f2314d1b6a14793561
We can then use this to improve VMOV (scalar to gp) and
VMOV (gp to scalar) so that we simply perform the memory
operation that we wanted, rather than inserting or
extracting from a 32-bit quantity.
These were the last uses of neon_load/store_reg, so remove them.
Backports 4d5fa5a80ac28f34b8497be1e85371272413a12e
Model these off the aa64 read/write_vec_element functions.
Use it within translate-neon.c.inc. The new functions do
not allocate or free temps, so this rearranges the calling
code a bit.
Backports a712266f5d5a36d04b22fe69fa15592d62bed019
This function makes it clear that we're talking about the whole
register, and not the 32-bit piece at index 0. This fixes a bug
when running on a big-endian host.
Backports 015ee81a4c06b644969f621fd9965cc6372b879e
If the M-profile low-overhead-branch extension is implemented, FPSCR
bits [18:16] are a new field LTPSIZE. If MVE is not implemented
(currently always true for us) then this field always reads as 4 and
ignores writes.
These bits used to be the vector-length field for the old
short-vector extension, so we need to take care that they are not
misinterpreted as setting vec_len. We do this with a rearrangement
of the vfp_set_fpscr() code that deals with vec_len, vec_stride
and also the QC bit; this obviates the need for the M-profile
only masking step that we used to have at the start of the function.
We provide a new field in CPUState for LTPSIZE, even though this
will always be 4, in preparation for MVE, so we don't have to
come back later and split it out of the vfp.xregs[FPSCR] value.
(This state struct field will be saved and restored as part of
the FPSCR value via the vmstate_fpscr in machine.c.)
Backports 8128c8e8cc9489a8387c74075974f86dc0222e7f
M-profile CPUs with half-precision floating point support should
be able to write to FPSCR.FZ16, but an M-profile specific masking
of the value at the top of vfp_set_fpscr() currently prevents that.
This is not yet an active bug because we have no M-profile
FP16 CPUs, but needs to be fixed before we can add any.
The bits that the masking is effectively preventing from being
set are the A-profile only short-vector Len and Stride fields,
plus the Neon QC bit. Rearrange the order of the function so
that those fields are handled earlier and only under a suitable
guard; this allows us to drop the M-profile specific masking,
making FZ16 writeable.
This change also makes the QC bit correctly RAZ/WI for older
no-Neon A-profile cores.
This refactoring also paves the way for the low-overhead-branch
LTPSIZE field, which uses some of the bits that are used for
A-profile Stride and Len.
Backports commit d31e2ce68d56f5bcc83831497e5fe4b8a7e18e85
v8.1M's "low-overhead-loop" extension has three instructions
for looping:
* DLS (start of a do-loop)
* WLS (start of a while-loop)
* LE (end of a loop)
The loop-start instructions are both simple operations to start a
loop whose iteration count (if any) is in LR. The loop-end
instruction handles "decrement iteration count and jump back to loop
start"; it also caches the information about the branch back to the
start of the loop to improve performance of the branch on subsequent
iterations.
As with the branch-future instructions, the architecture permits an
implementation to discard the LO_BRANCH_INFO cache at any time, and
QEMU takes the IMPDEF option to never set it in the first place
(equivalent to discarding it immediately), because for us a "real"
implementation would be unnecessary complexity.
(This implementation only provides the simple looping constructs; the
vector extension MVE (Helium) adds some extra variants to handle
looping across vectors. We'll add those later when we implement
MVE.)
Backports commit b7226369721896ab9ef71544e4fe95b40710e05a
v8.1M implements a new 'branch future' feature, which is a
set of instructions that request the CPU to perform a branch
"in the future", when it reaches a particular execution address.
In hardware, the expected implementation is that the information
about the branch location and destination is cached and then
acted upon when execution reaches the specified address.
However the architecture permits an implementation to discard
this cached information at any point, and so guest code must
always include a normal branch insn at the branch point as
a fallback. In particular, an implementation is specifically
permitted to treat all BF insns as NOPs (which is equivalent
to discarding the cached information immediately).
For QEMU, implementing this caching of branch information
would be complicated and would not improve the speed of
execution at all, so we make the IMPDEF choice to implement
all BF insns as NOPs.
Backports commit 05903f036edba8e3ed940cc215b8e27fb49265b9
The BLX immediate insn in the Thumb encoding always performs
a switch from Thumb to Arm state. This would be totally useless
in M-profile which has no Arm decoder, and so the instruction
does not exist at all there. Make the encoding UNDEF for M-profile.
(This part of the encoding space is used for the branch-future
and low-overhead-loop insns in v8.1M.)
Backports 920f04fa3ea789f8f85a52cee5395b8887b56cf7
The t32 decode has a group which represents a set of insns
which overlap with B_cond_thumb because they have [25:23]=111
(which is an invalid condition code field for the branch insn).
This group is currently defined using the {} overlap-OK syntax,
but it is almost entirely non-overlapping patterns. Switch
it over to use a non-overlapping group.
For this to be valid syntactically, CPS must move into the same
overlapping-group as the hint insns (CPS vs hints was the
only actual use of the overlap facility for the group).
The non-overlapping subgroup for CLREX/DSB/DMB/ISB/SB is no longer
necessary and so we can remove it (promoting those insns to
be members of the parent group).
Backports 45f11876ae86128bdee27e0b089045de43cc88e4
