In the v7M and v8M ARM ARM, the magic exception return values are
referred to as EXC_RETURN values, and in QEMU we use V7M_EXCRET_*
constants to define bits within them. Rename the 'type' variable
which holds the exception return value in do_v7m_exception_exit()
to excret, making it clearer that it does hold an EXC_RETURN value.
Backports commit 351e527a613147aa2a2e6910f92923deef27ee48 from qemu
The exception-return magic values get some new bits in v8M, which
makes some bit definitions for them worthwhile.
We don't use the bit definitions for the switch on the low bits
which checks the return type for v7M, because this is defined
in the v7M ARM ARM as a set of valid values rather than via
per-bit checks.
Backports commit 4d1e7a4745c050f7ccac49a1c01437526b5130b5 from qemu
In do_v7m_exception_exit(), there's no need to force the high 4
bits of 'type' to 1 when calling v7m_exception_taken(), because
we know that they're always 1 or we could not have got to this
"handle return to magic exception return address" code. Remove
the unnecessary ORs.
Backports commit 7115cdf5782922611bcc44c89eec5990db7f6466 from qemu
For a bus fault, the M profile BFSR bit PRECISERR means a bus
fault on a data access, and IBUSERR means a bus fault on an
instruction access. We had these the wrong way around; fix this.
Backports commit c6158878650c01b2c753b2ea7d0967c8fe5ca59e from qemu
For M profile we must clear the exclusive monitor on reset, exception
entry and exception exit. We weren't doing any of these things; fix
this bug.
Backports commit dc3c4c14f0f12854dbd967be3486f4db4e66d25b from qemu
Implement the BXNS v8M instruction, which is like BX but will do a
jump-and-switch-to-NonSecure if the branch target address has bit 0
clear.
This is the first piece of code which implements "switch to the
other security state", so the commit also includes the code to
switch the stack pointers around, which is the only complicated
part of switching security state.
BLXNS is more complicated than just "BXNS but set the link register",
so we leave it for a separate commit.
Backports commit fb602cb726b3ebdd01ef3b1732d74baf9fee7ec9 from qemu
Move the regime_is_secure() utility function to internals.h;
we are going to want to call it from translate.c.
Backports commit 61fcd69b0db268e7612b07fadc436b93def91768 from qemu
Make the CFSR register banked if v8M security extensions are enabled.
Not all the bits in this register are banked: the BFSR
bits [15:8] are shared between S and NS, and we store them
in the NS copy of the register.
Backports commit 334e8dad7a109d15cb20b090131374ae98682a50 from qemu
Make the CCR register banked if v8M security extensions are enabled.
This is slightly more complicated than the other "add banking"
patches because there is one bit in the register which is not
banked. We keep the live data in the NS copy of the register,
and adjust it on register reads and writes. (Since we don't
currently implement the behaviour that the bit controls, there
is nowhere else that needs to care.)
This patch includes the enforcement of the bits which are newly
RES1 in ARMv8M.
Backports commit 9d40cd8a68cfc7606f4548cc9e812bab15c6dc28 from qemu
Make the MPU registers MPU_MAIR0 and MPU_MAIR1 banked if v8M security
extensions are enabled.
We can freely add more items to vmstate_m_security without
breaking migration compatibility, because no CPU currently
has the ARM_FEATURE_M_SECURITY bit enabled and so this
subsection is not yet used by anything.
Backports commit 62c58ee0b24eafb44c06402fe059fbd7972eb409 from qemu
Make the FAULTMASK register banked if v8M security extensions are enabled.
Note that we do not yet implement the functionality of the new
AIRCR.PRIS bit (which allows the effect of the NS copy of FAULTMASK to
be restricted).
This patch includes the code to determine for v8M which copy
of FAULTMASK should be updated on exception exit; further
changes will be required to the exception exit code in general
to support v8M, so this is just a small piece of that.
The v8M ARM ARM introduces a notation where individual paragraphs
are labelled with R (for rule) or I (for information) followed
by a random group of subscript letters. In comments where we want
to refer to a particular part of the manual we use this convention,
which should be more stable across document revisions than using
section or page numbers.
Backports commit 42a6686b2f6199d086a58edd7731faeb2dbe7c14 from qemu
Make the PRIMASK register banked if v8M security extensions are enabled.
Note that we do not yet implement the functionality of the new
AIRCR.PRIS bit (which allows the effect of the NS copy of PRIMASK to
be restricted).
Backports commit 6d8048341995b31a77dc2e0dcaaf4e3df0e3121a from qemu
Make the BASEPRI register banked if v8M security extensions are enabled.
Note that we do not yet implement the functionality of the new
AIRCR.PRIS bit (which allows the effect of the NS copy of BASEPRI to
be restricted).
Backports commit acf949411ffb675edbfb707e235800b02e6a36f8 from qemu
Now that MPU lookups can return different results for v8M
when the CPU is in secure vs non-secure state, we need to
have separate MMU indexes; add the secure counterparts
to the existing three M profile MMU indexes.
Backports commit 66787c7868d05d29974e09201611b718c976f955 from qemu
Add a utility function for testing whether the CPU is in Handler
mode; this is just a check whether v7m.exception is non-zero, but
we do it in several places and it makes the code a bit easier
to read to not have to mentally figure out what the test is testing.
Backports commit 15b3f556bab4f961bf92141eb8521c8da3df5eb2 from qemu
For v7M, writes to the CONTROL register are only permitted for
privileged code. However even if the code is privileged, the
write must not affect the SPSEL bit in the CONTROL register
if the CPU is in Thread mode (as documented in the pseudocode
for the MSR instruction). Implement this, instead of permitting
SPSEL to be written in all cases.
This was causing mbed applications not to run, because the
RTX RTOS they use relies on this behaviour.
Backports commit 792dac309c8660306557ba058b8b5a6a75ab3c1f from qemu
Move the code in arm_v7m_cpu_do_interrupt() that calculates the
magic LR value down to when we're actually going to use it.
Having the calculation and use so far apart makes the code
a little harder to understand than it needs to be.
Backports commit bd70b29ba92e4446f9e4eb8b9acc19ef6ff4a4d5 from qemu
We currently store the M profile CPU register state PRIMASK and
FAULTMASK in the daif field of the CPU state in its I and F
bits. This is a legacy from the original implementation, which
tried to share the cpu_exec_interrupt code between A profile
and M profile. We've since separated out the two cases because
they are significantly different, so now there is no common
code between M and A profile which looks at env->daif: all the
uses are either in A-only or M-only code paths. Sharing the state
fields now is just confusing, and will make things awkward
when we implement v8M, where the PRIMASK and FAULTMASK
registers are banked between security states.
Switch M profile over to using v7m.faultmask and v7m.primask
fields for these registers.
Backports commit e6ae5981ea4b0f6feb223009a5108582e7644f8f from qemu
The M profile XPSR is almost the same format as the A profile CPSR,
but not quite. Define some XPSR_* macros and use them where we
definitely dealing with an XPSR rather than reusing the CPSR ones.
Backports commit 987ab45e108953c1c98126c338c2119c243c372b from qemu
When we switched our handling of exception exit to detect
the magic addresses at translate time rather than via
a do_unassigned_access hook, we forgot to update a
comment; correct the omission.
Backports commit 9d17da4b68a05fc78daa47f0f3d914eea5d802ea from qemu
Currently get_phys_addr() has PMSAv7 handling before the
"is translation disabled?" check, and then PMSAv5 after it.
Tidy this up by making the PMSAv5 code handle the "MPU disabled"
case itself, so that we have all the PMSA code in one place.
This will make adding the PMSAv8 code slightly cleaner, and
also means that pre-v7 PMSA cores benefit from the MPU lookup
logging that the PMSAv7 codepath had.
Backports commit 3279adb95e34dd3d67c66d729458f7784747cf8d from qemu
In the ARM get_phys_addr() code, switch to using the MMUAccessType
enum and its MMU_* values rather than int and literal 0/1/2.
Backports commit 03ae85f858fc46495258a5dd4551fff2c34bd495 from qemu
When the PMSAv7 implementation was originally added it was for R profile
CPUs only, and reset was handled using the cpreg .resetfn hooks.
Unfortunately for M profile cores this doesn't work, because they do
not register any cpregs. Move the reset handling into arm_cpu_reset(),
where it will work for both R profile and M profile cores.
Backports commit 69ceea64bf565559a2b865ffb2a097d2caab805b from qemu
Almost all of the PMSAv7 state is in the pmsav7 substruct of
the ARM CPU state structure. The exception is the region
number register, which is in cp15.c6_rgnr. This exception
is a bit odd for M profile, which otherwise generally does
not store state in the cp15 substruct.
Rename cp15.c6_rgnr to pmsav7.rnr accordingly.
Backports commit 8531eb4f614a60e6582d4832b15eee09f7d27874 from qemu
For an M profile v7PMSA, the system space (0xe0000000 - 0xffffffff) can
never be executable, even if the guest tries to set the MPU registers
up that way. Enforce this restriction.
Backports commit bf446a11dfb17ae7d8ed2b61a2444804eb458075 from qemu
The M profile PMSAv7 specification says that if the address being looked
up is in the PPB region (0xe0000000 - 0xe00fffff) then we do not use
the MPU regions but always use the default memory map. Implement this
(we were previously behaving like an R profile PMSAv7, which does not
special case this).
Backports commit 38aaa60ca464b48e6feef346709e97335d01b289 from qemu
Correct off-by-one bug in the PSMAv7 MPU tracing where it would print
a write access as "reading", an insn fetch as "writing", and a read
access as "execute".
Since we have an MMUAccessType enum now, we can make the code clearer
in the process by using that rather than the raw 0/1/2 values.
Backports commit 709e4407add7acacc593cb6cdac026558c9a8fb6 from qemu
M profile doesn't implement ARM, and the architecturally required
behaviour for attempts to execute with the Thumb bit clear is to
generate a UsageFault with the CFSR INVSTATE bit set. We were
incorrectly implementing this as generating an UNDEFINSTR UsageFault;
fix this.
Backports commit e13886e3a790b52f0b2e93cb5e84fdc2ada5471a from qemu
Implement the exception return consistency checks
described in the v7M pseudocode ExceptionReturn().
Inspired by a patch from Michael Davidsaver's series, but
this is a reimplementation from scratch based on the
ARM ARM pseudocode.
Backports commit aa488fe3bb5460c6675800ccd80f6dccbbd70159 from qemu
Extract the code from the tail end of arm_v7m_do_interrupt() which
enters the exception handler into a pair of utility functions
v7m_exception_taken() and v7m_push_stack(), which correspond roughly
to the pseudocode PushStack() and ExceptionTaken().
This also requires us to move the arm_v7m_load_vector() utility
routine up so we can call it.
Handling illegal exception returns has some cases where we want to
take a UsageFault either on an existing stack frame or with a new
stack frame but with a specific LR value, so we want to be able to
call these without having to go via arm_v7m_cpu_do_interrupt().
Backports commit 39ae2474e337247e5930e8be783b689adc9f6215 from qemu
All the places in armv7m_cpu_do_interrupt() which pend an
exception in the NVIC are doing so for synchronous
exceptions. We know that we will always take some
exception in this case, so we can just acknowledge it
immediately, rather than returning and then immediately
being called again because the NVIC has raised its outbound
IRQ line.
Backports commit a25dc805e2e63a55029e787a52335e12dabf07dc from qemu
Implement HFNMIENA support for the M profile MPU. This bit controls
whether the MPU is treated as enabled when executing at execution
priorities of less than zero (in NMI, HardFault or with the FAULTMASK
bit set).
Doing this requires us to use a different MMU index for "running
at execution priority < 0", because we will have different
access permissions for that case versus the normal case.
Backports commit 3bef7012560a7f0ea27b265105de5090ba117514 from qemu
The M series MPU is almost the same as the already implemented R
profile MPU (v7 PMSA). So all we need to implement here is the MPU
register interface in the system register space.
This implementation has the same restriction as the R profile MPU
that it doesn't permit regions to be sized down smaller than 1K.
We also do not yet implement support for MPU_CTRL.HFNMIENA; this
bit should if zero disable use of the MPU when running HardFault,
NMI or with FAULTMASK set to 1 (ie at an execution priority of
less than zero) -- if the MPU is enabled we don't treat these
cases any differently.
Backports commit 29c483a506070e8f554c77d22686f405e30b9114 from qemu
General logic is that operations stopped by the MPU are MemManage,
and those which go through the MPU and are caught by the unassigned
handle are BusFault. Distinguish these by looking at the
exception.fsr values, and set the CFSR bits and (if appropriate)
fill in the BFAR or MMFAR with the exception address.
Backports commit 5dd0641d234e355597be62e5279d8a519c831625 from qemu
Add support for the M profile default memory map which is used
if the MPU is not present or disabled.
The main differences in behaviour from implementing this
correctly are that we set the PAGE_EXEC attribute on
the right regions of memory, such that device regions
are not executable.
Backports commit 3a00d560bcfca7ad04327062c1986a016c104b1f from qemu
Improve the "-d mmu" tracing for the PMSAv7 MPU translation
process as an aid in debugging guest MPU configurations:
* fix a missing newline for a guest-error log
* report the region number with guest-error or unimp
logs of bad region register values
* add a log message for the overall result of the lookup
* print "0x" prefix for hex values
Backports commit c9f9f1246d630960bce45881e9c0d27b55be71e2 from qemu
Now that we enforce both:
* pmsav7_dregion == 0 implies has_mpu == false
* PMSA with has_mpu == false means SCTLR.M cannot be set
we can remove a check on pmsav7_dregion from get_phys_addr_pmsav7(),
because we can only reach this code path if the MPU is enabled
(and so region_translation_disabled() returned false).
Backports commit e9235c6983b261e04e897e8ff900b2b7a391e644 from qemu
If the CPU is a PMSA config with no MPU implemented, then the
SCTLR.M bit should be RAZ/WI, so that the guest can never
turn on the non-existent MPU.
Backports commit 06312febfb2d35367006ef23608ddd6a131214d4 from qemu
ARM CPUs come in two flavours:
* proper MMU ("VMSA")
* only an MPU ("PMSA")
For PMSA, the MPU may be implemented, or not (in which case there
is default "always acts the same" behaviour, but it isn't guest
programmable).
QEMU is a bit confused about how we indicate this: we have an
ARM_FEATURE_MPU, but it's not clear whether this indicates
"PMSA, not VMSA" or "PMSA and MPU present" , and sometimes we
use it for one purpose and sometimes the other.
Currently trying to implement a PMSA-without-MPU core won't
work correctly because we turn off the ARM_FEATURE_MPU bit
and then a lot of things which should still exist get
turned off too.
As the first step in cleaning this up, rename the feature
bit to ARM_FEATURE_PMSA, which indicates a PMSA CPU (with
or without MPU).
Backports commit 452a095526a0537f16c271516a2200877a272ea8 from qemu
Make M profile use completely separate ARMMMUIdx values from
those that A profile CPUs use. This is a prelude to adding
support for the MPU and for v8M, which together will require
6 MMU indexes which don't map cleanly onto the A profile
uses:
non secure User
non secure Privileged
non secure Privileged, execution priority < 0
secure User
secure Privileged
secure Privileged, execution priority < 0
Backports commit e7b921c2d9efc249f99b9feb0e7dca82c96aa5c4 from qemu
The v7M exception architecture requires that if a synchronous
exception cannot be taken immediately (because it is disabled
or at too low a priority) then it should be escalated to
HardFault (and the HardFault exception is then taken).
Implement this escalation logic.
Backports commit a73c98e159d18155445d29b6044be6ad49fd802f from qemu
The M profile CPU's MPU has an awkward corner case which we
would like to implement with a different MMU index.
We can avoid having to bump the number of MMU modes ARM
uses, because some of our existing MMU indexes are only
used by non-M-profile CPUs, so we can borrow one.
To avoid that getting too confusing, clean up the code
to try to keep the two meanings of the index separate.
Instead of ARMMMUIdx enum values being identical to core QEMU
MMU index values, they are now the core index values with some
high bits set. Any particular CPU always uses the same high
bits (so eventually A profile cores and M profile cores will
use different bits). New functions arm_to_core_mmu_idx()
and core_to_arm_mmu_idx() convert between the two.
In general core index values are stored in 'int' types, and
ARM values are stored in ARMMMUIdx types.
Backports commit 8bd5c82030b2cb09d3eef6b444f1620911cc9fc5 from qemu
The excnames[] array is defined in internals.h because we used
to use it from two different source files for handling logging
of AArch32 and AArch64 exception entry. Refactoring means that
it's now used only in arm_log_exception() in helper.c, so move
the array into that function.
Backports commit 2c4a7cc5afb1bfc1728a39abd951ddd7714c476e from qemu
Our implementation of writes to the APSR for M-profile via the MSR
instruction was badly broken.
First and worst, we had the sense wrong on the test of bit 2 of the
SYSm field -- this is supposed to request an APSR write if bit 2 is 0
but we were doing it if bit 2 was 1. This bug was introduced in
commit 58117c9bb429cd, so hasn't been in a QEMU release.
Secondly, the choice of exactly which parts of APSR should be written
is defined by bits in the 'mask' field. We were not passing these
through from instruction decode, making it impossible to check them
in the helper.
Pass the mask bits through from the instruction decode to the helper
function and process them appropriately; fix the wrong sense of the
SYSm bit 2 check.
Invalid mask values and invalid combinations of mask and register
number are UNPREDICTABLE; we choose to treat them as if the mask
values were valid.
Backports commit b28b3377d7e9ba35611d454d5a63ef50cab1f8c5 from qemu
