The memory writes done to push registers on the stack
on exception entry in M profile CPUs are supposed to
go via MPU permissions checks, which may cause us to
take a derived exception instead of the original one of
the MPU lookup fails. We were implementing these as
always-succeeds direct writes to physical memory.
Rewrite v7m_push_stack() to do the necessary checks.
Backports commit fd592d890ec40e3686760de84044230a8ebb1eb3 from qemu
In the v8M architecture, if the process of taking an exception
results in a further exception this is called a derived exception
(for example, an MPU exception when writing the exception frame to
memory). If the derived exception happens while pushing the initial
stack frame, we must ignore any subsequent possible exception
pushing the callee-saves registers.
In preparation for making the stack writes check for exceptions,
add a return value from v7m_push_stack() and a new parameter to
v7m_exception_taken(), so that the former can tell the latter that
it needs to ignore failures to write to the stack. We also plumb
the argument through to v7m_push_callee_stack(), which is where
the code to ignore the failures will be.
(Note that the v8M ARM pseudocode structures this slightly differently:
derived exceptions cause the attempt to process the original
exception to be abandoned; then at the top level it calls
DerivedLateArrival to prioritize the derived exception and call
TakeException from there. We choose to let the NVIC do the prioritization
and continue forward with a call to TakeException which will then
take either the original or the derived exception. The effect is
the same, but this structure works better for QEMU because we don't
have a convenient top level place to do the abandon-and-retry logic.)
Backports commit 0094ca70e165cfb69882fa2e100d935d45f1c983 from qemu
Currently armv7m_nvic_acknowledge_irq() does three things:
* make the current highest priority pending interrupt active
* return a bool indicating whether that interrupt is targeting
Secure or NonSecure state
* implicitly tell the caller which is the highest priority
pending interrupt by setting env->v7m.exception
We need to split these jobs, because v7m_exception_taken()
needs to know whether the pending interrupt targets Secure so
it can choose to stack callee-saves registers or not, but it
must not make the interrupt active until after it has done
that stacking, in case the stacking causes a derived exception.
Similarly, it needs to know the number of the pending interrupt
so it can read the correct vector table entry before the
interrupt is made active, because vector table reads might
also cause a derived exception.
Create a new armv7m_nvic_get_pending_irq_info() function which simply
returns information about the highest priority pending interrupt, and
use it to rearrange the v7m_exception_taken() code so we don't
acknowledge the exception until we've done all the things which could
possibly cause a derived exception.
Backports part of commit 6c9485188170e11ad31ce477c8ce200b8e8ce59d from qemu
In order to support derived exceptions (exceptions generated in
the course of trying to take an exception), we need to be able
to handle prioritizing whether to take the original exception
or the derived exception.
We do this by introducing a new function
armv7m_nvic_set_pending_derived() which the exception-taking code in
helper.c will call when a derived exception occurs. Derived
exceptions are dealt with mostly like normal pending exceptions, so
we share the implementation with the armv7m_nvic_set_pending()
function.
Note that the way we structure this is significantly different
from the v8M Arm ARM pseudocode: that does all the prioritization
logic in the DerivedLateArrival() function, whereas we choose to
let the existing "identify highest priority exception" logic
do the prioritization for us. The effect is the same, though.
Backports part of commit 5ede82b8ccb652382c106d53f656ed67997d76e8 from qemu
The MC68040 MMU provides the size of the access that
triggers the page fault.
This size is set in the Special Status Word which
is written in the stack frame of the access fault
exception.
So we need the size in m68k_cpu_unassigned_access() and
m68k_cpu_handle_mmu_fault().
To be able to do that, this patch modifies the prototype of
handle_mmu_fault handler, tlb_fill() and probe_write().
do_unassigned_access() already includes a size parameter.
This patch also updates handle_mmu_fault handlers and
tlb_fill() of all targets (only parameter, no code change).
Backports commit 98670d47cd8d63a529ff230fd39ddaa186156f8c from qemu
Rather than passing a regno to the helper, pass pointers to the
vector register directly. This eliminates the need to pass in
the environment pointer and reduces the number of places that
directly access env->vfp.regs[].
Backports commit e7c06c4e4c98c47899417f154df1f2ef4e8d09a0 from qemu
Rather than passing regnos to the helpers, pass pointers to the
vector registers directly. This eliminates the need to pass in
the environment pointer and reduces the number of places that
directly access env->vfp.regs[].
Backports commit b13708bbbdda54c7f7e28222b22453986c026391 from qemu
Rather than passing regnos to the helpers, pass pointers to the
vector registers directly. This eliminates the need to pass in
the environment pointer and reduces the number of places that
directly access env->vfp.regs[].
Backports commit 1a66ac61af45af04688d1d15896737310e366c06 from qemu
Commit ("3b39d734141a target/arm: Handle page table walk load failures
correctly") modified both versions of the page table walking code (i.e.,
arm_ldl_ptw and arm_ldq_ptw) to record the result of the translation in
a temporary 'data' variable so that it can be inspected before being
returned. However, arm_ldq_ptw() returns an uint64_t, and using a
temporary uint32_t variable truncates the upper bits, corrupting the
result. This causes problems when using more than 4 GB of memory in
a TCG guest. So use a uint64_t instead.
Backports commit 9aea1ea31af25fe344a88da086ff913cca09c667 from qemu
Instead of ignoring the response from address_space_ld*()
(indicating an attempt to read a page table descriptor from
an invalid physical address), use it to report the failure
correctly.
Since this is another couple of locations where we need to
decide the value of the ARMMMUFaultInfo ea bit based on a
MemTxResult, we factor out that operation into a helper
function.
Backports commit 3b39d734141a71296d08af3d4c32f872fafd782e from qemu
For PMSAv7, the v7A/R Arm ARM defines that setting AP to 0b111
is an UNPREDICTABLE reserved combination. However, for v7M
this value is documented as having the same behaviour as 0b110:
read-only for both privileged and unprivileged. Accept this
value on an M profile core rather than treating it as a guest
error and a no-access page.
Backports commit 8638f1ad7403b63db880dadce38e6690b5d82b64 from qemu
Refactor disas_thumb2_insn() so that it generates the code for raising
an UNDEF exception for invalid insns, rather than returning a flag
which the caller must check to see if it needs to generate the UNDEF
code. This brings the function in to line with the behaviour of
disas_thumb_insn() and disas_arm_insn().
Backports commit 2eea841c11096e8dcc457b80e21f3fbdc32d2590 from qemu
ldxp loads two consecutive doublewords from memory regardless of CPU
endianness. On store, stlxp currently assumes to work with a 128bit
value and consequently switches order in big-endian mode. With this
change it packs the doublewords in reverse order in anticipation of the
128bit big-endian store operation interposing them so they end up in
memory in the right order. This makes it work for both MTTCG and !MTTCG.
It effectively implements the ARM ARM STLXP operation pseudo-code:
data = if BigEndian() then el1:el2 else el2:el1;
With this change an aarch64_be Linux 4.14.4 kernel succeeds to boot up
in system emulation mode.
Backports commit 0785557f8811133bd69be02aeccf018d47a26373 from qemu
With no fixed array allocation, we can't overflow a buffer.
This will be important as optimizations related to host vectors
may expand the number of ops used.
Use QTAILQ to link the ops together.
Backports commit 15fa08f8451babc88d733bd411d4c94976f9d0f8 from qemu
cpu_restore_state officially supports being passed an address it can't
resolve the state for. As a result the checks in the helpers are
superfluous and can be removed. This makes the code consistent with
other users of cpu_restore_state.
Of course this does nothing to address what to do if cpu_restore_state
can't resolve the state but so far it seems this is handled elsewhere.
The change was made with included coccinelle script.
Backports commit 65255e8efdd5fca602bcc4ff61a879939ff75f4f from qemu
Normally we create an address space for that CPU and pass that address
space into the function. Let's just do it inside to unify address space
creations. It'll simplify my next patch to rename those address spaces.
Backports commit 80ceb07a83375e3a0091591f96bd47bce2f640ce from qemu
Now that do_ats_write() is entirely in control of whether to
generate a 32-bit PAR or a 64-bit PAR, we can make it use the
correct (complicated) condition for doing so.
Backports commit 1313e2d7e2cd8b21741e0cf542eb09dfc4188f79 from qemu
All of the callers of get_phys_addr() and arm_tlb_fill() now ignore
the FSR values they return, so we can just remove the argument
entirely.
Backports commit bc52bfeb3be2052942b7dac8ba284f342ac9605b from qemu
In do_ats_write(), rather than using the FSR value from get_phys_addr(),
construct the PAR values using the information in the ARMMMUFaultInfo
struct. This allows us to create a PAR of the correct format regardless
of what the translation table format is.
For the moment we leave the condition for "when should this be a
64 bit PAR" as it was previously; this will need to be fixed to
properly support AArch32 Hyp mode.
Backports commit 5efe9ed45dec775ebe91ce72bd805ee780d16064 from qemu
Now that ARMMMUFaultInfo is guaranteed to have enough information
to construct a fault status code, we can pass it in to the
deliver_fault() function and let it generate the correct type
of FSR for the destination, rather than relying on the value
provided by get_phys_addr().
I don't think there are any cases the old code was getting
wrong, but this is more obviously correct.
Backports commit 681f9a89d201d7891e2c60dff5e5415d8f618518 from qemu
Make get_phys_addr_pmsav8() return a fault type in the ARMMMUFaultInfo
structure, which we convert to the FSC at the callsite.
Backports commit 3f551b5b7380ff131fe22944aa6f5b166aa13caf from qemu
Make get_phys_addr_pmsav7() return a fault type in the ARMMMUFaultInfo
structure, which we convert to the FSC at the callsite.
Backports commit 9375ad15338b24e06109071ac3a85df48a2cc2e6 from qemu
Make get_phys_addr_pmsav5() return a fault type in the ARMMMUFaultInfo
structure, which we convert to the FSC at the callsite.
Note that PMSAv5 does not define any guest-visible fault status
register, so the different "fsr" values we were previously
returning are entirely arbitrary. So we can just switch to using
the most appropriae fi->type values without worrying that we
need to special-case FaultInfo->FSC conversion for PMSAv5.
Backports commit 53a4e5c5b07b2f50c538511b74b0d3d4964695ea from qemu
Make get_phys_addr_v6() return a fault type in the ARMMMUFaultInfo
structure, which we convert to the FSC at the callsite.
Backports commit da909b2c23a68e57bbcb6be98229e40df606f0c8 from qemu
Make get_phys_addr_v6() return a fault type in the ARMMMUFaultInfo
structure, which we convert to the FSC at the callsite.
Backports commit f06cf243945ccb24cb9578304306ae7fcb4cf3fd from qemu
Make get_phys_addr_v5() return a fault type in the ARMMMUFaultInfo
structure, which we convert to the FSC at the callsite.
Backports commit f989983e8dc9be6bc3468c6dbe46fcb1501a740c from qemu
All the callers of arm_ldq_ptw() and arm_ldl_ptw() ignore the value
that those functions store in the fsr argument on failure: if they
return failure to their callers they will always overwrite the fsr
value with something else.
Remove the argument from these functions and S1_ptw_translate().
This will simplify removing fsr from the calling functions.
Backports commit 3795a6de9f7ec4a7e3dcb8bf02a88a014147b0b0 from qemu
Currently get_phys_addr() and its various subfunctions return
a hard-coded fault status register value for translation
failures. This is awkward because FSR values these days may
be either long-descriptor format or short-descriptor format.
Worse, the right FSR type to use doesn't depend only on the
translation table being walked -- some cases, like fault
info reported to AArch32 EL2 for some kinds of ATS operation,
must be in long-descriptor format even if the translation
table being walked was short format. We can't get those cases
right with our current approach.
Provide fields in the ARMMMUFaultInfo struct which allow
get_phys_addr() to provide sufficient information for a caller to
construct an FSR value themselves, and utility functions which do
this for both long and short format FSR values, as a first step in
switching get_phys_addr() and its children to only returning the
failure cause in the ARMMMUFaultInfo struct.
Backports commit 1fa498fe0de979030bd1f481046e9f1c5574a584 from qemu
Implement the TT instruction which queries the security
state and access permissions of a memory location.
Backports commit 5158de241b0fb344a6c948dfcbc4e611ab5fafbe from qemu
For the TT instruction we're going to need to do an MPU lookup that
also tells us which MPU region the access hit. This requires us
to do the MPU lookup without first doing the SAU security access
check, so pull the MPU lookup parts of get_phys_addr_pmsav8()
out into their own function.
The TT instruction also needs to know the MPU region number which
the lookup hit, so provide this information to the caller of the
MPU lookup code, even though get_phys_addr_pmsav8() doesn't
need to know it.
Backports commit 54317c0ff3a3c0f6b2c3a1d3c8b5d93686a86d24 from qemu
The TT instruction is going to need to look up the MMU index
for a specified security and privilege state. Refactor the
existing arm_v7m_mmu_idx_for_secstate() into a version that
lets you specify the privilege state and one that uses the
current state of the CPU.
Backports commit ec8e3340286a87d3924c223d60ba5c994549f796 from qemu
For M profile, we currently have an mmu index MNegPri for
"requested execution priority negative". This fails to
distinguish "requested execution priority negative, privileged"
from "requested execution priority negative, usermode", but
the two can return different results for MPU lookups. Fix this
by splitting MNegPri into MNegPriPriv and MNegPriUser, and
similarly for the Secure equivalent MSNegPri.
This takes us from 6 M profile MMU modes to 8, which means
we need to bump NB_MMU_MODES; this is OK since the point
where we are forced to reduce TLB sizes is 9 MMU modes.
(It would in theory be possible to stick with 6 MMU indexes:
{mpu-disabled,user,privileged} x {secure,nonsecure} since
in the MPU-disabled case the result of an MPU lookup is
always the same for both user and privileged code. However
we would then need to rework the TB flags handling to put
user/priv into the TB flags separately from the mmuidx.
Adding an extra couple of mmu indexes is simpler.)
Backports commit 62593718d77c06ad2b5e942727cead40775d2395 from qemu
When we added the ARMMMUIdx_MSUser MMU index we forgot to
add it to the case statement in regime_is_user(), so we
weren't treating it as unprivileged when doing MPU lookups.
Correct the omission.
Backports commit 871bec7c44a453d9cab972ce1b5d12e1af0545ab from qemu
In ARMv7M the CPU ignores explicit writes to CONTROL.SPSEL
in Handler mode. In v8M the behaviour is slightly different:
writes to the bit are permitted but will have no effect.
We've already done the hard work to handle the value in
CONTROL.SPSEL being out of sync with what stack pointer is
actually in use, so all we need to do to fix this last loose
end is to update the condition we use to guard whether we
call write_v7m_control_spsel() on the register write.
Backports commit 83d7f86d3d27473c0aac79c1baaa5c2ab01b02d9 from qemu
For v8M it is possible for the CONTROL.SPSEL bit value and the
current stack to be out of sync. This means we need to update
the checks used in reads and writes of the PSP and MSP special
registers to use v7m_using_psp() rather than directly checking
the SPSEL bit in the control register.
Backports commit 1169d3aa5b19adca9384d954d80e1f48da388284 from qemu
The refactoring of commit 296e5a0a6c3935 has a nasty bug:
it accidentally dropped the generation of code to raise
the UNDEF exception when disas_thumb2_insn() returns nonzero.
This means that 32-bit Thumb2 instruction patterns that
ought to UNDEF just act like nops instead. This is likely
to break any number of things, including the kernel's "disable
the FPU and use the UNDEF exception to identify when to turn
it back on again" trick.
Backports commit 7472e2efb049ea65a6a5e7261b78ebf5c561bc2f from qemu
In do_ats_write(), rather than using extended_addresses_enabled() to
decide whether the value we get back from get_phys_addr() is a 64-bit
format PAR or a 32-bit one, use arm_s1_regime_using_lpae_format().
This is not really the correct answer, because the PAR format
depends on the AT instruction being used, not just on the
translation regime. However getting this correct requires a
significant refactoring, so that get_phys_addr() returns raw
information about the fault which the caller can then assemble
into a suitable FSR/PAR/syndrome for its purposes, rather than
get_phys_addr() returning a pre-formatted FSR.
However this change at least improves the situation by making
the PAR work correctly for address translation operations done
at AArch64 EL2 on the EL2 translation regime. In particular,
this is necessary for Xen to be able to run in our emulation,
so this seems like a safer interim fix given that we are in freeze.
Backports commit 50cd71b0d347c74517dcb7da447fe657fca57d9c from qemu
