Commit e350d8ca3ac7 ("target/mips: optimize indirect branches") made
indirect branches able to directly find the next TB and jump straight to
it without breaking out of translated code and going around the main
execution loop. This breaks the assumption in target/mips/translate.c
that BS_STOP is sufficient to cause pending interrupts to be handled,
since interrupts are only checked in the main loop.
Fix a few of these assumptions by using gen_save_pc to update the saved
PC and using BS_EXCP instead of BS_STOP:
- [D]MFC0 CP0_Count may trigger a timer interrupt which should be
immediately handled.
- [D]MTC0 CP0_Cause may trigger an interrupt (but in fact translation
was only even being stopped in the DMTC0 case).
- [D]MTC0 CP0_<any> when icount is used is assumed could potentially
cause interrupts.
- EI may trigger an interrupt which was pending. I specifically hit
this case when running KVM nested in mipsel-softmmu. A timer
interrupt while the 2nd guest was executing is caught by KVM which
switches back to the normal Linux exception base and re-enables
interrupts with EI. Since the above commit QEMU doesn't leave
translated code until the nested KVM has already restored the KVM
exception base and returned to the 2nd guest, at which point it is
too late to check for pending interrupts and it gets stuck in an
infinite loop of unhandled interrupts.
Something similar was needed for ARM in commit b29fd33db578
("target/arm: use DISAS_EXIT for eret handling").
Backports commit b74cddcbf6063f684725e3f8bca49a68e30cba71 from qemu
Writing to the MIPS DESAVE register (and now the KScratch registers)
will stop translation, supposedly due to risk of execution mode
switches. However these registers are basically RW scratch registers
with no side effects so there is no risk of them triggering execution
mode changes.
Drop the bstate = BS_STOP for these registers for both mtc0 and dmtc0.
Backports commit cb539fd241900f51de7d21244f7a55422ad0d40a from qemu
The optional segmentation control registers CP0_SegCtl0, CP0_SegCtl1 &
CP0_SegCtl2 control the behaviour and required privilege of the legacy
virtual memory segments.
Add them to the CP0 interface so they can be read and written when
CP0_Config3.SC=1, and initialise them to describe the standard legacy
layout so they can be used in future patches regardless of whether they
are exposed to the guest.
Backports commit cec56a733dd2c3fa81dbedbecf03922258747f7d from qemu
The MIPS mmu_idx is sometimes calculated from hflags without an env
pointer available as cpu_mmu_index() requires.
Create a common hflags_mmu_index() for the purpose of this calculation
which can operate on any hflags, not just with an env pointer, and
update cpu_mmu_index() itself and gen_intermediate_code() to use it.
Also update debug_post_eret() and helper_mtc0_status() to log the MMU
mode with the status change (SM, UM, or nothing for kernel mode) based
on cpu_mmu_index() rather than directly testing hflags.
This will also allow the logic to be more easily updated when a new MMU
mode is added.
Backports commit b0fc6003224543d2bdb172eca752656a6223e4a1 from qemu
Implement decoding of microMIPS EVA load and store instruction groups in
the POOL31C pool. These use the same gen_ld(), gen_st(), gen_st_cond()
helpers as the MIPS32 decoding, passing the equivalent MIPS32 opcodes as
opc.
Backports commit 8fffc64696783b1ff1d17262d098976479895660 from qemu
Add CP0.ErrCtl register with WST, SPR and ITC bits. In 34K and interAptiv
processors these bits are used to enable CACHE instruction access to
different arrays. When WST=0, SPR=0 and ITC=1 the CACHE instruction will
access ITC tag values.
Generally we do not model caches and we have been treating the CACHE
instruction as NOP. But since CACHE can operate on ITC Tags new
MIPS_HFLAG_ITC_CACHE hflag is introduced to generate the helper only when
CACHE is in the ITC Access mode.
Backports commit 0d74a222c27e26fc40f4f6120c61c3f9ceaa3776 from qemu
Implement decoding of MIPS32 EVA loads and stores. These access the user
address space from kernel mode when implemented, so for each instruction
we need to check that EVA is available from Config5.EVA & check for
sufficient COP0 privilege (with the new check_eva()), and then override
the mem_idx used for the operation.
Unfortunately some Loongson 2E instructions use overlapping encodings,
so we must be careful not to prevent those from being decoded when EVA
is absent.
Backports commit 7696414729b2d0f870c80ad1dd637d854bc78847 from qemu
EVA load and store instructions access the user mode address map, so
they need to use mem_idx of MIPS_HFLAG_UM. Update the various utility
functions to allow mem_idx to be more easily overridden from the
decoding logic.
Specifically we add a mem_idx argument to the op_ld/st_* helpers used
for atomics, and a mem_idx local variable to gen_ld(), gen_st(), and
gen_st_cond().
Backports commit dd4096cd2ccc19384770f336c930259da7a54980 from qemu
Add support for the CP0_EBase.WG bit, which allows upper bits to be
written (bits 31:30 on MIPS32, or bits 63:30 on MIPS64), along with the
CP0_Config5.CV bit to control whether the exception vector for Cache
Error exceptions is forced into KSeg1.
This is necessary on MIPS32 to support Segmentation Control and Enhanced
Virtual Addressing (EVA) extensions (where KSeg1 addresses may not
represent an unmapped uncached segment).
It is also useful on MIPS64 to allow the exception base to reside in
XKPhys, and possibly out of range of KSEG0 and KSEG1.
Backports commit 74dbf824a1313b6064bbebb981a7440951d70896 from qemu
Using MFC0 to read CP0_UserLocal uses tcg_gen_ld32s_tl, however
CP0_UserLocal is a target_ulong. On a big endian host with a MIPS64
target this reads and sign extends the more significant half of the
64-bit register.
Fix this by using ld_tl to load the whole target_ulong and ext32s_tl to
sign extend it, as done for various other target_ulong COP0 registers.
Backports commit e40df9a80bb7cdb0a4ca650985fa9fe572097fa7 from qemu
This patch fixes the msa copy_[s|u]_df instruction emulation when
the destination register rd is zero. Without this patch the zero
register would get clobbered, which should never happen because it
is supposed to be hardwired to 0.
Fix this corner case by explicitly checking rd = 0 and effectively
making these instructions emulation no-op in that case.
Backports commit cab4888136a92250fdd401402622824994f7ce0b from qemu
It is unnecessary to test R6 from delay/forbidden slot check
in gen_msa_branch().
https://bugs.launchpad.net/qemu/+bug/1663287
Backports commit 075a1fe788d36b271ec25507466c30b9a90b5d54 from qemu
this fixes many warnings like:
target/mips/translate.c:6253:13: warning: Value stored to 'rn' is never read
rn = "invalid sel";
^ ~~~~~~~~~~~~~
Backports commit 3570d7f6672836140f0a1ec9bf95dd5ea50a2aaa from qemu
Provide a new cpu_supports_isa function which allows callers to
determine whether a CPU supports one of the ISA_ flags, by testing
whether the associated struct mips_def_t sets the ISA flags in its
insn_flags field.
An example use of this is to allow boards which generate bootloader code
to determine the properties of the CPU that will be used, for example
whether the CPU is 64 bit or which architecture revision it implements.
Backports commit bed9e5ceb158c886d548fe59675a6eba18baeaeb from qemu
We've currently got 18 architectures in QEMU, and thus 18 target-xxx
folders in the root folder of the QEMU source tree. More architectures
(e.g. RISC-V, AVR) are likely to be included soon, too, so the main
folder of the QEMU sources slowly gets quite overcrowded with the
target-xxx folders.
To disburden the main folder a little bit, let's move the target-xxx
folders into a dedicated target/ folder, so that target-xxx/ simply
becomes target/xxx/ instead.
Backports commit fcf5ef2ab52c621a4617ebbef36bf43b4003f4c0 from qemu
