ERETNC is identical to ERET except that an ERETNC will not clear the LLbit
that is set by execution of an LL instruction, and thus when placed between
an LL and SC sequence, will never cause the SC to fail.
Presence of ERETNC is denoted by the Config5.LLB.
Backports commit ce9782f40ac16660ea9437bfaa2c9c34d5ed8110 from qemu
MIPS SIMD Architecture vector loads and stores require misalignment support.
MSA Memory access should work as an atomic operation. Therefore, it has to
check validity of all addresses for a vector store access if it is spanning
into two pages.
Separating helper functions for each data format as format is known in
translation.
To use mmu_idx from cpu_mmu_index() instead of calculating it from hflag.
Removing save_cpu_state() call in translation because it is able to use
cpu_restore_state() on fault as GETRA() is passed.
Backports commit adc370a48fd26b92188fa4848dfb088578b1936c from qemu
Fix CP0.Config3.ISAOnExc write accesses on microMIPS processors. This
bit is mandatory for any processor that implements the microMIPS
instruction set. This bit is r/w for processors that implement both the
standard MIPS and the microMIPS instruction set. This bit is r/o and
hardwired to 1 if only the microMIPS instruction set is implemented.
There is no other bit ever writable in CP0.Config3 so defining a
corresponding `CP0_Config3_rw_bitmask' member in `CPUMIPSState' is I
think an overkill. Therefore make the ability to write the bit rely on
the presence of ASE_MICROMIPS set in the instruction flags.
The read-only case of the microMIPS instruction set being implemented
only can be added when we add support for such a configuration. We do
not currently have such support, we have no instruction flag that would
control the presence of the standard MIPS instruction set nor any
associated code in instruction decoding.
This change is needed to boot a microMIPS Linux kernel successfully,
otherwise it hangs early on as interrupts are enabled and then the
exception handler invoked loops as its first instruction is interpreted
in the wrong execution mode and triggers another exception right away.
And then over and over again.
We already check the current setting of the CP0.Config3.ISAOnExc in
`set_hflags_for_handler' to set the ISA bit correctly on the exception
handler entry so it is the ability to set it that is missing only.
Backports commit 90f12d735d66ac1196d9a2bced039a432eefc03d from qemu
