About half of the Processor code is common across architectures, so
let's share it with a templated base class. Also, other code that can be
shared in some ways, like FPUState and TrapFrame functions, is adjusted
here. Functions which cannot be shared trivially (without internal
refactoring) are left alone for now.
This has KString, KBuffer, DoubleBuffer, KBufferBuilder, IOWindow,
UserOrKernelBuffer and ScopedCritical classes being moved to the
Kernel/Library subdirectory.
Also, move the panic and assertions handling code to that directory.
Even though we currently build all of Userland and the Kernel with the
-mstrict-align flag, the compiler will still emit unaligned memory
accesses. To work around this, we disable the check for now. See
https://github.com/SerenityOS/serenity/issues/17516 for the relevant
issue.
Until now the kernel was always executing with SP_EL0, as this made the
initial dropping to EL1 a bit easier. This commit changes this behaviour
to use the corresponding SP_ELx for each exception level.
To make sure that the execution of the C++ code can continue, the
current stack pointer is copied into the corresponding SP_ELx just
before dropping an exception level.
And use it the code that will be part of the early boot process.
The PANIC macro and dbgln functions cannot be used as it accesses global
variables, which in the early boot process do not work, since the MMU is
not yet enabled.
