This makes Processor::capture_stack_trace() work on all our
architectures. For this function to work on AArch64 and RISC-V, the
frame pointer has to be saved during context switches.
AArch64 and RISC-V don't support SMP yet, so the code for getting a
backtrace for processes running on other cores is guarded behind a
'#if ARCH(X86_64)'.
This function was only used to verify that we are running in kernel
mode. But it is pretty much impossible that we will ever end up in
kernel code and actually are able to execute it in user mode. A lot of
stuff must go completely wrong to end up in such a situation.
Getting the current privilege level is also impossible on RISC-V by
design.
We have many places in the kernel code that we have boolean flags that
are only set once, and never reset again but are checked multiple times
before and after the time they're being set, which matches the purpose
of the SetOnce class.
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 commit adds the concept of an InterruptsState to the kernel. This
will be used to make the Spinlock code architecture independent. A new
Processor.cpp file is added such that we don't have to duplicate the
code.
