kernel/x86_64: Fix overwriting the GDT/IDT by each CPU.

The constructor calls for GlobalDescriptorTable and
InterruptDescriptorTable were run on each CPU, each time clearing out
any changes already done on other CPUs.

For the IDT this didn't matter as the result would always be the same.
In case of the GDT the result would surprisingly be mostly hidden. The
used GDT entries are for the double fault stacks (which is rarely hit),
the user TLS (which will only be used in compat mode) and the TSS which
is immediately cached in the task register.

The clearing of the GDT allowed for a tiny window of time between
setting up the entry for the TSS and it actually being loaded (and
cached) in the task register. When this happened, the load of the TR
caused a not present fault, which at this point leads to a tripple
fault and reset due to no fault handlers being installed yet.

Fixes #14659.

Change-Id: I6e5c00d412ab17c3ef05740ba71228e6ca266c1e
Reviewed-on: https://review.haiku-os.org/810
Reviewed-by: Jérôme Duval <jerome.duval@gmail.com>

kernel/x86_64: Fix descriptor index off-by-one in assert.

This was apparently copied from GlobalDescriptorTable::SetTSS() which
needs two table entries and therefore checks for index + 1. For the
SetUserTLS case this isn't needed and would cause aborts when reaching
the maximum CPU count (64 currently).

Change-Id: I27bd777fedadbd3740ac8c791199ec9300b06327
Reviewed-on: https://review.haiku-os.org/809
Reviewed-by: waddlesplash <waddlesplash@gmail.com>

kernel: Small fixes for Clang.

kernel/x86_64: adjust descriptors tables for compatibility mode.

* also adjust BOOT_GDT_SEGMENT_COUNT for x86, the definition is used by the
boot loader.
* add some 32-bit definitions.
* add a UserTLSDescriptor class, this will be used by 32-bit threads.

Change-Id: I5b1d978969a1ce97091a16c9ec2ad7c0ca831656

white space cleanup

x86-64: handle stack fault for non-canonical address access

* With the amd64 architecture, the stack fault exception got a new
meaning: it is raised when an instruction tries to access a
non-canonical address, and the stack is referenced in the
instruction (e.g. by its addressing mode).
So unlike on x86, this is not a fatal exception and shouldn't
trigger a KDL -- instead, it is to be treated like a general
protection fault, terminating the team which caused it.

* Fixes #13744

kernel/x86_64: rework of IDT handling code

Similarly to previous patch regarding GDT this is mostly a rewrite of
IDT handling code from C to C++. Thanks to constexpr IDT is now entirely
generated at compile-time.

kernel/x86_64: x86_64 gdt handling code overhaul

Virtually no functional change, just rewriting the code from
"C in *.cpp files" to C++. Use of constexpr may be advantageous but
that code is not performance critical anyway.

x86_64: Relax ltr operand constraint

Any 16 bit general puprose register can be a ltr operand, no need
to force AX.

x86[_64]: Separate bootloader and kernel GDT and IDT logic

From now on bootloader sets up its own minimal valid GDT and IDT. Then
the kernel replaces them with its own tables.

x86: Let each CPU have its own GDT

Cleaner separation of 32-/64-bit specific CPU/interrupt code.

Renamed {32,64}/int.cpp to {32,64}/descriptors.cpp, which now contain
functions for GDT and TSS setup that were previously in arch_cpu.cpp,
as well as the IDT setup code. These get called from the init functions
in arch_cpu.cpp, rather than having a bunch of ifdef'd chunks of code
for 32/64.

kernel/x86_64: rework of IDT handling code

Similarly to previous patch regarding GDT this is mostly a rewrite of
IDT handling code from C to C++. Thanks to constexpr IDT is now entirely
generated at compile-time.

kernel/x86_64: x86_64 gdt handling code overhaul

Virtually no functional change, just rewriting the code from
"C in *.cpp files" to C++. Use of constexpr may be advantageous but
that code is not performance critical anyway.

x86_64: Relax ltr operand constraint

Any 16 bit general puprose register can be a ltr operand, no need
to force AX.

x86[_64]: Separate bootloader and kernel GDT and IDT logic

From now on bootloader sets up its own minimal valid GDT and IDT. Then
the kernel replaces them with its own tables.

x86: Let each CPU have its own GDT

Cleaner separation of 32-/64-bit specific CPU/interrupt code.

Renamed {32,64}/int.cpp to {32,64}/descriptors.cpp, which now contain
functions for GDT and TSS setup that were previously in arch_cpu.cpp,
as well as the IDT setup code. These get called from the init functions
in arch_cpu.cpp, rather than having a bunch of ifdef'd chunks of code
for 32/64.