Rename KERNEL_LOAD_BASE_64BIT to KERNEL_LOAD_BASE_64_BIT for consistency.

Fixed commpage for x86_64.

Since the commpage is at a kernel address, changed 64-bit paging code
to match x86's behaviour of allowing user-accessible mappings to be
created in the kernel portion of the address space. This is also
required by some drivers.

Support for SMP on x86_64.

No major changes to the kernel: just compiled in arch_smp.cpp and fixed the
IDT load in arch_cpu_init_percpu to use the correct limit for x86_64 (uses
sizeof(interrupt_descriptor)). In the boot loader, changed smp_boot_other_cpus
to construct a temporary GDT and get the page directory address from CR3, as
what's in kernel_args will be 64-bit stuff and will not work to switch the
CPUs into 32-bit mode in the trampoline code. Refactored 64-bit kernel entry
code to not use the stack after disabling paging, as the secondary CPUs are
given a 32-bit virtual stack address by the SMP trampoline code which will
no longer work.

Fixed a bug resulting from a mistake in the boot 64-bit paging setup.

This was an interesting bug to find. Was getting spurious triple faults
in the slab allocator. The problem was that the boot paging setup code
was mapping all page tables it created into the virtual address space,
but in the kernel no areas were being created to cover them, so during
arch_vm_init_end() the pages for them ended up being freed and then
overwritten later on. Fixed by unmapping page tables after populating
them in long_mmu_init().

A few improvements suggested by Ingo.

Some fixes to the long mode switch code.

* Wasn't storing the fixed virtual address of the PML4 in kernel_args.
* After switching to long mode, reload GDTR with the virtual address of
the GDT. This was working fine until now because the physical address
was identity mapped, but broke as soon as I removed the identity
mapping.

Removed accidently left in debug message.

Map all physical memory in the long mode paging setup.

Since x86_64 has such a large virtual address space all available physical
memory can be mapped in to it. The physical page mapper implementation for
x86_64 will use this mapping. Also changed the mapping code to map kernel
pages with the global flag.

Merged x86_64 headers into x86 headers.

Not many changes seeing as there's not much x86_64 stuff done yet. Small
differences are handled with ifdefs, large differences (descriptors.h,
struct iframe) have separate headers under arch/x86/32 and arch/x86/64.

Style fixes.

x86_64: Implemented exception handling.

Moved the common parts of arch_cpu.h between x86 and x86_64 to arch/common_x86/cpu.h.

Also need to fix the kernel_args_range addresses.

Pass correct kernel_args address to the kernel.

Implemented long mode setup/switch code, the bootloader can now start the 64-bit kernel!

The setup procedure is fairly simple: create a 64-bit GDT and 64-bit page
tables that include all kernel mappings from the 32-bit address space, but at
the correct 64-bit address, then go through kernel_args and changes all virtual
addresses to 64-bit addresses, and finally switch to long mode and jump to the
kernel.

Rename KERNEL_LOAD_BASE_64BIT to KERNEL_LOAD_BASE_64_BIT for consistency.

Fixed commpage for x86_64.

Since the commpage is at a kernel address, changed 64-bit paging code
to match x86's behaviour of allowing user-accessible mappings to be
created in the kernel portion of the address space. This is also
required by some drivers.

Support for SMP on x86_64.

No major changes to the kernel: just compiled in arch_smp.cpp and fixed the
IDT load in arch_cpu_init_percpu to use the correct limit for x86_64 (uses
sizeof(interrupt_descriptor)). In the boot loader, changed smp_boot_other_cpus
to construct a temporary GDT and get the page directory address from CR3, as
what's in kernel_args will be 64-bit stuff and will not work to switch the
CPUs into 32-bit mode in the trampoline code. Refactored 64-bit kernel entry
code to not use the stack after disabling paging, as the secondary CPUs are
given a 32-bit virtual stack address by the SMP trampoline code which will
no longer work.

Fixed a bug resulting from a mistake in the boot 64-bit paging setup.

This was an interesting bug to find. Was getting spurious triple faults
in the slab allocator. The problem was that the boot paging setup code
was mapping all page tables it created into the virtual address space,
but in the kernel no areas were being created to cover them, so during
arch_vm_init_end() the pages for them ended up being freed and then
overwritten later on. Fixed by unmapping page tables after populating
them in long_mmu_init().

A few improvements suggested by Ingo.

Some fixes to the long mode switch code.

* Wasn't storing the fixed virtual address of the PML4 in kernel_args.
* After switching to long mode, reload GDTR with the virtual address of
the GDT. This was working fine until now because the physical address
was identity mapped, but broke as soon as I removed the identity
mapping.

Removed accidently left in debug message.

Map all physical memory in the long mode paging setup.

Since x86_64 has such a large virtual address space all available physical
memory can be mapped in to it. The physical page mapper implementation for
x86_64 will use this mapping. Also changed the mapping code to map kernel
pages with the global flag.

Merged x86_64 headers into x86 headers.

Not many changes seeing as there's not much x86_64 stuff done yet. Small
differences are handled with ifdefs, large differences (descriptors.h,
struct iframe) have separate headers under arch/x86/32 and arch/x86/64.

Style fixes.

x86_64: Implemented exception handling.

Moved the common parts of arch_cpu.h between x86 and x86_64 to arch/common_x86/cpu.h.

Also need to fix the kernel_args_range addresses.

Pass correct kernel_args address to the kernel.

Implemented long mode setup/switch code, the bootloader can now start the 64-bit kernel!

The setup procedure is fairly simple: create a 64-bit GDT and 64-bit page
tables that include all kernel mappings from the 32-bit address space, but at
the correct 64-bit address, then go through kernel_args and changes all virtual
addresses to 64-bit addresses, and finally switch to long mode and jump to the
kernel.