A proper page fault handler was required for areas that were not locked
into the kernel address space. This enables the boot process to get
up to the point of trying to find the boot volume.
* Thread creation and switching is working fine, however threads do not yet
get interrupted because I've not implemented hardware interrupt handling
yet (I'll do that next).
* I've made some changes to struct iframe: I've removed the e/r prefixes
from the member names for both 32/64, so now they're just named ip, ax,
bp, etc. This makes it easier to write code that works with both 32/64
without having to deal with different iframe member names.
This has been done by adding typedefs in elf_common.h to the correct ELF
structures for the architecture, and changing all Elf32_* uses to those
types. I don't know whether image loading works as I cannot test it yet,
there may be some 64-bit safety issues around. However, symbol lookup for
the kernel is working correctly.
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().
* mmu_get_virtual_mapping() should check that the page directory entry is
present rather than assuming there's a page table there. This was resulting
in some invalid mappings being created in the 64-bit virtual address space.
* arch_vm_init_end() should clear from KERNEL_LOAD_BASE to virtual_end, not
from KERNEL_BASE. On x86_64 this was causing it to loop through ~512GB of
address space, which obviously was taking quite a while.
* Uses 64-bit multiplication, special handling for CPUs clocked < 1 GHz
in system_time_nsecs() not required like on x86.
* Tested against a straight conversion of the x86 version, noticably
faster with a large number of system_time() calls.
* vm_init now runs up until create_preloaded_image_areas(), which needs
fixing to handle ELF64.
* Not completely tested. I know Map(), Unmap() and Query() work fine, the
other methods have not been tested as the kernel doesn't boot far enough
for any of them to be called yet. As far as I know they're correct, though.
* Not yet implemented the destructor for X86VMTranslationMap64Bit or Init()
for a user address space.
Will be merged with the x86 one later on. Requires -fno-omit-frame-pointer on
the kernel build flags, GCC defaults to not generating stack frames on x86_64.
* 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.
* typedef for jmp_buf was using int where it should be long.
* setjmp was clearing the buffer pointer rather than the signal mask before
calling sigsetjmp.
* KDL now works without crashing on x86_64.
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.
* Added empty source files for all the 64-bit paging method code, and a
stub implementation of X86PagingMethod64Bit.
* arch_vm_translation_map.cpp has been modified to use X86PagingMethod64Bit
on x86_64.
* Some things are currently ifndef'd out completely for x86_64 because
they aren't implemented, there's a few other ifdef's to handle x86_64
differences but most of the code works unchanged.
* Renamed some i386_* functions to x86_*.
* Added a temporary method for setting the current thread on x86_64
(a global variable, not SMP safe). This will be changed to be done
via the GS segment but I've not implemented that yet.
Since the button was renamed from "Do it!" to the specific action,
an additional explanation in case of special user folders isn't
needed any more.
Split text into paragraphs for better readability.
