Finished the VMA kobject and added the related syscalls. Processes can
now allocate memory! Other changes in this commit:
- stop using g_frame_allocator and add frame_allocator::get()
- make sure to release all handles in the process dtor
- fix kutil::map::iterator never comparing to end()
vm_space no longer relies on page_manager to map pages during a page
fault. Other changes that come with this commit:
- C++ standard has been changed to C++17
- enum bitfield operators became constexpr
- enum bifrield operators can take a mix of ints and enum arguments
- added page table flags enum instead of relying on ints
- remove page_table::unmap_table and page_table::unmap_pages
As mentioned in the last commit, with processes owning spaces, there was
a weird extra space in the "kernel" process that owns the kernel
threads. Now we use that space as the global kernel space, and don't
create a separate one.
vm_space and page_table continue to take over duties from
page_manager:
- creation and deletion of address spaces / pml4s
- cross-address-space copies for endpoints
- taking over pml4 ownership from process
Also fixed the bug where the wrong process was being set in the cpu
data.
To solve: now the kernel process has its own vm_space which is not
g_kernel_space.
This is the first commit of several reworking the VM system. The main
focus is replacing page_manager's global functionality with objects
representing individual VM spaces. The main changes in this commit were:
- Adding the (as yet unused) vm_area object, which will be the main
point of control for programs to allocate or share memory.
- Replace the old vm_space with a new one based on state in its page
tables. They will also be containers for vm_areas.
- vm_space takes over from page_manager as the page fault handler
- Commented out the page walking in memory_bootstrap; I'll probably need
to recreate this functionality, but it was broken as it was.
- Split out the page_table.h implementations from page_manager.cpp into
the new page_table.cpp, updated it, and added page_table::iterator as
well.
