This patch greatly simplifies VMObject locking by doing two things:
1. Giving VMObject an IntrusiveList of all its mapping Region objects.
2. Removing VMObject::m_paging_lock in favor of VMObject::m_lock
Before (1), VMObject::for_each_region() was forced to acquire the
global MM lock (since it worked by walking MemoryManager's list of
all regions and checking for regions that pointed to itself.)
With each VMObject having its own list of Regions, VMObject's own
m_lock is all we need.
Before (2), page fault handlers used a separate mutex for preventing
overlapping work. This design required multiple temporary unlocks
and was generally extremely hard to reason about.
Instead, page fault handlers now use VMObject's own m_lock as well.
Despite what the declaration would have us believe these are not "u8*".
If they were we wouldn't have to use the & operator to get the address
of them and then cast them to "u8*"/FlatPtr afterwards.
Since we're taking from the committed set of pages, there should never
be a reason for this call to fail.
Also add a Badge to disallow taking committed pages from anywhere but
the Region class.
We don't need to have a dedicated API for creating a VMObject with a
single page, the multi-page API option works in all cases.
Also make the API take a Span<NonnullRefPtr<PhysicalPage>> instead of
a NonnullRefPtrVector<PhysicalPage>.
Depending on the values it might be difficult to figure out whether a
value is decimal or hexadecimal. So let's make this more obvious. Also
this allows copying and pasting those numbers into GNOME calculator and
probably also other apps which auto-detect the base.
Move these to MM to simplify the flow of the syscall handler.
While here, also make sure we hold the process space lock for
the duration of the validation to avoid potential issues where
another thread attempts to modify the process space during the
validation. This will allow us to move the validation out of the
big process lock scope in a future change.
Additionally utilize the new no_lock variants of functions to avoid
unnecessary recursive process space spinlock acquisitions.
The entire process is not needed, just require the user to pass in the
Space. Also provide no_lock variant to use when you already have the
VM/Space lock acquired, to avoid unnecessary recursive spinlock
acquisitions.
This implements a simple bootloader that is capable of loading ELF64
kernel images. It does this by using QEMU/GRUB to load the kernel image
from disk and pass it to our bootloader as a Multiboot module.
The bootloader then parses the ELF image and sets it up appropriately.
The kernel's entry point is a C++ function with architecture-native
code.
Co-authored-by: Liav A <liavalb@gmail.com>
We should never request a regions removal that we don't currently
own. We currently assert this everywhere else by all callers.
Instead lets just push the assert down into the RedBlackTree removal
and assume that we will always successfully remove the region.
This data structure is a much better fit for what is essentially a
sorted list of non-overlapping ranges.
Not using Vector means we no longer have to worry about Vector buffers
getting huge. Only nice & small allocations from now on.
We can have multiple PhysicalRegions (often the case when there is a
huge amount of RAM) so we really shouldn't print a debug message any
time someone tries to allocate from one. They will move on to another
region anyway.
We were incorrectly using sizeof(PhysicalPageEntry) for some address
calculations instead of sizeof(PageTableEntry).
It still worked correctly because they happen to be the same size.
We now keep all the PhysicalZones on one of two intrusive lists within
the PhysicalRegion.
The "usable" list contains all zones that can be allocated from,
and the "full" list contains all zones with no free pages.
Instead of creating a PhysicalRegion and then expanding it over and
over as we traverse the memory map on boot, we now compute the final
size of the contiguous physical range up front, and *then* create a
PhysicalRegion object.
