This involves refactoring VirtIOConsole into VirtIOConsole and
VirtIOConsolePort. VirtIOConsole is the VirtIODevice, it owns multiple
VirtIOConsolePorts as well as two control queues. Each
VirtIOConsolePort is a CharacterDevice.
By making sure the PhysicalPage instance is fully destructed the
allocators will have a chance to reclaim the PhysicalPageEntry for
free-list purposes. Just pass them the physical address of the page
that was freed, which is enough to lookup the PhysicalPageEntry later.
By moving the PhysicalPage classes out of the kernel heap into a static
array, one for each physical page, we can avoid the added overhead and
easily find them by indexing into an array.
This also wraps the PhysicalPage into a PhysicalPageEntry, which allows
us to re-use each slot with information where to find the next free
page.
We already use PAE for the NX bit, but this changes the PhysicalAddress
structure to be able to hold 64 bit physical addresses. This allows us
to use all the available physical memory.
Userland faulted on the very first instruction before because the
PML4T/PDPT/etc. weren't marked as user-accessible. For some reason
x86 doesn't care about that.
Also, we need to provide an appropriate userspace stack segment
selector to iretq.
This commit converts naked `new`s to `AK::try_make` and `AK::try_create`
wherever possible. If the called constructor is private, this can not be
done, so we instead now use the standard-defined and compiler-agnostic
`new (nothrow)`.
This adds just enough stubs to make the kernel compile on x86_64. Obviously
it won't do anything useful - in fact it won't even attempt to boot because
Multiboot doesn't support ELF64 binaries - but it gets those compiler errors
out of the way so more progress can be made getting all the missing
functionality in place.
This avoids allocations in the VMObject constructor. The number of
inline elements was determined empirically and covers most common cases
including LibC malloc.
Now that Region::name() has been changed to return a StringView we
can't rely on keeping a copy of the region's name past the region's
destruction just by holding a copy of the StringView.
- Make Region::create_kernel_only OOM safe.
- Make Region::create_user_accessible mostly OOM safe, there are still
some tendrils to untangle before it and be completely fixed.
Propagate allocation failure of m_shared_committed_cow_pages,
and uncommit previously committed COW pages on failure.
This method needs a closer look in terms of error handling, as we
will eventually need to rollback all changes on allocation failure.
Alternatively we could allocate the anonymous object much earlier
and only initialize it once the other steps have succeeded.
Replace the AK::String used for Region::m_name with a KString.
This seems beneficial across the board, but as a specific data point,
it reduces time spent in sys$set_mmap_name() by ~50% on test-js. :^)
Spinlocks guard short regions, with hopefully no other locks being taken
in the process. Violating constraints usually had detrimental effects on
platform stability as well as performance and scalability. Allocating
memory takes it own locks, and can in some cases even allocate new
regions, and thus violates these tenants.
Move the AnonymousVMObject creation outside of the spinlock as
creation does not modify any shared state.
Problem:
- `static` variables consume memory and sometimes are less
optimizable.
- `static const` variables can be `constexpr`, usually.
- `static` function-local variables require an initialization check
every time the function is run.
Solution:
- If a global `static` variable is only used in a single function then
move it into the function and make it non-`static` and `constexpr`.
- Make all global `static` variables `constexpr` instead of `const`.
- Change function-local `static const[expr]` variables to be just
`constexpr`.
By constraining two implementations, the compiler will select the best
fitting one. All this will require is duplicating the implementation and
simplifying for the `void` case.
This constraining also informs both the caller and compiler by passing
the callback parameter types as part of the constraint
(e.g.: `IterationFunction<int>`).
Some `for_each` functions in LibELF only take functions which return
`void`. This is a minimal correctness check, as it removes one way for a
function to incompletely do something.
There seems to be a possible idiom where inside a lambda, a `return;` is
the same as `continue;` in a for-loop.
AnonymousVMObject::create_with_physical_page(s) can't be NonnullRefPtr
as it allocates internally. Fixing the API then surfaced an issue in
ScatterGatherList, where the code was attempting to create an
AnonymousVMObject in the constructor which will not be observable
during OOM.
Fix all of these issues and start propagating errors at the callers
of the AnonymousVMObject and ScatterGatherList APis.
Currently, when passing buffers into VirtIOQueues, we use scatter-gather
lists, which contain an internal vector of buffers. This vector is
allocated, filled and the destroy whenever we try to provide buffers
into a virtqueue, which would happen a lot in performance cricital code
(the main transport mechanism for certain paravirtualized devices).
This commit moves it over to using VirtIOQueueChains and building the
chain in place in the VirtIOQueue. Also included are a bunch of fixups
for the VirtIO Console device, making it use an internal VM::RingBuffer
instead.
We want to move this out of the AHCI subsystem into the VM system,
since other parts of the kernel may need to perform scatter-gather IO.
We rename the current VM::ScatterGatherList impl that's used in the
virtio subsystem to VM::ScatterGatherRefList, since its distinguishing
feature from the AHCI scatter-gather list is that it doesn't own its
buffers.
The error handling in all these cases was still using the old style
negative values to indicate errors. We have a nicer solution for this
now with KResultOr<T>. This change switches the interface and then all
implementers to use the new style.
