Now that all KResult and KResultOr are used consistently throughout the
kernel, it's no longer necessary to return negative error codes.
However, we were still doing that in some places, so let's fix all those
(bugs) by removing the minuses. :^)
It's easy to forget the responsibility of validating and safely copying
kernel parameters in code that is far away from syscalls. ioctl's are
one such example, and bugs there are just as dangerous as at the root
syscall level.
To avoid this case, utilize the AK::Userspace<T> template in the ioctl
kernel interface so that implementors have no choice but to properly
validate and copy ioctl pointer arguments.
GCC and Clang allow us to inject a call to a function named
__sanitizer_cov_trace_pc on every edge. This function has to be defined
by us. By noting down the caller in that function we can trace the code
we have encountered during execution. Such information is used by
coverage guided fuzzers like AFL and LibFuzzer to determine if a new
input resulted in a new code path. This makes fuzzing much more
effective.
Additionally this adds a basic KCOV implementation. KCOV is an API that
allows user space to request the kernel to start collecting coverage
information for a given user space thread. Furthermore KCOV then exposes
the collected program counters to user space via a BlockDevice which can
be mmaped from user space.
This work is required to add effective support for fuzzing SerenityOS to
the Syzkaller syscall fuzzer. :^) :^)
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>.
These small changes fix the remaining warnings that come up during
kernel compilation with Clang. These specific fixes were for benign
things: unused lambda captures and braces around scalar initializers.
The `#pragma GCC diagnostic` part is needed because the class has
virtual methods with the same name but different arguments, and Clang
tries to warn us that we are not actually overriding anything with
these.
Weirdly enough, GCC does not seem to care.
This hack allows self-test mode run-tests-and-shutdown.sh to give
TestProcFs a stat(2)-able /proc/self/fd/0. For some reason, when
stdin is a SerialDevice, /proc/self/fd/0 will be a symlink to the device
as expected, but, calling realpath or stat on /proc/self/fd/0 will error
out. realpath will give the string from Device::absolute_path() which
would be something like "device:4,64 (SerialDevice)". When VFS is trying
to resolve_path so that we can stat the file, it would bail out on this
fake-y path.
Change the fake path (that doesn't show up when you ls a device, nor
when checking the devices tab in SystemMonitor) from the major/minor
device number and class_name() to /dev/device_name(). There's probably
a very hairy yak standing behind this issue that was only discovered due
to the ProcFS rework.
The new ProcFS design consists of two main parts:
1. The representative ProcFS class, which is derived from the FS class.
The ProcFS and its inodes are much more lean - merely 3 classes to
represent the common type of inodes - regular files, symbolic links and
directories. They're backed by a ProcFSExposedComponent object, which
is responsible for the functional operation behind the scenes.
2. The backend of the ProcFS - the ProcFSComponentsRegistrar class
and all derived classes from the ProcFSExposedComponent class. These
together form the entire backend and handle all the functions you can
expect from the ProcFS.
The ProcFSExposedComponent derived classes split to 3 types in the
manner of lifetime in the kernel:
1. Persistent objects - this category includes all basic objects, like
the root folder, /proc/bus folder, main blob files in the root folders,
etc. These objects are persistent and cannot die ever.
2. Semi-persistent objects - this category includes all PID folders,
and subdirectories to the PID folders. It also includes exposed objects
like the unveil JSON'ed blob. These object are persistent as long as the
the responsible process they represent is still alive.
3. Dynamic objects - this category includes files in the subdirectories
of a PID folder, like /proc/PID/fd/* or /proc/PID/stacks/*. Essentially,
these objects are always created dynamically and when no longer in need
after being used, they're deallocated.
Nevertheless, the new allocated backend objects and inodes try to use
the same InodeIndex if possible - this might change only when a thread
dies and a new thread is born with a new thread stack, or when a file
descriptor is closed and a new one within the same file descriptor
number is opened. This is needed to actually be able to do something
useful with these objects.
The new design assures that many ProcFS instances can be used at once,
with one backend for usage for all instances.
This does the exact thing as `adopt_ref`, which is a recent addition to
AK.
Note that pointers returned by a bare new (without `nothrow`) are
guaranteed not to return null, so they can safely be converted into
references.
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)`.
Instead, try to create the device objects in separate static methods,
and if we fail for some odd reason to allocate memory for such devices,
just panic with that reason.
We now store the device descriptor obtained from the device
during enumeration in the device's object in memory instead
of exposing all of the different members contained within it.
If we are in a shared interrupt handler, the called handlers might
indicate it was not their interrupt, so we should not increment the
call counter of these handlers.
These are the actual structures that allow USB to work (i.e the ones
actually defined in the specification). This should provide us enough
of a baseline implementation that we can build on to support
different types of USB device.
The changes in commit 20743e8 removed the s_max_virtual_consoles
constant and hardcoded the number of consoles to 4. But in
PS2KeyboardDevice the keyboard shortcuts for switching to consoles were
hardcoded to 6.
I reintroduced the constant and added it in both places.
Previously reads and writes to /dev/zero, /dev/full, /dev/null and
/dev/random were limited to 4096 bytes.
This removes that restriction so that users can enjoy more zero bytes
in their buffers.
Instead of processing the input after receiving an IRQ, we shift the
responsibility to the io work queue to handle this for us, so if a page
fault occurs when trying to switch the VirtualConsole, the kernel can
handle that.
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`.
There is a slight race condition in our implementation of write().
We call File::can_write() before attempting to write to it (blocking if
it returns false). If it returns true, we assume that we can write to
the file, and our code assumes that File::write() cannot possibly fail
by being blocked. There is, however, the rare case where another process
writes to the file and prevents further writes in between the call to
Files::can_write() and File::write() in the first process. This would
result in the first process calling File::write() when it cannot be
written to.
We fix this by adding a mechanism for File::can_write() to signal that
it was blocked, making it the responsibilty of File::write() to check
whether it can write and then finally making sys$write() check if the
write failed due to it being blocked.
This commit adds support for initializing multiple serial ports per
PCI board, as well as initializing multiple different pci serial boards
Currently we just choose the first PCI serial port seen as the debug
port, but this should probably be made configurable some how in the
future.
