This returns ENOSYS if you are running in the real kernel, and some
other result if you are running in UserspaceEmulator.
There are other ways we could check if we're inside an emulator, but
it seemed easier to just ask. :^)
The hierarchy is AHCIController, AHCIPortHandler, AHCIPort and
SATADiskDevice. Each AHCIController has at least one AHCIPortHandler.
An AHCIPortHandler is an interrupt handler that takes care of
enumeration of handled AHCI ports when an interrupt occurs. Each
AHCIPort takes care of one SATADiskDevice, and later on we can add
support for Port multiplier.
When we implement support of Message signalled interrupts, we can spawn
many AHCIPortHandlers, and allow each one of them to be responsible for
a set of AHCIPorts.
For some reason I don't yet understand, building the kernel with -O2
produces a way-too-large kernel on some people's systems.
Since there are some really nice performance benefits from -O2 in
userspace, let's do a compromise and build Userland with -O2 but
put Kernel back into the -Os box for now.
Due to the non-standard way the boot assembler code is linked into
the kernel (not and actual dependency, but linked via linker.ld script)
both make and ninja weren't re-linking the kernel when boot.S was
changed. This should theoretically work since we use the cmake
`add_dependencies(..)` directive to express a manual dependency
on boot from Kernel, but something is obviously broken in cmake.
We can work around that with a hack, which forces a dependency on
a file we know will always exist in the kernel (init.cpp). So if
boot.S is rebuilt, then init.cpp is forced to be rebuilt, and then
we re-link the kernel. init.cpp is also relatively small, so it
compiles fast.
With the kernel command line issue fixed, we can now enable these
KUBSAN options without getting triple faults on startup:
* alignment
* null
* pointer-overflow
Clangd (CLion) was choking on some of the -fsanitize options, and since
we're not building the kernel with Clang anyway, let's just disable
the options for non-GCC compilers for now.
This removes some hard references to the toolchain, some unnecessary
uses of an external install command, and disables a -Werror flag (for
the time being) - only if run inside serenity.
With this, we can build and link the kernel :^)
KASAN is a dynamic analysis tool that finds memory errors. It focuses
mostly on finding use-after-free and out-of-bound read/writes bugs.
KASAN works by allocating a "shadow memory" region which is used to store
whether each byte of memory is safe to access. The compiler then instruments
the kernel code and a check is inserted which validates the state of the
shadow memory region on every memory access (load or store).
To fully integrate KASAN into the SerenityOS kernel we need to:
a) Implement the KASAN interface to intercept the injected loads/stores.
void __asan_load*(address);
void __asan_store(address);
b) Setup KASAN region and determine the shadow memory offset + translation.
This might be challenging since Serenity is only 32bit at this time.
Ex: Linux implements kernel address -> shadow address translation like:
static inline void *kasan_mem_to_shadow(const void *addr)
{
return ((unsigned long)addr >> KASAN_SHADOW_SCALE_SHIFT)
+ KASAN_SHADOW_OFFSET;
}
c) Integrating KASAN with Kernel allocators.
The kernel allocators need to be taught how to record allocation state
in the shadow memory region.
This commit only implements the initial steps of this long process:
- A new (default OFF) CMake build flag `ENABLE_KERNEL_ADDRESS_SANITIZER`
- Stubs out enough of the KASAN interface to allow the Kernel to link clean.
Currently the KASAN kernel crashes on boot (triple fault because of the crash
in strlen other sanitizer are seeing) but the goal here is to just get started,
and this should help others jump in and continue making progress on KASAN.
References:
* ASAN Paper: https://static.googleusercontent.com/media/research.google.com/en//pubs/archive/37752.pdf
* KASAN Docs: https://github.com/google/kasan
* NetBSD KASAN Blog: https://blog.netbsd.org/tnf/entry/kernel_address_sanitizer_part_3
* LWN KASAN Article: https://lwn.net/Articles/612153/
* Tracking Issue #5351
Let's be a little more expressive when inducing a kernel panic. :^)
PANIC(...) passes any arguments you give it to dmesgln(), then prints
a backtrace and hangs the machine.
CLion doesn't understand that we switch compilers mid-build (which I
can understand since it's a bit unusual.) Defining __serenity__ makes
the majority of IDE features work correctly in the kernel context.
This patch adds Space, a class representing a process's address space.
- Each Process has a Space.
- The Space owns the PageDirectory and all Regions in the Process.
This allows us to reorganize sys$execve() so that it constructs and
populates a new Space fully before committing to it.
Previously, we would construct the new address space while still
running in the old one, and encountering an error meant we had to do
tedious and error-prone rollback.
Those problems are now gone, replaced by what's hopefully a set of much
smaller problems and missing cleanups. :^)
We now build the kernel with partial UBSAN support.
The following -fsanitize sub-options are enabled:
* nonnull-attribute
* bool
If the kernel detects UB at runtime, it will now print a debug message
with a stack trace. This is very cool! I'm leaving it on by default for
now, but we'll probably have to re-evaluate this as more options are
enabled and slowdown increases.
This adds support for FUTEX_WAKE_OP, FUTEX_WAIT_BITSET, FUTEX_WAKE_BITSET,
FUTEX_REQUEUE, and FUTEX_CMP_REQUEUE, as well well as global and private
futex and absolute/relative timeouts against the appropriate clock. This
also changes the implementation so that kernel resources are only used when
a thread is blocked on a futex.
Global futexes are implemented as offsets in VMObjects, so that different
processes can share a futex against the same VMObject despite potentially
being mapped at different virtual addresses.
All users of this mechanism have been switched to anonymous files and
passing file descriptors with sendfd()/recvfd().
Shbufs got us where we are today, but it's time we say good-bye to them
and welcome a much more idiomatic replacement. :^)
This patch adds a new AnonymousFile class which is a File backed by
an AnonymousVMObject that can only be mmap'ed and nothing else, really.
I'm hoping that this can become a replacement for shbufs. :^)
This patch merges the profiling functionality in the kernel with the
performance events mechanism. A profiler sample is now just another
perf event, rather than a dedicated thing.
Since perf events were already per-process, this now makes profiling
per-process as well.
Processes with perf events would already write out a perfcore.PID file
to the current directory on death, but since we may want to profile
a process and then let it continue running, recorded perf events can
now be accessed at any time via /proc/PID/perf_events.
This patch also adds information about process memory regions to the
perfcore JSON format. This removes the need to supply a core dump to
the Profiler app for symbolication, and so the "profiler coredump"
mechanism is removed entirely.
There's still a hard limit of 4MB worth of perf events per process,
so this is by no means a perfect final design, but it's a nice step
forward for both simplicity and stability.
Fixes#4848Fixes#4849
This patch adds sys$abort() which immediately crashes the process with
SIGABRT. This makes assertion backtraces a lot nicer by removing all
the gunk that otherwise happens between __assertion_failed() and
actually crashing from the SIGABRT.
Insert stack canaries to find stack corruptions in the kernel.
It looks like this was enabled in the past (842716a) but appears to have been
lost during the CMake conversion.
The `-fstack-protector-strong` variant was chosen because it catches more issues
than `-fstack-protector`, but doesn't have substantial performance impact like
`-fstack-protector-all`.
Instead of specifying the boot argument to be root=/dev/hdXY, now
one can write root=PARTUUID= with the right UUID, and if the partition
is found, the kernel will boot from it.
This feature is mainly used with GUID partitions, and is considered to
be the most reliable way for the kernel to identify partitions.
RTTI is still disabled for the Kernel, and for the Dynamic Loader. This
allows for much less awkward navigation of class heirarchies in LibCore,
LibGUI, LibWeb, and LibJS (eventually). Measured RootFS size increase
was < 1%, and libgui.so binary size was ~3.3%. The small binary size
increase here seems worth it :^)
* Add SERENITY_ARCH option to CMake for selecting the target toolchain
* Port all build scripts but continue to use i686
* Update GitHub Actions cache to include BuildIt.sh
The partitioning code was very outdated, and required a full refactor.
The new subsystem removes duplicated code and uses more AK containers.
The most important change is that all implementations of the
PartitionTable class conform to one interface, which made it possible
to remove unnecessary code in the EBRPartitionTable class.
Finding partitions is now done in the StorageManagement singleton,
instead of doing so in init.cpp.
Also, now we don't try to find partitions on demand - the kernel will
try to detect if a StorageDevice is partitioned, and if so, will check
what is the partition table, which could be MBR, GUID or EBR.
Then, it will create DiskPartitionMetadata object for each partition
that is available in the partition table. This object will be used
by the partition enumeration code to create a DiskPartition with the
correct minor number.
The DevFS along with DevPtsFS give a complete solution for populating
device nodes in /dev. The main purpose of DevFS is to eliminate the
need of device nodes generation when building the system.
Later on, DevFS will assist with exposing disk partition nodes.
This new flag controls two things:
- Whether the kernel will generate core dumps for the process
- Whether the EUID:EGID should own the process's files in /proc
Processes are automatically made non-dumpable when their EUID or EGID is
changed, either via syscalls that specifically modify those ID's, or via
sys$execve(), when a set-uid or set-gid program is executed.
A process can change its own dumpable flag at any time by calling the
new sys$prctl(PR_SET_DUMPABLE) syscall.
Fixes#4504.
This commit gets rid of ELF::Loader entirely since its very ambiguous
purpose was actually to load executables for the kernel, and that is
now handled by the kernel itself.
This patch includes some drive-by cleanup in LibDebug and CrashDaemon
enabled by the fact that we no longer need to keep the ref-counted
ELF::Loader around.
The StorageManagement class has 2 roles:
1. During boot, it should find all storage controllers in the machine,
and then determine what is the boot device.
2. Later on boot, it is a registrar of all storage controllers and
storage devices. Thus, it could be used to show information about these
devices when implemented.
This change allows the user to specify a boot driver other than /dev/hda
and if it's connected in the machine - it will boot.
This new subsystem is somewhat replacing the IDE disk code we had with a
new flexible design.
StorageDevice is a generic class that represent a generic storage
device. It is meant that specific storage hardware will override the
interface. StorageController is a generic class that represent
a storage controller that can be found in a machine.
The IDEController class governs two IDEChannels. An IDEChannel is
responsible to manage the master & slave devices of the channel,
therefore an IDEChannel is an IRQHandler.
Such device is not an IRQHandler by itself, but actually a controller of
many IRQ or MSI devices. The purpose of this class is to manage multiple
sources of interrupts.
For example, a generic ISA IDE controller controls 2 IRQ sources - 14
and 15. So, when we initialize the IDE controller, it will initialize
two IDE channels (also known as PATAChannels) to utilize IRQ 14 and 15,
respectively. NVMe with MSI-X support can theoretically handle up to
2048 interrupts.
When a process crashes, we generate a coredump file and write it in
/tmp/coredumps/.
The coredump file is an ELF file of type ET_CORE.
It contains a segment for every userspace memory region of the process,
and an additional PT_NOTE segment that contains the registers state for
each thread, and a additional data about memory regions
(e.g their name).
This makes the Scheduler a lot leaner by not having to evaluate
block conditions every time it is invoked. Instead evaluate them as
the states change, and unblock threads at that point.
This also implements some more waitid/waitpid/wait features and
behavior. For example, WUNTRACED and WNOWAIT are now supported. And
wait will now not return EINTR when SIGCHLD is delivered at the
same time.
This allows issuing asynchronous requests for devices and waiting
on the completion of the request. The requests can cascade into
multiple sub-requests.
Since IRQs may complete at any time, if the current process is no
longer the same that started the process, we need to swich the
paging context before accessing user buffers.
Change the PATA driver to use this model.
Rework the PS/2 keyboard and mouse drivers to use a common 8042
controller driver. Also, reset and reconfigure the 8042 controller
as they are not guaranteed to be in the state that we expect.
This allows issuing asynchronous requests for devices and waiting
on the completion of the request. The requests can cascade into
multiple sub-requests.
Since IRQs may complete at any time, if the current process is no
longer the same that started the process, we need to swich the
paging context before accessing user buffers.
Change the PATA driver to use this model.
This enables the APIC timer on all CPUs, which means Scheduler::timer_tick
is now called on all CPUs independently. We still don't do anything on
the APs as it instantly crashes due to a number of other problems.
This finally takes care of the kind-of excessive boilerplate code that were the
ctype adapters. On the other hand, I had to link `LibC/ctype.cpp` to the Kernel
(for `AK/JsonParser.cpp` and `AK/Format.cpp`). The previous commit actually makes
sense now: the `string.h` includes in `ctype.{h,cpp}` would require to link more LibC
stuff to the Kernel when it only needs the `_ctype_` array of `ctype.cpp`, and there
wasn't any string stuff used in ctype.
Instead of all this I could have put static derivatives of `is_any_of()` in the
concerned AK files, however that would have meant more boilerplate and workarounds;
so I went for the Kernel approach.
This function is not avaliable in the kernel.
In the future it would be nice to have some sort of <charconv> header
that does this for all integer types and then call it in strtoull and et
cetera.
The difference would be that this function say 'from_chars' would return
an Optional and not just interpret anything invalid as zero.
Since the CPU already does almost all necessary validation steps
for us, we don't really need to attempt to do this. Doing it
ourselves doesn't really work very reliably, because we'd have to
account for other processors modifying virtual memory, and we'd
have to account for e.g. pages not being able to be allocated
due to insufficient resources.
So change the copy_to/from_user (and associated helper functions)
to use the new safe_memcpy, which will return whether it succeeded
or not. The only manual validation step needed (which the CPU
can't perform for us) is making sure the pointers provided by user
mode aren't pointing to kernel mappings.
To make it easier to read/write from/to either kernel or user mode
data add the UserOrKernelBuffer helper class, which will internally
either use copy_from/to_user or directly memcpy, or pass the data
through directly using a temporary buffer on the stack.
Last but not least we need to keep syscall params trivial as we
need to copy them from/to user mode using copy_from/to_user.
The JS tests pointed out that the implementation in DateTime
had an off-by-one in the month when doing the leap year check,
so this change fixes that bug.
This does not add any behaviour change to the processes, but it ties a
TTY to an active process group via TIOCSPGRP, and returns the TTY to the
kernel when all processes in the process group die.
Also makes the TTY keep a link to the original controlling process' parent (for
SIGCHLD) instead of the process itself.
This is racy in userspace and non-racy in kernelspace so let's keep
it in kernelspace.
The behavior change where CLOEXEC is preserved when dup2() is called
with (old_fd == new_fd) was good though, let's keep that.
By having a separate list of constructors for the kernel heap
code, we can properly use constructors without re-running them
after the heap was already initialized. This solves some problems
where values were wiped out because they were overwritten by
running their constructors later in the initialization process.
This syscall allows a parent process to disown a child process, setting
its parent PID to 0.
Unparented processes are automatically reaped by the kernel upon exit,
and no sys$waitid() is required. This will make it much nicer to do
spawn-and-forget which is common in the GUI environment.
This is something I've been meaning to do for a long time, and here we
finally go. This patch moves all sys$foo functions out of Process.cpp
and into files in Kernel/Syscalls/.
It's not exactly one syscall per file (although it could be, but I got
a bit tired of the repetitive work here..)
This makes hacking on individual syscalls a lot less painful since you
don't have to rebuild nearly as much code every time. I'm also hopeful
that this makes it easier to understand individual syscalls. :^)
FileBackedFileSystem is one that's backed by (mounted from) a file, in other
words one that has a "source" of the mount; that doesn't mean it deals in
blocks. The hierarchy now becomes:
* FS
* ProcFS
* DevPtsFS
* TmpFS
* FileBackedFS
* (future) Plan9FS
* BlockBasedFS
* Ext2FS
The SDL port failed to build because the CMake toolchain filed pointed
to the old root. Now the toolchain file assumes that the Root is in
Build/Root.
Additionally, the AK/ and Kernel/ headers need to be installed in the
root too.
And move canonicalized_path() to a static method on LexicalPath.
This is to make it clear that FileSystemPath/canonicalized_path() only
perform *lexical* canonicalization.
This patch adds a MappedROM abstraction to the Kernel VM subsystem.
It's basically the read-only byte buffer equivalent of a TypedMapping.
We use this in the ACPI and MP table parsers to scan for interesting
stuff in low memory instead of doing a bunch of address arithmetic.
Make sure that userspace is always referencing "system" headers in a way
that would build on target :). This means removing the explicit
include_directories of Libraries/LibC in favor of having it export its
headers as SYSTEM. Also remove a redundant include_directories of
Libraries in the 'serenity build' part of the build script. It's already
set at the top.
This causes issues for the Kernel, and for crt0.o. These special cases
are handled individually.
This was supposed to be the foundation for some kind of pre-kernel
environment, but nobody is working on it right now, so let's move
everything back into the kernel and remove all the confusion.
