It was determined that deadlocks inside `KThread::UpdatePriorityInheritance` would not only arise from the first level of locking with `waitingOn->waiterMutex` but also the second level of locking with `nextThread->waiterMutex` which has now also been fixed to fallback when facing contention.
Two issues exist with locking of `KThread::waiterMutex`:
* It was not always locked when accessing waiter members such as `waitThread`, `waitKey` and `waitTag` which would lead to a race that could end up in a deadlock or most notably a segfault inside `UpdatePriorityInheritance`
* There could be a deadlock from `UpdatePriorityInheritance` locking `waiterMutex` of a thread and waiting to get the owner's `waiterMutex` while on another thread `MutexUnlock` holds the owner's `waiterMutex` and waits on locking the `waiterMutex` held by `UpdatePriorityInheritance`
This commit fixes both issues by adding appropriate locking to all locations where waiter members are accessed in addition to adding a fallback mechanism inside `UpdatePriorityInheritance` that unlocks `waiterMutex` on contention to avoid a deadlock.
The CAS condition for KThread PI was inverted which lead to entirely incorrect behavior for CAS conditions which while it might work in the vast majority of cases would lead to significantly inaccurate behavior.
We utilize `pthread_setname_np` to set the thread names but didn't check for any errors which resulted in the `Skyline-Choreographer` and `ChannelCmdFifo` not having proper names as they exceeded the 16 character limit on thread names for the pthread function. This has now been fixed by changing the names and introducing error checking to invocations of this function.
A lot of logs are incomplete due to being unable to flush inside the signal handler, now we flush after any exceptions so that there is a guarantee of any exceptions being logged as this is crucial for proper debugging.
armed.
It was discovered during testing of 'Hatsune Miku Project DIVA: Mega Mix'
that if a thread was starting while preemption was being enabled a NULL
pointer dereference could occur in the timer_settime call as
timer_create may not have been called yet.
Add Tracing for SVCs, Services, NVDRV, and Synchronization Primitives. In addition, fix `TRACE_EVENT_END("guest")` being emitted when a signal is received while being in the guest rather than host which would cause an exception. This commit also disables warnings for the Perfetto library as we do not control fixing them.
The following scheduler bugs were fixed:
* It was assumed that all non-cooperative `Rotate` calls were from a preemptive yield and changed the state of `KThread::isPreempted` incorrectly which could lead to UB, an example of a scenario with it would be:
* * Preemptive thread A gets a signal to yield from cooperative thread B due to it being ready to schedule and higher priority
* * A complies with this request but there's an assumption that the signal was actually from it's preemption timer therefore it doesn't reset it (As it isn't required if the timer was responsible for the signal)
* * A receives the actual preemption signal a while later, causing UB as the signal handler is invoked twice
* `Scheduler::UpdatePriority`
* * A check for `currentIt == core->queue.begin()` existed which caused an incorrect early return
* * The preemption timer was armed correctly when a priority transition from cooperative priority -> preemption priority occurred but not disarmed when a transition from preemption priority -> cooperative priority occurred
* * The timer was unnecessarily disarmed in the case of updating the priority of a non-running thread, this isn't as much a bug as it is just pointless
* Priority inheritance in `KProcess::MutexLock` is fundamentally broken as it performs UB with `waitThread` being accessed prior to being assigned
* When a thread sets its own priority using `SvcSetThreadCoreMask` and its current core is no longer in the affinity mask, it wouldn't actually move to the new thread until the next time the thread is load balanced
This addresses all CR comments including more codebase-wide changes arising from certain review comments like proper usage of its/it's and consistent contraction of it is into it's.
An overhaul was made to the presentation and formatting of `KThread.h` and `LoadBalance` works has been superseded by `GetOptimalCoreForThread` which can be used alongside `InsertThread` or `MigrateToCore`. It makes the API far more atomic and neater. This was a major point of contention for the design prior, it's simplified some code and potentially improved performance.
An exceptional signal handler allows us to convert an OS signal into a C++ exception, this allows us to alleviate a lot of crashes that would otherwise occur from signals being thrown during execution of games and be able to handle them gracefully.
This commit mainly finishes up refactor by fixing everything brought up in the CR + Improving NCE somewhat and actually killing the child processes properly now.
We earlier moved to LGPLv3.0 or Later. This was a mistake as what we wanted was being able to link to proprietary libraries but LGPL is the opposite and it allows linking proprietary libraries to libskyline instead. After further consideration, we've moved to MPL-2.0, it allows linking to proprietary libraries and is a standardized license as compared to adding an exception to GPL.
This commit mainly fixes the problem with process leakage before where the guest process wouldn't be killed. In addition, it clears up the problem with naming differences with PID/TID where purely PID was used before but that term is generally used to refer to the PGID. So, `KProcess` has a `pid` member but `KThread` has a `tid` member.
This commit fixes a lot of style errors throughout the project by letting the Android Studio Formatter fix them. This commit also splits the Circular Buffer into it's own file.
This refactored common by:
* Moving out as many constants to class/function local scopes from being declared in `common`
* Spacing out common and any function to which a constant was moved out to
* Fixing comments here and there
In addition, some naming inconsistencies were fixed as well.
This commit fixed the issues outlined in the CR (Mainly correlated to formatting), moves to a sorted vector from a sorted list for the memory map in addition to using binary search for sorting through rather than iteratively and fixes item duplication in the game list when directory is changed in Settings.
This commit does a major refactor of the memory implementation, it forms a memory map which is far cleaner than trying to access it through a handle table lookup. In addition, it creates a common interface for all memory kernel objects: KMemory from which all other kernel memory objects inherit. This allows doing resizing, permission change, etc without casting to the base memory type.
This commit makes the kernel completely thread-safe and fixes an issue that caused libNX games to not work due to an error with KSharedMemory. In addition, implement GroupMutex to allow the kernel threads to run in parallel but still allow them to not overlap with the JNI thread.
This commit is a huge step in the direction of better performance, as we move from ptrace to junction branching and have kernel call overhead similar to that of a native kernel call! In addition, this sets the base for the kernel to go fully multi-threaded. However, the kernel is currently not thread-safe and therefore this commit currently causes a crash.
