In the previous change, the memory writing was moved into the service
function itself, however it still had a problem, in that the entire
MemoryInfo structure wasn't being written out, only the first 32 bytes
of it were being written out. We still need to write out the trailing
two reference count members and zero out the padding bits.
Not doing this can result in wrong behavior in userland code in the following
scenario:
MemoryInfo info; // Put on the stack, not quaranteed to be zeroed out.
svcQueryMemory(&info, ...);
if (info.device_refcount == ...) // Whoops, uninitialized read.
This can also cause the wrong thing to happen if the user code uses
std::memcmp to compare the struct, with another one (questionable, but
allowed), as the padding bits are not guaranteed to be a deterministic
value. Note that the kernel itself also fully zeroes out the structure
before writing it out including the padding bits.
Moves the memory writes directly into QueryProcessMemory instead of
letting the wrapper function do it. It would be inaccurate to allow the
handler to do it because there's cases where memory shouldn't even be
written to. For example, if the given process handle is invalid.
HOWEVER, if the memory writing is within the wrapper, then we have no
control over if these memory writes occur, meaning in an error case, 68
bytes of memory randomly get trashed with zeroes, 64 of those being
written to wherever the memory info address points to, and the remaining
4 being written wherever the page info address points to.
One solution in this case would be to just conditionally check within
the handler itself, but this is kind of smelly, given the handler
shouldn't be performing conditional behavior itself, it's a behavior of
the managed function. In other words, if you remove the handler from the
equation entirely, does the function still retain its proper behavior?
In this case, no.
Now, we don't potentially trash memory from this function if an invalid
query is performed.
Amends the MemoryState enum to use the same values like the actual
kernel does. Also provides the necessary operators to operate on them.
This will be necessary in the future for implementing
svcSetMemoryAttribute, as memory block state is checked before applying
the attribute.
The Process object kept itself alive indefinitely because its handle_table
contains a SharedMemory object which owns a reference to the same Process object,
creating a circular ownership scenario.
Break that up by storing only a non-owning pointer in the SharedMemory object.
This was only ever public so that code could check whether or not a
handle was valid or not. Instead of exposing the object directly and
allowing external code to potentially mess with the map contents, we
just provide a member function that allows checking whether or not a
handle is valid.
This makes all member variables of the VMManager class private except
for the page table.
While partially correct, this service call allows the retrieved event to
be null, as it also uses the same handle to check if it was referring to
a Process instance. The previous two changes put the necessary machinery
in place to allow for this, so we can simply call those member functions
here and be done with it.
This function simply does a handle table lookup for a writable event
instance identified by the given handle value. If a writable event
cannot be found for the given handle, then an invalid handle error is
returned. If a writable event is found, then it simply signals the
event, as one would expect.
svcCreateEvent operates by creating both a readable and writable event
and then attempts to add both to the current process' handle table.
If adding either of the events to the handle table fails, then the
relevant error from the handle table is returned.
If adding the readable event after the writable event to the table
fails, then the writable event is removed from the handle table and the
relevant error from the handle table is returned.
Note that since we do not currently test resource limits, we don't check
the resource limit table yet.
Two kernel object should absolutely never have the same handle ID type.
This can cause incorrect behavior when it comes to retrieving object
types from the handle table. In this case it allows converting a
WritableEvent into a ReadableEvent and vice-versa, which is undefined
behavior, since the object types are not the same.
This also corrects ClearEvent() to check both kernel types like the
kernel itself does.
The kernel uses the handle table of the current process to retrieve the
process that should be used to retrieve certain information. To someone
not familiar with the kernel, this might raise the question of "Ok,
sounds nice, but doesn't this make it impossible to retrieve information
about the current process?".
No, it doesn't, because HandleTable instances in the kernel have the
notion of a "pseudo-handle", where certain values allow the kernel to
lookup objects outside of a given handle table. Currently, there's only
a pseudo-handle for the current process (0xFFFF8001) and a pseudo-handle
for the current thread (0xFFFF8000), so to retrieve the current process,
one would just pass 0xFFFF8001 into svcGetInfo.
The lookup itself in the handle table would be something like:
template <typename T>
T* Lookup(Handle handle) {
if (handle == PSEUDO_HANDLE_CURRENT_PROCESS) {
return CurrentProcess();
}
if (handle == PSUEDO_HANDLE_CURRENT_THREAD) {
return CurrentThread();
}
return static_cast<T*>(&objects[handle]);
}
which, as is shown, allows accessing the current process or current
thread, even if those two objects aren't actually within the HandleTable
instance.
Our implementation of svcGetInfo was slightly incorrect in that we
weren't doing proper error checking everywhere. Instead, reorganize it
to be similar to how the kernel seems to do it.
The opposite of the getter functions, this function sets the limit value
for a particular ResourceLimit resource category, with the restriction
that the new limit value must be equal to or greater than the current
resource value. If this is violated, then ERR_INVALID_STATE is returned.
e.g.
Assume:
current[Events] = 10;
limit[Events] = 20;
a call to this service function lowering the limit value to 10 would be
fine, however, attempting to lower it to 9 in this case would cause an
invalid state error.
This kernel service function is essentially the exact same as
svcGetResourceLimitLimitValue(), with the only difference being that it
retrieves the current value for a given resource category using the
provided resource limit handle, rather than retrieving the limiting
value of that resource limit instance.
Given these are exactly the same and only differ on returned values, we
can extract the existing code for svcGetResourceLimitLimitValue() to
handle both values.
This kernel service function retrieves the maximum allowable value for
a provided resource category for a given resource limit instance. Given
we already have the functionality added to the resource limit instance
itself, it's sufficient to just hook it up.
The error scenarios for this are:
1. If an invalid resource category type is provided, then ERR_INVALID_ENUM is returned.
2. If an invalid handle is provided, then ERR_INVALID_HANDLE is returned (bad thing goes in, bad thing goes out, as one would expect).
If neither of the above error cases occur, then the out parameter is
provided with the maximum limit value for the given category and success
is returned.
This function simply creates a ResourceLimit instance and attempts to
create a handle for it within the current process' handle table. If the
kernal fails to either create the ResourceLimit instance or create a
handle for the ResourceLimit instance, it returns a failure code
(OUT_OF_RESOURCE, and HANDLE_TABLE_FULL respectively). Finally, it exits
by providing the output parameter with the handle value for the
ResourceLimit instance and returning that it was successful.
Note: We do not return OUT_OF_RESOURCE because, if yuzu runs out of
available memory, then new will currently throw. We *could* allocate the
kernel instance with std::nothrow, however this would be inconsistent
with how all other kernel objects are currently allocated.
Cleans out the citra/3DS-specific implementation details that don't
apply to the Switch. Sets the stage for implementing ResourceLimit
instances properly.
While we're at it, remove the erroneous checks within CreateThread() and
SetThreadPriority(). While these are indeed checked in some capacity,
they are not checked via a ResourceLimit instance.
In the process of moving out Citra-specifics, this also replaces the
system ResourceLimit instance's values with ones from the Switch.
Both member functions assume the passed in target process will not be
null. Instead of making this assumption implicit, we can change the
functions to be references and enforce this at the type-system level.
