Kernel: Make KCOVDevice::ioctl() return KResult

Recent ioctl() changes broke this, this commit fixes that
and the build.

Kernel/Devices/KCOVDevice.cpp

@@ -75,9 +75,9 @@ KResultOr<NonnullRefPtr<FileDescription>> KCOVDevice::open(int options)
     return File::open(options);
 }
 
-int KCOVDevice::ioctl(FileDescription&, unsigned request, FlatPtr arg)
+KResult KCOVDevice::ioctl(FileDescription&, unsigned request, Userspace<void*> arg)
 {
-    int error = 0;
+    KResult return_value = KSuccess;
     auto thread = Thread::current();
     auto tid = thread->tid();
     auto pid = thread->pid();
@@ -90,19 +90,19 @@ int KCOVDevice::ioctl(FileDescription&, unsigned request, FlatPtr arg)
     switch (request) {
     case KCOV_SETBUFSIZE: {
         if (kcov_instance->state >= KCOVInstance::TRACING) {
-            error = EBUSY;
+            return_value = EBUSY;
             break;
         }
-        error = kcov_instance->buffer_allocate(arg);
+        return_value = kcov_instance->buffer_allocate((FlatPtr)arg.unsafe_userspace_ptr());
         break;
     }
     case KCOV_ENABLE: {
         if (kcov_instance->state >= KCOVInstance::TRACING) {
-            error = EBUSY;
+            return_value = EBUSY;
             break;
         }
         if (!kcov_instance->has_buffer()) {
-            error = ENOBUFS;
+            return_value = ENOBUFS;
             break;
         }
         VERIFY(kcov_instance->state == KCOVInstance::OPENED);
@@ -113,7 +113,7 @@ int KCOVDevice::ioctl(FileDescription&, unsigned request, FlatPtr arg)
     case KCOV_DISABLE: {
         auto maybe_kcov_instance = thread_instance->get(tid);
         if (!maybe_kcov_instance.has_value()) {
-            error = ENOENT;
+            return_value = ENOENT;
             break;
         }
         VERIFY(kcov_instance->state == KCOVInstance::TRACING);
@@ -122,11 +122,11 @@ int KCOVDevice::ioctl(FileDescription&, unsigned request, FlatPtr arg)
         break;
     }
     default: {
-        error = EINVAL;
+        return_value = EINVAL;
     }
     };
 
-    return error;
+    return return_value;
 }
 
 KResultOr<Region*> KCOVDevice::mmap(Process& process, FileDescription&, const Range& range, u64 offset, int prot, bool shared)

Kernel/Devices/KCOVDevice.h

@@ -37,7 +37,7 @@ protected:
     virtual void start_request(AsyncBlockDeviceRequest& request) override final { request.complete(AsyncDeviceRequest::Failure); }
     virtual KResultOr<size_t> read(FileDescription&, u64, UserOrKernelBuffer&, size_t) override { return -EINVAL; }
     virtual KResultOr<size_t> write(FileDescription&, u64, const UserOrKernelBuffer&, size_t) override { return -EINVAL; }
-    virtual int ioctl(FileDescription&, unsigned request, FlatPtr arg) override;
+    virtual KResult ioctl(FileDescription&, unsigned request, Userspace<void*> arg) override;
 
 private:
     KCOVDevice();

Kernel/Devices/KCOVInstance.cpp

@@ -15,7 +15,7 @@ KCOVInstance::KCOVInstance(ProcessID pid)
     state = UNUSED;
 }
 
-int KCOVInstance::buffer_allocate(size_t buffer_size_in_entries)
+KResult KCOVInstance::buffer_allocate(size_t buffer_size_in_entries)
 {
     // first entry contains index of last PC
     this->m_buffer_size_in_entries = buffer_size_in_entries - 1;
@@ -40,7 +40,7 @@ int KCOVInstance::buffer_allocate(size_t buffer_size_in_entries)
     if (!this->has_buffer())
         return ENOMEM;
 
-    return 0;
+    return KSuccess;
 }
 
 void KCOVInstance::buffer_add_pc(u64 pc)

Kernel/Devices/KCOVInstance.h

@@ -30,7 +30,7 @@ class KCOVInstance final {
 public:
     explicit KCOVInstance(ProcessID pid);
 
-    int buffer_allocate(size_t buffer_size_in_entries);
+    KResult buffer_allocate(size_t buffer_size_in_entries);
     bool has_buffer() const { return m_buffer != nullptr; }
     void buffer_add_pc(u64 pc);