kern: add KAddressArbiter::WaitIfEqual

libraries/libmesosphere/source/kern_k_address_arbiter.cpp

@@ -0,0 +1,108 @@
+/*
+ * Copyright (c) 2018-2020 Atmosphère-NX
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+#include <mesosphere.hpp>
+
+namespace ams::kern {
+
+    namespace {
+
+        constinit KThread g_arbiter_compare_thread;
+
+        ALWAYS_INLINE bool ReadFromUser(s32 *out, KProcessAddress address) {
+            return UserspaceAccess::CopyMemoryFromUserSize32Bit(out, GetVoidPointer(address));
+        }
+
+    }
+
+    Result KAddressArbiter::Signal(uintptr_t addr, s32 count) {
+        MESOSPHERE_UNIMPLEMENTED();
+    }
+
+    Result KAddressArbiter::SignalAndIncrementIfEqual(uintptr_t addr, s32 value, s32 count) {
+        MESOSPHERE_UNIMPLEMENTED();
+    }
+
+    Result KAddressArbiter::SignalAndModifyByWaitingCountIfEqual(uintptr_t addr, s32 value, s32 count) {
+        MESOSPHERE_UNIMPLEMENTED();
+    }
+
+    Result KAddressArbiter::WaitIfLessThan(uintptr_t addr, s32 value, bool decrement, s64 timeout) {
+        MESOSPHERE_UNIMPLEMENTED();
+    }
+
+    Result KAddressArbiter::WaitIfEqual(uintptr_t addr, s32 value, s64 timeout) {
+        /* Prepare to wait. */
+        KThread *cur_thread = GetCurrentThreadPointer();
+        KHardwareTimer *timer;
+
+        {
+            KScopedSchedulerLockAndSleep slp(std::addressof(timer), cur_thread, timeout);
+
+            /* Check that the thread isn't terminating. */
+            if (cur_thread->IsTerminationRequested()) {
+                slp.CancelSleep();
+                return svc::ResultTerminationRequested();
+            }
+
+            /* Set the synced object. */
+            cur_thread->SetSyncedObject(nullptr, ams::svc::ResultTimedOut());
+
+            /* Read the value from userspace. */
+            s32 user_value;
+            if (!ReadFromUser(std::addressof(user_value), addr)) {
+                slp.CancelSleep();
+                return svc::ResultInvalidCurrentMemory();
+            }
+
+            /* Check that the value is equal. */
+            if (value != user_value) {
+                slp.CancelSleep();
+                return svc::ResultInvalidState();
+            }
+
+            /* Check that the timeout is non-zero. */
+            if (timeout == 0) {
+                slp.CancelSleep();
+                return svc::ResultTimedOut();
+            }
+
+            /* Set the arbiter. */
+            cur_thread->SetAddressArbiter(std::addressof(this->tree), addr);
+            this->tree.insert(*cur_thread);
+            cur_thread->SetState(KThread::ThreadState_Waiting);
+        }
+
+        /* Cancel the timer wait. */
+        if (timer != nullptr) {
+            timer->CancelTask(cur_thread);
+        }
+
+        /* Remove from the address arbiter. */
+        {
+            KScopedSchedulerLock sl;
+
+            if (cur_thread->IsWaitingForAddressArbiter()) {
+                this->tree.erase(this->tree.iterator_to(*cur_thread));
+                cur_thread->ClearAddressArbiter();
+            }
+        }
+
+        /* Get the result. */
+        KSynchronizationObject *dummy;
+        return cur_thread->GetWaitResult(std::addressof(dummy));
+    }
+
+}