kern: implement KResourceLimit

libraries/libmesosphere/source/kern_k_resource_limit.cpp

@@ -0,0 +1,160 @@
+/*
+ * 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 {
+
+    void KResourceLimit::Initialize() {
+        /* This should be unnecessary for us, because our constructor will clear all fields. */
+        /* The following is analagous to what Nintendo's implementation (no constexpr constructor) would do, though. */
+        /*
+            this->waiter_count = 0;
+            for (size_t i = 0; i < util::size(this->limit_values); i++) {
+                this->limit_values[i]    = 0;
+                this->current_values[i]  = 0;
+                this->current_hints[i] = 0;
+            }
+        */
+    }
+
+    void KResourceLimit::Finalize() {
+        /* ... */
+    }
+
+    s64 KResourceLimit::GetLimitValue(ams::svc::LimitableResource which) const {
+        MESOSPHERE_ASSERT_THIS();
+
+        s64 value;
+        {
+            KScopedLightLock lk(this->lock);
+            value = this->limit_values[which];
+            MESOSPHERE_ASSERT(value >= 0);
+            MESOSPHERE_ASSERT(this->current_values[which] <= this->limit_values[which]);
+            MESOSPHERE_ASSERT(this->current_hints[which]  <= this->current_values[which]);
+        }
+
+        return value;
+    }
+
+    s64 KResourceLimit::GetCurrentValue(ams::svc::LimitableResource which) const {
+        MESOSPHERE_ASSERT_THIS();
+
+        s64 value;
+        {
+            KScopedLightLock lk(this->lock);
+            value = this->current_values[which];
+            MESOSPHERE_ASSERT(value >= 0);
+            MESOSPHERE_ASSERT(this->current_values[which] <= this->limit_values[which]);
+            MESOSPHERE_ASSERT(this->current_hints[which]  <= this->current_values[which]);
+        }
+
+        return value;
+    }
+
+    s64 KResourceLimit::GetFreeValue(ams::svc::LimitableResource which) const {
+        MESOSPHERE_ASSERT_THIS();
+
+        s64 value;
+        {
+            KScopedLightLock lk(this->lock);
+            MESOSPHERE_ASSERT(this->current_values[which] >= 0);
+            MESOSPHERE_ASSERT(this->current_values[which] <= this->limit_values[which]);
+            MESOSPHERE_ASSERT(this->current_hints[which]  <= this->current_values[which]);
+            value = this->limit_values[which] - this->current_values[which];
+        }
+
+        return value;
+    }
+
+    Result KResourceLimit::SetLimitValue(ams::svc::LimitableResource which, s64 value) {
+        MESOSPHERE_ASSERT_THIS();
+
+        KScopedLightLock lk(this->lock);
+        R_UNLESS(this->current_values[which] <= value, svc::ResultInvalidState());
+
+        this->limit_values[which] = value;
+
+        return ResultSuccess();
+    }
+
+    bool KResourceLimit::Reserve(ams::svc::LimitableResource which, s64 value) {
+        /* TODO: constexpr definition for this default timeout (it's 10 seconds) */
+        return this->Reserve(which, value, KHardwareTimer::GetTick() + 192'000'000);
+    }
+
+    bool KResourceLimit::Reserve(ams::svc::LimitableResource which, s64 value, s64 timeout) {
+        MESOSPHERE_ASSERT_THIS();
+        MESOSPHERE_ASSERT(value >= 0);
+
+        KScopedLightLock lk(this->lock);
+
+        MESOSPHERE_ASSERT(this->current_hints[which] <= this->current_values[which]);
+        if (this->current_hints[which] >= this->limit_values[which]) {
+            return false;
+        }
+
+        /* Loop until we reserve or run out of time. */
+        while (true) {
+            MESOSPHERE_ASSERT(this->current_values[which] <= this->limit_values[which]);
+            MESOSPHERE_ASSERT(this->current_hints[which]  <= this->current_values[which]);
+
+            /* If we would overflow, don't allow to succeed. */
+            if (this->current_values[which] + value <= this->current_values[which]) {
+                break;
+            }
+
+            if (this->current_values[which] + value <= this->limit_values[which]) {
+                this->current_values[which] += value;
+                this->current_hints[which] += value;
+                return true;
+            }
+
+            if (this->current_hints[which] + value <= this->limit_values[which] && (timeout < 0 || KHardwareTimer::GetTick() < timeout)) {
+                this->waiter_count++;
+                this->cond_var.Wait(&this->lock, timeout);
+                this->waiter_count--;
+            } else {
+                break;
+            }
+        }
+
+        return false;
+    }
+
+    void KResourceLimit::Release(ams::svc::LimitableResource which, s64 value) {
+        this->Release(which, value, value);
+    }
+
+    void KResourceLimit::Release(ams::svc::LimitableResource which, s64 value, s64 hint) {
+        MESOSPHERE_ASSERT_THIS();
+        MESOSPHERE_ASSERT(value >= 0);
+        MESOSPHERE_ASSERT(hint  >= 0);
+
+        KScopedLightLock lk(this->lock);
+        MESOSPHERE_ASSERT(this->current_values[which] <= this->limit_values[which]);
+        MESOSPHERE_ASSERT(this->current_hints[which]  <= this->current_values[which]);
+        MESOSPHERE_ASSERT(value <= this->current_values[which]);
+        MESOSPHERE_ASSERT(hint  <= this->current_hints[which]);
+
+        this->current_values[which] -= value;
+        this->current_hints[which] -= hint;
+
+        if (this->waiter_count != 0) {
+            this->cond_var.Broadcast();
+        }
+    }
+
+}