kern: fix slab heap atomics

libraries/libmesosphere/include/mesosphere/arch/arm64/kern_k_slab_heap_impl.hpp

@@ -0,0 +1,69 @@
+/*
+ * 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/>.
+ */
+#pragma once
+#include <vapours.hpp>
+#include <mesosphere/kern_select_cpu.hpp>
+
+namespace ams::kern::arch::arm64 {
+
+    template<typename T>
+    concept SlabHeapNode = requires (T &t) {
+        { t.next } -> std::convertible_to<T *>;
+    };
+
+    template<typename T> requires SlabHeapNode<T>
+    ALWAYS_INLINE T *AllocateFromSlabAtomic(T **head) {
+        u32 tmp;
+        T *node, *next;
+
+        __asm__ __volatile__(
+            "1:\n"
+            "    ldaxr  %[node], [%[head]]\n"
+            "    cbz    %[node], 2f\n"
+            "    ldr    %[next], [%[node]]\n"
+            "    stlxr  %w[tmp], %[next], [%[head]]\n"
+            "    cbnz   %w[tmp], 1b\n"
+            "    b      3f\n"
+            "2:\n"
+            "    clrex\n"
+            "3:\n"
+            : [tmp]"=&r"(tmp), [node]"=&r"(node), [next]"=&r"(next), [head]"+&r"(head)
+            :
+            : "cc", "memory"
+        );
+
+        return node;
+    }
+
+    template<typename T> requires SlabHeapNode<T>
+    ALWAYS_INLINE void FreeToSlabAtomic(T **head, T *node) {
+        u32 tmp;
+        T *next;
+
+        __asm__ __volatile__(
+            "1:\n"
+            "    ldaxr  %[next], [%[head]]\n"
+            "    str    %[next], [%[node]]\n"
+            "    stlxr  %w[tmp], %[node], [%[head]]\n"
+            "    cbnz   %w[tmp], 1b\n"
+            "2:\n"
+            : [tmp]"=&r"(tmp), [node]"+&r"(node), [next]"=&r"(next), [head]"+&r"(head)
+            :
+            : "cc", "memory"
+        );
+    }
+
+}