Kernel: Introduce global variables and stats in /sys/kernel directory

The ProcFS is an utter mess currently, so let's start move things that
are not related to processes-info. To ensure it's done in a sane manner,
we start by duplicating all /proc/ global nodes to the /sys/kernel/
directory, then we will move Userland to use the new directory so the
old directory nodes can be removed from the /proc directory.

Kernel/FileSystem/SysFS/Subsystems/Kernel/CPUInfo.cpp

@@ -0,0 +1,83 @@
+/*
+ * Copyright (c) 2022, Liav A. <liavalb@hotmail.co.il>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <AK/JsonObjectSerializer.h>
+#include <Kernel/Arch/x86/ProcessorInfo.h>
+#include <Kernel/FileSystem/SysFS/Subsystems/Kernel/CPUInfo.h>
+#include <Kernel/Sections.h>
+
+namespace Kernel {
+
+UNMAP_AFTER_INIT SysFSCPUInformation::SysFSCPUInformation(SysFSDirectory const& parent_directory)
+    : SysFSGlobalInformation(parent_directory)
+{
+}
+
+UNMAP_AFTER_INIT NonnullLockRefPtr<SysFSCPUInformation> SysFSCPUInformation::must_create(SysFSDirectory const& parent_directory)
+{
+    return adopt_lock_ref_if_nonnull(new (nothrow) SysFSCPUInformation(parent_directory)).release_nonnull();
+}
+
+ErrorOr<void> SysFSCPUInformation::try_generate(KBufferBuilder& builder)
+{
+    auto array = TRY(JsonArraySerializer<>::try_create(builder));
+    TRY(Processor::try_for_each(
+        [&](Processor& proc) -> ErrorOr<void> {
+            auto& info = proc.info();
+            auto obj = TRY(array.add_object());
+            TRY(obj.add("processor"sv, proc.id()));
+            TRY(obj.add("vendor_id"sv, info.vendor_id_string()));
+            TRY(obj.add("family"sv, info.display_family()));
+            if (!info.hypervisor_vendor_id_string().is_null())
+                TRY(obj.add("hypervisor_vendor_id"sv, info.hypervisor_vendor_id_string()));
+
+            auto features_array = TRY(obj.add_array("features"sv));
+            auto keep_empty = SplitBehavior::KeepEmpty;
+
+            ErrorOr<void> result; // FIXME: Make this nicer
+            info.features_string().for_each_split_view(' ', keep_empty, [&](StringView feature) {
+                if (result.is_error())
+                    return;
+                result = features_array.add(feature);
+            });
+            TRY(result);
+
+            TRY(features_array.finish());
+
+            TRY(obj.add("model"sv, info.display_model()));
+            TRY(obj.add("stepping"sv, info.stepping()));
+            TRY(obj.add("type"sv, info.type()));
+            TRY(obj.add("brand"sv, info.brand_string()));
+
+            auto caches = TRY(obj.add_object("caches"sv));
+
+            auto add_cache_info = [&](StringView name, ProcessorInfo::Cache const& cache) -> ErrorOr<void> {
+                auto cache_object = TRY(caches.add_object(name));
+                TRY(cache_object.add("size"sv, cache.size));
+                TRY(cache_object.add("line_size"sv, cache.line_size));
+                TRY(cache_object.finish());
+                return {};
+            };
+
+            if (info.l1_data_cache().has_value())
+                TRY(add_cache_info("l1_data"sv, *info.l1_data_cache()));
+            if (info.l1_instruction_cache().has_value())
+                TRY(add_cache_info("l1_instruction"sv, *info.l1_instruction_cache()));
+            if (info.l2_cache().has_value())
+                TRY(add_cache_info("l2"sv, *info.l2_cache()));
+            if (info.l3_cache().has_value())
+                TRY(add_cache_info("l3"sv, *info.l3_cache()));
+
+            TRY(caches.finish());
+
+            TRY(obj.finish());
+            return {};
+        }));
+    TRY(array.finish());
+    return {};
+}
+
+}