From 1e43292c3bee9fe9160cece8260f5c46daa54cd6 Mon Sep 17 00:00:00 2001
From: Andreas Kling <kling@serenityos.org>
Date: Tue, 27 Jul 2021 14:30:26 +0200
Subject: Kernel: Introduce ProcessorSpecific<T> for per-CPU data structures

To add a new per-CPU data structure, add an ID for it to the
ProcessorSpecificDataID enum.

Then call ProcessorSpecific<T>::initialize() when you are ready to
construct the per-CPU data structure on the current CPU. It can then
be accessed via ProcessorSpecific<T>::get().

This patch replaces the existing hard-coded mechanisms for Scheduler
and MemoryManager per-CPU data structure.
---
 Kernel/Arch/x86/Processor.h          | 44 +++++++++++++++++++++---------------
 Kernel/Arch/x86/common/Processor.cpp |  2 --
 2 files changed, 26 insertions(+), 20 deletions(-)

(limited to 'Kernel/Arch')

diff --git a/Kernel/Arch/x86/Processor.h b/Kernel/Arch/x86/Processor.h
index 478ab0c2f7..1a27e071c7 100644
--- a/Kernel/Arch/x86/Processor.h
+++ b/Kernel/Arch/x86/Processor.h
@@ -21,10 +21,14 @@
 namespace Kernel {
 
 class ProcessorInfo;
-class SchedulerPerProcessorData;
-struct MemoryManagerData;
 struct ProcessorMessageEntry;
 
+enum class ProcessorSpecificDataID {
+    MemoryManager,
+    Scheduler,
+    __Count,
+};
+
 #if ARCH(X86_64)
 #    define MSR_FS_BASE 0xc0000100
 #    define MSR_GS_BASE 0xc0000101
@@ -127,8 +131,6 @@ class Processor {
     u8 m_physical_address_bit_width;
 
     ProcessorInfo* m_info;
-    MemoryManagerData* m_mm_data;
-    SchedulerPerProcessorData* m_scheduler_data;
     Thread* m_current_thread;
     Thread* m_idle_thread;
 
@@ -142,6 +144,8 @@ class Processor {
     DeferredCallEntry* m_free_deferred_call_pool_entry;
     DeferredCallEntry m_deferred_call_pool[5];
 
+    void* m_processor_specific_data[(size_t)ProcessorSpecificDataID::__Count];
+
     void gdt_init();
     void write_raw_gdt_entry(u16 selector, u32 low, u32 high);
     void write_gdt_entry(u16 selector, Descriptor& descriptor);
@@ -259,24 +263,15 @@ public:
             read_gs_ptr(__builtin_offsetof(Processor, m_self)) != 0;
     }
 
-    ALWAYS_INLINE void set_scheduler_data(SchedulerPerProcessorData& scheduler_data)
-    {
-        m_scheduler_data = &scheduler_data;
-    }
-
-    ALWAYS_INLINE SchedulerPerProcessorData& get_scheduler_data() const
-    {
-        return *m_scheduler_data;
-    }
-
-    ALWAYS_INLINE void set_mm_data(MemoryManagerData& mm_data)
+    template<typename T>
+    T* get_specific()
     {
-        m_mm_data = &mm_data;
+        return static_cast<T*>(m_processor_specific_data[static_cast<size_t>(T::processor_specific_data_id())]);
     }
 
-    ALWAYS_INLINE MemoryManagerData& get_mm_data() const
+    void set_specific(ProcessorSpecificDataID specific_id, void* ptr)
     {
-        return *m_mm_data;
+        m_processor_specific_data[static_cast<size_t>(specific_id)] = ptr;
     }
 
     ALWAYS_INLINE void set_idle_thread(Thread& idle_thread)
@@ -449,4 +444,17 @@ public:
     String platform_string() const;
 };
 
+template<typename T>
+class ProcessorSpecific {
+public:
+    static void initialize()
+    {
+        Processor::current().set_specific(T::processor_specific_data_id(), new T);
+    }
+    static T& get()
+    {
+        return *Processor::current().get_specific<T>();
+    }
+};
+
 }
diff --git a/Kernel/Arch/x86/common/Processor.cpp b/Kernel/Arch/x86/common/Processor.cpp
index 2a3ba5e907..29eed55ae4 100644
--- a/Kernel/Arch/x86/common/Processor.cpp
+++ b/Kernel/Arch/x86/common/Processor.cpp
@@ -304,8 +304,6 @@ UNMAP_AFTER_INIT void Processor::early_initialize(u32 cpu)
     m_message_queue = nullptr;
     m_idle_thread = nullptr;
     m_current_thread = nullptr;
-    m_scheduler_data = nullptr;
-    m_mm_data = nullptr;
     m_info = nullptr;
 
     m_halt_requested = false;
-- 
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