Kernel: Store current processor pointer in IA32_GS_BASE

This allows easier access to processors fields

kernel/kernel/Processor.cpp

@@ -1,57 +1,70 @@
-#include <BAN/Vector.h>
+#include <kernel/Memory/kmalloc.h>
 #include <kernel/Processor.h>
 
+#include <kernel/Debug.h>
+
 namespace Kernel
 {
 
+	static constexpr uint32_t MSR_IA32_GS_BASE = 0xC0000101;
+
 	ProcessorID Processor::s_bsb_id { PROCESSOR_NONE };
 
-	static BAN::Vector<Processor> s_processors;
+	static BAN::Array<Processor, 0xFF> s_processors;
+
+	static ProcessorID read_processor_id()
+	{
+		uint8_t id;
+		asm volatile(
+			"movl $1, %%eax;"
+			"cpuid;"
+			"shrl $24, %%ebx;"
+			"movb %%bl, %0;"
+			: "=rm"(id)
+			:: "eax", "ebx", "ecx", "edx"
+		);
+		return id;
+	}
 
 	Processor& Processor::create(ProcessorID id)
 	{
 		// bsb is the first processor
 		if (s_bsb_id == PROCESSOR_NONE)
-			s_bsb_id = id;
+			s_bsb_id = id = read_processor_id();
 
-		while (s_processors.size() <= id)
-			MUST(s_processors.emplace_back());
 		auto& processor = s_processors[id];
-		if (processor.m_stack == nullptr)
-		{
-			processor.m_stack = kmalloc(m_stack_size, 4096, true);
-			ASSERT(processor.m_stack);
-		}
+
+		ASSERT(processor.m_id == PROCESSOR_NONE);
+		processor.m_id = id;
+
+		processor.m_stack = kmalloc(s_stack_size, 4096, true);
+		ASSERT(processor.m_stack);
+
+		processor.m_gdt = GDT::create();
+		ASSERT(processor.m_gdt);
+
+		processor.m_idt = IDT::create(id == s_bsb_id);
+		ASSERT(processor.m_idt);
+
 		return processor;
 	}
 
-	Processor::~Processor()
+	Processor& Processor::initialize()
 	{
-		if (m_stack)
-			kfree(m_stack);
-		m_stack = nullptr;
+		auto id = read_processor_id();
+		auto& processor = s_processors[id];
 
-		if (m_gdt)
-			delete m_gdt;
-		m_gdt = nullptr;
-	}
+		// set gs base to pointer to this processor
+		uint64_t ptr = reinterpret_cast<uint64_t>(&processor);
+		asm volatile("wrmsr" :: "d"(ptr >> 32), "a"(ptr), "c"(MSR_IA32_GS_BASE));
 
-	Processor& Processor::get(ProcessorID id)
-	{
-		return s_processors[id];
-	}
+		ASSERT(processor.m_gdt);
+		processor.gdt().load();
 
-	void Processor::initialize()
-	{
-		ASSERT(this == &Processor::current());
+		ASSERT(processor.m_idt);
+		processor.idt().load();
 
-		ASSERT(m_gdt == nullptr);
-		m_gdt = GDT::create();
-		ASSERT(m_gdt);
-
-		ASSERT(m_idt == nullptr);
-		m_idt = IDT::create();
-		ASSERT(m_idt);
+		return processor;
 	}
 
 }