Handout

kernel/arch/tss.h

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+
+/*! \file
+ *  \brief Task State Segment
+ */
+
+#pragma once
+#include "../types.h"
+
+/*! \brief Task State Segment
+ */
+namespace TSS {
+
+/*! \brief TSS Format structure
+ *
+ * \see [ISDMv3 7.7 Task Management in 64-bit](intel_manual_vol3.pdf#page=252)
+ */
+struct Entry {
+	uint32_t : 32;
+	void* sp0;	///< Saves the stack pointer for every ring
+	void* sp1;
+	void* sp2;
+	uint64_t : 64;
+	void* ist1;
+	void*
+		ist2;  ///< Interrupt Stack Table, stack pointer used by the instruction
+	void* ist3;	 ///< handlers when the interrupt descriptor table (IDT) is set
+	///< up accordingly:
+	void* ist4;	 ///< If IST is set to a non-zero value (i.e., 1 - 7),
+	void* ist5;	 ///< the CPU automagically locals the respective value into the
+	///< RSP.
+	void* ist6;	 ///<
+	void* ist7;	 ///< See https://wiki.osdev.org/Task_State_Segment
+	uint64_t : 64;
+	uint32_t : 16;
+	uint32_t iomap_base : 16;  ///< Offset to IO Permission Bitmap
+} __attribute__((packed));
+
+static_assert(sizeof(Entry) == 104, "TaskStateSegment Entry has wrong size");
+
+/*! \brief Initialize TSS for active core
+ */
+void init();
+
+/*! \brief Set initial stack pointer in TSS
+ *  \param ptr New (next) stack pointer
+ */
+void setStackpointer(void* ptr);
+
+}  // namespace TSS