From ecaad9ecce8557722e3471cab6088167acfdd085 Mon Sep 17 00:00:00 2001
From: Reto Buerki <reet@codelabs.ch>
Date: Thu, 26 Feb 2015 13:51:56 +0100
Subject: [PATCH] hw_x86_64: Add private _virt_idt_address member to Idt class

This function calculates the address of the IDT for a given virtual
mode transition base address.
---
 repos/base-hw/src/core/include/spec/x86_64/idt.h |  6 ++++++
 repos/base-hw/src/core/spec/x86_64/idt.cc        | 10 ++++++++++
 2 files changed, 16 insertions(+)

diff --git a/repos/base-hw/src/core/include/spec/x86_64/idt.h b/repos/base-hw/src/core/include/spec/x86_64/idt.h
index 7c51ac4d3..67666a9d8 100644
--- a/repos/base-hw/src/core/include/spec/x86_64/idt.h
+++ b/repos/base-hw/src/core/include/spec/x86_64/idt.h
@@ -21,6 +21,12 @@ class Genode::Idt
 			SYSCALL_VEC = 0x80,
 		};
 
+		/**
+		 * Return virtual address of the IDT for given virtual mode transition
+		 * base.
+		 */
+		static addr_t _virt_idt_addr(addr_t const virt_base);
+
 		/**
 		 * 64-Bit Mode IDT gate, see Intel SDM Vol. 3A, section 6.14.1.
 		 */
diff --git a/repos/base-hw/src/core/spec/x86_64/idt.cc b/repos/base-hw/src/core/spec/x86_64/idt.cc
index 4f3cf52f8..a14b1d82f 100644
--- a/repos/base-hw/src/core/spec/x86_64/idt.cc
+++ b/repos/base-hw/src/core/spec/x86_64/idt.cc
@@ -1,5 +1,8 @@
 #include "idt.h"
 
+extern int _mt_begin;
+extern int _mt_idt;
+
 using namespace Genode;
 
 class Descriptor
@@ -13,6 +16,13 @@ class Descriptor
 } __attribute__((packed));
 
 
+addr_t Idt::_virt_idt_addr(addr_t const virt_base)
+{
+	addr_t const phys      = (addr_t)&_mt_idt;
+	addr_t const phys_base = (addr_t)&_mt_begin;
+	return virt_base + (phys - phys_base);
+}
+
 void Idt::setup()
 {
 	/* TODO: Calculate from _mt_isrs label */