x86: Add support for (paging-based) protection domains

This patch implements a simple, lightweight form of protection domains
using a pluggable framework.  Currently, the following plugin is
available:

 - Flat memory model with paging.

The overall goal of a protection domain implementation within this
framework is to define a set of resources that should be accessible to
each protection domain and to prevent that protection domain from
accessing other resources.  The details of each implementation of
protection domains may differ substantially, but they should all be
guided by the principle of least privilege.  However, that idealized
principle is balanced against the practical objectives of limiting the
number of relatively time-consuming context switches and minimizing
changes to existing code.

For additional information, please refer to cpu/x86/mm/README.md.

This patch also causes the C compiler to be used as the default linker
and assembler.

platform/galileo/README.md

@@ -44,6 +44,9 @@ Standard APIs:
   * Stdio library (stdout and stderr only). Console output through UART 1
     device (connected to Galileo Gen2 FTDI header)
 
+Optional support for protection domains is also implemented and is
+described in cpu/x86/mm/README.md.
+
 Building
 --------
 

platform/galileo/contiki-main.c

@@ -33,12 +33,17 @@
 #include "contiki.h"
 #include "contiki-net.h"
 #include "cpu.h"
+#include "eth.h"
 #include "eth-conf.h"
 #include "galileo-pinmux.h"
 #include "gpio.h"
+#include "helpers.h"
 #include "i2c.h"
 #include "imr-conf.h"
 #include "interrupt.h"
+#include "irq.h"
+#include "pci.h"
+#include "prot-domains.h"
 #include "shared-isr.h"
 #include "uart.h"
 
@@ -49,31 +54,12 @@ PROCINIT(  &etimer_process
 #endif
          );
 
-int
-main(void)
+/*---------------------------------------------------------------------------*/
+void
+app_main(void)
 {
-  cpu_init();
-#ifdef X86_CONF_RESTRICT_DMA
-  quarkX1000_imr_conf();
-#endif
-  /* Initialize UART connected to Galileo Gen2 FTDI header */
-  quarkX1000_uart_init(QUARK_X1000_UART_1);
-  clock_init();
-  rtimer_init();
-
   printf("Starting Contiki\n");
 
-  quarkX1000_i2c_init();
-  quarkX1000_i2c_configure(QUARKX1000_I2C_SPEED_STANDARD,
-                           QUARKX1000_I2C_ADDR_MODE_7BIT);
-  /* use default pinmux configuration */
-  if(galileo_pinmux_initialize() < 0) {
-    fprintf(stderr, "Failed to initialize pinmux\n");
-  }
-  quarkX1000_gpio_init();
-
-  ENABLE_IRQ();
-
   process_init();
   procinit_init();
   ctimer_init();
@@ -81,11 +67,45 @@ main(void)
 
   eth_init();
 
-  shared_isr_init();
-
   while(1) {
     process_run();
   }
 
+  halt();
+}
+/*---------------------------------------------------------------------------*/
+/* Kernel entrypoint */
+int
+main(void)
+{
+#ifdef X86_CONF_RESTRICT_DMA
+  quarkX1000_imr_conf();
+#endif
+  irq_init();
+  /* Initialize UART connected to Galileo Gen2 FTDI header */
+  quarkX1000_uart_init(QUARK_X1000_UART_1);
+  clock_init();
+  rtimer_init();
+
+  pci_root_complex_init();
+  quarkX1000_eth_init();
+  quarkX1000_i2c_init();
+  quarkX1000_i2c_configure(QUARKX1000_I2C_SPEED_STANDARD,
+                           QUARKX1000_I2C_ADDR_MODE_7BIT);
+  /* use default pinmux configuration */
+  if(galileo_pinmux_initialize() < 0) {
+    fprintf(stderr, "Failed to initialize pinmux\n");
+  }
+  quarkX1000_gpio_init();
+  shared_isr_init();
+
+  /* The ability to remap interrupts is not needed after this point and should
+   * thus be disabled according to the principle of least privilege.
+   */
+  pci_root_complex_lock();
+
+  prot_domains_leave_main();
+
   return 0;
 }
+/*---------------------------------------------------------------------------*/

platform/galileo/net/eth-conf.c

@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2015, Intel Corporation. All rights reserved.
+ * Copyright (C) 2015-2016, Intel Corporation. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
@@ -29,7 +29,6 @@
  */
 
 #include "eth-conf.h"
-#include "eth.h"
 #include "net/eth-proc.h"
 #include "contiki-net.h"
 #include "net/linkaddr.h"
@@ -45,6 +44,7 @@ const linkaddr_t linkaddr_null = { { 0, 0, 0, 0, 0, 0 } };
 #define NAMESERVER_IP   GATEWAY_IP
 #endif
 
+/*---------------------------------------------------------------------------*/
 void
 eth_init(void)
 {
@@ -69,7 +69,6 @@ eth_init(void)
 #endif
 #endif
 
-  quarkX1000_eth_init();
-
   process_start(&eth_process, NULL);
 }
+/*---------------------------------------------------------------------------*/