Add module for controlling the MPU.

The MPU is a module in arm chips which allow for memory access
protection. They are more primitive than full MMUs, but can still
provide at least basic access control between different process
controls.

1 files changed, 84 insertions, 0 deletions

diff --git a/include/kern/mpu/mpu_manager.h b/include/kern/mpu/mpu_manager.h
new file mode 100644
index 0000000..5e0bc7b
--- /dev/null
+++ b/include/kern/mpu/mpu_manager.h
@@ -0,0 +1,84 @@
+#ifndef KERN_MPU_MPU_MANAGER_H_
+#define KERN_MPU_MPU_MANAGER_H_
+
+#include "kern/common.h"
+
+typedef enum {
+  REGION_SIZE_32 = 4,
+  REGION_SIZE_64 = 5,
+  REGION_SIZE_128 = 6,
+  REGION_SIZE_256 = 7,
+  REGION_SIZE_512 = 8,
+  REGION_SIZE_1Kb = 9,
+  REGION_SIZE_2Kb = 10,
+  REGION_SIZE_4Kb = 11,
+  REGION_SIZE_8Kb = 12,
+  REGION_SIZE_16Kb = 13,
+  REGION_SIZE_32Kb = 14,
+  REGION_SIZE_64Kb = 15,
+  REGION_SIZE_128Kb = 16,
+  REGION_SIZE_256Kb = 17,
+  REGION_SIZE_512Kb = 18,
+  REGION_SIZE_1Mb = 19,
+  REGION_SIZE_2Mb = 20,
+  REGION_SIZE_4Mb = 21,
+  REGION_SIZE_8Mb = 22,
+  REGION_SIZE_16Mb = 23,
+  REGION_SIZE_32Mb = 24,
+  REGION_SIZE_64Mb = 25,
+  REGION_SIZE_128Mb = 26,
+  REGION_SIZE_256Mb = 27,
+  REGION_SIZE_512Mb = 28,
+  REGION_SIZE_1Gb = 29,
+  REGION_SIZE_2Gb = 30,
+  REGION_SIZE_4Gb = 31,
+} region_size_t;
+
+#define region_size_mask(region_size) ((1 << (region_size)) - 1)
+
+typedef enum {
+  /* Neither Privileged nor non-Privileged code cannnot access this region */
+  ACCESS_PERMS_NO_ACCESS = 0,
+
+  /* Only privileged users can access this memory. */
+  ACCESS_PERMS_ONLY_PERMS = 1,
+
+  /* Privileged code can access fully, but non-privilege only has Read-only
+     access.*/
+  ACCESS_NON_PERMS_RO = 2,
+
+  /* Both Privileged and non-Privileged code can access this region fully. */
+  ACCESS_PERMS_FULL = 3,
+
+  /* Only privileged users can access this memory, and only as Read-only. */
+  ACCESS_PERMS_ONLY_PRIV_RO = 5,
+
+  /* Both privileged and non-privileged users can access this memory, but only
+     as Read-only.*/
+  ACCESS_PERMS_BOTH_RO = 5,
+} access_perms_t;
+
+typedef struct {
+  region_size_t size;
+  uint8_t subregion_disable;
+
+  struct {
+    bool enable : 1;
+    bool sharable : 1;
+    bool cacheable : 1;
+    bool bufferable : 1;
+    bool executable : 1;
+    uint8_t tex : 3;
+  };
+
+  access_perms_t perms;
+  void* region;
+} memory_region_opts_t;
+
+void mpu_set_enabled(bool enabled);
+
+/* Configures a memory region. The region number must be on the interval [0,8).
+ */
+void mpu_configure_region(int region_number, memory_region_opts_t* opts);
+
+#endif /* KERN_MPU_MPU_MANAGER_H_ */