riscv-virtual-memory: Add virtual memory setup

Execution in supervisor level code in RISCV requires early setup of
virtual memory. Add initialization calls in
src/arch/riscv/virtual_memory.c to implement the required page table
setup, and helper functions to use when jumping to the payload correctly
in riscv.

Change-Id: I46e080e0ee8dc13277d567dcd4bf0f61a4507b76
Signed-off-by: Thaminda Edirisooriya <thaminda@google.com>
Reviewed-on: http://review.coreboot.org/11369
Tested-by: build bot (Jenkins)
Reviewed-by: Ronald G. Minnich <rminnich@gmail.com>

src/arch/riscv/include/vm.h

@@ -0,0 +1,74 @@
+/*
+ * Copyright (c) 2013, The Regents of the University of California (Regents).
+ * All Rights Reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ * 1. Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of the Regents nor the
+ * names of its contributors may be used to endorse or promote products
+ * derived from this software without specific prior written permission.
+ *
+ * IN NO EVENT SHALL REGENTS BE LIABLE TO ANY PARTY FOR DIRECT, INDIRECT,
+ * SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES, INCLUDING LOST PROFITS, ARISING
+ * OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN IF REGENTS HAS
+ * BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ * REGENTS SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
+ * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+ * PURPOSE. THE SOFTWARE AND ACCOMPANYING DOCUMENTATION, IF ANY, PROVIDED
+ * HEREUNDER IS PROVIDED "AS IS". REGENTS HAS NO OBLIGATION TO PROVIDE
+ * MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
+ */
+
+#ifndef _VM_H
+#define _VM_H
+
+#include <string.h>
+#include <stdint.h>
+
+#define SUPERPAGE_SIZE ((uintptr_t)(RISCV_PGSIZE << RISCV_PGLEVEL_BITS))
+#define VM_CHOICE VM_SV39
+#define VA_BITS 39
+#define MEGAPAGE_SIZE (SUPERPAGE_SIZE << RISCV_PGLEVEL_BITS)
+
+#define PROT_READ 1
+#define PROT_WRITE 2
+#define PROT_EXEC 4
+
+#define MAP_PRIVATE 0x2
+#define MAP_FIXED 0x10
+#define MAP_ANONYMOUS 0x20
+#define MAP_POPULATE 0x8000
+#define MREMAP_FIXED 0x2
+
+#define EXTRACT_FIELD(val, which) (((val) & (which)) / ((which) & ~((which)-1)))
+#define INSERT_FIELD(val, which, fieldval) (((val) & ~(which)) | ((fieldval) * ((which) & ~((which)-1))))
+
+#define supervisor_paddr_valid(start, length) \
+  ((uintptr_t)(start) >= current.first_user_vaddr + current.bias \
+   && (uintptr_t)(start) + (length) < mem_size \
+   && (uintptr_t)(start) + (length) >= (uintptr_t)(start))
+
+typedef uintptr_t pte_t;
+extern pte_t* root_page_table;
+
+void enter_supervisor(void);
+void initVirtualMemory(void);
+
+size_t pte_ppn(pte_t pte);
+pte_t ptd_create(uintptr_t ppn);
+pte_t pte_create(uintptr_t ppn, int prot, int user);
+
+void walk_page_table(void);
+
+void init_vm(uintptr_t virtMemStart, uintptr_t physMemStart, uintptr_t pageTableStart);
+void mstatus_init(void); // need to setup mstatus so we know we have virtual memory
+
+void flush_tlb(void);
+
+#endif