From cc081ec813276d0d13ec8fb942df611f93c892f1 Mon Sep 17 00:00:00 2001
From: Zihao Yu <yuzihao@ict.ac.cn>
Date: Fri, 11 Oct 2019 16:43:15 +0800
Subject: [PATCH] riscv64,mmu: support sv39 paging

---
 src/isa/riscv64/mmu.c | 65 ++++++++++++++++++++++++++-----------------
 1 file changed, 39 insertions(+), 26 deletions(-)

diff --git a/src/isa/riscv64/mmu.c b/src/isa/riscv64/mmu.c
index 30ca5011..4ab97e81 100644
--- a/src/isa/riscv64/mmu.c
+++ b/src/isa/riscv64/mmu.c
@@ -2,7 +2,6 @@
 #include "memory/memory.h"
 #include "csr.h"
 
-/* the 32bit Page Table Entry(second level page table) data structure */
 typedef union PageTableEntry {
   struct {
     uint32_t valid  : 1;
@@ -14,57 +13,71 @@ typedef union PageTableEntry {
     uint32_t access : 1;
     uint32_t dirty  : 1;
     uint32_t rsw    : 2;
-    uint32_t ppn    :22;
+    uint64_t ppn    :44;
+    uint32_t pad    :10;
   };
-  uint32_t val;
+  uint64_t val;
 } PTE;
 
 typedef union {
   struct {
-    uint32_t pf_off		:12;
-    uint32_t pt_idx		:10;
-    uint32_t pdir_idx	:10;
+    uint64_t pf_off		:12;
+    uint64_t vpn0  		: 9;
+    uint64_t vpn1  		: 9;
+    uint64_t vpn2  		: 9;
   };
-  uint32_t addr;
+  uint64_t addr;
 } PageAddr;
 
-static paddr_t page_walk(vaddr_t vaddr, bool is_write) {
+// Sv39 page walk
+static word_t page_walk(vaddr_t vaddr, bool is_write) {
   PageAddr *addr = (void *)&vaddr;
-  paddr_t pdir_base = satp->ppn << 12;
+  word_t pdir_base = satp->ppn << 12;
 
-  PTE pde;
-  pde.val	= paddr_read(pdir_base + addr->pdir_idx * 4, 4);
-  if (!pde.valid) {
-    panic("pc = %lx, vaddr = %lx, pdir_base = %x, pde = %x", cpu.pc, vaddr, pdir_base, pde.val);
+  PTE pte2;
+  pte2.val	= paddr_read(pdir_base + addr->vpn2 * 8, 8);
+  if (!pte2.valid) {
+    panic("pc = " FMT_WORD ", vaddr = " FMT_WORD ", pdir_base = " FMT_WORD ", pte2 = " FMT_WORD,
+        cpu.pc, vaddr, pdir_base, pte2.val);
   }
 
-  paddr_t pt_base = pde.ppn << 12;
-  PTE pte;
-  pte.val = paddr_read(pt_base + addr->pt_idx * 4, 4);
-  if (!pte.valid) {
-    panic("pc = %lx, vaddr = %lx, pt_base = %x, pte = %x", cpu.pc, vaddr, pt_base, pte.val);
+  word_t pt_base1 = pte2.ppn << 12;
+  PTE pte1;
+  pte1.val = paddr_read(pt_base1 + addr->vpn1 * 8, 8);
+  if (!pte1.valid) {
+    panic("pc = " FMT_WORD ", vaddr = " FMT_WORD ", pt_base1 = " FMT_WORD ", pte1 = " FMT_WORD,
+      cpu.pc, vaddr, pt_base1, pte1.val);
   }
 
-  if (!pte.access || (pte.dirty == 0 && is_write)) {
-    pte.access = 1;
-    pte.dirty |= is_write;
-    paddr_write(pt_base + addr->pt_idx * 4, pte.val, 4);
+  word_t pt_base0 = pte1.ppn << 12;
+  PTE pte0;
+  pte0.val = paddr_read(pt_base0 + addr->vpn0 * 8, 8);
+  if (!pte0.valid) {
+    panic("pc = " FMT_WORD ", vaddr = " FMT_WORD ", pt_base0 = " FMT_WORD ", pte0 = " FMT_WORD,
+      cpu.pc, vaddr, pt_base0, pte0.val);
   }
 
-  return pte.ppn << 12;
+  //if (!pte.access || (pte.dirty == 0 && is_write)) {
+  //  pte.access = 1;
+  //  pte.dirty |= is_write;
+  //  paddr_write(pt_base + addr->pt_idx * 4, pte.val, 4);
+  //}
+
+  return pte0.ppn << 12;
 }
 
 static inline paddr_t page_translate(vaddr_t addr, bool is_write) {
-  printf("There's page translate\n");
   return page_walk(addr, is_write) | (addr & PAGE_MASK);
 }
 
 word_t isa_vaddr_read(vaddr_t addr, int len) {
-  paddr_t paddr = (satp->mode ? page_translate(addr, false) : addr);
+  assert(satp->mode == 0 || satp->mode == 4);
+  paddr_t paddr = (satp->mode == 4 ? page_translate(addr, false) : addr);
   return paddr_read(paddr, len);
 }
 
 void isa_vaddr_write(vaddr_t addr, word_t data, int len) {
-  paddr_t paddr = (satp->mode ? page_translate(addr, true) : addr);
+  assert(satp->mode == 0 || satp->mode == 4);
+  paddr_t paddr = (satp->mode == 4 ? page_translate(addr, true) : addr);
   paddr_write(paddr, data, len);
 }
-- 
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