riscv32-nemu: add vme

am/arch/riscv32-nemu/include/riscv32.h

@@ -15,8 +15,11 @@ static inline void outb(uintptr_t addr, uint8_t  data) { *(volatile uint8_t  *)M
 static inline void outw(uintptr_t addr, uint16_t data) { *(volatile uint16_t *)MMIO_OFFSET(addr) = data; }
 static inline void outl(uintptr_t addr, uint32_t data) { *(volatile uint32_t *)MMIO_OFFSET(addr) = data; }
 
-#define PTE_V 0x2
-#define PTE_D 0x4
+#define PTE_V 0x01
+#define PTE_R 0x02
+#define PTE_W 0x04
+#define PTE_X 0x08
+#define PTE_U 0x10
 
 // Page directory and page table constants
 #define NR_PDE    1024    // # directory entries per page directory
@@ -37,7 +40,10 @@ typedef uint32_t PDE;
 #define OFF(va)     ((uint32_t)(va) & 0xfff)
 
 // Address in page table or page directory entry
-#define PTE_ADDR(pte)   ((uint32_t)(pte) & ~0xfff)
+#define PTE_ADDR(pte)   (((uint32_t)(pte) & ~0x3ff) << 2)
+
+// construct virtual address from indexes and offset
+#define PGADDR(d, t, o) ((uint32_t)((d) << PDXSHFT | (t) << PTXSHFT | (o)))
 
 #endif
 

am/arch/riscv32-nemu/src/cte.c

@@ -8,7 +8,7 @@ void get_cur_as(_Context *c);
 void _switch(_Context *c);
 
 _Context* irq_handle(_Context *c) {
-//  get_cur_as(c);
+  get_cur_as(c);
 
   _Context *next = c;
   if (user_handler) {
@@ -28,7 +28,7 @@ _Context* irq_handle(_Context *c) {
     }
   }
 
-//  _switch(next);
+  _switch(next);
 
   return next;
 }

am/arch/riscv32-nemu/src/vme.c

@@ -3,26 +3,65 @@
 
 #define PG_ALIGN __attribute((aligned(PGSIZE)))
 
+static PDE kpdirs[NR_PDE] PG_ALIGN;
+static PTE kptabs[PMEM_SIZE / PGSIZE * 2] PG_ALIGN;
 static void* (*pgalloc_usr)(size_t);
 static void (*pgfree_usr)(void*);
 
 _Area segments[] = {      // Kernel memory mappings
-  {.start = (void*)0,          .end = (void*)PMEM_SIZE}
+  {.start = (void*)0,           .end = (void*)(0x400000)},
+  {.start = (void*)0x80000000u, .end = (void*)(0x80000000u + PMEM_SIZE)}
 };
 
 #define NR_KSEG_MAP (sizeof(segments) / sizeof(segments[0]))
 
+static inline void set_satp(void *pdir) {
+  asm volatile("csrw satp, %0" : : "r"(0x80000000 | ((uintptr_t)pdir >> 12)));
+}
+
 int _vme_init(void* (*pgalloc_f)(size_t), void (*pgfree_f)(void*)) {
   pgalloc_usr = pgalloc_f;
   pgfree_usr = pgfree_f;
 
+  // make all PDEs invalid
+  int i;
+  for (i = 0; i < NR_PDE; i ++) {
+    kpdirs[i] = 0;
+  }
+
+  PTE *ptab = kptabs;
+  for (i = 0; i < NR_KSEG_MAP; i ++) {
+    uint32_t pdir_idx = (uintptr_t)segments[i].start / (PGSIZE * NR_PTE);
+    uint32_t pdir_idx_end = (uintptr_t)segments[i].end / (PGSIZE * NR_PTE);
+    for (; pdir_idx < pdir_idx_end; pdir_idx ++) {
+      // fill PDE
+      kpdirs[pdir_idx] = ((uintptr_t)ptab >> PGSHFT << 10) | PTE_V;
+
+      // fill PTE
+      PTE pte = (PGADDR(pdir_idx, 0, 0) >> PGSHFT << 10) | PTE_V;
+      PTE pte_end = (PGADDR(pdir_idx + 1, 0, 0) >> PGSHFT << 10) | PTE_V;
+      for (; pte < pte_end; pte += (1 << 10)) {
+        *ptab = pte;
+        ptab ++;
+      }
+    }
+  }
+
+  set_satp(kpdirs);
+
   return 0;
 }
 
 int _protect(_Protect *p) {
-  p->ptr = (PDE*)(pgalloc_usr(1));
+  PDE *updir = (PDE*)(pgalloc_usr(1));
   p->pgsize = 4096;
 
+  p->ptr = updir;
+  // map kernel space
+  for (int i = 0; i < NR_PDE; i ++) {
+    updir[i] = kpdirs[i];
+  }
+
   return 0;
 }
 
@@ -35,6 +74,7 @@ void get_cur_as(_Context *c) {
 }
 
 void _switch(_Context *c) {
+  set_satp(c->prot->ptr);
   cur_as = c->prot;
 }
 
@@ -42,12 +82,11 @@ int _map(_Protect *p, void *va, void *pa, int mode) {
   PDE *pt = (PDE*)p->ptr;
   PDE *pde = &pt[PDX(va)];
   if (!(*pde & PTE_V)) {
-    *pde = PTE_V | (uint32_t)pgalloc_usr(1);
+    *pde = PTE_V | ((uint32_t)pgalloc_usr(1) >> PGSHFT << 10);
   }
   PTE *pte = &((PTE*)PTE_ADDR(*pde))[PTX(va)];
   if (!(*pte & PTE_V)) {
-    assert(0);
-    //*pte = PTE_V | PTE_D | (((uint32_t)pa >> PGSHFT) << 6);
+    *pte = PTE_V | PTE_R | PTE_W | PTE_X | PTE_U | ((uint32_t)pa >> PGSHFT << 10);
   }
 
   return 0;
@@ -58,6 +97,6 @@ _Context *_ucontext(_Protect *p, _Area ustack, _Area kstack, void *entry, void *
 
   c->prot = p;
   c->epc = (uintptr_t)entry;
-  c->status = 0x3;
+  //c->status = 0x3;
   return c;
 }