Task 3

kernel.c

@@ -157,17 +157,16 @@ void process_setup(pid_t pid, const char* program_name) {
         for (uintptr_t a = round_down(seg.va(), PAGESIZE);
              a < seg.va() + seg.size();
              a += PAGESIZE) {
-            // (NB this is physical page allocation!)
-            assert(!pages[a / PAGESIZE].used());
-            ++pages[a / PAGESIZE].refcount;
-            map_to_user_space(process_pagetable, a);
+            uintptr_t pa = (uintptr_t) kalloc(PAGESIZE);
+            memory_map(process_pagetable, a, pa, PTE_PWU);
         }
     }
 
     // initialize data in loadable segments
     for (auto seg = pgm.begin(); seg != pgm.end(); ++seg) {
-        memset((void*) seg.va(), 0, seg.size());
-        memcpy((void*) seg.va(), seg.data(), seg.data_size());
+        void *pa = memory_virtual_to_physical(process_pagetable, seg.va());
+        memset(pa, 0, seg.size());
+        memcpy(pa, seg.data(), seg.data_size());
     }
 
     // mark entry point
@@ -175,10 +174,8 @@ void process_setup(pid_t pid, const char* program_name) {
 
     // allocate and map stack segment
     uintptr_t stack_addr = PROC_START_ADDR + PROC_SIZE * pid - PAGESIZE;
-    // (NB this is physical page allocation!)
-    assert(!pages[stack_addr / PAGESIZE].used());
-    ++pages[stack_addr / PAGESIZE].refcount;
-    map_to_user_space(process_pagetable, stack_addr);
+    uintptr_t pa = (uintptr_t) kalloc(PAGESIZE);
+    memory_map(process_pagetable, stack_addr, pa, PTE_PWU);
     ptable[pid].regs.reg_rsp = stack_addr + PAGESIZE;
 
     // mark process as runnable
@@ -327,10 +324,9 @@ uintptr_t syscall(regstate* regs) {
 //    in `u-lib.hh` (but in the handout code, it does not).
 
 int syscall_page_alloc(uintptr_t addr) {
-    assert(!pages[addr / PAGESIZE].used());
-    pages[addr / PAGESIZE].refcount = 1;
-    memset((void*) addr, 0, PAGESIZE);
-    map_to_user_space(current->pagetable, addr);
+    uintptr_t pa = (uintptr_t) kalloc(PAGESIZE);
+    memory_map(current->pagetable, addr, pa, PTE_PWU);
+    memset(memory_virtual_to_physical(current->pagetable, addr), 0, PAGESIZE);
     return 0;
 }