1 files changed, 83 insertions, 1 deletions

diff --git a/kernel/proc.c b/kernel/proc.c
index 58a8a0b..9a9bae9 100644
--- a/kernel/proc.c
+++ b/kernel/proc.c
@@ -39,6 +39,7 @@ proc_mapstacks(pagetable_t kpgtbl)
     if(pa == 0)
       panic("kalloc");
     uint64 va = KSTACK((int) (p - proc));
+  p->alarm_tickspassed = 0;
     kvmmap(kpgtbl, va, (uint64)pa, PGSIZE, PTE_R | PTE_W);
   }
 }
@@ -132,6 +133,25 @@ found:
     return 0;
   }
 
+  // Allocate a usyscall page and fill pid.
+  if((p->usyscall = (struct usyscall *)kalloc()) == 0){
+    freeproc(p);
+    release(&p->lock);
+    return 0;
+  }
+  p->usyscall->pid = p->pid;
+
+  // reset sigalarm props 
+  p->alarm_interval = 0;
+  p->alarm_handler = 0;
+  p->alarm_tickspassed = 0;
+  p->alarm_caninvoke = 1;
+  if((p->atpfm = (struct trapframe *)kalloc()) == 0){
+    freeproc(p);
+    release(&p->lock);
+    return 0;
+  }
+
   // An empty user page table.
   p->pagetable = proc_pagetable(p);
   if(p->pagetable == 0){
@@ -158,8 +178,18 @@ freeproc(struct proc *p)
   if(p->trapframe)
     kfree((void*)p->trapframe);
   p->trapframe = 0;
+  if(p->usyscall)
+    kfree((void*)p->usyscall);
+  p->usyscall = 0;
   if(p->pagetable)
     proc_freepagetable(p->pagetable, p->sz);
+  if(p->atpfm)
+    kfree((void*)p->atpfm);
+  p->atpfm = 0;
+  p->alarm_interval = 0;
+  p->alarm_handler = 0;
+  p->alarm_tickspassed = 0;
+  p->alarm_caninvoke = 1;
   p->pagetable = 0;
   p->sz = 0;
   p->pid = 0;
@@ -172,7 +202,7 @@ freeproc(struct proc *p)
 }
 
 // Create a user page table for a given process, with no user memory,
-// but with trampoline and trapframe pages.
+// but with trampoline, trapframe and usyscall pages.
 pagetable_t
 proc_pagetable(struct proc *p)
 {
@@ -202,6 +232,14 @@ proc_pagetable(struct proc *p)
     return 0;
   }
 
+  // map the usyscall page below the trapframe page, for
+  // ugetpid().
+  if(mappages(pagetable, USYSCALL, PGSIZE,
+              (uint64)(p->usyscall), PTE_R | PTE_U) < 0){
+    uvmunmap(pagetable, USYSCALL, 1, 0);
+    uvmfree(pagetable, 0);
+    return 0;
+  }
   return pagetable;
 }
 
@@ -212,6 +250,7 @@ proc_freepagetable(pagetable_t pagetable, uint64 sz)
 {
   uvmunmap(pagetable, TRAMPOLINE, 1, 0);
   uvmunmap(pagetable, TRAPFRAME, 1, 0);
+  uvmunmap(pagetable, USYSCALL, 1, 0);
   uvmfree(pagetable, sz);
 }
 
@@ -299,6 +338,9 @@ fork(void)
   // copy saved user registers.
   *(np->trapframe) = *(p->trapframe);
 
+  // inherit trace_mask
+  np->trace_mask = p->trace_mask;
+
   // Cause fork to return 0 in the child.
   np->trapframe->a0 = 0;
 
@@ -686,3 +728,43 @@ procdump(void)
     printf("\n");
   }
 }
+
+int
+get_nproc(void)
+{
+  int n = 0;
+  struct proc *p;
+
+  for(int i = 0; i < NPROC; i++) {
+    p = &proc[i];
+    acquire(&p->lock);
+    if(p->state != UNUSED)
+      n++;
+    release(&p->lock);
+  }
+
+  return n;
+}
+
+// lab pagetable: report which pages have been accessed (r/w)
+// according to PTE_A and store it in a bit mask (3rd param)
+int
+pgaccess(uint64 base, int len, uint64 mask_addr)
+{
+  struct proc *p = myproc();
+  pagetable_t pgtbl = p->pagetable;
+  pte_t *pte;
+  int mask = 0;
+  
+  // iterater thru pages
+  for(int i = 0; i < len; i++) {
+    pte = walk(pgtbl, base + i * PGSIZE, 0);
+    if(*pte & PTE_A) {
+      *pte &= (~PTE_A); // clear PTE_A to avoid setting it forever
+      mask |= (1L << i);
+    }
+  }
+
+  // now copyout the mask to user memory
+  return copyout(pgtbl, mask_addr, (char *)&mask, sizeof(mask));
+}