lab pgtbl: finishpgtbl

9 files changed, 94 insertions, 5 deletions

diff --git a/kernel/defs.h b/kernel/defs.h
index c8eeef3..bd85d1f 100644
--- a/kernel/defs.h
+++ b/kernel/defs.h
@@ -109,6 +109,7 @@ int             either_copyout(int user_dst, uint64 dst, void *src, uint64 len);
 int             either_copyin(void *dst, int user_src, uint64 src, uint64 len);
 void            procdump(void);
 int             get_nproc(void);
+int             pgaccess(uint64 base, int len, uint64 mask);
 
 // swtch.S
 void            swtch(struct context*, struct context*);
@@ -179,6 +180,7 @@ uint64          walkaddr(pagetable_t, uint64);
 int             copyout(pagetable_t, uint64, char *, uint64);
 int             copyin(pagetable_t, char *, uint64, uint64);
 int             copyinstr(pagetable_t, char *, uint64, uint64);
+void            vmprint(pagetable_t);
 
 // plic.c
 void            plicinit(void);
diff --git a/kernel/exec.c b/kernel/exec.c
index e18bbb6..35b35f5 100644
--- a/kernel/exec.c
+++ b/kernel/exec.c
@@ -128,6 +128,10 @@ exec(char *path, char **argv)
   p->trapframe->sp = sp; // initial stack pointer
   proc_freepagetable(oldpagetable, oldsz);
 
+  if(p->pid == 1){
+    vmprint(p->pagetable);
+  }
+
   return argc; // this ends up in a0, the first argument to main(argc, argv)
 
  bad:
diff --git a/kernel/proc.c b/kernel/proc.c
index 5aa616f..3d215a5 100644
--- a/kernel/proc.c
+++ b/kernel/proc.c
@@ -132,6 +132,14 @@ 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;
+
   // An empty user page table.
   p->pagetable = proc_pagetable(p);
   if(p->pagetable == 0){
@@ -158,6 +166,9 @@ 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);
   p->pagetable = 0;
@@ -172,7 +183,7 @@ 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 +213,14 @@ 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 +231,7 @@ 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);
 }
 
@@ -706,3 +726,26 @@ get_nproc(void)
 
   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));
+}
diff --git a/kernel/proc.h b/kernel/proc.h
index 4a2ca6c..c816ae2 100644
--- a/kernel/proc.h
+++ b/kernel/proc.h
@@ -101,6 +101,7 @@ struct proc {
   uint64 sz;                   // Size of process memory (bytes)
   pagetable_t pagetable;       // User page table
   struct trapframe *trapframe; // data page for trampoline.S
+  struct usyscall *usyscall;   // data page for usyscall
   struct context context;      // swtch() here to run process
   struct file *ofile[NOFILE];  // Open files
   struct inode *cwd;           // Current directory
diff --git a/kernel/riscv.h b/kernel/riscv.h
index 20a01db..33fa9ee 100644
--- a/kernel/riscv.h
+++ b/kernel/riscv.h
@@ -343,6 +343,7 @@ typedef uint64 *pagetable_t; // 512 PTEs
 #define PTE_W (1L << 2)
 #define PTE_X (1L << 3)
 #define PTE_U (1L << 4) // user can access
+#define PTE_A (1L << 6) // riscv access bit                      
 
 // shift a physical address to the right place for a PTE.
 #define PA2PTE(pa) ((((uint64)pa) >> 12) << 10)
diff --git a/kernel/syscall.c b/kernel/syscall.c
index 4907f0f..394b980 100644
--- a/kernel/syscall.c
+++ b/kernel/syscall.c
@@ -168,6 +168,12 @@ static char *syscall_names[] = {
 [SYS_link]    "link",
 [SYS_mkdir]   "mkdir",
 [SYS_close]   "close",
+#ifdef LAB_NET
+[SYS_connect] "connect",
+#endif
+#ifdef LAB_PGTBL
+[SYS_pgaccess] "pgaccess",
+#endif
 [SYS_trace]   "trace",
 [SYS_sysinfo] "sysinfo",
 };
@@ -198,3 +204,4 @@ syscall(void)
     p->trapframe->a0 = -1;
   }
 }
+
diff --git a/kernel/syscall.h b/kernel/syscall.h
index d930252..8da572e 100644
--- a/kernel/syscall.h
+++ b/kernel/syscall.h
@@ -31,5 +31,3 @@
 #define SYS_munmap    28
 #define SYS_connect   29
 #define SYS_pgaccess  30
-#define SYS_trace  22
-#define SYS_sysinfo 23
diff --git a/kernel/sysproc.c b/kernel/sysproc.c
index 4cf0697..bd9d0f0 100644
--- a/kernel/sysproc.c
+++ b/kernel/sysproc.c
@@ -74,8 +74,14 @@ sys_sleep(void)
 int
 sys_pgaccess(void)
 {
-  // lab pgtbl: your code here.
-  return 0;
+  uint64 base, mask;
+  int len;
+
+  
+  argaddr(0, &base);
+  argint(1, &len);
+  argaddr(2, &mask);
+  return pgaccess(base, len, mask);
 }
 #endif
 
diff --git a/kernel/vm.c b/kernel/vm.c
index 5c31e87..9c17fe7 100644
--- a/kernel/vm.c
+++ b/kernel/vm.c
@@ -449,3 +449,30 @@ copyinstr(pagetable_t pagetable, char *dst, uint64 srcva, uint64 max)
     return -1;
   }
 }
+
+static void
+walkprint(pagetable_t pgtbl, int level)
+{
+  for(int i = 0; i < 512; i++){
+    pte_t pte = pgtbl[i];
+    if(pte & PTE_V){
+      for(int j = 0; j < level; j++){
+        printf(" ..");
+      }
+      printf("%d: pte %p pa %p\n", i, pte, PTE2PA(pte));
+      if((pte & (PTE_R|PTE_W|PTE_X)) == 0){
+        // this PTE points to a lower-level page table.
+        walkprint((pagetable_t)PTE2PA(pte), level+1);
+      }
+    }
+  }
+}
+
+// Print the contents of a page table
+void
+vmprint(pagetable_t pgtbl)
+{
+  printf("page table %p\n", pgtbl);
+
+  walkprint(pgtbl, 1);
+}