From 50cbc7510250a64674d619d13f5912edf08b767d Mon Sep 17 00:00:00 2001
From: Robert Morris <rtm@csail.mit.edu>
Date: Sat, 1 Jun 2019 05:33:38 -0400
Subject: first shell prints $ prompt, though no console input yet

---
 vm.c | 76 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++----
 1 file changed, 72 insertions(+), 4 deletions(-)

(limited to 'vm.c')

diff --git a/vm.c b/vm.c
index 27fb690..791f78f 100644
--- a/vm.c
+++ b/vm.c
@@ -13,7 +13,7 @@ pagetable_t kernel_pagetable;
 
 extern char etext[];  // kernel.ld sets this to end of kernel code.
 
-extern char trampstart[]; // trampoline.S
+extern char trampout[]; // trampoline.S
 
 /*
  * create a direct-map page table for the kernel and
@@ -45,7 +45,7 @@ kvminit()
   // map the trampoline for trap entry/exit to
   // the highest virtual address in the kernel.
   mappages(kernel_pagetable, TRAMPOLINE, PGSIZE,
-           (uint64)trampstart, PTE_R | PTE_X);
+           (uint64)trampout, PTE_R | PTE_X);
 
   kvmswitch();
 }
@@ -213,7 +213,7 @@ uvmalloc(pagetable_t pagetable, uint64 oldsz, uint64 newsz)
       return 0;
     }
     memset(mem, 0, PGSIZE);
-    mappages(pagetable, a, PGSIZE, (uint64)mem, PTE_W|PTE_X|PTE_R);
+    mappages(pagetable, a, PGSIZE, (uint64)mem, PTE_W|PTE_X|PTE_R|PTE_U);
   }
   return newsz;
 }
@@ -287,8 +287,8 @@ uvmcopy(pagetable_t old, pagetable_t new, uint64 sz)
   }
 }
 
+// Copy from kernel to user.
 // Copy len bytes from src to virtual address dstva in a given page table.
-// Most useful when pagetable is not the current page table.
 // Return 0 on success, -1 on error.
 int
 copyout(pagetable_t pagetable, uint64 dstva, char *src, uint64 len)
@@ -311,3 +311,71 @@ copyout(pagetable_t pagetable, uint64 dstva, char *src, uint64 len)
   }
   return 0;
 }
+
+// Copy from user to kernel.
+// Copy len bytes to dst from virtual address srcva in a given page table.
+// Return 0 on success, -1 on error.
+int
+copyin(pagetable_t pagetable, char *dst, uint64 srcva, uint64 len)
+{
+  uint64 n, va0, pa0;
+
+  while(len > 0){
+    va0 = (uint)PGROUNDDOWN(srcva);
+    pa0 = walkaddr(pagetable, va0);
+    if(pa0 == 0)
+      return -1;
+    n = PGSIZE - (srcva - va0);
+    if(n > len)
+      n = len;
+    memmove(dst, (void *)(pa0 + (srcva - va0)), n);
+
+    len -= n;
+    dst += n;
+    srcva = va0 + PGSIZE;
+  }
+  return 0;
+}
+
+// Copy a null-terminated from user to kernel.
+// Copy bytes to dst from virtual address srcva in a given page table,
+// until a '\0', or max.
+// Return 0 on success, -1 on error.
+int
+copyinstr(pagetable_t pagetable, char *dst, uint64 srcva, uint64 max)
+{
+  uint64 n, va0, pa0;
+  int got_null = 0;
+
+  while(got_null == 0 && max > 0){
+    va0 = (uint)PGROUNDDOWN(srcva);
+    pa0 = walkaddr(pagetable, va0);
+    if(pa0 == 0)
+      return -1;
+    n = PGSIZE - (srcva - va0);
+    if(n > max)
+      n = max;
+
+    char *p = (char *) (pa0 + (srcva - va0));
+    while(n > 0){
+      if(*p == '\0'){
+        *dst = '\0';
+        got_null = 1;
+        break;
+      } else {
+        *dst = *p;
+      }
+      --n;
+      --max;
+      p++;
+      dst++;
+    }
+
+    srcva = va0 + PGSIZE;
+  }
+  if(got_null){
+    return 0;
+  } else {
+    return -1;
+  }
+}
-- 
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