Fixing provisioning of gdbinit

copyuvm() should not allow new copied pages to inherit more
permissions than the original pages.

.gitignore

@@ -14,3 +14,4 @@ kernel
 kernelmemfs
 mkfs
 .gdbinit
+.vagrant

Makefile

@@ -28,11 +28,7 @@ OBJS = \
 	vectors.o\
 	vm.o\
 
-# Cross-compiling (e.g., on Mac OS X)
-#TOOLPREFIX = i386-jos-elf-
-
-# Using native tools (e.g., on X86 Linux)
-#TOOLPREFIX = 
+TOOLPREFIX = 
 
 # Try to infer the correct TOOLPREFIX if not set
 ifndef TOOLPREFIX
@@ -51,7 +47,7 @@ TOOLPREFIX := $(shell if i386-jos-elf-objdump -i 2>&1 | grep '^elf32-i386$$' >/d
 endif
 
 # If the makefile can't find QEMU, specify its path here
-#QEMU = 
+QEMU = qemu-system-i386
 
 # Try to infer the correct QEMU
 ifndef QEMU
@@ -146,7 +142,13 @@ _forktest: forktest.o $(ULIB)
 	$(OBJDUMP) -S _forktest > forktest.asm
 
 mkfs: mkfs.c fs.h
-	gcc -m32 -Werror -Wall -o mkfs mkfs.c
+	gcc -Werror -Wall -o mkfs mkfs.c
+
+# Prevent deletion of intermediate files, e.g. cat.o, after first build, so
+# that disk image changes after first build are persistent until clean.  More
+# details:
+# http://www.gnu.org/software/make/manual/html_node/Chained-Rules.html
+.PRECIOUS: %.o
 
 UPROGS=\
 	_cat\
@@ -164,6 +166,8 @@ UPROGS=\
 	_usertests\
 	_wc\
 	_zombie\
+	_bigtest\
+	#_getcount\
 
 fs.img: mkfs README $(UPROGS)
 	./mkfs fs.img README $(UPROGS)
@@ -200,9 +204,9 @@ QEMUGDB = $(shell if $(QEMU) -help | grep -q '^-gdb'; \
 	then echo "-gdb tcp::$(GDBPORT)"; \
 	else echo "-s -p $(GDBPORT)"; fi)
 ifndef CPUS
-CPUS := 2
+CPUS := 1
 endif
-QEMUOPTS = -hdb fs.img xv6.img -smp $(CPUS) -m 512 $(QEMUEXTRA)
+QEMUOPTS = -hdb fs.img xv6.img -smp $(CPUS) -m 512 $(QEMUEXTRA) -snapshot
 
 qemu: fs.img xv6.img
 	$(QEMU) -serial mon:stdio $(QEMUOPTS)

Vagrantfile

@@ -0,0 +1,21 @@
+# -*- mode: ruby -*-
+# vi: set ft=ruby :
+
+# Vagrantfile API/syntax version. Don't touch unless you know what you're doing!
+VAGRANTFILE_API_VERSION = "2"
+
+Vagrant.configure(VAGRANTFILE_API_VERSION) do |config|
+  config.vm.box = "ubuntu/trusty64"
+
+  # Share an additional folder to the guest VM. The first argument is
+  # the path on the host to the actual folder. The second argument is
+  # the path on the guest to mount the folder. And the optional third
+  # argument is a set of non-required options.
+  # config.vm.synced_folder "../data", "/vagrant_data"
+
+  config.vm.provider "virtualbox" do |vb|
+    vb.customize ["modifyvm", :id, "--memory", "1024"]
+  end
+
+  config.vm.provision :shell, path: "vagrantprov.sh"
+end

bigtest.c

@@ -0,0 +1,51 @@
+#include "types.h"
+#include "stat.h"
+#include "user.h"
+#include "fcntl.h"
+
+int
+main()
+{
+  char buf[512];
+  int fd, i, sectors;
+
+  fd = open("big.file", O_CREATE | O_WRONLY);
+  if(fd < 0){
+    printf(2, "big: cannot open big.file for writing\n");
+    exit();
+  }
+
+  sectors = 0;
+  while(1){
+    *(int*)buf = sectors;
+    int cc = write(fd, buf, sizeof(buf));
+    if(cc <= 0)
+      break;
+    sectors++;
+	if (sectors % 100 == 0)
+		printf(2, ".");
+  }
+
+  printf(1, "\nwrote %d sectors\n", sectors);
+
+  close(fd);
+  fd = open("big.file", O_RDONLY);
+  if(fd < 0){
+    printf(2, "big: cannot re-open big.file for reading\n");
+    exit();
+  }
+  for(i = 0; i < sectors; i++){
+    int cc = read(fd, buf, sizeof(buf));
+    if(cc <= 0){
+      printf(2, "big: read error at sector %d\n", i);
+      exit();
+    }
+    if(*(int*)buf != i){
+      printf(2, "big: read the wrong data (%d) for sector %d\n",
+             *(int*)buf, i);
+      exit();
+    }
+  }
+
+  exit();
+}

getcount.c

@@ -0,0 +1,19 @@
+#include "types.h"
+#include "user.h"
+#include "syscall.h"
+
+int
+main(int argc, char *argv[])
+{
+  printf(1, "initial fork count %d\n", getcount(SYS_fork));
+  if (fork() == 0) {
+    printf(1, "child fork count %d\n", getcount(SYS_fork));
+    printf(1, "child write count %d\n", getcount(SYS_write));
+  } else {
+    wait();
+    printf(1, "parent fork count %d\n", getcount(SYS_fork));
+    printf(1, "parent write count %d\n", getcount(SYS_write));
+  }
+  printf(1, "wait count %d\n", getcount(SYS_wait));
+  exit();
+}

ide.c

@@ -134,11 +134,11 @@ iderw(struct buf *b)
   if(b->dev != 0 && !havedisk1)
     panic("iderw: ide disk 1 not present");
 
-  acquire(&idelock);  //DOC: acquire-lock
+  acquire(&idelock);  //DOC:acquire-lock
 
   // Append b to idequeue.
   b->qnext = 0;
-  for(pp=&idequeue; *pp; pp=&(*pp)->qnext)  //DOC: insert-queue
+  for(pp=&idequeue; *pp; pp=&(*pp)->qnext)  //DOC:insert-queue
     ;
   *pp = b;
   

mkfs.c

@@ -11,10 +11,12 @@
 #include "stat.h"
 #include "param.h"
 
-int nblocks = 985;
+#define static_assert(a, b) do { switch (0) case 0: case (a): ; } while (0)
+
+int nblocks = 25000;
 int nlog = LOGSIZE;
 int ninodes = 200;
-int size = 1024;
+int size = 25045;
 
 int fsfd;
 struct superblock sb;
@@ -64,6 +66,9 @@ main(int argc, char *argv[])
   char buf[512];
   struct dinode din;
 
+
+  static_assert(sizeof(int) == 4, "Integers must be 4 bytes!");
+
   if(argc < 2){
     fprintf(stderr, "Usage: mkfs fs.img files...\n");
     exit(1);

mmu.h

@@ -142,6 +142,7 @@ struct segdesc {
 
 // Address in page table or page directory entry
 #define PTE_ADDR(pte)   ((uint)(pte) & ~0xFFF)
+#define PTE_FLAGS(pte)  ((uint)(pte) &  0xFFF)
 
 #ifndef __ASSEMBLER__
 typedef uint pte_t;

vagrantprov.sh

@@ -0,0 +1,6 @@
+#!/usr/bin/env bash
+
+apt-get update
+apt-get install -y qemu-system-x86
+apt-get install -y gdb
+echo "set auto-load safe-path /" > /home/vagrant/.gdbinit

vm.c

@@ -311,7 +311,7 @@ copyuvm(pde_t *pgdir, uint sz)
 {
   pde_t *d;
   pte_t *pte;
-  uint pa, i;
+  uint pa, i, flags;
   char *mem;
 
   if((d = setupkvm()) == 0)
@@ -322,10 +322,11 @@ copyuvm(pde_t *pgdir, uint sz)
     if(!(*pte & PTE_P))
       panic("copyuvm: page not present");
     pa = PTE_ADDR(*pte);
+    flags = PTE_FLAGS(*pte);
     if((mem = kalloc()) == 0)
       goto bad;
     memmove(mem, (char*)p2v(pa), PGSIZE);
-    if(mappages(d, (void*)i, PGSIZE, v2p(mem), PTE_W|PTE_U) < 0)
+    if(mappages(d, (void*)i, PGSIZE, v2p(mem), flags) < 0)
       goto bad;
   }
   return d;