make grade 100/100

61810

.gitignore

@@ -15,3 +15,12 @@ mkfs
 kernel/kernel
 user/usys.S
 .gdbinit
+myapi.key
+*-handin.tar.gz
+xv6.out*
+.vagrant/
+submissions/
+ph
+barrier
+/lab-*.json
+.DS_Store

Makefile

@@ -1,14 +1,16 @@
+
+# To compile and run with a lab solution, set the lab name in conf/lab.mk
+# (e.g., LAB=util).  Run make grade to test solution with the lab's
+# grade script (e.g., grade-lab-util).
+
+-include conf/lab.mk
+
 K=kernel
 U=user
 
 OBJS = \
   $K/entry.o \
-  $K/start.o \
-  $K/console.o \
-  $K/printf.o \
-  $K/uart.o \
   $K/kalloc.o \
-  $K/spinlock.o \
   $K/string.o \
   $K/main.o \
   $K/vm.o \
@@ -30,6 +32,34 @@ OBJS = \
   $K/plic.o \
   $K/virtio_disk.o
 
+OBJS_KCSAN = \
+  $K/start.o \
+  $K/console.o \
+  $K/printf.o \
+  $K/uart.o \
+  $K/spinlock.o
+
+ifdef KCSAN
+OBJS_KCSAN += \
+	$K/kcsan.o
+endif
+
+ifeq ($(LAB),$(filter $(LAB), lock))
+OBJS += \
+	$K/stats.o\
+	$K/sprintf.o
+endif
+
+
+ifeq ($(LAB),net)
+OBJS += \
+	$K/e1000.o \
+	$K/net.o \
+	$K/sysnet.o \
+	$K/pci.o
+endif
+
+
 # riscv64-unknown-elf- or riscv64-linux-gnu-
 # perhaps in /opt/riscv/bin
 #TOOLPREFIX = 
@@ -57,12 +87,28 @@ OBJCOPY = $(TOOLPREFIX)objcopy
 OBJDUMP = $(TOOLPREFIX)objdump
 
 CFLAGS = -Wall -Werror -O -fno-omit-frame-pointer -ggdb -gdwarf-2
+
+ifdef LAB
+LABUPPER = $(shell echo $(LAB) | tr a-z A-Z)
+XCFLAGS += -DSOL_$(LABUPPER) -DLAB_$(LABUPPER)
+endif
+
+CFLAGS += $(XCFLAGS)
 CFLAGS += -MD
 CFLAGS += -mcmodel=medany
 CFLAGS += -ffreestanding -fno-common -nostdlib -mno-relax
 CFLAGS += -I.
 CFLAGS += $(shell $(CC) -fno-stack-protector -E -x c /dev/null >/dev/null 2>&1 && echo -fno-stack-protector)
 
+ifeq ($(LAB),net)
+CFLAGS += -DNET_TESTS_PORT=$(SERVERPORT)
+endif
+
+ifdef KCSAN
+CFLAGS += -DKCSAN
+KCSANFLAG = -fsanitize=thread
+endif
+
 # Disable PIE when possible (for Ubuntu 16.10 toolchain)
 ifneq ($(shell $(CC) -dumpspecs 2>/dev/null | grep -e '[^f]no-pie'),)
 CFLAGS += -fno-pie -no-pie
@@ -73,11 +119,17 @@ endif
 
 LDFLAGS = -z max-page-size=4096
 
-$K/kernel: $(OBJS) $K/kernel.ld $U/initcode
+$K/kernel: $(OBJS) $(OBJS_KCSAN) $K/kernel.ld $U/initcode
-	$(LD) $(LDFLAGS) -T $K/kernel.ld -o $K/kernel $(OBJS) 
+	$(LD) $(LDFLAGS) -T $K/kernel.ld -o $K/kernel $(OBJS) $(OBJS_KCSAN)
 	$(OBJDUMP) -S $K/kernel > $K/kernel.asm
 	$(OBJDUMP) -t $K/kernel | sed '1,/SYMBOL TABLE/d; s/ .* / /; /^$$/d' > $K/kernel.sym
 
+$(OBJS): EXTRAFLAG := $(KCSANFLAG)
+
+$K/%.o: $K/%.c
+	$(CC) $(CFLAGS) $(EXTRAFLAG) -c -o $@ $<
+
+
 $U/initcode: $U/initcode.S
 	$(CC) $(CFLAGS) -march=rv64g -nostdinc -I. -Ikernel -c $U/initcode.S -o $U/initcode.o
 	$(LD) $(LDFLAGS) -N -e start -Ttext 0 -o $U/initcode.out $U/initcode.o
@@ -89,6 +141,10 @@ tags: $(OBJS) _init
 
 ULIB = $U/ulib.o $U/usys.o $U/printf.o $U/umalloc.o
 
+ifeq ($(LAB),$(filter $(LAB), lock))
+ULIB += $U/statistics.o
+endif
+
 _%: %.o $(ULIB)
 	$(LD) $(LDFLAGS) -T $U/user.ld -o $@ $^
 	$(OBJDUMP) -S $@ > $*.asm
@@ -107,7 +163,7 @@ $U/_forktest: $U/forktest.o $(ULIB)
 	$(OBJDUMP) -S $U/_forktest > $U/forktest.asm
 
 mkfs/mkfs: mkfs/mkfs.c $K/fs.h $K/param.h
-	gcc -Werror -Wall -I. -o mkfs/mkfs mkfs/mkfs.c
+	gcc $(XCFLAGS) -Werror -Wall -I. -o mkfs/mkfs 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
@@ -133,8 +189,79 @@ UPROGS=\
 	$U/_wc\
 	$U/_zombie\
 
-fs.img: mkfs/mkfs README $(UPROGS)
+
-	mkfs/mkfs fs.img README $(UPROGS)
+
+
+ifeq ($(LAB),$(filter $(LAB), lock))
+UPROGS += \
+	$U/_stats
+endif
+
+ifeq ($(LAB),traps)
+UPROGS += \
+	$U/_call\
+	$U/_bttest
+endif
+
+ifeq ($(LAB),lazy)
+UPROGS += \
+	$U/_lazytests
+endif
+
+ifeq ($(LAB),cow)
+UPROGS += \
+	$U/_cowtest
+endif
+
+ifeq ($(LAB),thread)
+UPROGS += \
+	$U/_uthread
+
+$U/uthread_switch.o : $U/uthread_switch.S
+	$(CC) $(CFLAGS) -c -o $U/uthread_switch.o $U/uthread_switch.S
+
+$U/_uthread: $U/uthread.o $U/uthread_switch.o $(ULIB)
+	$(LD) $(LDFLAGS) -N -e main -Ttext 0 -o $U/_uthread $U/uthread.o $U/uthread_switch.o $(ULIB)
+	$(OBJDUMP) -S $U/_uthread > $U/uthread.asm
+
+ph: notxv6/ph.c
+	gcc -o ph -g -O2 $(XCFLAGS) notxv6/ph.c -pthread
+
+barrier: notxv6/barrier.c
+	gcc -o barrier -g -O2 $(XCFLAGS) notxv6/barrier.c -pthread
+endif
+
+ifeq ($(LAB),pgtbl)
+UPROGS += \
+	$U/_pgtbltest
+endif
+
+ifeq ($(LAB),lock)
+UPROGS += \
+	$U/_kalloctest\
+	$U/_bcachetest
+endif
+
+ifeq ($(LAB),fs)
+UPROGS += \
+	$U/_bigfile
+endif
+
+
+
+ifeq ($(LAB),net)
+UPROGS += \
+	$U/_nettests
+endif
+
+UEXTRA=
+ifeq ($(LAB),util)
+	UEXTRA += user/xargstest.sh
+endif
+
+
+fs.img: mkfs/mkfs README $(UEXTRA) $(UPROGS)
+	mkfs/mkfs fs.img README $(UEXTRA) $(UPROGS)
 
 -include kernel/*.d user/*.d
 
@@ -144,7 +271,8 @@ clean:
 	$U/initcode $U/initcode.out $K/kernel fs.img \
 	mkfs/mkfs .gdbinit \
         $U/usys.S \
-	$(UPROGS)
+	$(UPROGS) \
+	ph barrier
 
 # try to generate a unique GDB port
 GDBPORT = $(shell expr `id -u` % 5000 + 25000)
@@ -155,12 +283,22 @@ QEMUGDB = $(shell if $(QEMU) -help | grep -q '^-gdb'; \
 ifndef CPUS
 CPUS := 3
 endif
+ifeq ($(LAB),fs)
+CPUS := 1
+endif
+
+FWDPORT = $(shell expr `id -u` % 5000 + 25999)
 
 QEMUOPTS = -machine virt -bios none -kernel $K/kernel -m 128M -smp $(CPUS) -nographic
 QEMUOPTS += -global virtio-mmio.force-legacy=false
 QEMUOPTS += -drive file=fs.img,if=none,format=raw,id=x0
 QEMUOPTS += -device virtio-blk-device,drive=x0,bus=virtio-mmio-bus.0
 
+ifeq ($(LAB),net)
+QEMUOPTS += -netdev user,id=net0,hostfwd=udp::$(FWDPORT)-:2000 -object filter-dump,id=net0,netdev=net0,file=packets.pcap
+QEMUOPTS += -device e1000,netdev=net0,bus=pcie.0
+endif
+
 qemu: $K/kernel fs.img
 	$(QEMU) $(QEMUOPTS)
 
@@ -171,3 +309,102 @@ qemu-gdb: $K/kernel .gdbinit fs.img
 	@echo "*** Now run 'gdb' in another window." 1>&2
 	$(QEMU) $(QEMUOPTS) -S $(QEMUGDB)
 
+ifeq ($(LAB),net)
+# try to generate a unique port for the echo server
+SERVERPORT = $(shell expr `id -u` % 5000 + 25099)
+
+server:
+	python3 server.py $(SERVERPORT)
+
+ping:
+	python3 ping.py $(FWDPORT)
+endif
+
+##
+##  FOR testing lab grading script
+##
+
+ifneq ($(V),@)
+GRADEFLAGS += -v
+endif
+
+print-gdbport:
+	@echo $(GDBPORT)
+
+grade:
+	@echo $(MAKE) clean
+	@$(MAKE) clean || \
+          (echo "'make clean' failed.  HINT: Do you have another running instance of xv6?" && exit 1)
+	./grade-lab-$(LAB) $(GRADEFLAGS)
+
+##
+## FOR web handin
+##
+
+
+WEBSUB := https://6828.scripts.mit.edu/2022/handin.py
+
+handin: tarball-pref myapi.key
+	@SUF=$(LAB); \
+	curl -f -F file=@lab-$$SUF-handin.tar.gz -F key=\<myapi.key $(WEBSUB)/upload \
+	    > /dev/null || { \
+		echo ; \
+		echo Submit seems to have failed.; \
+		echo Please go to $(WEBSUB)/ and upload the tarball manually.; }
+
+handin-check:
+	@if ! test -d .git; then \
+		echo No .git directory, is this a git repository?; \
+		false; \
+	fi
+	@if test "$$(git symbolic-ref HEAD)" != refs/heads/$(LAB); then \
+		git branch; \
+		read -p "You are not on the $(LAB) branch.  Hand-in the current branch? [y/N] " r; \
+		test "$$r" = y; \
+	fi
+	@if ! git diff-files --quiet || ! git diff-index --quiet --cached HEAD; then \
+		git status -s; \
+		echo; \
+		echo "You have uncomitted changes.  Please commit or stash them."; \
+		false; \
+	fi
+	@if test -n "`git status -s`"; then \
+		git status -s; \
+		read -p "Untracked files will not be handed in.  Continue? [y/N] " r; \
+		test "$$r" = y; \
+	fi
+
+UPSTREAM := $(shell git remote -v | grep -m 1 "xv6-labs-2022" | awk '{split($$0,a," "); print a[1]}')
+
+tarball: handin-check
+	git archive --format=tar HEAD | gzip > lab-$(LAB)-handin.tar.gz
+
+tarball-pref: handin-check
+	@SUF=$(LAB); \
+	git archive --format=tar HEAD > lab-$$SUF-handin.tar; \
+	git diff $(UPSTREAM)/$(LAB) > /tmp/lab-$$SUF-diff.patch; \
+	tar -rf lab-$$SUF-handin.tar /tmp/lab-$$SUF-diff.patch; \
+	gzip -c lab-$$SUF-handin.tar > lab-$$SUF-handin.tar.gz; \
+	rm lab-$$SUF-handin.tar; \
+	rm /tmp/lab-$$SUF-diff.patch; \
+
+myapi.key:
+	@echo Get an API key for yourself by visiting $(WEBSUB)/
+	@read -p "Please enter your API key: " k; \
+	if test `echo "$$k" |tr -d '\n' |wc -c` = 32 ; then \
+		TF=`mktemp -t tmp.XXXXXX`; \
+		if test "x$$TF" != "x" ; then \
+			echo "$$k" |tr -d '\n' > $$TF; \
+			mv -f $$TF $@; \
+		else \
+			echo mktemp failed; \
+			false; \
+		fi; \
+	else \
+		echo Bad API key: $$k; \
+		echo An API key should be 32 characters long.; \
+		false; \
+	fi;
+
+
+.PHONY: handin tarball tarball-pref clean grade handin-check

README

@@ -6,7 +6,7 @@ ACKNOWLEDGMENTS
 
 xv6 is inspired by John Lions's Commentary on UNIX 6th Edition (Peer
 to Peer Communications; ISBN: 1-57398-013-7; 1st edition (June 14,
-2000)).  See also https://pdos.csail.mit.edu/6.828/, which provides
+2000)).  See also https://pdos.csail.mit.edu/6.1810/, which provides
 pointers to on-line resources for v6.
 
 The following people have made contributions: Russ Cox (context switching,
@@ -14,29 +14,31 @@ locking), Cliff Frey (MP), Xiao Yu (MP), Nickolai Zeldovich, and Austin
 Clements.
 
 We are also grateful for the bug reports and patches contributed by
-Takahiro Aoyagi, Silas Boyd-Wickizer, Anton Burtsev, Ian Chen, Dan
+Takahiro Aoyagi, Silas Boyd-Wickizer, Anton Burtsev, carlclone, Ian
-Cross, Cody Cutler, Mike CAT, Tej Chajed, Asami Doi, eyalz800, Nelson
+Chen, Dan Cross, Cody Cutler, Mike CAT, Tej Chajed, Asami Doi,
-Elhage, Saar Ettinger, Alice Ferrazzi, Nathaniel Filardo, flespark,
+eyalz800, Nelson Elhage, Saar Ettinger, Alice Ferrazzi, Nathaniel
-Peter Froehlich, Yakir Goaron, Shivam Handa, Matt Harvey, Bryan Henry,
+Filardo, flespark, Peter Froehlich, Yakir Goaron, Shivam Handa, Matt
-jaichenhengjie, Jim Huang, Matúš Jókay, Alexander Kapshuk, Anders
+Harvey, Bryan Henry, jaichenhengjie, Jim Huang, Matúš Jókay, John
-Kaseorg, kehao95, Wolfgang Keller, Jungwoo Kim, Jonathan Kimmitt,
+Jolly, Alexander Kapshuk, Anders Kaseorg, kehao95, Wolfgang Keller,
-Eddie Kohler, Vadim Kolontsov, Austin Liew, l0stman, Pavan
+Jungwoo Kim, Jonathan Kimmitt, Eddie Kohler, Vadim Kolontsov, Austin
-Maddamsetti, Imbar Marinescu, Yandong Mao, Matan Shabtay, Hitoshi
+Liew, l0stman, Pavan Maddamsetti, Imbar Marinescu, Yandong Mao, Matan
-Mitake, Carmi Merimovich, Mark Morrissey, mtasm, Joel Nider,
+Shabtay, Hitoshi Mitake, Carmi Merimovich, Mark Morrissey, mtasm, Joel
-OptimisticSide, Greg Price, Jude Rich, Ayan Shafqat, Eldar Sehayek,
+Nider, Hayato Ohhashi, OptimisticSide, Harry Porter, Greg Price, Jude
-Yongming Shen, Fumiya Shigemitsu, Cam Tenny, tyfkda, Warren Toomey,
+Rich, segfault, Ayan Shafqat, Eldar Sehayek, Yongming Shen, Fumiya
-Stephen Tu, Rafael Ubal, Amane Uehara, Pablo Ventura, Xi Wang, Keiichi
+Shigemitsu, Cam Tenny, tyfkda, Warren Toomey, Stephen Tu, Rafael Ubal,
-Watanabe, Nicolas Wolovick, wxdao, Grant Wu, Jindong Zhang, Icenowy
+Amane Uehara, Pablo Ventura, Xi Wang, WaheedHafez, Keiichi Watanabe,
-Zheng, ZhUyU1997, and Zou Chang Wei.
+Nicolas Wolovick, wxdao, Grant Wu, Jindong Zhang, Icenowy Zheng,
+ZhUyU1997, and Zou Chang Wei.
+
 
 The code in the files that constitute xv6 is
-Copyright 2006-2020 Frans Kaashoek, Robert Morris, and Russ Cox.
+Copyright 2006-2022 Frans Kaashoek, Robert Morris, and Russ Cox.
 
 ERROR REPORTS
 
 Please send errors and suggestions to Frans Kaashoek and Robert Morris
 (kaashoek,rtm@mit.edu).  The main purpose of xv6 is as a teaching
-operating system for MIT's 6.S081, so we are more interested in
+operating system for MIT's 6.1810, so we are more interested in
 simplifications and clarifications than new features.
 
 BUILDING AND RUNNING XV6

conf/lab.mk

@@ -0,0 +1 @@
+LAB=net

grade-lab-net

@@ -0,0 +1,43 @@
+#!/usr/bin/env python3
+
+import re
+import subprocess
+from gradelib import *
+
+r = Runner(save("xv6.out"))
+
+@test(0, "running nettests")
+def test_nettest():
+    server = subprocess.Popen(["make", "server"], stdout=subprocess.PIPE, stderr=subprocess.PIPE)
+    r.run_qemu(shell_script([
+        'nettests'
+    ]), timeout=30)
+    server.terminate()
+    server.communicate()
+
+@test(40, "nettest: ping", parent=test_nettest)
+def test_nettest_():
+    r.match('^testing ping: OK$')
+
+@test(20, "nettest: single process", parent=test_nettest)
+def test_nettest_():
+    r.match('^testing single-process pings: OK$')
+
+@test(20, "nettest: multi-process", parent=test_nettest)
+def test_nettest_fork_test():
+    r.match('^testing multi-process pings: OK$')
+
+@test(19, "nettest: DNS", parent=test_nettest)
+def test_nettest_dns_test():
+    r.match('^DNS OK$')
+
+#@test(10, "answers-net.txt")
+#def test_answers():
+#    # just a simple sanity check, will be graded manually
+#    check_answers("answers-net.txt")
+
+@test(1, "time")
+def test_time():
+    check_time()
+
+run_tests()

gradelib.py

@@ -0,0 +1,611 @@
+from __future__ import print_function
+
+import sys, os, re, time, socket, select, subprocess, errno, shutil, random, string
+from subprocess import check_call, Popen
+from optparse import OptionParser
+
+__all__ = []
+
+##################################################################
+# Test structure
+#
+
+__all__ += ["test", "end_part", "run_tests", "get_current_test"]
+
+TESTS = []
+TOTAL = POSSIBLE = 0
+PART_TOTAL = PART_POSSIBLE = 0
+CURRENT_TEST = None
+
+def test(points, title=None, parent=None):
+    """Decorator for declaring test functions.  If title is None, the
+    title of the test will be derived from the function name by
+    stripping the leading "test_" and replacing underscores with
+    spaces."""
+
+    def register_test(fn, title=title):
+        if not title:
+            assert fn.__name__.startswith("test_")
+            title = fn.__name__[5:].replace("_", " ")
+        if parent:
+            title = "  " + title
+
+        def run_test():
+            global TOTAL, POSSIBLE, CURRENT_TEST
+
+            # Handle test dependencies
+            if run_test.complete:
+                return run_test.ok
+            run_test.complete = True
+            parent_failed = False
+            if parent:
+                parent_failed = not parent()
+
+            # Run the test
+            fail = None
+            start = time.time()
+            CURRENT_TEST = run_test
+            sys.stdout.write("== Test %s == " % title)
+            if parent:
+                sys.stdout.write("\n")
+            sys.stdout.flush()
+            try:
+                if parent_failed:
+                    raise AssertionError('Parent failed: %s' % parent.__name__)
+                fn()
+            except AssertionError as e:
+                fail = str(e)
+
+            # Display and handle test result
+            POSSIBLE += points
+            if points:
+                print("%s: %s" % (title, \
+                    (color("red", "FAIL") if fail else color("green", "OK"))), end=' ')
+            if time.time() - start > 0.1:
+                print("(%.1fs)" % (time.time() - start), end=' ')
+            print()
+            if fail:
+                print("    %s" % fail.replace("\n", "\n    "))
+            else:
+                TOTAL += points
+            for callback in run_test.on_finish:
+                callback(fail)
+            CURRENT_TEST = None
+
+            run_test.ok = not fail
+            return run_test.ok
+
+        # Record test metadata on the test wrapper function
+        run_test.__name__ = fn.__name__
+        run_test.title = title
+        run_test.complete = False
+        run_test.ok = False
+        run_test.on_finish = []
+        TESTS.append(run_test)
+        return run_test
+    return register_test
+
+def end_part(name):
+    def show_part():
+        global PART_TOTAL, PART_POSSIBLE
+        print("Part %s score: %d/%d" % \
+            (name, TOTAL - PART_TOTAL, POSSIBLE - PART_POSSIBLE))
+        print()
+        PART_TOTAL, PART_POSSIBLE = TOTAL, POSSIBLE
+    show_part.title = ""
+    TESTS.append(show_part)
+
+def run_tests():
+    """Set up for testing and run the registered test functions."""
+
+    # Handle command line
+    global options
+    parser = OptionParser(usage="usage: %prog [-v] [filters...]")
+    parser.add_option("-v", "--verbose", action="store_true",
+                      help="print commands")
+    parser.add_option("--color", choices=["never", "always", "auto"],
+                      default="auto", help="never, always, or auto")
+    (options, args) = parser.parse_args()
+
+    # Start with a full build to catch build errors
+    make()
+
+    # Clean the file system if there is one
+    reset_fs()
+
+    # Run tests
+    limit = list(map(str.lower, args))
+    try:
+        for test in TESTS:
+            if not limit or any(l in test.title.lower() for l in limit):
+                test()
+        if not limit:
+            print("Score: %d/%d" % (TOTAL, POSSIBLE))
+    except KeyboardInterrupt:
+        pass
+    if TOTAL < POSSIBLE:
+        sys.exit(1)
+
+def get_current_test():
+    if not CURRENT_TEST:
+        raise RuntimeError("No test is running")
+    return CURRENT_TEST
+
+##################################################################
+# Assertions
+#
+
+__all__ += ["assert_equal", "assert_lines_match"]
+
+def assert_equal(got, expect, msg=""):
+    if got == expect:
+        return
+    if msg:
+        msg += "\n"
+    raise AssertionError("%sgot:\n  %s\nexpected:\n  %s" %
+                         (msg, str(got).replace("\n", "\n  "),
+                          str(expect).replace("\n", "\n  ")))
+
+def assert_lines_match(text, *regexps, **kw):
+    """Assert that all of regexps match some line in text.  If a 'no'
+    keyword argument is given, it must be a list of regexps that must
+    *not* match any line in text."""
+
+    def assert_lines_match_kw(no=[]):
+        return no
+    no = assert_lines_match_kw(**kw)
+
+    # Check text against regexps
+    lines = text.splitlines()
+    good = set()
+    bad = set()
+    for i, line in enumerate(lines):
+        if any(re.match(r, line) for r in regexps):
+            good.add(i)
+            regexps = [r for r in regexps if not re.match(r, line)]
+        if any(re.match(r, line) for r in no):
+            bad.add(i)
+
+    if not regexps and not bad:
+        return
+
+    # We failed; construct an informative failure message
+    show = set()
+    for lineno in good.union(bad):
+        for offset in range(-2, 3):
+            show.add(lineno + offset)
+    if regexps:
+        show.update(n for n in range(len(lines) - 5, len(lines)))
+
+    msg = []
+    last = -1
+    for lineno in sorted(show):
+        if 0 <= lineno < len(lines):
+            if lineno != last + 1:
+                msg.append("...")
+            last = lineno
+            msg.append("%s %s" % (color("red", "BAD ") if lineno in bad else
+                                  color("green", "GOOD") if lineno in good
+                                  else "    ",
+                                  lines[lineno]))
+    if last != len(lines) - 1:
+        msg.append("...")
+    if bad:
+        msg.append("unexpected lines in output")
+    for r in regexps:
+        msg.append(color("red", "MISSING") + " '%s'" % r)
+    raise AssertionError("\n".join(msg))
+
+##################################################################
+# Utilities
+#
+
+__all__ += ["make", "maybe_unlink", "reset_fs", "color", "random_str", "check_time", "check_answers"]
+
+MAKE_TIMESTAMP = 0
+
+def pre_make():
+    """Delay prior to running make to ensure file mtimes change."""
+    while int(time.time()) == MAKE_TIMESTAMP:
+        time.sleep(0.1)
+
+def post_make():
+    """Record the time after make completes so that the next run of
+    make can be delayed if needed."""
+    global MAKE_TIMESTAMP
+    MAKE_TIMESTAMP = int(time.time())
+
+def make(*target):
+    pre_make()
+    if Popen(("make",) + target).wait():
+        sys.exit(1)
+    post_make()
+
+def show_command(cmd):
+    from pipes import quote
+    print("\n$", " ".join(map(quote, cmd)))
+
+def maybe_unlink(*paths):
+    for path in paths:
+        try:
+            os.unlink(path)
+        except EnvironmentError as e:
+            if e.errno != errno.ENOENT:
+                raise
+
+COLORS = {"default": "\033[0m", "red": "\033[31m", "green": "\033[32m"}
+
+def color(name, text):
+    if options.color == "always" or (options.color == "auto" and os.isatty(1)):
+        return COLORS[name] + text + COLORS["default"]
+    return text
+
+def reset_fs():
+    if os.path.exists("obj/fs/clean-fs.img"):
+        shutil.copyfile("obj/fs/clean-fs.img", "obj/fs/fs.img")
+
+def random_str(n=8):
+    letters = string.ascii_letters + string.digits
+    return ''.join(random.choice(letters) for _ in range(n))
+
+def check_time():
+    try:
+        print("")
+        with open('time.txt') as f:
+            d = f.read().strip()
+            if not re.match(r'^\d+$', d):
+                raise AssertionError('time.txt does not contain a single integer (number of hours spent on the lab)')
+    except IOError:
+        raise AssertionError('Cannot read time.txt')
+
+def check_answers(file, n=10):
+    try:
+        with open(file) as f:
+            d = f.read().strip()
+            if len(d) < n:
+                raise AssertionError('%s does not seem to contain enough text' % file)
+    except IOError:
+        raise AssertionError('Cannot read %s' % file)
+
+
+##################################################################
+# Controllers
+#
+
+__all__ += ["QEMU", "GDBClient"]
+
+class QEMU(object):
+    _GDBPORT = None
+
+    def __init__(self, *make_args):
+        # Check that QEMU is not currently running
+        try:
+            GDBClient(self.get_gdb_port(), timeout=0).close()
+        except socket.error:
+            pass
+        else:
+            print("""\
+GDB stub found on port %d.
+QEMU appears to already be running.  Please exit it if possible or use
+'killall qemu' or 'killall qemu.real'.""" % self.get_gdb_port(), file=sys.stderr)
+            sys.exit(1)
+
+        if options.verbose:
+            show_command(("make",) + make_args)
+        cmd = ("make", "-s", "--no-print-directory") + make_args
+        self.proc = Popen(cmd, stdout=subprocess.PIPE,
+                          stderr=subprocess.STDOUT,
+                          stdin=subprocess.PIPE)
+        # Accumulated output as a string
+        self.output = ""
+        # Accumulated output as a bytearray
+        self.outbytes = bytearray()
+        self.on_output = []
+
+    @staticmethod
+    def get_gdb_port():
+        if QEMU._GDBPORT is None:
+            p = Popen(["make", "-s", "--no-print-directory", "print-gdbport"],
+                      stdout=subprocess.PIPE)
+            (out, _) = p.communicate()
+            if p.returncode:
+                raise RuntimeError(
+                    "Failed to get gdbport: make exited with %d" %
+                    p.returncode)
+            QEMU._GDBPORT = int(out)
+        return QEMU._GDBPORT
+
+    def fileno(self):
+        if self.proc:
+            return self.proc.stdout.fileno()
+
+    def handle_read(self):
+        buf = os.read(self.proc.stdout.fileno(), 4096)
+        self.outbytes.extend(buf)
+        self.output = self.outbytes.decode("utf-8", "replace")
+        for callback in self.on_output:
+            callback(buf)
+        if buf == b"":
+            self.wait()
+            return
+
+    def write(self, buf):
+        if isinstance(buf, str):
+            buf = buf.encode('utf-8')
+        self.proc.stdin.write(buf)
+        self.proc.stdin.flush()
+
+    def wait(self):
+        if self.proc:
+            self.proc.wait()
+            self.proc = None
+
+    def kill(self):
+        if self.proc:
+            self.proc.terminate()
+
+class GDBClient(object):
+    def __init__(self, port, timeout=15):
+        start = time.time()
+        while True:
+            self.sock = socket.socket()
+            try:
+                self.sock.settimeout(1)
+                self.sock.connect(("localhost", port))
+                break
+            except socket.error:
+                if time.time() >= start + timeout:
+                    raise
+        self.__buf = ""
+
+    def fileno(self):
+        if self.sock:
+            return self.sock.fileno()
+
+    def handle_read(self):
+        try:
+            data = self.sock.recv(4096).decode("ascii", "replace")
+        except socket.error:
+            data = ""
+        if data == "":
+            self.sock.close()
+            self.sock = None
+            return
+        self.__buf += data
+
+        while True:
+            m = re.search(r"\$([^#]*)#[0-9a-zA-Z]{2}", self.__buf)
+            if not m:
+                break
+            pkt = m.group(1)
+            self.__buf = self.__buf[m.end():]
+
+            if pkt.startswith("T05"):
+                # Breakpoint
+                raise TerminateTest
+
+    def __send(self, cmd):
+        packet = "$%s#%02x" % (cmd, sum(map(ord, cmd)) % 256)
+        self.sock.sendall(packet.encode("ascii"))
+
+    def __send_break(self):
+        self.sock.sendall(b"\x03")
+
+    def close(self):
+        if self.sock:
+            self.sock.close()
+            self.sock = None
+
+    def cont(self):
+        self.__send("c")
+
+    def breakpoint(self, addr):
+        self.__send("Z1,%x,1" % addr)
+
+
+##################################################################
+# QEMU test runner
+#
+
+__all__ += ["TerminateTest", "Runner"]
+
+class TerminateTest(Exception):
+    pass
+
+class Runner():
+    def __init__(self, *default_monitors):
+        self.__default_monitors = default_monitors
+
+    def run_qemu(self, *monitors, **kw):
+        """Run a QEMU-based test.  monitors should functions that will
+        be called with this Runner instance once QEMU and GDB are
+        started.  Typically, they should register callbacks that throw
+        TerminateTest when stop events occur.  The target_base
+        argument gives the make target to run.  The make_args argument
+        should be a list of additional arguments to pass to make.  The
+        timeout argument bounds how long to run before returning."""
+
+        def run_qemu_kw(target_base="qemu", make_args=[], timeout=30):
+            return target_base, make_args, timeout
+        target_base, make_args, timeout = run_qemu_kw(**kw)
+
+        # Start QEMU
+        pre_make()
+        self.qemu = QEMU(target_base + "-gdb", *make_args)
+        self.gdb = None
+
+        try:
+            # Wait for QEMU to start or make to fail.  This will set
+            # self.gdb if QEMU starts.
+            self.qemu.on_output = [self.__monitor_start]
+            self.__react([self.qemu], timeout=90)
+            self.qemu.on_output = []
+            if self.gdb is None:
+                print("Failed to connect to QEMU; output:")
+                print(self.qemu.output)
+                sys.exit(1)
+            post_make()
+
+            # QEMU and GDB are up
+            self.reactors = [self.qemu, self.gdb]
+
+            # Start monitoring
+            for m in self.__default_monitors + monitors:
+                m(self)
+
+            # Run and react
+            self.gdb.cont()
+            self.__react(self.reactors, timeout)
+        finally:
+            # Shutdown QEMU
+            try:
+                if self.gdb is None:
+                    sys.exit(1)
+                self.qemu.kill()
+                self.__react(self.reactors, 5)
+                self.gdb.close()
+                self.qemu.wait()
+            except:
+                print("""\
+Failed to shutdown QEMU.  You might need to 'killall qemu' or
+'killall qemu.real'.
+""")
+                raise
+
+    def __monitor_start(self, output):
+        if b"\n" in output:
+            try:
+                self.gdb = GDBClient(self.qemu.get_gdb_port(), timeout=2)
+                raise TerminateTest
+            except socket.error:
+                pass
+        if not len(output):
+            raise TerminateTest
+
+    def __react(self, reactors, timeout):
+        deadline = time.time() + timeout
+        try:
+            while True:
+                timeleft = deadline - time.time()
+                if timeleft < 0:
+                    sys.stdout.write("Timeout! ")
+                    sys.stdout.flush()
+                    return
+
+                rset = [r for r in reactors if r.fileno() is not None]
+                if not rset:
+                    return
+
+                rset, _, _ = select.select(rset, [], [], timeleft)
+                for reactor in rset:
+                    reactor.handle_read()
+        except TerminateTest:
+            pass
+
+    def user_test(self, binary, *monitors, **kw):
+        """Run a user test using the specified binary.  Monitors and
+        keyword arguments are as for run_qemu.  This runs on a disk
+        snapshot unless the keyword argument 'snapshot' is False."""
+
+        maybe_unlink("obj/kern/init.o", "obj/kern/kernel")
+        if kw.pop("snapshot", True):
+            kw.setdefault("make_args", []).append("QEMUEXTRA+=-snapshot")
+        self.run_qemu(target_base="run-%s" % binary, *monitors, **kw)
+
+    def match(self, *args, **kwargs):
+        """Shortcut to call assert_lines_match on the most recent QEMU
+        output."""
+
+        assert_lines_match(self.qemu.output, *args, **kwargs)
+
+##################################################################
+# Monitors
+#
+
+__all__ += ["save", "stop_breakpoint", "call_on_line", "stop_on_line", "shell_script"]
+
+def save(path):
+    """Return a monitor that writes QEMU's output to path.  If the
+    test fails, copy the output to path.test-name."""
+
+    def setup_save(runner):
+        f.seek(0)
+        f.truncate()
+        runner.qemu.on_output.append(f.write)
+        get_current_test().on_finish.append(save_on_finish)
+
+    def save_on_finish(fail):
+        f.flush()
+        save_path = path + "." + get_current_test().__name__[5:]
+        if fail:
+            shutil.copyfile(path, save_path)
+            print("    QEMU output saved to %s" % save_path)
+        elif os.path.exists(save_path):
+            os.unlink(save_path)
+            print("    (Old %s failure log removed)" % save_path)
+
+    f = open(path, "wb")
+    return setup_save
+
+def stop_breakpoint(addr):
+    """Returns a monitor that stops when addr is reached.  addr may be
+    a number or the name of a symbol."""
+
+    def setup_breakpoint(runner):
+        if isinstance(addr, str):
+            addrs = [int(sym[:16], 16) for sym in open("kernel/kernel.sym")
+                     if sym[17:].strip() == addr]
+            assert len(addrs), "Symbol %s not found" % addr
+            runner.gdb.breakpoint(addrs[0])
+        else:
+            runner.gdb.breakpoint(addr)
+    return setup_breakpoint
+
+def call_on_line(regexp, callback):
+    """Returns a monitor that calls 'callback' when QEMU prints a line
+    matching 'regexp'."""
+
+    def setup_call_on_line(runner):
+        buf = bytearray()
+        def handle_output(output):
+            buf.extend(output)
+            while b"\n" in buf:
+                line, buf[:] = buf.split(b"\n", 1)
+                line = line.decode("utf-8", "replace")
+                if re.match(regexp, line):
+                    callback(line)
+        runner.qemu.on_output.append(handle_output)
+    return setup_call_on_line
+
+def stop_on_line(regexp):
+    """Returns a monitor that stops when QEMU prints a line matching
+    'regexp'."""
+
+    def stop(line):
+        raise TerminateTest
+    return call_on_line(regexp, stop)
+
+def shell_script(script, terminate_match=None):
+    """Returns a monitor that plays the script, and stops when the script is
+    done executing."""
+
+    def setup_call_on_line(runner):
+        class context:
+            n = 0
+            buf = bytearray()
+        def handle_output(output):
+            context.buf.extend(output)
+            if terminate_match is not None:
+                if re.match(terminate_match, context.buf.decode('utf-8', 'replace')):
+                    raise TerminateTest
+            if b'$ ' in context.buf:
+                context.buf = bytearray()
+                if context.n < len(script):
+                    runner.qemu.write(script[context.n])
+                    runner.qemu.write('\n')
+                    context.n += 1
+                else:
+                    if terminate_match is None:
+                        raise TerminateTest
+        runner.qemu.on_output.append(handle_output)
+    return setup_call_on_line

kernel/defs.h

@@ -8,6 +8,10 @@ struct spinlock;
 struct sleeplock;
 struct stat;
 struct superblock;
+#ifdef LAB_NET
+struct mbuf;
+struct sock;
+#endif
 
 // bio.c
 void            binit(void);
@@ -117,6 +121,11 @@ void            initlock(struct spinlock*, char*);
 void            release(struct spinlock*);
 void            push_off(void);
 void            pop_off(void);
+uint64          lockfree_read8(uint64 *addr);
+int             lockfree_read4(int *addr);
+#ifdef LAB_LOCK
+void            freelock(struct spinlock*);
+#endif
 
 // sleeplock.c
 void            acquiresleep(struct sleeplock*);
@@ -187,3 +196,44 @@ void            virtio_disk_intr(void);
 
 // number of elements in fixed-size array
 #define NELEM(x) (sizeof(x)/sizeof((x)[0]))
+
+
+
+#ifdef LAB_PGTBL
+// vmcopyin.c
+int             copyin_new(pagetable_t, char *, uint64, uint64);
+int             copyinstr_new(pagetable_t, char *, uint64, uint64);
+#endif
+
+// stats.c
+void            statsinit(void);
+void            statsinc(void);
+
+// sprintf.c
+int             snprintf(char*, int, char*, ...);
+
+#ifdef KCSAN
+void            kcsaninit();
+#endif
+
+#ifdef LAB_NET
+// pci.c
+void            pci_init();
+
+// e1000.c
+void            e1000_init(uint32 *);
+void            e1000_intr(void);
+int             e1000_transmit(struct mbuf*);
+
+// net.c
+void            net_rx(struct mbuf*);
+void            net_tx_udp(struct mbuf*, uint32, uint16, uint16);
+
+// sysnet.c
+void            sockinit(void);
+int             sockalloc(struct file **, uint32, uint16, uint16);
+void            sockclose(struct sock *);
+int             sockread(struct sock *, uint64, int);
+int             sockwrite(struct sock *, uint64, int);
+void            sockrecvudp(struct mbuf*, uint32, uint16, uint16);
+#endif

kernel/e1000.c

@@ -0,0 +1,162 @@
+#include "types.h"
+#include "param.h"
+#include "memlayout.h"
+#include "riscv.h"
+#include "spinlock.h"
+#include "proc.h"
+#include "defs.h"
+#include "e1000_dev.h"
+#include "net.h"
+
+#define TX_RING_SIZE 16
+static struct tx_desc tx_ring[TX_RING_SIZE] __attribute__((aligned(16)));
+static struct mbuf *tx_mbufs[TX_RING_SIZE];
+
+#define RX_RING_SIZE 16
+static struct rx_desc rx_ring[RX_RING_SIZE] __attribute__((aligned(16)));
+static struct mbuf *rx_mbufs[RX_RING_SIZE];
+
+// remember where the e1000's registers live.
+static volatile uint32 *regs;
+
+struct spinlock e1000_lock;
+
+// called by pci_init().
+// xregs is the memory address at which the
+// e1000's registers are mapped.
+void
+e1000_init(uint32 *xregs)
+{
+  int i;
+
+  initlock(&e1000_lock, "e1000");
+
+  regs = xregs;
+
+  // Reset the device
+  regs[E1000_IMS] = 0; // disable interrupts
+  regs[E1000_CTL] |= E1000_CTL_RST;
+  regs[E1000_IMS] = 0; // redisable interrupts
+  __sync_synchronize();
+
+  // [E1000 14.5] Transmit initialization
+  memset(tx_ring, 0, sizeof(tx_ring));
+  for (i = 0; i < TX_RING_SIZE; i++) {
+    tx_ring[i].status = E1000_TXD_STAT_DD;
+    tx_mbufs[i] = 0;
+  }
+  regs[E1000_TDBAL] = (uint64) tx_ring;
+  if(sizeof(tx_ring) % 128 != 0)
+    panic("e1000");
+  regs[E1000_TDLEN] = sizeof(tx_ring);
+  regs[E1000_TDH] = regs[E1000_TDT] = 0;
+  
+  // [E1000 14.4] Receive initialization
+  memset(rx_ring, 0, sizeof(rx_ring));
+  for (i = 0; i < RX_RING_SIZE; i++) {
+    rx_mbufs[i] = mbufalloc(0);
+    if (!rx_mbufs[i])
+      panic("e1000");
+    rx_ring[i].addr = (uint64) rx_mbufs[i]->head;
+  }
+  regs[E1000_RDBAL] = (uint64) rx_ring;
+  if(sizeof(rx_ring) % 128 != 0)
+    panic("e1000");
+  regs[E1000_RDH] = 0;
+  regs[E1000_RDT] = RX_RING_SIZE - 1;
+  regs[E1000_RDLEN] = sizeof(rx_ring);
+
+  // filter by qemu's MAC address, 52:54:00:12:34:56
+  regs[E1000_RA] = 0x12005452;
+  regs[E1000_RA+1] = 0x5634 | (1<<31);
+  // multicast table
+  for (int i = 0; i < 4096/32; i++)
+    regs[E1000_MTA + i] = 0;
+
+  // transmitter control bits.
+  regs[E1000_TCTL] = E1000_TCTL_EN |  // enable
+    E1000_TCTL_PSP |                  // pad short packets
+    (0x10 << E1000_TCTL_CT_SHIFT) |   // collision stuff
+    (0x40 << E1000_TCTL_COLD_SHIFT);
+  regs[E1000_TIPG] = 10 | (8<<10) | (6<<20); // inter-pkt gap
+
+  // receiver control bits.
+  regs[E1000_RCTL] = E1000_RCTL_EN | // enable receiver
+    E1000_RCTL_BAM |                 // enable broadcast
+    E1000_RCTL_SZ_2048 |             // 2048-byte rx buffers
+    E1000_RCTL_SECRC;                // strip CRC
+  
+  // ask e1000 for receive interrupts.
+  regs[E1000_RDTR] = 0; // interrupt after every received packet (no timer)
+  regs[E1000_RADV] = 0; // interrupt after every packet (no timer)
+  regs[E1000_IMS] = (1 << 7); // RXDW -- Receiver Descriptor Write Back
+}
+
+int
+e1000_transmit(struct mbuf *m)
+{
+  //
+  // Your code here.
+  //
+  // the mbuf contains an ethernet frame; program it into
+  // the TX descriptor ring so that the e1000 sends it. Stash
+  // a pointer so that it can be freed after sending.
+  //
+
+  acquire(&e1000_lock);
+  int tdt = regs[E1000_TDT];
+  if (!(tx_ring[tdt].status & E1000_TXD_STAT_DD)) {
+    release(&e1000_lock);
+    return -1;
+  }
+  if (tx_mbufs[tdt]) {
+    mbuffree(tx_mbufs[tdt]);
+    tx_mbufs[tdt] = 0;
+  }
+  tx_mbufs[tdt] = m;
+  tx_ring[tdt].addr = (uint64)m->head;
+  tx_ring[tdt].length = m->len;
+  tx_ring[tdt].cmd = E1000_TXD_CMD_RS | E1000_TXD_CMD_EOP;
+  regs[E1000_TDT] = (tdt + 1) % TX_RING_SIZE;
+  release(&e1000_lock);
+  return 0;
+}
+
+static void
+e1000_recv(void)
+{
+  //
+  // Your code here.
+  //
+  // Check for packets that have arrived from the e1000
+  // Create and deliver an mbuf for each packet (using net_rx()).
+  //
+  acquire(&e1000_lock);
+  int rdt = regs[E1000_RDT];
+  rdt = (rdt + 1) % RX_RING_SIZE;
+  while (rx_ring[rdt].status & E1000_RXD_STAT_DD)
+  {
+    if (!holding(&e1000_lock)) acquire(&e1000_lock);
+    rx_mbufs[rdt]->len = rx_ring[rdt].length;
+    struct mbuf* m = rx_mbufs[rdt];
+    rx_mbufs[rdt] = mbufalloc(0);
+    if (!rx_mbufs[rdt]) panic("e1000 recv");
+    rx_ring[rdt].addr = (uint64)rx_mbufs[rdt]->head;
+    rx_ring[rdt].status = 0;
+    regs[E1000_RDT] = rdt;
+    rdt = (rdt + 1) % RX_RING_SIZE;
+    release(&e1000_lock);
+    net_rx(m);
+  }
+}
+
+void
+e1000_intr(void)
+{
+  // tell the e1000 we've seen this interrupt;
+  // without this the e1000 won't raise any
+  // further interrupts.
+  regs[E1000_ICR] = 0xffffffff;
+
+  e1000_recv();
+}

kernel/e1000_dev.h

@@ -0,0 +1,125 @@
+//
+// E1000 hardware definitions: registers and DMA ring format.
+// from the Intel 82540EP/EM &c manual.
+//
+
+/* Registers */
+#define E1000_CTL      (0x00000/4)  /* Device Control Register - RW */
+#define E1000_ICR      (0x000C0/4)  /* Interrupt Cause Read - R */
+#define E1000_IMS      (0x000D0/4)  /* Interrupt Mask Set - RW */
+#define E1000_RCTL     (0x00100/4)  /* RX Control - RW */
+#define E1000_TCTL     (0x00400/4)  /* TX Control - RW */
+#define E1000_TIPG     (0x00410/4)  /* TX Inter-packet gap -RW */
+#define E1000_RDBAL    (0x02800/4)  /* RX Descriptor Base Address Low - RW */
+#define E1000_RDTR     (0x02820/4)  /* RX Delay Timer */
+#define E1000_RADV     (0x0282C/4)  /* RX Interrupt Absolute Delay Timer */
+#define E1000_RDH      (0x02810/4)  /* RX Descriptor Head - RW */
+#define E1000_RDT      (0x02818/4)  /* RX Descriptor Tail - RW */
+#define E1000_RDLEN    (0x02808/4)  /* RX Descriptor Length - RW */
+#define E1000_RSRPD    (0x02C00/4)  /* RX Small Packet Detect Interrupt */
+#define E1000_TDBAL    (0x03800/4)  /* TX Descriptor Base Address Low - RW */
+#define E1000_TDLEN    (0x03808/4)  /* TX Descriptor Length - RW */
+#define E1000_TDH      (0x03810/4)  /* TX Descriptor Head - RW */
+#define E1000_TDT      (0x03818/4)  /* TX Descripotr Tail - RW */
+#define E1000_MTA      (0x05200/4)  /* Multicast Table Array - RW Array */
+#define E1000_RA       (0x05400/4)  /* Receive Address - RW Array */
+
+/* Device Control */
+#define E1000_CTL_SLU     0x00000040    /* set link up */
+#define E1000_CTL_FRCSPD  0x00000800    /* force speed */
+#define E1000_CTL_FRCDPLX 0x00001000    /* force duplex */
+#define E1000_CTL_RST     0x00400000    /* full reset */
+
+/* Transmit Control */
+#define E1000_TCTL_RST    0x00000001    /* software reset */
+#define E1000_TCTL_EN     0x00000002    /* enable tx */
+#define E1000_TCTL_BCE    0x00000004    /* busy check enable */
+#define E1000_TCTL_PSP    0x00000008    /* pad short packets */
+#define E1000_TCTL_CT     0x00000ff0    /* collision threshold */
+#define E1000_TCTL_CT_SHIFT 4
+#define E1000_TCTL_COLD   0x003ff000    /* collision distance */
+#define E1000_TCTL_COLD_SHIFT 12
+#define E1000_TCTL_SWXOFF 0x00400000    /* SW Xoff transmission */
+#define E1000_TCTL_PBE    0x00800000    /* Packet Burst Enable */
+#define E1000_TCTL_RTLC   0x01000000    /* Re-transmit on late collision */
+#define E1000_TCTL_NRTU   0x02000000    /* No Re-transmit on underrun */
+#define E1000_TCTL_MULR   0x10000000    /* Multiple request support */
+
+/* Receive Control */
+#define E1000_RCTL_RST            0x00000001    /* Software reset */
+#define E1000_RCTL_EN             0x00000002    /* enable */
+#define E1000_RCTL_SBP            0x00000004    /* store bad packet */
+#define E1000_RCTL_UPE            0x00000008    /* unicast promiscuous enable */
+#define E1000_RCTL_MPE            0x00000010    /* multicast promiscuous enab */
+#define E1000_RCTL_LPE            0x00000020    /* long packet enable */
+#define E1000_RCTL_LBM_NO         0x00000000    /* no loopback mode */
+#define E1000_RCTL_LBM_MAC        0x00000040    /* MAC loopback mode */
+#define E1000_RCTL_LBM_SLP        0x00000080    /* serial link loopback mode */
+#define E1000_RCTL_LBM_TCVR       0x000000C0    /* tcvr loopback mode */
+#define E1000_RCTL_DTYP_MASK      0x00000C00    /* Descriptor type mask */
+#define E1000_RCTL_DTYP_PS        0x00000400    /* Packet Split descriptor */
+#define E1000_RCTL_RDMTS_HALF     0x00000000    /* rx desc min threshold size */
+#define E1000_RCTL_RDMTS_QUAT     0x00000100    /* rx desc min threshold size */
+#define E1000_RCTL_RDMTS_EIGTH    0x00000200    /* rx desc min threshold size */
+#define E1000_RCTL_MO_SHIFT       12            /* multicast offset shift */
+#define E1000_RCTL_MO_0           0x00000000    /* multicast offset 11:0 */
+#define E1000_RCTL_MO_1           0x00001000    /* multicast offset 12:1 */
+#define E1000_RCTL_MO_2           0x00002000    /* multicast offset 13:2 */
+#define E1000_RCTL_MO_3           0x00003000    /* multicast offset 15:4 */
+#define E1000_RCTL_MDR            0x00004000    /* multicast desc ring 0 */
+#define E1000_RCTL_BAM            0x00008000    /* broadcast enable */
+/* these buffer sizes are valid if E1000_RCTL_BSEX is 0 */
+#define E1000_RCTL_SZ_2048        0x00000000    /* rx buffer size 2048 */
+#define E1000_RCTL_SZ_1024        0x00010000    /* rx buffer size 1024 */
+#define E1000_RCTL_SZ_512         0x00020000    /* rx buffer size 512 */
+#define E1000_RCTL_SZ_256         0x00030000    /* rx buffer size 256 */
+/* these buffer sizes are valid if E1000_RCTL_BSEX is 1 */
+#define E1000_RCTL_SZ_16384       0x00010000    /* rx buffer size 16384 */
+#define E1000_RCTL_SZ_8192        0x00020000    /* rx buffer size 8192 */
+#define E1000_RCTL_SZ_4096        0x00030000    /* rx buffer size 4096 */
+#define E1000_RCTL_VFE            0x00040000    /* vlan filter enable */
+#define E1000_RCTL_CFIEN          0x00080000    /* canonical form enable */
+#define E1000_RCTL_CFI            0x00100000    /* canonical form indicator */
+#define E1000_RCTL_DPF            0x00400000    /* discard pause frames */
+#define E1000_RCTL_PMCF           0x00800000    /* pass MAC control frames */
+#define E1000_RCTL_BSEX           0x02000000    /* Buffer size extension */
+#define E1000_RCTL_SECRC          0x04000000    /* Strip Ethernet CRC */
+#define E1000_RCTL_FLXBUF_MASK    0x78000000    /* Flexible buffer size */
+#define E1000_RCTL_FLXBUF_SHIFT   27            /* Flexible buffer shift */
+
+#define DATA_MAX 1518
+
+/* Transmit Descriptor command definitions [E1000 3.3.3.1] */
+#define E1000_TXD_CMD_EOP    0x01 /* End of Packet */
+#define E1000_TXD_CMD_RS     0x08 /* Report Status */
+
+/* Transmit Descriptor status definitions [E1000 3.3.3.2] */
+#define E1000_TXD_STAT_DD    0x00000001 /* Descriptor Done */
+
+// [E1000 3.3.3]
+struct tx_desc
+{
+  uint64 addr;
+  uint16 length;
+  uint8 cso;
+  uint8 cmd;
+  uint8 status;
+  uint8 css;
+  uint16 special;
+};
+
+/* Receive Descriptor bit definitions [E1000 3.2.3.1] */
+#define E1000_RXD_STAT_DD       0x01    /* Descriptor Done */
+#define E1000_RXD_STAT_EOP      0x02    /* End of Packet */
+
+// [E1000 3.2.3]
+struct rx_desc
+{
+  uint64 addr;       /* Address of the descriptor's data buffer */
+  uint16 length;     /* Length of data DMAed into data buffer */
+  uint16 csum;       /* Packet checksum */
+  uint8 status;      /* Descriptor status */
+  uint8 errors;      /* Descriptor Errors */
+  uint16 special;
+};
+

kernel/file.c

@@ -80,6 +80,11 @@ fileclose(struct file *f)
     iput(ff.ip);
     end_op();
   }
+#ifdef LAB_NET
+  else if(ff.type == FD_SOCK){
+    sockclose(ff.sock);
+  }
+#endif
 }
 
 // Get metadata about file f.
@@ -122,7 +127,13 @@ fileread(struct file *f, uint64 addr, int n)
     if((r = readi(f->ip, 1, addr, f->off, n)) > 0)
       f->off += r;
     iunlock(f->ip);
-  } else {
+  }
+#ifdef LAB_NET
+  else if(f->type == FD_SOCK){
+    r = sockread(f->sock, addr, n);
+  }
+#endif
+  else {
     panic("fileread");
   }
 
@@ -173,7 +184,13 @@ filewrite(struct file *f, uint64 addr, int n)
       i += r;
     }
     ret = (i == n ? n : -1);
-  } else {
+  }
+#ifdef LAB_NET
+  else if(f->type == FD_SOCK){
+    ret = sockwrite(f->sock, addr, n);
+  }
+#endif
+  else {
     panic("filewrite");
   }
 

kernel/file.h

@@ -1,10 +1,17 @@
 struct file {
+#ifdef LAB_NET
+  enum { FD_NONE, FD_PIPE, FD_INODE, FD_DEVICE, FD_SOCK } type;
+#else
   enum { FD_NONE, FD_PIPE, FD_INODE, FD_DEVICE } type;
+#endif
   int ref; // reference count
   char readable;
   char writable;
   struct pipe *pipe; // FD_PIPE
   struct inode *ip;  // FD_INODE and FD_DEVICE
+#ifdef LAB_NET
+  struct sock *sock; // FD_SOCK
+#endif
   uint off;          // FD_INODE
   short major;       // FD_DEVICE
 };
@@ -38,3 +45,4 @@ struct devsw {
 extern struct devsw devsw[];
 
 #define CONSOLE 1
+#define STATS   2

kernel/main.c

@@ -12,6 +12,9 @@ main()
 {
   if(cpuid() == 0){
     consoleinit();
+#if defined(LAB_LOCK)
+    statsinit();
+#endif
     printfinit();
     printf("\n");
     printf("xv6 kernel is booting\n");
@@ -28,11 +31,18 @@ main()
     iinit();         // inode table
     fileinit();      // file table
     virtio_disk_init(); // emulated hard disk
+#ifdef LAB_NET
+    pci_init();
+    sockinit();
+#endif    
     userinit();      // first user process
+#ifdef KCSAN
+    kcsaninit();
+#endif
     __sync_synchronize();
     started = 1;
   } else {
-    while(started == 0)
+    while(lockfree_read4((int *) &started) == 0)
       ;
     __sync_synchronize();
     printf("hart %d starting\n", cpuid());

kernel/memlayout.h

@@ -25,6 +25,10 @@
 #define VIRTIO0 0x10001000
 #define VIRTIO0_IRQ 1
 
+#ifdef LAB_NET
+#define E1000_IRQ 33
+#endif
+
 // core local interruptor (CLINT), which contains the timer.
 #define CLINT 0x2000000L
 #define CLINT_MTIMECMP(hartid) (CLINT + 0x4000 + 8*(hartid))
@@ -53,7 +57,7 @@
 
 // map kernel stacks beneath the trampoline,
 // each surrounded by invalid guard pages.
-#define KSTACK(p) (TRAMPOLINE - ((p)+1)* 2*PGSIZE)
+#define KSTACK(p) (TRAMPOLINE - (p)*2*PGSIZE - 3*PGSIZE)
 
 // User memory layout.
 // Address zero first:
@@ -62,6 +66,14 @@
 //   fixed-size stack
 //   expandable heap
 //   ...
+//   USYSCALL (shared with kernel)
 //   TRAPFRAME (p->trapframe, used by the trampoline)
 //   TRAMPOLINE (the same page as in the kernel)
 #define TRAPFRAME (TRAMPOLINE - PGSIZE)
+#ifdef LAB_PGTBL
+#define USYSCALL (TRAPFRAME - PGSIZE)
+
+struct usyscall {
+  int pid;  // Process ID
+};
+#endif

kernel/net.c

@@ -0,0 +1,374 @@
+//
+// networking protocol support (IP, UDP, ARP, etc.).
+//
+
+#include "types.h"
+#include "param.h"
+#include "memlayout.h"
+#include "riscv.h"
+#include "spinlock.h"
+#include "proc.h"
+#include "net.h"
+#include "defs.h"
+
+static uint32 local_ip = MAKE_IP_ADDR(10, 0, 2, 15); // qemu's idea of the guest IP
+static uint8 local_mac[ETHADDR_LEN] = { 0x52, 0x54, 0x00, 0x12, 0x34, 0x56 };
+static uint8 broadcast_mac[ETHADDR_LEN] = { 0xFF, 0XFF, 0XFF, 0XFF, 0XFF, 0XFF };
+
+// Strips data from the start of the buffer and returns a pointer to it.
+// Returns 0 if less than the full requested length is available.
+char *
+mbufpull(struct mbuf *m, unsigned int len)
+{
+  char *tmp = m->head;
+  if (m->len < len)
+    return 0;
+  m->len -= len;
+  m->head += len;
+  return tmp;
+}
+
+// Prepends data to the beginning of the buffer and returns a pointer to it.
+char *
+mbufpush(struct mbuf *m, unsigned int len)
+{
+  m->head -= len;
+  if (m->head < m->buf)
+    panic("mbufpush");
+  m->len += len;
+  return m->head;
+}
+
+// Appends data to the end of the buffer and returns a pointer to it.
+char *
+mbufput(struct mbuf *m, unsigned int len)
+{
+  char *tmp = m->head + m->len;
+  m->len += len;
+  if (m->len > MBUF_SIZE)
+    panic("mbufput");
+  return tmp;
+}
+
+// Strips data from the end of the buffer and returns a pointer to it.
+// Returns 0 if less than the full requested length is available.
+char *
+mbuftrim(struct mbuf *m, unsigned int len)
+{
+  if (len > m->len)
+    return 0;
+  m->len -= len;
+  return m->head + m->len;
+}
+
+// Allocates a packet buffer.
+struct mbuf *
+mbufalloc(unsigned int headroom)
+{
+  struct mbuf *m;
+ 
+  if (headroom > MBUF_SIZE)
+    return 0;
+  m = kalloc();
+  if (m == 0)
+    return 0;
+  m->next = 0;
+  m->head = (char *)m->buf + headroom;
+  m->len = 0;
+  memset(m->buf, 0, sizeof(m->buf));
+  return m;
+}
+
+// Frees a packet buffer.
+void
+mbuffree(struct mbuf *m)
+{
+  kfree(m);
+}
+
+// Pushes an mbuf to the end of the queue.
+void
+mbufq_pushtail(struct mbufq *q, struct mbuf *m)
+{
+  m->next = 0;
+  if (!q->head){
+    q->head = q->tail = m;
+    return;
+  }
+  q->tail->next = m;
+  q->tail = m;
+}
+
+// Pops an mbuf from the start of the queue.
+struct mbuf *
+mbufq_pophead(struct mbufq *q)
+{
+  struct mbuf *head = q->head;
+  if (!head)
+    return 0;
+  q->head = head->next;
+  return head;
+}
+
+// Returns one (nonzero) if the queue is empty.
+int
+mbufq_empty(struct mbufq *q)
+{
+  return q->head == 0;
+}
+
+// Intializes a queue of mbufs.
+void
+mbufq_init(struct mbufq *q)
+{
+  q->head = 0;
+}
+
+// This code is lifted from FreeBSD's ping.c, and is copyright by the Regents
+// of the University of California.
+static unsigned short
+in_cksum(const unsigned char *addr, int len)
+{
+  int nleft = len;
+  const unsigned short *w = (const unsigned short *)addr;
+  unsigned int sum = 0;
+  unsigned short answer = 0;
+
+  /*
+   * Our algorithm is simple, using a 32 bit accumulator (sum), we add
+   * sequential 16 bit words to it, and at the end, fold back all the
+   * carry bits from the top 16 bits into the lower 16 bits.
+   */
+  while (nleft > 1)  {
+    sum += *w++;
+    nleft -= 2;
+  }
+
+  /* mop up an odd byte, if necessary */
+  if (nleft == 1) {
+    *(unsigned char *)(&answer) = *(const unsigned char *)w;
+    sum += answer;
+  }
+
+  /* add back carry outs from top 16 bits to low 16 bits */
+  sum = (sum & 0xffff) + (sum >> 16);
+  sum += (sum >> 16);
+  /* guaranteed now that the lower 16 bits of sum are correct */
+
+  answer = ~sum; /* truncate to 16 bits */
+  return answer;
+}
+
+// sends an ethernet packet
+static void
+net_tx_eth(struct mbuf *m, uint16 ethtype)
+{
+  struct eth *ethhdr;
+
+  ethhdr = mbufpushhdr(m, *ethhdr);
+  memmove(ethhdr->shost, local_mac, ETHADDR_LEN);
+  // In a real networking stack, dhost would be set to the address discovered
+  // through ARP. Because we don't support enough of the ARP protocol, set it
+  // to broadcast instead.
+  memmove(ethhdr->dhost, broadcast_mac, ETHADDR_LEN);
+  ethhdr->type = htons(ethtype);
+  if (e1000_transmit(m)) {
+    mbuffree(m);
+  }
+}
+
+// sends an IP packet
+static void
+net_tx_ip(struct mbuf *m, uint8 proto, uint32 dip)
+{
+  struct ip *iphdr;
+
+  // push the IP header
+  iphdr = mbufpushhdr(m, *iphdr);
+  memset(iphdr, 0, sizeof(*iphdr));
+  iphdr->ip_vhl = (4 << 4) | (20 >> 2);
+  iphdr->ip_p = proto;
+  iphdr->ip_src = htonl(local_ip);
+  iphdr->ip_dst = htonl(dip);
+  iphdr->ip_len = htons(m->len);
+  iphdr->ip_ttl = 100;
+  iphdr->ip_sum = in_cksum((unsigned char *)iphdr, sizeof(*iphdr));
+
+  // now on to the ethernet layer
+  net_tx_eth(m, ETHTYPE_IP);
+}
+
+// sends a UDP packet
+void
+net_tx_udp(struct mbuf *m, uint32 dip,
+           uint16 sport, uint16 dport)
+{
+  struct udp *udphdr;
+
+  // put the UDP header
+  udphdr = mbufpushhdr(m, *udphdr);
+  udphdr->sport = htons(sport);
+  udphdr->dport = htons(dport);
+  udphdr->ulen = htons(m->len);
+  udphdr->sum = 0; // zero means no checksum is provided
+
+  // now on to the IP layer
+  net_tx_ip(m, IPPROTO_UDP, dip);
+}
+
+// sends an ARP packet
+static int
+net_tx_arp(uint16 op, uint8 dmac[ETHADDR_LEN], uint32 dip)
+{
+  struct mbuf *m;
+  struct arp *arphdr;
+
+  m = mbufalloc(MBUF_DEFAULT_HEADROOM);
+  if (!m)
+    return -1;
+
+  // generic part of ARP header
+  arphdr = mbufputhdr(m, *arphdr);
+  arphdr->hrd = htons(ARP_HRD_ETHER);
+  arphdr->pro = htons(ETHTYPE_IP);
+  arphdr->hln = ETHADDR_LEN;
+  arphdr->pln = sizeof(uint32);
+  arphdr->op = htons(op);
+
+  // ethernet + IP part of ARP header
+  memmove(arphdr->sha, local_mac, ETHADDR_LEN);
+  arphdr->sip = htonl(local_ip);
+  memmove(arphdr->tha, dmac, ETHADDR_LEN);
+  arphdr->tip = htonl(dip);
+
+  // header is ready, send the packet
+  net_tx_eth(m, ETHTYPE_ARP);
+  return 0;
+}
+
+// receives an ARP packet
+static void
+net_rx_arp(struct mbuf *m)
+{
+  struct arp *arphdr;
+  uint8 smac[ETHADDR_LEN];
+  uint32 sip, tip;
+
+  arphdr = mbufpullhdr(m, *arphdr);
+  if (!arphdr)
+    goto done;
+
+  // validate the ARP header
+  if (ntohs(arphdr->hrd) != ARP_HRD_ETHER ||
+      ntohs(arphdr->pro) != ETHTYPE_IP ||
+      arphdr->hln != ETHADDR_LEN ||
+      arphdr->pln != sizeof(uint32)) {
+    goto done;
+  }
+
+  // only requests are supported so far
+  // check if our IP was solicited
+  tip = ntohl(arphdr->tip); // target IP address
+  if (ntohs(arphdr->op) != ARP_OP_REQUEST || tip != local_ip)
+    goto done;
+
+  // handle the ARP request
+  memmove(smac, arphdr->sha, ETHADDR_LEN); // sender's ethernet address
+  sip = ntohl(arphdr->sip); // sender's IP address (qemu's slirp)
+  net_tx_arp(ARP_OP_REPLY, smac, sip);
+
+done:
+  mbuffree(m);
+}
+
+// receives a UDP packet
+static void
+net_rx_udp(struct mbuf *m, uint16 len, struct ip *iphdr)
+{
+  struct udp *udphdr;
+  uint32 sip;
+  uint16 sport, dport;
+
+
+  udphdr = mbufpullhdr(m, *udphdr);
+  if (!udphdr)
+    goto fail;
+
+  // TODO: validate UDP checksum
+
+  // validate lengths reported in headers
+  if (ntohs(udphdr->ulen) != len)
+    goto fail;
+  len -= sizeof(*udphdr);
+  if (len > m->len)
+    goto fail;
+  // minimum packet size could be larger than the payload
+  mbuftrim(m, m->len - len);
+
+  // parse the necessary fields
+  sip = ntohl(iphdr->ip_src);
+  sport = ntohs(udphdr->sport);
+  dport = ntohs(udphdr->dport);
+  sockrecvudp(m, sip, dport, sport);
+  return;
+
+fail:
+  mbuffree(m);
+}
+
+// receives an IP packet
+static void
+net_rx_ip(struct mbuf *m)
+{
+  struct ip *iphdr;
+  uint16 len;
+
+  iphdr = mbufpullhdr(m, *iphdr);
+  if (!iphdr)
+	  goto fail;
+
+  // check IP version and header len
+  if (iphdr->ip_vhl != ((4 << 4) | (20 >> 2)))
+    goto fail;
+  // validate IP checksum
+  if (in_cksum((unsigned char *)iphdr, sizeof(*iphdr)))
+    goto fail;
+  // can't support fragmented IP packets
+  if (htons(iphdr->ip_off) != 0)
+    goto fail;
+  // is the packet addressed to us?
+  if (htonl(iphdr->ip_dst) != local_ip)
+    goto fail;
+  // can only support UDP
+  if (iphdr->ip_p != IPPROTO_UDP)
+    goto fail;
+
+  len = ntohs(iphdr->ip_len) - sizeof(*iphdr);
+  net_rx_udp(m, len, iphdr);
+  return;
+
+fail:
+  mbuffree(m);
+}
+
+// called by e1000 driver's interrupt handler to deliver a packet to the
+// networking stack
+void net_rx(struct mbuf *m)
+{
+  struct eth *ethhdr;
+  uint16 type;
+
+  ethhdr = mbufpullhdr(m, *ethhdr);
+  if (!ethhdr) {
+    mbuffree(m);
+    return;
+  }
+
+  type = ntohs(ethhdr->type);
+  if (type == ETHTYPE_IP)
+    net_rx_ip(m);
+  else if (type == ETHTYPE_ARP)
+    net_rx_arp(m);
+  else
+    mbuffree(m);
+}

kernel/net.h

@@ -0,0 +1,173 @@
+//
+// packet buffer management
+//
+
+#define MBUF_SIZE              2048
+#define MBUF_DEFAULT_HEADROOM  128
+
+struct mbuf {
+  struct mbuf  *next; // the next mbuf in the chain
+  char         *head; // the current start position of the buffer
+  unsigned int len;   // the length of the buffer
+  char         buf[MBUF_SIZE]; // the backing store
+};
+
+char *mbufpull(struct mbuf *m, unsigned int len);
+char *mbufpush(struct mbuf *m, unsigned int len);
+char *mbufput(struct mbuf *m, unsigned int len);
+char *mbuftrim(struct mbuf *m, unsigned int len);
+
+// The above functions manipulate the size and position of the buffer:
+//            <- push            <- trim
+//             -> pull            -> put
+// [-headroom-][------buffer------][-tailroom-]
+// |----------------MBUF_SIZE-----------------|
+//
+// These marcos automatically typecast and determine the size of header structs.
+// In most situations you should use these instead of the raw ops above.
+#define mbufpullhdr(mbuf, hdr) (typeof(hdr)*)mbufpull(mbuf, sizeof(hdr))
+#define mbufpushhdr(mbuf, hdr) (typeof(hdr)*)mbufpush(mbuf, sizeof(hdr))
+#define mbufputhdr(mbuf, hdr) (typeof(hdr)*)mbufput(mbuf, sizeof(hdr))
+#define mbuftrimhdr(mbuf, hdr) (typeof(hdr)*)mbuftrim(mbuf, sizeof(hdr))
+
+struct mbuf *mbufalloc(unsigned int headroom);
+void mbuffree(struct mbuf *m);
+
+struct mbufq {
+  struct mbuf *head;  // the first element in the queue
+  struct mbuf *tail;  // the last element in the queue
+};
+
+void mbufq_pushtail(struct mbufq *q, struct mbuf *m);
+struct mbuf *mbufq_pophead(struct mbufq *q);
+int mbufq_empty(struct mbufq *q);
+void mbufq_init(struct mbufq *q);
+
+
+//
+// endianness support
+//
+
+static inline uint16 bswaps(uint16 val)
+{
+  return (((val & 0x00ffU) << 8) |
+          ((val & 0xff00U) >> 8));
+}
+
+static inline uint32 bswapl(uint32 val)
+{
+  return (((val & 0x000000ffUL) << 24) |
+          ((val & 0x0000ff00UL) << 8) |
+          ((val & 0x00ff0000UL) >> 8) |
+          ((val & 0xff000000UL) >> 24));
+}
+
+// Use these macros to convert network bytes to the native byte order.
+// Note that Risc-V uses little endian while network order is big endian.
+#define ntohs bswaps
+#define ntohl bswapl
+#define htons bswaps
+#define htonl bswapl
+
+
+//
+// useful networking headers
+//
+
+#define ETHADDR_LEN 6
+
+// an Ethernet packet header (start of the packet).
+struct eth {
+  uint8  dhost[ETHADDR_LEN];
+  uint8  shost[ETHADDR_LEN];
+  uint16 type;
+} __attribute__((packed));
+
+#define ETHTYPE_IP  0x0800 // Internet protocol
+#define ETHTYPE_ARP 0x0806 // Address resolution protocol
+
+// an IP packet header (comes after an Ethernet header).
+struct ip {
+  uint8  ip_vhl; // version << 4 | header length >> 2
+  uint8  ip_tos; // type of service
+  uint16 ip_len; // total length
+  uint16 ip_id;  // identification
+  uint16 ip_off; // fragment offset field
+  uint8  ip_ttl; // time to live
+  uint8  ip_p;   // protocol
+  uint16 ip_sum; // checksum
+  uint32 ip_src, ip_dst;
+};
+
+#define IPPROTO_ICMP 1  // Control message protocol
+#define IPPROTO_TCP  6  // Transmission control protocol
+#define IPPROTO_UDP  17 // User datagram protocol
+
+#define MAKE_IP_ADDR(a, b, c, d)           \
+  (((uint32)a << 24) | ((uint32)b << 16) | \
+   ((uint32)c << 8) | (uint32)d)
+
+// a UDP packet header (comes after an IP header).
+struct udp {
+  uint16 sport; // source port
+  uint16 dport; // destination port
+  uint16 ulen;  // length, including udp header, not including IP header
+  uint16 sum;   // checksum
+};
+
+// an ARP packet (comes after an Ethernet header).
+struct arp {
+  uint16 hrd; // format of hardware address
+  uint16 pro; // format of protocol address
+  uint8  hln; // length of hardware address
+  uint8  pln; // length of protocol address
+  uint16 op;  // operation
+
+  char   sha[ETHADDR_LEN]; // sender hardware address
+  uint32 sip;              // sender IP address
+  char   tha[ETHADDR_LEN]; // target hardware address
+  uint32 tip;              // target IP address
+} __attribute__((packed));
+
+#define ARP_HRD_ETHER 1 // Ethernet
+
+enum {
+  ARP_OP_REQUEST = 1, // requests hw addr given protocol addr
+  ARP_OP_REPLY = 2,   // replies a hw addr given protocol addr
+};
+
+// an DNS packet (comes after an UDP header).
+struct dns {
+  uint16 id;  // request ID
+
+  uint8 rd: 1;  // recursion desired
+  uint8 tc: 1;  // truncated
+  uint8 aa: 1;  // authoritive
+  uint8 opcode: 4; 
+  uint8 qr: 1;  // query/response
+  uint8 rcode: 4; // response code
+  uint8 cd: 1;  // checking disabled
+  uint8 ad: 1;  // authenticated data
+  uint8 z:  1;  
+  uint8 ra: 1;  // recursion available
+  
+  uint16 qdcount; // number of question entries
+  uint16 ancount; // number of resource records in answer section
+  uint16 nscount; // number of NS resource records in authority section
+  uint16 arcount; // number of resource records in additional records
+} __attribute__((packed));
+
+struct dns_question {
+  uint16 qtype;
+  uint16 qclass;
+} __attribute__((packed));
+  
+#define ARECORD (0x0001)
+#define QCLASS  (0x0001)
+
+struct dns_data {
+  uint16 type;
+  uint16 class;
+  uint32 ttl;
+  uint16 len;
+} __attribute__((packed));

kernel/pci.c

@@ -0,0 +1,61 @@
+//
+// simple PCI-Express initialization, only
+// works for qemu and its e1000 card.
+//
+
+#include "types.h"
+#include "param.h"
+#include "memlayout.h"
+#include "riscv.h"
+#include "spinlock.h"
+#include "proc.h"
+#include "defs.h"
+
+void
+pci_init()
+{
+  // we'll place the e1000 registers at this address.
+  // vm.c maps this range.
+  uint64 e1000_regs = 0x40000000L;
+
+  // qemu -machine virt puts PCIe config space here.
+  // vm.c maps this range.
+  uint32  *ecam = (uint32 *) 0x30000000L;
+  
+  // look at each possible PCI device on bus 0.
+  for(int dev = 0; dev < 32; dev++){
+    int bus = 0;
+    int func = 0;
+    int offset = 0;
+    uint32 off = (bus << 16) | (dev << 11) | (func << 8) | (offset);
+    volatile uint32 *base = ecam + off;
+    uint32 id = base[0];
+    
+    // 100e:8086 is an e1000
+    if(id == 0x100e8086){
+      // command and status register.
+      // bit 0 : I/O access enable
+      // bit 1 : memory access enable
+      // bit 2 : enable mastering
+      base[1] = 7;
+      __sync_synchronize();
+
+      for(int i = 0; i < 6; i++){
+        uint32 old = base[4+i];
+
+        // writing all 1's to the BAR causes it to be
+        // replaced with its size.
+        base[4+i] = 0xffffffff;
+        __sync_synchronize();
+
+        base[4+i] = old;
+      }
+
+      // tell the e1000 to reveal its registers at
+      // physical address 0x40000000.
+      base[4+0] = e1000_regs;
+
+      e1000_init((uint32*)e1000_regs);
+    }
+  }
+}

kernel/plic.c

@@ -14,6 +14,13 @@ plicinit(void)
   // set desired IRQ priorities non-zero (otherwise disabled).
   *(uint32*)(PLIC + UART0_IRQ*4) = 1;
   *(uint32*)(PLIC + VIRTIO0_IRQ*4) = 1;
+  
+#ifdef LAB_NET
+  // PCIE IRQs are 32 to 35
+  for(int irq = 1; irq < 0x35; irq++){
+    *(uint32*)(PLIC + irq*4) = 1;
+  }
+#endif  
 }
 
 void
@@ -25,6 +32,11 @@ plicinithart(void)
   // for the uart and virtio disk.
   *(uint32*)PLIC_SENABLE(hart) = (1 << UART0_IRQ) | (1 << VIRTIO0_IRQ);
 
+#ifdef LAB_NET
+  // hack to get at next 32 IRQs for e1000
+  *(uint32*)(PLIC_SENABLE(hart)+4) = 0xffffffff;
+#endif
+  
   // set this hart's S-mode priority threshold to 0.
   *(uint32*)PLIC_SPRIORITY(hart) = 0;
 }

kernel/spinlock.c

@@ -8,12 +8,52 @@
 #include "proc.h"
 #include "defs.h"
 
+#ifdef LAB_LOCK
+#define NLOCK 500
+
+static struct spinlock *locks[NLOCK];
+struct spinlock lock_locks;
+
+void
+freelock(struct spinlock *lk)
+{
+  acquire(&lock_locks);
+  int i;
+  for (i = 0; i < NLOCK; i++) {
+    if(locks[i] == lk) {
+      locks[i] = 0;
+      break;
+    }
+  }
+  release(&lock_locks);
+}
+
+static void
+findslot(struct spinlock *lk) {
+  acquire(&lock_locks);
+  int i;
+  for (i = 0; i < NLOCK; i++) {
+    if(locks[i] == 0) {
+      locks[i] = lk;
+      release(&lock_locks);
+      return;
+    }
+  }
+  panic("findslot");
+}
+#endif
+
 void
 initlock(struct spinlock *lk, char *name)
 {
   lk->name = name;
   lk->locked = 0;
   lk->cpu = 0;
+#ifdef LAB_LOCK
+  lk->nts = 0;
+  lk->n = 0;
+  findslot(lk);
+#endif  
 }
 
 // Acquire the lock.
@@ -25,12 +65,21 @@ acquire(struct spinlock *lk)
   if(holding(lk))
     panic("acquire");
 
+#ifdef LAB_LOCK
+    __sync_fetch_and_add(&(lk->n), 1);
+#endif      
+
   // On RISC-V, sync_lock_test_and_set turns into an atomic swap:
   //   a5 = 1
   //   s1 = &lk->locked
   //   amoswap.w.aq a5, a5, (s1)
-  while(__sync_lock_test_and_set(&lk->locked, 1) != 0)
+  while(__sync_lock_test_and_set(&lk->locked, 1) != 0) {
+#ifdef LAB_LOCK
+    __sync_fetch_and_add(&(lk->nts), 1);
+#else
    ;
+#endif
+  }
 
   // Tell the C compiler and the processor to not move loads or stores
   // past this point, to ensure that the critical section's memory
@@ -108,3 +157,69 @@ pop_off(void)
   if(c->noff == 0 && c->intena)
     intr_on();
 }
+
+// Read a shared 64-bit value without holding a lock
+uint64
+lockfree_read8(uint64 *addr) {
+  uint64 val;
+  __atomic_load(addr, &val, __ATOMIC_SEQ_CST);
+  return val;
+}
+
+// Read a shared 32-bit value without holding a lock
+int
+lockfree_read4(int *addr) {
+  uint32 val;
+  __atomic_load(addr, &val, __ATOMIC_SEQ_CST);
+  return val;
+}
+
+#ifdef LAB_LOCK
+int
+snprint_lock(char *buf, int sz, struct spinlock *lk)
+{
+  int n = 0;
+  if(lk->n > 0) {
+    n = snprintf(buf, sz, "lock: %s: #test-and-set %d #acquire() %d\n",
+                 lk->name, lk->nts, lk->n);
+  }
+  return n;
+}
+
+int
+statslock(char *buf, int sz) {
+  int n;
+  int tot = 0;
+
+  acquire(&lock_locks);
+  n = snprintf(buf, sz, "--- lock kmem/bcache stats\n");
+  for(int i = 0; i < NLOCK; i++) {
+    if(locks[i] == 0)
+      break;
+    if(strncmp(locks[i]->name, "bcache", strlen("bcache")) == 0 ||
+       strncmp(locks[i]->name, "kmem", strlen("kmem")) == 0) {
+      tot += locks[i]->nts;
+      n += snprint_lock(buf +n, sz-n, locks[i]);
+    }
+  }
+  
+  n += snprintf(buf+n, sz-n, "--- top 5 contended locks:\n");
+  int last = 100000000;
+  // stupid way to compute top 5 contended locks
+  for(int t = 0; t < 5; t++) {
+    int top = 0;
+    for(int i = 0; i < NLOCK; i++) {
+      if(locks[i] == 0)
+        break;
+      if(locks[i]->nts > locks[top]->nts && locks[i]->nts < last) {
+        top = i;
+      }
+    }
+    n += snprint_lock(buf+n, sz-n, locks[top]);
+    last = locks[top]->nts;
+  }
+  n += snprintf(buf+n, sz-n, "tot= %d\n", tot);
+  release(&lock_locks);  
+  return n;
+}
+#endif

kernel/syscall.c

@@ -102,6 +102,13 @@ extern uint64 sys_link(void);
 extern uint64 sys_mkdir(void);
 extern uint64 sys_close(void);
 
+#ifdef LAB_NET
+extern uint64 sys_connect(void);
+#endif
+#ifdef LAB_PGTBL
+extern uint64 sys_pgaccess(void);
+#endif
+
 // An array mapping syscall numbers from syscall.h
 // to the function that handles the system call.
 static uint64 (*syscalls[])(void) = {
@@ -126,8 +133,16 @@ static uint64 (*syscalls[])(void) = {
 [SYS_link]    sys_link,
 [SYS_mkdir]   sys_mkdir,
 [SYS_close]   sys_close,
+#ifdef LAB_NET
+[SYS_connect] sys_connect,
+#endif
+#ifdef LAB_PGTBL
+[SYS_pgaccess] sys_pgaccess,
+#endif
 };
 
+
+
 void
 syscall(void)
 {

kernel/syscall.h

@@ -20,3 +20,14 @@
 #define SYS_link   19
 #define SYS_mkdir  20
 #define SYS_close  21
+
+// System calls for labs
+#define SYS_trace     22
+#define SYS_sysinfo   23
+#define SYS_sigalarm  24
+#define SYS_sigreturn 25
+#define SYS_symlink   26
+#define SYS_mmap      27
+#define SYS_munmap    28
+#define SYS_connect   29
+#define SYS_pgaccess  30

kernel/sysfile.c

@@ -503,3 +503,29 @@ sys_pipe(void)
   }
   return 0;
 }
+
+
+#ifdef LAB_NET
+int
+sys_connect(void)
+{
+  struct file *f;
+  int fd;
+  uint32 raddr;
+  uint32 rport;
+  uint32 lport;
+
+  argint(0, (int*)&raddr);
+  argint(1, (int*)&lport);
+  argint(2, (int*)&rport);
+
+  if(sockalloc(&f, raddr, lport, rport) < 0)
+    return -1;
+  if((fd=fdalloc(f)) < 0){
+    fileclose(f);
+    return -1;
+  }
+
+  return fd;
+}
+#endif

kernel/sysnet.c

@@ -0,0 +1,185 @@
+//
+// network system calls.
+//
+
+#include "types.h"
+#include "param.h"
+#include "memlayout.h"
+#include "riscv.h"
+#include "spinlock.h"
+#include "proc.h"
+#include "defs.h"
+#include "fs.h"
+#include "sleeplock.h"
+#include "file.h"
+#include "net.h"
+
+struct sock {
+  struct sock *next; // the next socket in the list
+  uint32 raddr;      // the remote IPv4 address
+  uint16 lport;      // the local UDP port number
+  uint16 rport;      // the remote UDP port number
+  struct spinlock lock; // protects the rxq
+  struct mbufq rxq;  // a queue of packets waiting to be received
+};
+
+static struct spinlock lock;
+static struct sock *sockets;
+
+void
+sockinit(void)
+{
+  initlock(&lock, "socktbl");
+}
+
+int
+sockalloc(struct file **f, uint32 raddr, uint16 lport, uint16 rport)
+{
+  struct sock *si, *pos;
+
+  si = 0;
+  *f = 0;
+  if ((*f = filealloc()) == 0)
+    goto bad;
+  if ((si = (struct sock*)kalloc()) == 0)
+    goto bad;
+
+  // initialize objects
+  si->raddr = raddr;
+  si->lport = lport;
+  si->rport = rport;
+  initlock(&si->lock, "sock");
+  mbufq_init(&si->rxq);
+  (*f)->type = FD_SOCK;
+  (*f)->readable = 1;
+  (*f)->writable = 1;
+  (*f)->sock = si;
+
+  // add to list of sockets
+  acquire(&lock);
+  pos = sockets;
+  while (pos) {
+    if (pos->raddr == raddr &&
+        pos->lport == lport &&
+	pos->rport == rport) {
+      release(&lock);
+      goto bad;
+    }
+    pos = pos->next;
+  }
+  si->next = sockets;
+  sockets = si;
+  release(&lock);
+  return 0;
+
+bad:
+  if (si)
+    kfree((char*)si);
+  if (*f)
+    fileclose(*f);
+  return -1;
+}
+
+void
+sockclose(struct sock *si)
+{
+  struct sock **pos;
+  struct mbuf *m;
+
+  // remove from list of sockets
+  acquire(&lock);
+  pos = &sockets;
+  while (*pos) {
+    if (*pos == si){
+      *pos = si->next;
+      break;
+    }
+    pos = &(*pos)->next;
+  }
+  release(&lock);
+
+  // free any pending mbufs
+  while (!mbufq_empty(&si->rxq)) {
+    m = mbufq_pophead(&si->rxq);
+    mbuffree(m);
+  }
+
+  kfree((char*)si);
+}
+
+int
+sockread(struct sock *si, uint64 addr, int n)
+{
+  struct proc *pr = myproc();
+  struct mbuf *m;
+  int len;
+
+  acquire(&si->lock);
+  while (mbufq_empty(&si->rxq) && !pr->killed) {
+    sleep(&si->rxq, &si->lock);
+  }
+  if (pr->killed) {
+    release(&si->lock);
+    return -1;
+  }
+  m = mbufq_pophead(&si->rxq);
+  release(&si->lock);
+
+  len = m->len;
+  if (len > n)
+    len = n;
+  if (copyout(pr->pagetable, addr, m->head, len) == -1) {
+    mbuffree(m);
+    return -1;
+  }
+  mbuffree(m);
+  return len;
+}
+
+int
+sockwrite(struct sock *si, uint64 addr, int n)
+{
+  struct proc *pr = myproc();
+  struct mbuf *m;
+
+  m = mbufalloc(MBUF_DEFAULT_HEADROOM);
+  if (!m)
+    return -1;
+
+  if (copyin(pr->pagetable, mbufput(m, n), addr, n) == -1) {
+    mbuffree(m);
+    return -1;
+  }
+  net_tx_udp(m, si->raddr, si->lport, si->rport);
+  return n;
+}
+
+// called by protocol handler layer to deliver UDP packets
+void
+sockrecvudp(struct mbuf *m, uint32 raddr, uint16 lport, uint16 rport)
+{
+  //
+  // Find the socket that handles this mbuf and deliver it, waking
+  // any sleeping reader. Free the mbuf if there are no sockets
+  // registered to handle it.
+  //
+  struct sock *si;
+
+  acquire(&lock);
+  si = sockets;
+  while (si) {
+    if (si->raddr == raddr && si->lport == lport && si->rport == rport)
+      goto found;
+    si = si->next;
+  }
+  release(&lock);
+  mbuffree(m);
+  return;
+
+found:
+  acquire(&si->lock);
+  mbufq_pushtail(&si->rxq, m);
+  wakeup(&si->rxq);
+  release(&si->lock);
+  release(&lock);
+}

kernel/sysproc.c

@@ -55,6 +55,8 @@ sys_sleep(void)
   uint ticks0;
 
   argint(0, &n);
+  if(n < 0)
+    n = 0;
   acquire(&tickslock);
   ticks0 = ticks;
   while(ticks - ticks0 < n){

kernel/trap.c

@@ -68,6 +68,8 @@ usertrap(void)
   } else if((which_dev = devintr()) != 0){
     // ok
   } else {
+
+    
     printf("usertrap(): unexpected scause %p pid=%d\n", r_scause(), p->pid);
     printf("            sepc=%p stval=%p\n", r_sepc(), r_stval());
     setkilled(p);
@@ -76,6 +78,7 @@ usertrap(void)
   if(killed(p))
     exit(-1);
   
+
   // give up the CPU if this is a timer interrupt.
   if(which_dev == 2)
     yield();
@@ -190,7 +193,13 @@ devintr()
       uartintr();
     } else if(irq == VIRTIO0_IRQ){
       virtio_disk_intr();
-    } else if(irq){
+    }
+#ifdef LAB_NET
+    else if(irq == E1000_IRQ){
+      e1000_intr();
+    }
+#endif
+    else if(irq){
       printf("unexpected interrupt irq=%d\n", irq);
     }
 

kernel/vm.c

@@ -4,6 +4,8 @@
 #include "elf.h"
 #include "riscv.h"
 #include "defs.h"
+#include "spinlock.h"
+#include "proc.h"
 #include "fs.h"
 
 /*
@@ -30,6 +32,14 @@ kvmmake(void)
   // virtio mmio disk interface
   kvmmap(kpgtbl, VIRTIO0, VIRTIO0, PGSIZE, PTE_R | PTE_W);
 
+#ifdef LAB_NET
+  // PCI-E ECAM (configuration space), for pci.c
+  kvmmap(kpgtbl, 0x30000000L, 0x30000000L, 0x10000000, PTE_R | PTE_W);
+
+  // pci.c maps the e1000's registers here.
+  kvmmap(kpgtbl, 0x40000000L, 0x40000000L, 0x20000, PTE_R | PTE_W);
+#endif  
+
   // PLIC
   kvmmap(kpgtbl, PLIC, PLIC, 0x400000, PTE_R | PTE_W);
 
@@ -179,8 +189,10 @@ uvmunmap(pagetable_t pagetable, uint64 va, uint64 npages, int do_free)
   for(a = va; a < va + npages*PGSIZE; a += PGSIZE){
     if((pte = walk(pagetable, a, 0)) == 0)
       panic("uvmunmap: walk");
-    if((*pte & PTE_V) == 0)
+    if((*pte & PTE_V) == 0) {
+      printf("va=%p pte=%p\n", a, *pte);
       panic("uvmunmap: not mapped");
+    }
     if(PTE_FLAGS(*pte) == PTE_V)
       panic("uvmunmap: not a leaf");
     if(do_free){
@@ -437,3 +449,6 @@ copyinstr(pagetable_t pagetable, char *dst, uint64 srcva, uint64 max)
     return -1;
   }
 }
+
+
+

ping.py

@@ -0,0 +1,12 @@
+import socket
+import sys
+import time
+
+sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
+addr = ('localhost', int(sys.argv[1]))
+buf = "this is a ping!".encode('utf-8')
+
+while True:
+	print("pinging...", file=sys.stderr)
+	sock.sendto(buf, ("127.0.0.1", int(sys.argv[1])))
+	time.sleep(1)

server.py

@@ -0,0 +1,13 @@
+import socket
+import sys
+
+sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
+addr = ('localhost', int(sys.argv[1]))
+print('listening on %s port %s' % addr, file=sys.stderr)
+sock.bind(addr)
+
+while True:
+    buf, raddr = sock.recvfrom(4096)
+    print(buf.decode("utf-8"), file=sys.stderr)
+    if buf:
+        sent = sock.sendto(b'this is the host!', raddr)

time.txt

@@ -0,0 +1 @@
+5

user/cat.c

@@ -1,5 +1,6 @@
 #include "kernel/types.h"
 #include "kernel/stat.h"
+#include "kernel/fcntl.h"
 #include "user/user.h"
 
 char buf[512];
@@ -32,7 +33,7 @@ main(int argc, char *argv[])
   }
 
   for(i = 1; i < argc; i++){
-    if((fd = open(argv[i], 0)) < 0){
+    if((fd = open(argv[i], O_RDONLY)) < 0){
       fprintf(2, "cat: cannot open %s\n", argv[i]);
       exit(1);
     }

user/grep.c

@@ -2,6 +2,7 @@
 
 #include "kernel/types.h"
 #include "kernel/stat.h"
+#include "kernel/fcntl.h"
 #include "user/user.h"
 
 char buf[1024];
@@ -51,7 +52,7 @@ main(int argc, char *argv[])
   }
 
   for(i = 2; i < argc; i++){
-    if((fd = open(argv[i], 0)) < 0){
+    if((fd = open(argv[i], O_RDONLY)) < 0){
       printf("grep: cannot open %s\n", argv[i]);
       exit(1);
     }

user/ls.c

@@ -2,6 +2,7 @@
 #include "kernel/stat.h"
 #include "user/user.h"
 #include "kernel/fs.h"
+#include "kernel/fcntl.h"
 
 char*
 fmtname(char *path)
@@ -30,7 +31,7 @@ ls(char *path)
   struct dirent de;
   struct stat st;
 
-  if((fd = open(path, 0)) < 0){
+  if((fd = open(path, O_RDONLY)) < 0){
     fprintf(2, "ls: cannot open %s\n", path);
     return;
   }

user/nettests.c

@@ -0,0 +1,297 @@
+#include "kernel/types.h"
+#include "kernel/net.h"
+#include "kernel/stat.h"
+#include "user/user.h"
+
+//
+// send a UDP packet to the localhost (outside of qemu),
+// and receive a response.
+//
+static void
+ping(uint16 sport, uint16 dport, int attempts)
+{
+  int fd;
+  char *obuf = "a message from xv6!";
+  uint32 dst;
+
+  // 10.0.2.2, which qemu remaps to the external host,
+  // i.e. the machine you're running qemu on.
+  dst = (10 << 24) | (0 << 16) | (2 << 8) | (2 << 0);
+
+  // you can send a UDP packet to any Internet address
+  // by using a different dst.
+  
+  if((fd = connect(dst, sport, dport)) < 0){
+    fprintf(2, "ping: connect() failed\n");
+    exit(1);
+  }
+
+  for(int i = 0; i < attempts; i++) {
+    if(write(fd, obuf, strlen(obuf)) < 0){
+      fprintf(2, "ping: send() failed\n");
+      exit(1);
+    }
+  }
+
+  char ibuf[128];
+  int cc = read(fd, ibuf, sizeof(ibuf)-1);
+  if(cc < 0){
+    fprintf(2, "ping: recv() failed\n");
+    exit(1);
+  }
+
+  close(fd);
+  ibuf[cc] = '\0';
+  if(strcmp(ibuf, "this is the host!") != 0){
+    fprintf(2, "ping didn't receive correct payload\n");
+    exit(1);
+  }
+}
+
+// Encode a DNS name
+static void
+encode_qname(char *qn, char *host)
+{
+  char *l = host; 
+  
+  for(char *c = host; c < host+strlen(host)+1; c++) {
+    if(*c == '.') {
+      *qn++ = (char) (c-l);
+      for(char *d = l; d < c; d++) {
+        *qn++ = *d;
+      }
+      l = c+1; // skip .
+    }
+  }
+  *qn = '\0';
+}
+
+// Decode a DNS name
+static void
+decode_qname(char *qn, int max)
+{
+  char *qnMax = qn + max;
+  while(1){
+    if(qn >= qnMax){
+      printf("invalid DNS reply\n");
+      exit(1);
+    }
+    int l = *qn;
+    if(l == 0)
+      break;
+    for(int i = 0; i < l; i++) {
+      *qn = *(qn+1);
+      qn++;
+    }
+    *qn++ = '.';
+  }
+}
+
+// Make a DNS request
+static int
+dns_req(uint8 *obuf)
+{
+  int len = 0;
+  
+  struct dns *hdr = (struct dns *) obuf;
+  hdr->id = htons(6828);
+  hdr->rd = 1;
+  hdr->qdcount = htons(1);
+  
+  len += sizeof(struct dns);
+  
+  // qname part of question
+  char *qname = (char *) (obuf + sizeof(struct dns));
+  char *s = "pdos.csail.mit.edu.";
+  encode_qname(qname, s);
+  len += strlen(qname) + 1;
+
+  // constants part of question
+  struct dns_question *h = (struct dns_question *) (qname+strlen(qname)+1);
+  h->qtype = htons(0x1);
+  h->qclass = htons(0x1);
+
+  len += sizeof(struct dns_question);
+  return len;
+}
+
+// Process DNS response
+static void
+dns_rep(uint8 *ibuf, int cc)
+{
+  struct dns *hdr = (struct dns *) ibuf;
+  int len;
+  char *qname = 0;
+  int record = 0;
+
+  if(cc < sizeof(struct dns)){
+    printf("DNS reply too short\n");
+    exit(1);
+  }
+
+  if(!hdr->qr) {
+    printf("Not a DNS reply for %d\n", ntohs(hdr->id));
+    exit(1);
+  }
+
+  if(hdr->id != htons(6828)){
+    printf("DNS wrong id: %d\n", ntohs(hdr->id));
+    exit(1);
+  }
+  
+  if(hdr->rcode != 0) {
+    printf("DNS rcode error: %x\n", hdr->rcode);
+    exit(1);
+  }
+  
+  //printf("qdcount: %x\n", ntohs(hdr->qdcount));
+  //printf("ancount: %x\n", ntohs(hdr->ancount));
+  //printf("nscount: %x\n", ntohs(hdr->nscount));
+  //printf("arcount: %x\n", ntohs(hdr->arcount));
+  
+  len = sizeof(struct dns);
+
+  for(int i =0; i < ntohs(hdr->qdcount); i++) {
+    char *qn = (char *) (ibuf+len);
+    qname = qn;
+    decode_qname(qn, cc - len);
+    len += strlen(qn)+1;
+    len += sizeof(struct dns_question);
+  }
+
+  for(int i = 0; i < ntohs(hdr->ancount); i++) {
+    if(len >= cc){
+      printf("invalid DNS reply\n");
+      exit(1);
+    }
+    
+    char *qn = (char *) (ibuf+len);
+
+    if((int) qn[0] > 63) {  // compression?
+      qn = (char *)(ibuf+qn[1]);
+      len += 2;
+    } else {
+      decode_qname(qn, cc - len);
+      len += strlen(qn)+1;
+    }
+      
+    struct dns_data *d = (struct dns_data *) (ibuf+len);
+    len += sizeof(struct dns_data);
+    //printf("type %d ttl %d len %d\n", ntohs(d->type), ntohl(d->ttl), ntohs(d->len));
+    if(ntohs(d->type) == ARECORD && ntohs(d->len) == 4) {
+      record = 1;
+      printf("DNS arecord for %s is ", qname ? qname : "" );
+      uint8 *ip = (ibuf+len);
+      printf("%d.%d.%d.%d\n", ip[0], ip[1], ip[2], ip[3]);
+      if(ip[0] != 128 || ip[1] != 52 || ip[2] != 129 || ip[3] != 126) {
+        printf("wrong ip address");
+        exit(1);
+      }
+      len += 4;
+    }
+  }
+
+  // needed for DNS servers with EDNS support
+  for(int i = 0; i < ntohs(hdr->arcount); i++) {
+    char *qn = (char *) (ibuf+len);
+    if(*qn != 0) {
+      printf("invalid name for EDNS\n");
+      exit(1);
+    }
+    len += 1;
+
+    struct dns_data *d = (struct dns_data *) (ibuf+len);
+    len += sizeof(struct dns_data);
+    if(ntohs(d->type) != 41) {
+      printf("invalid type for EDNS\n");
+      exit(1);
+    }
+    len += ntohs(d->len);
+  }
+
+  if(len != cc) {
+    printf("Processed %d data bytes but received %d\n", len, cc);
+    exit(1);
+  }
+  if(!record) {
+    printf("Didn't receive an arecord\n");
+    exit(1);
+  }
+}
+
+static void
+dns()
+{
+  #define N 1000
+  uint8 obuf[N];
+  uint8 ibuf[N];
+  uint32 dst;
+  int fd;
+  int len;
+
+  memset(obuf, 0, N);
+  memset(ibuf, 0, N);
+  
+  // 8.8.8.8: google's name server
+  dst = (8 << 24) | (8 << 16) | (8 << 8) | (8 << 0);
+
+  if((fd = connect(dst, 10000, 53)) < 0){
+    fprintf(2, "ping: connect() failed\n");
+    exit(1);
+  }
+
+  len = dns_req(obuf);
+  
+  if(write(fd, obuf, len) < 0){
+    fprintf(2, "dns: send() failed\n");
+    exit(1);
+  }
+  int cc = read(fd, ibuf, sizeof(ibuf));
+  if(cc < 0){
+    fprintf(2, "dns: recv() failed\n");
+    exit(1);
+  }
+  dns_rep(ibuf, cc);
+
+  close(fd);
+}  
+
+int
+main(int argc, char *argv[])
+{
+  int i, ret;
+  uint16 dport = NET_TESTS_PORT;
+
+  printf("nettests running on port %d\n", dport);
+  
+  printf("testing ping: ");
+  ping(2000, dport, 1);
+  printf("OK\n");
+  
+  printf("testing single-process pings: ");
+  for (i = 0; i < 100; i++)
+    ping(2000, dport, 1);
+  printf("OK\n");
+  
+  printf("testing multi-process pings: ");
+  for (i = 0; i < 10; i++){
+    int pid = fork();
+    if (pid == 0){
+      ping(2000 + i + 1, dport, 1);
+      exit(0);
+    }
+  }
+  for (i = 0; i < 10; i++){
+    wait(&ret);
+    if (ret != 0)
+      exit(1);
+  }
+  printf("OK\n");
+  
+  printf("testing DNS\n");
+  dns();
+  printf("DNS OK\n");
+  
+  printf("all tests passed.\n");
+  exit(0);
+}

user/pingpong.c

@@ -0,0 +1,52 @@
+#include "kernel/types.h"
+#include "kernel/stat.h"
+#include "user/user.h"
+
+#define N 5
+char buf[N];
+
+void
+pong(int *parent_to_child, int *child_to_parent) {
+  if (read(parent_to_child[0], buf, N) < 0) {
+    printf("read failed\n");
+  }
+  printf("%d: received %s\n", getpid(), buf);
+  if (write(child_to_parent[1], "pong", 4) != 4) {
+    printf("write failed\n");
+  }
+}
+
+void
+ping(int *parent_to_child, int *child_to_parent) {
+  
+  if (write(parent_to_child[1], "ping", 4) != 4) {
+    printf("write failed\n");
+  }
+  if (read(child_to_parent[0], buf, N) < 0) {
+    printf("read failed\n");
+  }
+  printf("%d: received %s\n", getpid(), buf);
+}
+
+int
+main(int argc, char *argv[])
+{
+  int parent_to_child[2];
+  int child_to_parent[2];
+
+  int pid;
+
+  if (pipe(parent_to_child) < 0 || pipe(child_to_parent) < 0) {
+    printf("pipe failed\n");
+  }
+  if ((pid = fork()) < 0) {
+    printf("fork failed\n");
+  }
+  if (pid == 0) {
+    pong(parent_to_child, child_to_parent);
+  } else {
+    ping(parent_to_child, child_to_parent);
+  }
+  
+  exit(0);
+}

user/user.h

@@ -22,6 +22,14 @@ int getpid(void);
 char* sbrk(int);
 int sleep(int);
 int uptime(void);
+#ifdef LAB_NET
+int connect(uint32, uint16, uint16);
+#endif
+#ifdef LAB_PGTBL
+int pgaccess(void *base, int len, void *mask);
+// usyscall region
+int ugetpid(void);
+#endif
 
 // ulib.c
 int stat(const char*, struct stat*);
@@ -39,3 +47,4 @@ void free(void*);
 int atoi(const char*);
 int memcmp(const void *, const void *, uint);
 void *memcpy(void *, const void *, uint);
+int statistics(void*, int);

user/usys.pl

@@ -36,3 +36,5 @@ entry("getpid");
 entry("sbrk");
 entry("sleep");
 entry("uptime");
+entry("connect");
+entry("pgaccess");

user/wc.c

@@ -1,5 +1,6 @@
 #include "kernel/types.h"
 #include "kernel/stat.h"
+#include "kernel/fcntl.h"
 #include "user/user.h"
 
 char buf[512];
@@ -43,7 +44,7 @@ main(int argc, char *argv[])
   }
 
   for(i = 1; i < argc; i++){
-    if((fd = open(argv[i], 0)) < 0){
+    if((fd = open(argv[i], O_RDONLY)) < 0){
       printf("wc: cannot open %s\n", argv[i]);
       exit(1);
     }