move all our stuff into /lkmc in guest

Motivation: userland is getting several new subdirectories, it would be
too insane to just dump all of that in the guest root filesystem.

To alleviate the cd pain, .profile puts user inside /lkmc by default.

rootfs_overlay/lkmc/README.adoc

@@ -0,0 +1 @@
+https://github.com/cirosantilli/linux-kernel-module-cheat#rootfs_overlay

rootfs_overlay/lkmc/anonymous_inode.sh

@@ -0,0 +1,5 @@
+#!/bin/sh
+set -e
+insmod anonymous_inode.ko
+[ "$(/anonymous_inode.out /sys/kernel/debug/lkmc_anonymous_inode 3)" = "$(printf '1\n10\n100')" ]
+rmmod anonymous_inode

rootfs_overlay/lkmc/character_device.sh

@@ -0,0 +1,7 @@
+#!/bin/sh
+set -e
+insmod character_device.ko
+/mknoddev.sh lkmc_character_device
+[ "$(cat /dev/lkmc_character_device)" = 'abcd' ]
+rm /dev/lkmc_character_device
+rmmod character_device

rootfs_overlay/lkmc/character_device_create.sh

@@ -0,0 +1,7 @@
+#!/bin/sh
+set -e
+insmod character_device_create.ko
+dev='/dev/lkmc_character_device_create_dev'
+[ "$(cat "$dev")" = abcd ]
+rmmod character_device_create
+[ ! -e "$dev" ]

rootfs_overlay/lkmc/conf.sh

@@ -0,0 +1,3 @@
+#!/bin/sh
+# https://github.com/cirosantilli/linux-kernel-module-cheat#find-the-kernel-config
+zcat /proc/config.gz | grep -Ei "${1:-}"

rootfs_overlay/lkmc/count.sh

@@ -0,0 +1,9 @@
+#!/bin/sh
+# Count to infinity with 1 second sleep between each increment.
+# Generate infinitely many system calls :-)
+i=0
+while true; do
+  echo "$i"
+  i=$(($i+1))
+  sleep 1
+done

rootfs_overlay/lkmc/debugfs.sh

@@ -0,0 +1,13 @@
+#!/bin/sh
+set -e
+d=/debugfs
+mkdir -p "$d"
+mount -t debugfs none "$d"
+insmod debugfs.ko
+[ "$(cat "${d}/lkmc_debugfs/myfile")" = 42 ]
+echo 13 > "${d}/lkmc_debugfs/myfile"
+[ "$(cat "${d}/lkmc_debugfs/myfile")" = 13 ]
+echo 666 > "${d}/lkmc_debugfs_file"
+[ "$(cat "${d}/lkmc_debugfs/myfile")" = 666 ]
+rmmod debugfs
+umount "$d"

rootfs_overlay/lkmc/dep.sh

@@ -0,0 +1,27 @@
+#!/bin/sh
+set -e
+f=/sys/kernel/debug/lkmc_dep
+f2=/sys/kernel/debug/lkmc_dep2
+
+insmod dep.ko
+insmod dep2.ko
+
+# Initial value.
+[ "$(cat "$f")" = 0 ]
+
+# Changhing dep2 also changes dep.
+printf 1 > "$f2"
+[ "$(cat "$f")" = 1 ]
+
+# Changhing dep also changes dep2.
+printf 2 > "$f"
+[ "$(cat "$f2")" = 2 ]
+
+# sysfs shows us that the module has dependants.
+[ "$(cat /sys/module/dep/refcnt)" = 1 ]
+[ "$(ls /sys/module/dep/holders)" = dep2 ]
+rmmod dep2.ko
+[ "$(cat /sys/module/dep/refcnt)" = 0 ]
+[ -z "$(ls /sys/module/dep/holders)" ]
+
+rmmod dep.ko

rootfs_overlay/lkmc/eval_base64.sh

@@ -0,0 +1,4 @@
+#!/bin/sh
+# https://github.com/cirosantilli/linux-kernel-module-cheat#replace-init
+cd "$lkmc_home"
+eval "$(printf "$lkmc_eval" | base64 -d)"

rootfs_overlay/lkmc/fb.sh

@@ -0,0 +1,2 @@
+#!/bin/sh
+cat /dev/urandom > "/dev/fb${1:-0}"

rootfs_overlay/lkmc/fops.sh

@@ -0,0 +1,30 @@
+#!/bin/sh
+set -e
+
+# Setup
+f=/sys/kernel/debug/lkmc_fops
+insmod fops.ko
+
+# read
+[ "$(cat "$f")" = abcd ]
+
+# write
+printf 01 > "$f"
+[ "$(cat "$f")" = 01cd ]
+
+# ENOSPC
+printf abcd > "$f"
+set +e
+printf 12345 > "$f"
+exit_status="$?"
+set -e
+[ "$exit_status" -eq 8 ]
+[ "$(cat "$f")" = abcd ]
+
+# seek
+printf 1234 > "$f"
+printf z | dd bs=1 of="$f" seek=2
+[ "$(cat "$f")" = 12z4 ]
+
+# Teardown
+rmmod fops

rootfs_overlay/lkmc/gdbserver.sh

@@ -0,0 +1,3 @@
+#!/bin/sh
+/sbin/ifup -a
+gdbserver :45455 "$@"

rootfs_overlay/lkmc/gem5.sh

@@ -0,0 +1,6 @@
+#!/bin/sh
+# https://github.com/cirosantilli/linux-kernel-module-cheat#gem5-restore-new-scrip
+m5 checkpoint
+m5 resetstats
+m5 readfile | sh
+m5 exit

rootfs_overlay/lkmc/gem5_exit.sh

@@ -0,0 +1,4 @@
+#!/bin/sh
+# To be able to do init=/gem5_exit.sh, since kernel CLI argument passing is too messy:
+# https://github.com/cirosantilli/linux-kernel-module-cheat#init-arguments
+m5 exit

rootfs_overlay/lkmc/gpio.sh

@@ -0,0 +1,27 @@
+#!/bin/sh
+set -e
+cd /sys/class/gpio
+echo 480 > export
+echo 481 > export
+echo 482 > export
+echo 488 > export
+echo 496 > export
+echo out > gpio480/direction
+echo out > gpio481/direction
+echo out > gpio482/direction
+echo out > gpio488/direction
+echo out > gpio496/direction
+v=1
+while true; do
+  echo $v > gpio480/value
+  echo $v > gpio481/value
+  echo $v > gpio482/value
+  echo $v > gpio488/value
+  echo $v > gpio496/value
+  if [ $v -eq 1 ]; then
+    v=0
+  else
+    v=1
+  fi
+  sleep 1
+done

rootfs_overlay/lkmc/init_forward.sh

@@ -0,0 +1,6 @@
+#!/bin/sh
+# Failed attempt at debugging /init, because:
+#     init must be run as pid 1
+# Is this just a random BusyBox sanity check?
+# - https://stackoverflow.com/questions/35019995/strace-init-process-pid-1-in-linux
+/sbin/init "$@"

rootfs_overlay/lkmc/init_lkmc.sh

@@ -0,0 +1,30 @@
+#!/bin/sh
+
+# This is an attempt to replace /etc/inittab with a single shell file,
+# in order to to make everything explicit and sane.
+#
+# The rationale is that it will make it easier to port our setup to any image
+# if our minimal init is contained in a single portable file.
+#
+# Of course, packages that rely on extra init may start failing at any
+# point with this minimized setup, but this is a risk worth taking, especially
+# because gem5 is slow and basically mandates a minimal init.
+#
+# Here we try to some basic common init tasks that will cover what the large
+# majority of software will need.
+#
+# We don't care about shutdown commands since we focus on stateless disks.
+
+export PATH=/bin:/sbin:/usr/bin:/usr/sbin
+mount -t proc proc /proc
+mkdir -p /dev/pts
+mkdir -p /dev/shm
+# TODO do mounts direclty here. fstab only adds the fschk as extra functionality,
+# but we don't care since our disks are stateless.
+mount -a
+login=/tmp/login
+printf '#!/bin/sh
+exec /bin/login root
+' > "$login"
+chmod +x "$login"
+exec /sbin/getty -n -L -l "$login" console 0 vt100

rootfs_overlay/lkmc/init_module.sh

@@ -0,0 +1,4 @@
+#!/bin/sh
+set -e
+insmod init_module.ko
+rmmod init_module

rootfs_overlay/lkmc/insrm.sh

@@ -0,0 +1,13 @@
+#!/bin/sh
+# Insert and remove a module n times to check for spurious errors / deadlocks.
+set -e
+mod="$1"
+n="${2:-1}"
+i=0
+while [ $i -lt $n ]; do
+  echo "insmod $i"
+  insmod "/$mod.ko"
+  echo "rmmod $i"
+  rmmod "$mod"
+  i=$(($i+1))
+done

rootfs_overlay/lkmc/ioctl.sh

@@ -0,0 +1,7 @@
+#!/bin/sh
+set -e
+f=/sys/kernel/debug/lkmc_ioctl
+insmod ioctl.ko
+[ "$(/ioctl.out "$f" 0 1)" = 2 ]
+[ "$(/ioctl.out "$f" 1 1 1)" = '2 0' ]
+rmmod ioctl

rootfs_overlay/lkmc/kgdb.sh

@@ -0,0 +1,2 @@
+#!/bin/sh
+echo g > /proc/sysrq-trigger

rootfs_overlay/lkmc/kstrto.sh

@@ -0,0 +1,8 @@
+#!/bin/sh
+set -e
+f=/sys/kernel/debug/lkmc_kstrto
+insmod kstrto.ko
+printf 123 > "$f"
+[ "$(cat "$f")" = 124 ]
+echo foobar > "$f" && exit 1
+rmmod kstrto

rootfs_overlay/lkmc/loginroot.sh

@@ -0,0 +1,3 @@
+#!/bin/sh
+# https://github.com/cirosantilli/linux-kernel-module-cheat#tty
+exec /bin/login root

rootfs_overlay/lkmc/mknoddev.sh

@@ -0,0 +1,4 @@
+#!/bin/sh
+dev="$1"
+major="$(awk -F ' ' '$2 == "'"$dev"'" { print $1 }' /proc/devices)"
+mknod "/dev/$dev" c "$major" 0

rootfs_overlay/lkmc/mmap.sh

@@ -0,0 +1,5 @@
+#!/bin/sh
+set -e
+insmod mmap.ko
+./mmap.out /proc/lkmc_mmap 2>&1 1>/dev/null
+rmmod mmap.ko

rootfs_overlay/lkmc/netlink.sh

@@ -0,0 +1,7 @@
+#!/bin/sh
+set -e
+insmod netlink.ko
+[ "$(/netlink.out)" = 0 ]
+[ "$(/netlink.out)" = 1 ]
+[ "$(/netlink.out)" = 2 ]
+rmmod netlink

rootfs_overlay/lkmc/params.sh

@@ -0,0 +1,20 @@
+#!/bin/sh
+set -e
+d=/sys/module/params/parameters
+i="${d}/i"
+j="${d}/j"
+f=/sys/kernel/debug/lkmc_params
+
+insmod params.ko
+[ "$(cat "$i")" = 0 ]
+[ "$(cat "$j")" = 0 ]
+[ "$(cat "$f")" = '0 0' ]
+printf 1 > "$i"
+[ "$(cat "$f")" = '1 0' ]
+printf 2 > "$j"
+[ "$(cat "$f")" = '1 2' ]
+rmmod params
+
+insmod params.ko i=3 j=4
+[ "$(cat "$f")" = '3 4' ]
+rmmod params

rootfs_overlay/lkmc/pci_rescan.sh

@@ -0,0 +1,2 @@
+#!/bin/sh
+echo 1 > /sys/bus/pci/rescan

rootfs_overlay/lkmc/pmccntr.sh

@@ -0,0 +1,4 @@
+#!/bin/sh
+insmod pmccntr.ko
+cd /sys/kernel/debug
+cat lkmc_pmccntr

rootfs_overlay/lkmc/poll.sh

@@ -0,0 +1,5 @@
+#!/bin/sh
+set -e
+insmod poll.ko
+./poll.out /sys/kernel/debug/lkmc_poll
+#rmmod poll

rootfs_overlay/lkmc/pr_debug.sh

@@ -0,0 +1,3 @@
+#!/bin/sh
+echo 8 > /proc/sys/kernel/printk
+echo 'file kernel/module.c +p' > /sys/kernel/debug/dynamic_debug/control

rootfs_overlay/lkmc/procfs.sh

@@ -0,0 +1,5 @@
+#!/bin/sh
+set -e
+insmod procfs.ko
+[ "$(cat "/proc/lkmc_procfs")" = abcd ]
+rmmod procfs

rootfs_overlay/lkmc/psa.sh

@@ -0,0 +1,4 @@
+#!/bin/sh
+# Show All possible ps fields to get better process visibility.
+# TODO for some reason nothing shows after args, so we put it last.
+ps -o user,group,comm,pid,ppid,sid,pgid,tty,vsz,rss,stat,args

rootfs_overlay/lkmc/qemu_edu.sh

@@ -0,0 +1,56 @@
+#!/bin/sh
+
+set -ex
+
+# Our modules does not the PCI device yet.
+lspci -k
+# => 00:04.0 Class 00ff: 1234:11e8 lkmc_pci
+
+# Interrupt counts before we generate our interrupts.
+cat /proc/interrupts
+
+# Setup.
+insmod qemu_edu.ko
+/mknoddev.sh lkmc_pci
+
+# Shows that this module owns the PCI device.
+lspci -k
+# => 00:04.0 Class 00ff: 1234:11e8 lkmc_pci
+
+# Identifiction: just returns some fixed magic bytes.
+dd bs=4 status=none if=/dev/lkmc_pci count=1 skip=0 | od -An -t x1
+# => 010000ed
+
+# Negator. Sanity check that the hardware is getting updated.
+dd bs=4 status=none if=/dev/lkmc_pci count=1 skip=1 | od -An -t x1
+printf '\xF0\xF0\xF0\xF0' | dd bs=4 status=none of=/dev/lkmc_pci count=1 seek=1
+dd bs=4 status=none if=/dev/lkmc_pci count=1 skip=1 | od -An -t x1
+# => 0F0F0F0F
+
+# Factorial calculator.
+# Request interrupt when the computation is over.
+printf '\x80\x00\x00\x00' | dd bs=4 status=none of=/dev/lkmc_pci count=1 seek=8
+# factorial(0xC) = 0x1c8cfc00
+printf '\x0C\x00\x00\x00' | dd bs=4 status=none of=/dev/lkmc_pci count=1 seek=2
+# => irq_handler .*
+# Yes, we should use the interrupt to notify poll, but lazy.
+sleep 1
+dd bs=4 status=none if=/dev/lkmc_pci count=1 skip=2 | od -An -t x1
+dd bs=4 status=none if=/dev/lkmc_pci count=1 skip=8 | od -An -t x1
+# => 1c8cfc00
+
+# Manual IRQ raising.
+printf '\x04\x03\x02\x01' | dd bs=4 status=none of=/dev/lkmc_pci count=1 seek=24
+# => irq_handler .*
+sleep 1
+printf '\x08\x07\x06\x05' | dd bs=4 status=none of=/dev/lkmc_pci count=1 seek=24
+# => irq_handler .*
+sleep 1
+
+# Teardown.
+rm /dev/lkmc_pci
+rmmod qemu_edu
+
+# Interrupt counts after we generate our interrupts.
+# Compare with before.
+cat /proc/interrupts

rootfs_overlay/lkmc/rand_check_poweroff.sh

@@ -0,0 +1,12 @@
+#!/bin/sh
+set -ex
+./rand_check.out
+
+# Check if network is being replayed.
+# https://superuser.com/questions/635020/how-to-know-current-time-from-internet-from-command-line-in-linux
+# https://tf.nist.gov/tf-cgi/servers.cgi
+#echo | nc 129.6.15.28 13
+
+# busybox's poweroff panics, TODO why. Likely tries to kill shell.
+# So just use our super raw command.
+./poweroff.out

rootfs_overlay/lkmc/seq_file.sh

@@ -0,0 +1,10 @@
+#!/bin/sh
+set -e
+f=/sys/kernel/debug/lkmc_seq_file
+insmod seq_file.ko
+[ "$(cat "$f")" = "$(printf '0\n1\n2\n')" ]
+[ "$(cat "$f")" = "$(printf '0\n1\n2\n')" ]
+[ "$(dd if="$f" bs=1 count=2 skip=0 status=none)" = "$(printf '0\n')" ]
+[ "$(dd if="$f" bs=1 count=2 skip=2 status=none)" = "$(printf '1\n')" ]
+[ "$(dd if="$f" bs=4 count=1 skip=0 status=none)" = "$(printf '0\n1\n')" ]
+rmmod seq_file

rootfs_overlay/lkmc/seq_file_single_open.sh

@@ -0,0 +1,7 @@
+#!/bin/sh
+set -e
+f=/sys/kernel/debug/lkmc_seq_file_single_open
+insmod seq_file_single_open.ko
+[ "$(cat "$f")" = "$(printf 'ab\ncd\n')" ]
+[ "$(dd if="$f" bs=1 count=3 skip=1)" = "$(printf "b\nc\n")" ]
+rmmod seq_file_single_open

rootfs_overlay/lkmc/sshd.sh

@@ -0,0 +1,4 @@
+#!/bin/sh
+/sbin/ifup -a
+/usr/bin/ssh-keygen -A
+/usr/sbin/sshd

rootfs_overlay/lkmc/sysfs.sh

@@ -0,0 +1,11 @@
+#!/bin/sh
+set -e
+insmod sysfs.ko
+f=/sys/kernel/lkmc_sysfs/foo
+# write
+printf 12345 > "$f"
+# read
+[ "$(cat "$f")" = 1234 ]
+# seek
+[ "$(dd if="$f" bs=1 count=2 skip=1 status=none)" = 23 ]
+rmmod sysfs

rootfs_overlay/lkmc/test_all.sh

@@ -0,0 +1,27 @@
+#!/bin/sh
+test_dir="${1:-.}"
+for test in \
+  anonymous_inode.sh \
+  character_device.sh \
+  character_device_create.sh \
+  debugfs.sh \
+  dep.sh \
+  fops.sh \
+  init_module.sh \
+  ioctl.sh \
+  kstrto.sh \
+  mmap.sh \
+  netlink.sh \
+  params.sh \
+  procfs.sh \
+  seq_file.sh \
+  seq_file_single_open.sh \
+  sysfs.sh \
+; do
+  if ! "${test_dir}/${test}"; then
+    echo "Test failed: ${test}"
+    ./test_fail.sh
+    exit 1
+  fi
+done
+echo 'All tests passed.'

rootfs_overlay/lkmc/test_fail.sh

@@ -0,0 +1,3 @@
+#!/bin/sh
+# https://github.com/cirosantilli/linux-kernel-module-cheat#magic-failure-string
+echo lkmc_test_fail

rootfs_overlay/lkmc/uio_read.sh

@@ -0,0 +1,17 @@
+#!/bin/sh
+# https://github.com/cirosantilli/linux-kernel-module-cheat#uio
+set -e
+modprobe uio_pci_generic
+# pci_min device
+echo '1234 11e9' > /sys/bus/pci/drivers/uio_pci_generic/new_id
+./uio_read.out &
+# Helper to observe interrupts.
+insmod irq.ko
+base="$(setpci -d 1234:11e9 BASE_ADDRESS_0)"
+# Start generating interrupt.
+devmem "0x${base}" w 0x12345678
+# Stop generating interrupt.
+devmem "0x$(($base + 4))" w 0x12345678
+devmem "0x${base}" w 0x12345678
+devmem "0x$(($base + 4))" w 0x12345678
+modprobe -r uio_pci_generic

rootfs_overlay/lkmc/vermagic.sh

@@ -0,0 +1,4 @@
+#!/bin/sh
+set -e
+insmod vermagic.ko
+rmmod vermagic

rootfs_overlay/lkmc/virt_to_phys.sh

@@ -0,0 +1,17 @@
+#!/bin/sh
+set -ex
+insmod virt_to_phys.ko
+cd /sys/kernel/debug
+cat lkmc_virt_to_phys
+# k = 0x12345678
+# i = 0x12345678
+addr=$(awk '$1 == "virt_to_phys_k" { print $2 }' lkmc_virt_to_phys)
+devmem "$addr"
+devmem "$addr" w 0x9ABCDEF0
+addr=$(awk '$1 == "virt_to_phys_i" { print $2 }' lkmc_virt_to_phys)
+devmem "$addr"
+devmem "$addr" w 0x9ABCDEF0
+cat lkmc_virt_to_phys
+# k = 0x9ABCDEF0
+# i = 0x12345678
+rmmod virt_to_phys