kexec-tools: bump version and add support for crashdump kernel

split kexec-tools into two packages, kexec and kdump.
* kexec to simply execute a new kernel
* kdump is for loading and collecting debris of a crashed kernel with
  support for kdump forensics.

In order to properly support booting into a crashkernel, an init script
as well as UCI configuration has been added.
As modifying the kernel cmdline is required for this to work in x86
platforms use an uci-defaults script to modify /boot/grub/grub.cfg.

To test collecting crash information, use the 'c' sysrq-trigger, ie.
echo c > /proc/sysrq-trigger

This should result in the crash kernel being executed and (depending
on the configution) dmesg and/or vmcore getting saved.

To check if the crash kernel was loaded properly, use the 'status'
command of the kdump init script.

Signed-off-by: Daniel Golle <daniel@makrotopia.org>

3 files changed, 200 insertions, 0 deletions

diff --git a/package/boot/kexec-tools/files/kdump.config b/package/boot/kexec-tools/files/kdump.config
new file mode 100644
index 0000000000..dc6054ffdf
--- /dev/null
+++ b/package/boot/kexec-tools/files/kdump.config
@@ -0,0 +1,7 @@
+
+config kdump
+	option enabled '1'
+	option save_dmesg '1'
+	option save_vmcore '0'
+# using an external partition to store vmcore is highly recommended!
+#	option path '/mnt/crashdump'
diff --git a/package/boot/kexec-tools/files/kdump.defaults b/package/boot/kexec-tools/files/kdump.defaults
new file mode 100644
index 0000000000..2f15e757bf
--- /dev/null
+++ b/package/boot/kexec-tools/files/kdump.defaults
@@ -0,0 +1,11 @@
+#!/bin/sh
+
+case $(uname -m) in
+	i?86|x86_64)
+		if ! grep -q crashkernel /boot/grub/grub.cfg; then
+			mount /boot -o remount,rw
+			sed -i 's/linux.*/& crashkernel=32M@32M/' /boot/grub/grub.cfg
+			mount /boot -o remount,ro
+		fi
+		;;
+esac
diff --git a/package/boot/kexec-tools/files/kdump.init b/package/boot/kexec-tools/files/kdump.init
new file mode 100755
index 0000000000..057b8cc17a
--- /dev/null
+++ b/package/boot/kexec-tools/files/kdump.init
@@ -0,0 +1,182 @@
+#!/bin/sh /etc/rc.common
+
+START=41
+STOP=98
+
+EXTRA_COMMANDS="status"
+EXTRA_HELP="        status  Print crashkernel status"
+
+verify_kdump() {
+	local cfg="$1"
+	local enabled
+	local path
+	local save_vmcore
+	local save_dmesg
+
+	config_get_bool enabled "$cfg" enabled 1
+	config_get_bool save_dmesg "$cfg" save_dmesg 1
+	config_get_bool save_vmcore "$cfg" save_vmcore 0
+
+	[ "$enabled" -gt 0 ] || return 2
+
+	[ "$save_dmesg" -gt 0 ] || [ "$save_vmcore" -gt 0 ] || return 2
+
+	config_get path "$cfg" path "/"
+
+	[ -d "$path" ] || mkdir -p "$path" 2>/dev/null || return 1
+}
+
+run_kdump() {
+	local cfg="$1"
+	local enabled
+	local path
+	local save_vmcore
+	local save_dmesg
+
+	config_get_bool enabled "$cfg" enabled 1
+	[ "$enabled" -gt 0 ] || return
+
+	config_get_bool save_dmesg "$cfg" save_dmesg 1
+	config_get_bool save_vmcore "$cfg" save_vmcore 0
+	config_get path "$cfg" path "/"
+
+	timestamp=$(date "+%Y%m%dT%H%M%S")
+
+	if [ "$save_vmcore" -eq 1 ]; then
+		# would like 'sparse' but busybox doesn't support it
+		dd if=/proc/vmcore of="$path/vmcore-$timestamp" conv=fsync bs=1M
+	fi
+
+	if [ "$save_dmesg" -eq 1 ]; then
+		vmcore-dmesg /proc/vmcore > "$path/dmesg-$timestamp"
+	fi
+
+	sync
+	reboot -f
+}
+
+find_kernel() {
+	. /lib/functions.sh
+	local kernel
+
+	kernel="$BOOT_IMAGE"
+	if [ -r "$kernel" ]; then
+		echo $kernel
+		return 0
+	fi
+
+	kernel="$(find_mtd_part kernel)"
+	if [ -r "$kernel" ]; then
+		echo $kernel
+		return 0
+	fi
+
+	for voldir in /sys/class/ubi/ubi*_*; do
+		[ ! -e "$voldir" ] && continue
+		if [ "$(cat "${voldir}/name")" = "kernel" ]; then
+			kernel="/dev/$(basename "$voldir")"
+			echo $kernel
+			return 0
+		fi
+	done
+
+	return 1
+}
+
+load_crashkernel() {
+	local append_cmdline
+	local kernel
+
+	kernel="$(find_kernel)"
+	[ $? -gt 0 ] && return 1
+
+	case "$(uname -m)" in
+		i?86|x86_64)
+			grep -q "crashkernel=" /proc/cmdline || return 1
+			append_cmdline="1 irqpoll reset_devices maxcpus=1"
+			;;
+		arm*)
+			append_cmdline="1 maxcpus=1 reset_devices"
+			;;
+	esac
+	kexec -p "$kernel" --reuse-cmdline --append="$append_cmdline"
+	return $?
+}
+
+start() {
+	local retval
+
+	if [ ! -e /sys/kernel/kexec_crash_loaded ]; then
+		return 1
+	fi
+
+	if [ -e /proc/vmcore ]; then
+		config_load kdump
+		config_foreach run_kdump kdump
+	else
+		config_load kdump
+		config_foreach verify_kdump kdump
+		retval=$?
+		[ $retval = 1 ] && return 1
+		[ $retval = 0 ] && load_crashkernel
+		return $?
+	fi
+}
+
+stop() {
+	[ "$(cat /sys/kernel/kexec_crash_loaded)" = "1" ] || return
+
+	if [ -e "$BOOT_IMAGE" ]; then
+		kexec -p -u "$BOOT_IMAGE"
+	fi
+}
+
+status() {
+	local retval kernel
+
+	if [ ! -e /sys/kernel/kexec_crash_loaded ]; then
+		echo "crashdump not supported by kernel"
+		return
+	fi
+
+	if [ $(cat /sys/kernel/kexec_crash_size) -eq 0 ]; then
+		echo "memory for crashdump kernel not reserved!"
+		echo "check crashkernel= kernel cmdline parameter"
+		echo "(a reboot is required after installing kdump)"
+		return
+	fi
+
+	kernel="$(find_kernel)"
+	if [ $? -gt 0 ]; then
+		echo "cannot find kernel image"
+		return
+	else
+		echo "using kernel image $kernel"
+	fi
+
+	echo -n "kdump configuration is "
+	config_load kdump
+	retval=$?
+	if [ $retval = 0 ]; then
+		if [ "$(config_foreach echo kdump)" ]; then
+			config_foreach verify_kdump kdump
+			retval=$?
+		else
+			retval=1
+		fi
+	fi
+
+	if [ $retval = 0 ]; then
+		echo "valid"
+	elif [ $retval = 2 ]; then
+		echo "disabled"
+	else
+		echo "BROKEN"
+	fi
+
+	echo -n "kexec crash kernel "
+	if [ "$(cat /sys/kernel/kexec_crash_loaded)" = "0" ]; then
+		echo -n "not "
+	fi
+	echo "loaded"
+}