initramfs: Switch to the alpm-hooks approach, supporting both initcpio/dracut

This is one of the major changes/refactors so far, touches a lot of
files, and more important, it completely changes some premises.
With this patch, we now support fully both dracut-based and initcpio
initramfs systems.

For that to happen, we needed to decouple the initramfs creation from
scripts, by using alpm-hooks. These hooks allow scripts to be run on
events like kernel package installation or in the installation of the very
package responsible to create the initramfs image. We still have the
"kdump-load create-initrd" command though.

One of the biggest modifications here was in the Makefile, that now
composes multiple files by changing keywords (like INITRD) to the
respective initramfs system (dracut or mkinitcpio). Notice that this
brought some extra complexity to the package.

The logic used for supporting both initramfs systems was basically
de-duplicate all possible code (having dup code in common files),
using Makefile tricks to merge such files and have the unique
bits in dracut/initcpio specific files. We currently support dracut
and both mkinitcpio and mkinitcpio-git packages.

Caveats: currently the initramfs specific package removal is not handled
here. So, if the user has dracut and installs kdump, we install the
dracut hooks. In case this user decides to remove dracut and installs
mkinitcpio, we install the mkinitcpio hooks and all should work, but
the previous dracut hooks installed are not unistalled by us; likely
the dracut package removal would drop the files itself.

This was a deliberate move to avoid even more alpm-hooks, should be
a rare case and as said, the package removal should clear the files
itself, without requiring our interaction. Also, by using the
alpm-hooks, we see "errors" (warnings really) about the other
initramfs package not being present - not sure if it's possible to
disable this behavior.

Finally, while at it:

* Added a new approach to dracut initramfs creation to pick the most
common block drivers - since it's hostonly, it doesn't add the ones
that aren't loaded, hence image is not bloated by that.

* Chenged the "command -v makedumpfile" validation to something
more elegant - thanks for the suggestion Clayton (@craftyguy).

Signed-off-by: Guilherme G. Piccoli <gpiccoli@igalia.com>

initramfs/alpm-hook.generic

@@ -0,0 +1,27 @@
+#  SPDX-License-Identifier: LGPL-2.1+
+#
+#  Copyright (c) 2022 Valve.
+#  Maintainer: Guilherme G. Piccoli <gpiccoli@igalia.com>
+#
+#  alpm hook to deal with the kdump initramfs creation/deletion
+#  for INITRD users. This hook would act upon kernel installation,
+#  upgrade and removal, also on INITRD package installation.
+#
+[Trigger]
+Type = Path
+Operation = Install
+Operation = Remove
+Operation = Upgrade
+Target = usr/lib/modules/*/vmlinuz
+
+[Trigger]
+Type = Package
+Operation = Install
+Target = INITRD
+
+[Action]
+Description = Managing kdump minimal initramfs and INITRD hooks...
+Depends=INITRD
+When = PostTransaction
+Exec = /usr/lib/kdump/kdump-INITRD-hook.sh
+NeedsTargets

initramfs/alpm-script.header

@@ -0,0 +1,16 @@
+#!/bin/bash
+set -eo pipefail #  exclude -u on purpose to avoid issues with param checking
+#
+#  SPDX-License-Identifier: LGPL-2.1+
+#
+#  Copyright (c) 2022 Valve.
+#  Maintainer: Guilherme G. Piccoli <gpiccoli@igalia.com>
+#
+#  This is the generic alpm-hook script that handles kernel/package
+#  installation for INITRD users, on behalf of kdump. Covers both manual
+#  invocation (to create the initramfs image for a given kernel) as
+#  well as kernel package installation/removal trigger. It also handles
+#  the event of installing the package INITRD, which requires the
+#  installation of initramfs hooks to be executed early in boot time,
+#  in case of a kdump.
+#

initramfs/alpm-script.sh.in

@@ -0,0 +1,43 @@
+load_kdump_config
+
+#  General comment of a caveat here: INITRD_installation() must be
+#  reentrant and only install the INITRD handlers if they're not
+#  already installed. This is necessary due to a kinda chicken-egg
+#  problem: the first time initramfs creation is attempted, we did't
+#  necessarily run the INITRD package installation hooks yet, hence
+#  we may be unable to properly create the initramfs image. "Easy"
+#  solution is to just try to install them always, it's cheap and not
+#  dependent of package install time magic.
+
+#  Parameter passing case - since this is invoked by the kdump-load
+#  script, we must be sure that the INITRD package is available.
+if [ -n "$1" ]; then
+
+	if command -v INITRD 1>/dev/null; then
+		INITRD_installation
+		create_initramfs_INITRD "$1"
+	fi
+	exit 0
+fi
+
+while read -r line; do
+	#  First case is the INITRD package installation.
+	if [[ "$line" != */vmlinuz ]]; then
+		INITRD_installation
+		exit 0
+	fi
+
+	#  If reaching this point, we're installing/removing the kernel image.
+	VERSION="$(basename "$(dirname "$line")")"
+
+	#  If the file exists, means it's an installation step;
+	#  notice that alpm suppresses the leading '/'.
+	if [ -f /"$line" ]; then
+		INITRD_installation
+		create_initramfs_INITRD "$VERSION"
+	else
+		rm -f "${MOUNT_FOLDER}"/kdump-initrd-"$VERSION".img
+
+	fi
+	exit 0
+done

initramfs/dracut/dracut-common.sh

@@ -0,0 +1,34 @@
+#  Functions to deal with dracut specifics, both for building
+#  the initramfs for dracut users, but also with regards to
+#  installing dracut specific hooks/scripts.
+#
+#  IMPORTANT: it is assumed that kdump configuration was loaded
+#  before running any of these functions!
+#
+create_initramfs_dracut() {
+	rm -f "${MOUNT_FOLDER}/kdump-initrd-$1.img"
+
+	DRACUT_NO_XATTR=1 dracut --no-early-microcode --host-only -q -m\
+	"bash systemd systemd-initrd systemd-sysusers modsign dbus-daemon kdump dbus udev-rules dracut-systemd base fs-lib shutdown"\
+	--kver "$1" "${MOUNT_FOLDER}/kdump-initrd-$1.img"
+
+	if [ -s "${MOUNT_FOLDER}/kdump-initrd-$1.img" ]; then
+		logger "kdump: created dracut minimal initramfs"
+	fi
+}
+
+dracut_installation() {
+	HOOKS_DIR="/usr/lib/kdump/dracut/"
+
+	DRACUT_DIR="$(pkg-config --variable=dracutmodulesdir dracut 2>/dev/null)"
+	if [ -z "${DRACUT_DIR}" ]; then
+		DRACUT_DIR="/usr/lib/dracut/modules.d/"
+	fi
+
+	if [ ! -d "${DRACUT_DIR}"/55kdump/ ]; then
+		install -D -m0755 "${HOOKS_DIR}"/kdump-collect.sh "${DRACUT_DIR}"/55kdump/kdump-collect.sh
+		install -D -m0755 "${HOOKS_DIR}"/module-setup.sh "${DRACUT_DIR}"/55kdump/module-setup.sh
+		logger "kdump: dracut hooks/scripts installed"
+	fi
+}
+

initramfs/dracut/module-setup.header

@@ -0,0 +1,10 @@
+#!/bin/bash
+#
+#  SPDX-License-Identifier: LGPL-2.1+
+#
+#  Copyright (c) 2021 Valve.
+#  Maintainer: Guilherme G. Piccoli <gpiccoli@igalia.com>
+#
+#  Kdump-initrd module construction/inclusion script for
+#  Dracut-based initramfs.
+#

initramfs/dracut/module-setup.sh.in

@@ -0,0 +1,76 @@
+#  Only include kdump if it is explicitly asked in the argument list
+check() {
+	return 255
+}
+
+installkernel() {
+	load_kdump_config
+
+	#  First clear all unnecessary firmwares/drivers added by drm in order
+	#  to reduce the size of the minimal initramfs being created - kdump
+	#  is an non-graphical environment. This should have been already done
+	#  via dracut cmdline arguments, but play safe and delete here as well.
+	#  Our list includes the most common FWs/drivers (amd, i915, nvidia).
+	rm -rf "$initdir"/usr/lib/firmware/{amdgpu,i915,nvidia,radeon}
+	rm -rf "$initdir"/usr/lib/modules/*/kernel/drivers/gpu/drm/{amd,i915,nouveau,radeon}
+
+	FSMOD="$(findmnt -n -o FSTYPE --target "${MOUNT_FOLDER}")"
+	if [ -z "${FSMOD}" ]; then
+		logger "kdump: error on filesystem discovery"
+		exit 1
+	fi
+
+	instmods "${FSMOD}"
+
+	#  We try here to be comprehensive and include the most common
+	#  block modules to allow mounting the target device - notice
+	#  that since we use hostonly, only the ones that make sense would
+	#  get added, hence this list won't bloat the minimal image!
+	instmods aacraid
+	instmods ahci
+	instmods hpsa
+	instmods megaraid_sas
+	instmods mpt3sas
+	instmods nvme
+	instmods virtio_blk
+	instmods virtio-scsi
+}
+
+install() {
+	# A valid makedumpfile is essential for the kdump initrd creation.
+	if ! command -v makedumpfile 1>/dev/null; then
+		logger "kdump: failed to create dracut initrd, makedumpfile is missing"
+		exit 1
+	fi
+
+	load_kdump_config
+
+	#  Install necessary binaries
+	inst date
+	inst sync
+	inst makedumpfile
+
+	#  Copying kdump config/lib files is essential for a functional kdump.
+	cp -LR --preserve=all /usr/share/kdump.d/ "$initdir"/usr/share/
+	cp -LR --preserve=all /usr/lib/kdump/ "$initdir"/usr/lib/
+
+	#  Finally, we need to derive the proper place to save the dump from the
+	#  config files, in a way that makes possible to mount it in early boot.
+	DEVNODE="$(findmnt -n -o SOURCE --target "${MOUNT_FOLDER}")"
+	if [ -z "${DEVNODE}" ]; then
+		logger "kdump: error on devnode discovery"
+		exit 1
+	fi
+	echo "${DEVNODE}" > "$initdir"/usr/lib/kdump/kdump.mnt
+
+	TGT="$(findmnt -n -o TARGET --target "${MOUNT_FOLDER}")"
+	if [ -z "${TGT}" ]; then
+		logger "kdump: error on base folder discovery"
+		exit 1
+	fi
+
+	BASE_FLD="${MOUNT_FOLDER#*$TGT}"
+	echo "${BASE_FLD}" > "$initdir"/usr/lib/kdump/kdump.dir
+
+	inst_hook pre-mount 01 "$moddir/kdump-collect.sh"
+}

initramfs/initcpio/initcpio-common.sh

@@ -0,0 +1,29 @@
+#  Functions to deal with initcpio specifics, both for building
+#  the initramfs for mkinitcpio users, but also with regards to
+#  installing its specific hooks.
+#
+#  IMPORTANT: it is assumed that kdump configuration was loaded
+#  before running any of these functions!
+#
+create_initramfs_mkinitcpio() {
+	rm -f "${MOUNT_FOLDER}/kdump-initrd-$1.img"
+
+	mkinitcpio -A kdump -g "${MOUNT_FOLDER}/kdump-initrd-$1.img" "$1" 1>/dev/null
+
+	if [ -s "${MOUNT_FOLDER}/kdump-initrd-$1.img" ]; then
+		logger "kdump: created initcpio minimal initramfs"
+	fi
+}
+
+mkinitcpio_installation() {
+	KDUMP_HOOKS_DIR="/usr/lib/kdump/initcpio/"
+	INITCPIO_HOOKS="/usr/lib/initcpio/hooks"
+	INITCPIO_INST="/usr/lib/initcpio/install"
+
+	if [ ! -e "${INITCPIO_HOOKS}"/kdump ] || [ ! -e "${INITCPIO_INST}"/kdump ]; then
+		install -D -m0644 "${KDUMP_HOOKS_DIR}"/kdump.hook "${INITCPIO_HOOKS}"/kdump
+		install -D -m0644 "${KDUMP_HOOKS_DIR}"/kdump.install "${INITCPIO_INST}"/kdump
+		logger "kdump: initcpio hooks installed"
+	fi
+}
+

initramfs/initcpio/kdump.install.header

@@ -0,0 +1,9 @@
+#!/bin/bash
+#  SPDX-License-Identifier: LGPL-2.1+
+#
+#  Copyright (c) 2022 Valve.
+#  Maintainer: Guilherme G. Piccoli <gpiccoli@igalia.com>
+#
+#  Kdump-initrd module construction/inclusion script for
+#  initcpio-based initramfs.
+#

initramfs/initcpio/kdump.install.in

@@ -0,0 +1,51 @@
+build() {
+    load_kdump_config
+
+    # A valid makedumpfile is essential for the kdump initrd creation.
+    if ! command -v makedumpfile 1>/dev/null; then
+        logger "kdump: failed to create minimal initrd, makedumpfile is missing"
+        exit 1
+    fi
+
+    add_binary /usr/bin/date
+    add_binary /usr/bin/sync
+    add_binary "$(command -v makedumpfile)"
+
+    #  Copying kdump config/lib files is essential for a functional kdump.
+    add_full_dir /usr/share/kdump.d/
+    add_full_dir /usr/lib/kdump/
+
+    #  We need to derive the proper place to save the dump from the
+    #  config files, in a way that makes possible to mount it in early boot.
+    DEVNODE="$(findmnt -n -o SOURCE --target "${MOUNT_FOLDER}")"
+    if [ -z "${DEVNODE}" ]; then
+        logger "kdump: error on devnode discovery"
+        exit 1
+    fi
+    echo "${DEVNODE}" > "${BUILDROOT}"/usr/lib/kdump/kdump.mnt
+
+    TGT="$(findmnt -n -o TARGET --target "${MOUNT_FOLDER}")"
+    if [ -z "${TGT}" ]; then
+        logger "kdump: error on base folder discovery"
+        exit 1
+    fi
+
+    BASE_FLD="${MOUNT_FOLDER#*$TGT}"
+    echo "${BASE_FLD}" > "${BUILDROOT}"/usr/lib/kdump/kdump.dir
+
+    #  Finally, we shouldn't have DRM/GPU drivers and firmwares here,
+    #  but...just in case, let's remove all of that nevertheless.
+    #  Our list includes the most common FWs/drivers (amd, i915, nvidia).
+    rm -rf "${BUILDROOT}"/usr/lib/firmware/{amdgpu,i915,nvidia,radeon}
+    rm -rf "${BUILDROOT}"/usr/lib/modules/*/kernel/drivers/gpu/drm/{amd,i915,nouveau,radeon}
+
+    add_runscript
+}
+
+help() {
+    cat <<HELPEOF
+This hook is responsible for creating the minimal kdump initramfs.
+HELPEOF
+}
+
+# vim: set ft=sh ts=4 sw=4 et:

initramfs/kdump-collect.sh

@@ -0,0 +1,61 @@
+#!/bin/sh
+#
+#  SPDX-License-Identifier: LGPL-2.1+
+#
+#  Copyright (c) 2022 Valve.
+#  Maintainer: Guilherme G. Piccoli <gpiccoli@igalia.com>
+#
+#  Script for effectively collecting the core dump/dmesg from
+#  within a minimal initrd - part of the kdump/pstore tooling.
+#  The most fail-prone operations are guarded with conditionals to
+#  bail in case we indeed fail - worst thing here would be to have
+#  a bad condition and get stuck in this minimal initrd with no
+#  output for the user. Notice that the script is used in both
+#  dracut and initcpio cases.
+#
+
+#ENTRY POINT
+    #  Bail out in case we don't have a vmcore, i.e. either we're not kdumping
+    #  or something is pretty wrong and we wouldn't be able to progress.
+    VMCORE="/proc/vmcore"
+    if [ ! -f "$VMCORE" ]; then
+	    reboot -f
+    fi
+
+    #  We have a more controlled situation with regards the config
+    #  files here, since we manually added them in the initrd and
+    #  the validation also happened there, during such addition,
+    #  hence not requiring checks here.
+    for cfg in "/usr/share/kdump.d"/*; do
+	. "$cfg"
+    done
+
+    KDUMP_TIMESTAMP=$(date -u +"%Y%m%d%H%M")
+    MOUNT_POINT="$(cat /usr/lib/kdump/kdump.mnt)"
+    BASE_FOLDER="$(cat /usr/lib/kdump/kdump.dir)"
+    KDUMP_FOLDER="/kdump_path/${BASE_FOLDER}/crash/${KDUMP_TIMESTAMP}"
+
+    mkdir -p "/kdump_path"
+    if ! mount "${MOUNT_POINT}" /kdump_path; then
+        reboot -f
+    fi
+
+    mkdir -p "${KDUMP_FOLDER}"
+
+    #  we want to split on spaces, it's a set of parameters!
+    #  shellcheck disable=SC2086
+    /usr/bin/makedumpfile ${MAKEDUMPFILE_DMESG_CMD} $VMCORE "${KDUMP_FOLDER}/dmesg.txt"
+    sync "${KDUMP_FOLDER}/dmesg.txt"
+
+    if [ "${FULL_COREDUMP}" -ne 0 ]; then
+        #  shellcheck disable=SC2086
+        /usr/bin/makedumpfile ${MAKEDUMPFILE_COREDUMP_CMD} $VMCORE "${KDUMP_FOLDER}/vmcore.compressed"
+        sync "${KDUMP_FOLDER}/vmcore.compressed"
+    fi
+
+    umount "${MOUNT_POINT}"
+    sync
+
+    reboot -f
+#END
+