From 2dbaf9f9919a602fede9482c4ab568c23fac5ef2 Mon Sep 17 00:00:00 2001
From: Benjamin Block <bblock@linux.ibm.com>
Date: Fri, 17 Sep 2021 12:29:47 +0200
Subject: [PATCH] chreipl-fcp-mpath: test if the system uses s390x IPL and
 re-IPL is from FCP
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Add second filter stage to the udev rules: only continue with the
toolset, if the system uses s390x IPL and if the current re-IPL target
is from FCP.

For the test, whether the next re-IPL target is planned to be done from
FCP, a helper `chreipl-fcp-mpath-is-reipl-zfcp` is added, and the
information in /sys/firmware/reipl/reipl_type is used.

If either one or both of the tests are not true, the udev rules will
exit.

For debugging, the toolset can be built with the Make variable `D` set
to 1 (e.g.: make D=1; make install D=1). This causes the toolset to
write shell traces of the helper to $(DEBUGOUTDIR) (per default:
/run/udev); otherwise no output is generated. `dbginfo.sh` will be
changed to collect this data automatically.

Reviewed-by: Steffen Maier <maier@linux.ibm.com>
Signed-off-by: Benjamin Block <bblock@linux.ibm.com>
Signed-off-by: Jan Höppner <hoeppner@linux.ibm.com>
---
 chreipl-fcp-mpath/.gitignore                  |  3 +
 chreipl-fcp-mpath/Makefile                    | 99 ++++++++++++++++++-
 .../chreipl-fcp-mpath-common.sh.in            | 44 +++++++++
 .../chreipl-fcp-mpath-is-reipl-zfcp.in        | 25 +++++
 chreipl-fcp-mpath/chreipl-fcp-mpath.mak       | 25 +++++
 .../udev/rules.d/70-chreipl-fcp-mpath.rules   |  8 ++
 6 files changed, 203 insertions(+), 1 deletion(-)
 create mode 100644 chreipl-fcp-mpath/.gitignore
 create mode 100644 chreipl-fcp-mpath/chreipl-fcp-mpath-common.sh.in
 create mode 100644 chreipl-fcp-mpath/chreipl-fcp-mpath-is-reipl-zfcp.in

diff --git a/chreipl-fcp-mpath/.gitignore b/chreipl-fcp-mpath/.gitignore
new file mode 100644
index 00000000..e1121d76
--- /dev/null
+++ b/chreipl-fcp-mpath/.gitignore
@@ -0,0 +1,3 @@
+# build artifacts
+/chreipl-fcp-mpath-common.sh
+/chreipl-fcp-mpath-is-reipl-zfcp
diff --git a/chreipl-fcp-mpath/Makefile b/chreipl-fcp-mpath/Makefile
index 0294ecba..4ea3423f 100644
--- a/chreipl-fcp-mpath/Makefile
+++ b/chreipl-fcp-mpath/Makefile
@@ -40,9 +40,27 @@ chreipl-fcp-mpath-clean:
 all: chreipl-fcp-mpath
 clean: chreipl-fcp-mpath-clean
 
-udev/rules.d/70-chreipl-fcp-mpath.rules:
+# common function used in the helper scripts
+CHREIPL_FCP_MPATH_COMMON	:=					\
+	chreipl-fcp-mpath-common.sh
+CHREIPL_FCP_MPATH_UDEV_HELPER	:=					\
+	chreipl-fcp-mpath-is-reipl-zfcp
+
+$(CHREIPL_FCP_MPATH_UDEV_HELPER) $(CHREIPL_FCP_MPATH_COMMON): $(MAKEFILE_LIST)
+$(CHREIPL_FCP_MPATH_UDEV_HELPER) $(CHREIPL_FCP_MPATH_COMMON): % : %.in
+	$(call chreiplzfcpmp-sed-buildvar-replace,$(<),$(@))
+	chmod a+x $(@)
+
+$(CHREIPL_FCP_MPATH_UDEV_HELPER): $(CHREIPL_FCP_MPATH_COMMON)
+
+.PHONY: chreipl-fcp-mpath-udev-helper-clean
+chreipl-fcp-mpath-udev-helper-clean:
+	rm -f $(CHREIPL_FCP_MPATH_UDEV_HELPER) $(CHREIPL_FCP_MPATH_COMMON)
+
+udev/rules.d/70-chreipl-fcp-mpath.rules: $(CHREIPL_FCP_MPATH_UDEV_HELPER)
 
 chreipl-fcp-mpath: udev/rules.d/70-chreipl-fcp-mpath.rules
+chreipl-fcp-mpath-clean: chreipl-fcp-mpath-udev-helper-clean
 
 #
 ## Install
@@ -69,3 +87,82 @@ chreipl-fcp-mpath-install-udev-rules: udev/rules.d/70-chreipl-fcp-mpath.rules
 		udev/rules.d/70-chreipl-fcp-mpath.rules
 
 chreipl-fcp-mpath-install: chreipl-fcp-mpath-install-udev-rules
+
+# install udev helper programs
+INSTDIRS += $(UDEVDIR)
+
+.PHONY: chreipl-fcp-mpath-install-udev-helper
+chreipl-fcp-mpath-install-udev-helper: | $(DESTDIR)$(UDEVDIR)
+chreipl-fcp-mpath-install-udev-helper: $(CHREIPL_FCP_MPATH_UDEV_HELPER)
+	$(INSTALL_EXEC) -t $(DESTDIR)$(UDEVDIR) $(CHREIPL_FCP_MPATH_UDEV_HELPER)
+
+chreipl-fcp-mpath-install: chreipl-fcp-mpath-install-udev-helper
+
+# install common library files
+INSTDIRS += $(CHREIPLZFCPMPDIR)
+
+.PHONY: chreipl-fcp-mpath-install-libfiles
+chreipl-fcp-mpath-install-libfiles: | $(DESTDIR)$(CHREIPLZFCPMPDIR)
+chreipl-fcp-mpath-install-libfiles: $(CHREIPL_FCP_MPATH_COMMON)
+	$(INSTALL_DATA) -t $(DESTDIR)$(CHREIPLZFCPMPDIR)		\
+		$(CHREIPL_FCP_MPATH_COMMON)
+
+chreipl-fcp-mpath-install: chreipl-fcp-mpath-install-libfiles
+
+#
+## Utility
+#
+
+# Utilities for the debug feature of chreipl-fcp-mpath-common.sh.
+#
+# When `chreipl-fcp-mpath` is built with D=1 (default is D=0), each run
+# of one of the helper scripts will create a debug log in $(DEBUGOUTDIR)
+# (default: /run/udev) which among other things contains the complete shell
+# trace of that script run, with some added information that would not be
+# inspectable otherwise with just the trace.
+#
+# There is currently no way of enabling/disabling this at runtime.
+#
+# chreipl-fcp-mpath-common.sh defines debug log file name as
+# "chreiplzfcpmp-${debug_trace_tag}-${SEQNUM:-0}.XXXXXXXXXX" where SEQNUM is a
+# udev rule environment variable and each X is replaced with some [[:alnum:]]
+# by mktemp. For a definition of `debug_trace_tag`, please see the comments
+# in the source.
+#
+# The following targets can be used for some simple access and filtering of the
+# logs during development.
+
+DEBUG_LOG_GLOB = $(DEBUGOUTDIR)/chreiplzfcpmp-[[:digit:]][[:digit:]][[:alpha:]][[:alpha:]][[:alpha:]][[:alpha:]]-+([[:digit:]]).[[:alnum:]][[:alnum:]][[:alnum:]][[:alnum:]][[:alnum:]][[:alnum:]][[:alnum:]][[:alnum:]][[:alnum:]][[:alnum:]]
+
+# display all debug log files on the system
+.PHONY: chreipl-fcp-mpath-debug-logs
+chreipl-fcp-mpath-debug-logs:
+	@ls -1d $(DEBUG_LOG_GLOB)
+
+# display only debug log files of script runs that exited with status 0 (= good)
+#
+# XXX: `sed -n -e '$p'` is used instead of `tail -n1` to prevent an other
+#      dependency just for that (both invocations do the same thing).
+.PHONY: chreipl-fcp-mpath-debug-logs-filter-good
+chreipl-fcp-mpath-debug-logs-filter-good:
+	@for lg in $(DEBUG_LOG_GLOB); do				\
+		sed -e '/^+ trap_exit$$/,/^+ trap - EXIT$$/d' "$${lg}"	\
+		    | sed -n -e '$$p'					\
+		    | grep -q -e '^+ exit 0$$'		|| continue;	\
+		ls -d "$${lg}";						\
+	done
+
+# display only debug log files of script runs that didn't exit with status 0
+# (= bad)
+.PHONY: chreipl-fcp-mpath-debug-logs-filter-bad
+chreipl-fcp-mpath-debug-logs-filter-bad:
+	@for lg in $(DEBUG_LOG_GLOB); do				\
+		sed -e '/^+ trap_exit$$/,/^+ trap - EXIT$$/d' "$${lg}"	\
+		    | sed -n -e '$$p'					\
+		    | grep -q -e '^+ exit 0$$'		&& continue;	\
+		ls -d "$${lg}";						\
+	done
+
+.PHONY: chreipl-fcp-mpath-debug-logs-clean
+chreipl-fcp-mpath-debug-logs-clean:
+	rm -f $(DEBUG_LOG_GLOB)
diff --git a/chreipl-fcp-mpath/chreipl-fcp-mpath-common.sh.in b/chreipl-fcp-mpath/chreipl-fcp-mpath-common.sh.in
new file mode 100644
index 00000000..dd64cc5c
--- /dev/null
+++ b/chreipl-fcp-mpath/chreipl-fcp-mpath-common.sh.in
@@ -0,0 +1,44 @@
+#!/bin/bash
+# SPDX-License-Identifier: MIT
+#
+# chreipl-fcp-mpath: use multipath information to change FCP IPL target
+# (C) Copyright IBM Corp. 2021
+#
+# Uses the following system-utilities (and shell-builtins):
+#   GNU coreutils:
+#     - mktemp
+
+# Makes use of udev event environment variables:
+#	SEQNUM
+
+# (1) don't overwrite existing files using redirects (e.g.: `>`)
+set -o noclobber
+
+# make sure any state files created are only writeable by the owning user
+umask 027
+
+# create log if DEBUG is enabled (with Make: D=1)
+#
+# Each script importing this library and expecting a debug log to be created
+# must declare a *trace tag* in a variable `debug_trace_tag`. This is used as
+# identifier in the log file name. The format is:
+#
+#     [[:digit:]][[:digit:]][[:alpha:]][[:alpha:]][[:alpha:]][[:alpha:]]
+#     \                    /\                                          /
+#      --------\  /--------  -------------------\  /-------------------
+#               \/                               \/
+#      relative position of  some unique abbreviation for the script
+#      execution in the      name, excluding any common prefix
+#      udev rules
+if '@DEBUG@' && [ -v debug_trace_tag ] && tlg="$(
+	mktemp -p '@debugoutdir@'					\
+		"chreiplzfcpmp-${debug_trace_tag}-${SEQNUM:-0}.XXXXXXXXXX" \
+		2>/dev/null)"
+then
+	readonly tlg
+	exec >|"${tlg}" 2>&1
+	set -x
+	set
+else
+	unset tlg
+fi
diff --git a/chreipl-fcp-mpath/chreipl-fcp-mpath-is-reipl-zfcp.in b/chreipl-fcp-mpath/chreipl-fcp-mpath-is-reipl-zfcp.in
new file mode 100644
index 00000000..7b8fb299
--- /dev/null
+++ b/chreipl-fcp-mpath/chreipl-fcp-mpath-is-reipl-zfcp.in
@@ -0,0 +1,25 @@
+#!/bin/bash
+# SPDX-License-Identifier: MIT
+#
+# chreipl-fcp-mpath: use multipath information to change FCP IPL target
+# (C) Copyright IBM Corp. 2021
+#
+# Uses the following system-utilities (and shell-builtins):
+#   Those necessary for sourced library:
+#     - chreipl-fcp-mpath-common.sh
+
+# Find out whether ReIPL is gonna happen from a SCSI volume attached via zFCP
+
+# shellcheck disable=SC2034
+declare -gr debug_trace_tag=00iriz
+# shellcheck disable=SC1091
+source '@chreiplzfcpmp-lib@' || exit 127
+
+declare reipl_type
+
+{ read -r reipl_type _ < /sys/firmware/reipl/reipl_type; } 2>/dev/null || exit 1
+if '@DEBUG@'; then declare -p reipl_type 1>&2; fi
+
+[ "${reipl_type}" = "fcp" ]					|| exit 2
+
+exit 0
diff --git a/chreipl-fcp-mpath/chreipl-fcp-mpath.mak b/chreipl-fcp-mpath/chreipl-fcp-mpath.mak
index ac022d43..642f3713 100644
--- a/chreipl-fcp-mpath/chreipl-fcp-mpath.mak
+++ b/chreipl-fcp-mpath/chreipl-fcp-mpath.mak
@@ -6,14 +6,39 @@
 # Uses the following system-utilities (and shell-builtins):
 #   Utilities list in GNU Make Conventions:
 #     https://www.gnu.org/software/make/manual/make.html#Utilities-in-Makefiles
+#   GNU coreutils:
+#     - mktemp
 
 #
 ## Paths and Build Variables
 #
 
 # https://www.gnu.org/software/make/manual/make.html#Directory-Variables
+CHREIPLZFCPMPDIR = $(USRLIBDIR)/chreipl-fcp-mpath
 UDEVDIR		 = $(USRLIBDIR)/udev
 UDEVRULESDIR	 = $(UDEVDIR)/rules.d
+UDEVRUNDIR	 = /run/udev
+DEBUGOUTDIR	 = $(UDEVRUNDIR)
 
 INSTALL_EXEC	 = $(INSTALL) -g $(GROUP) -o $(OWNER) --preserve-timestamps
 INSTALL_DATA	 = $(INSTALL_EXEC) --mode=0644
+
+.DELETE_ON_ERROR:
+
+# export build-time definitions to the scripts/built-components
+define chreiplzfcpmp-sed-buildvar-replace =
+tmpout=$$(mktemp -p ./ .make.tmp.XXXXXXXXXXXXXXXX) && {			\
+	$(SED) -E 							\
+		-e 's|@DEBUG@|$(if $(filter 1,$(D)),true,false)|g'	\
+		-e 's|@chreiplzfcpmp-lib@|$(CHREIPLZFCPMPDIR)/chreipl-fcp-mpath-common.sh|g' \
+		-e 's|@debugoutdir@|$(DEBUGOUTDIR)|g'			\
+		$(1) > $${tmpout}					\
+	    && mv $${tmpout} $(2)					\
+	    || { rm $${tmpout}; false; }				\
+; }
+endef
+
+.PHONY: clean-mk-temp
+clean: clean-mk-temp
+clean-mk-temp:
+	rm -f .make.tmp.[[:alnum:]][[:alnum:]][[:alnum:]][[:alnum:]][[:alnum:]][[:alnum:]][[:alnum:]][[:alnum:]][[:alnum:]][[:alnum:]][[:alnum:]][[:alnum:]][[:alnum:]][[:alnum:]][[:alnum:]][[:alnum:]]
diff --git a/chreipl-fcp-mpath/udev/rules.d/70-chreipl-fcp-mpath.rules b/chreipl-fcp-mpath/udev/rules.d/70-chreipl-fcp-mpath.rules
index f8e490e7..dbf78561 100644
--- a/chreipl-fcp-mpath/udev/rules.d/70-chreipl-fcp-mpath.rules
+++ b/chreipl-fcp-mpath/udev/rules.d/70-chreipl-fcp-mpath.rules
@@ -15,4 +15,12 @@ ACTION=="add", KERNEL=="sd[a-z]*", SUBSYSTEM=="block",			\
 GOTO="chreipl_fcp_mpath_end"
 LABEL="chreipl_fcp_mpath_path_change"
 
+# Is this system IPL'ed (IOW, are we on s390x)? And do we ReIPL via zFCP?
+#
+#    udev(7): If no absolute path is given, the program is expected to live
+#             in /usr/lib/udev; otherwise, the absolute path must be
+#             specified.
+TEST!="/sys/firmware/ipl", GOTO="chreipl_fcp_mpath_end"
+PROGRAM!="chreipl-fcp-mpath-is-reipl-zfcp", GOTO="chreipl_fcp_mpath_end"
+
 LABEL="chreipl_fcp_mpath_end"