selftests: add build/cross-build dependency check script

Add build/cross-build dependency check script kselftest_deps.sh
This script does the following:

Usage: ./kselftest_deps.sh -[p] <compiler> [test_name]

kselftest_deps.sh [-p] gcc
kselftest_deps.sh [-p] gcc vm
kselftest_deps.sh [-p] aarch64-linux-gnu-gcc
kselftest_deps.sh [-p] aarch64-linux-gnu-gcc vm

- Should be run in selftests directory in the kernel repo.
- Checks if Kselftests can be built/cross-built on a system.
- Parses all test/sub-test Makefile to find library dependencies.
- Runs compile test on a trivial C file with LDLIBS specified
in the test Makefiles to identify missing library dependencies.
- Prints suggested target list for a system filtering out tests
failed the build dependency check from the TARGETS in Selftests
the main Makefile when optional -p is specified.
- Prints pass/fail dependency check for each tests/sub-test.
- Prints pass/fail targets and libraries.
- Default: runs dependency checks on all tests.
- Optional test name can be specified to check dependencies for it.

To make LDLIBS parsing easier
- change gpio and memfd Makefiles to use the same temporary variable used
to find and add libraries to LDLIBS.
- simlify LDLIBS append logic in intel_pstate/Makefile.

Results from run on x86_64 system (trimmed detailed pass/fail list):
========================================================
Kselftest Dependency Check for [./kselftest_deps.sh gcc ] results...
========================================================
Checked tests defining LDLIBS dependencies
--------------------------------------------------------
Total tests with Dependencies:
55 Pass: 53 Fail: 2
--------------------------------------------------------
Targets passed build dependency check on system:
bpf capabilities filesystems futex gpio intel_pstate membarrier memfd
mqueue net powerpc ptp rseq rtc safesetid timens timers vDSO vm
--------------------------------------------------------
FAIL: netfilter/Makefile dependency check: -lmnl
FAIL: gpio/Makefile dependency check: -lmount
--------------------------------------------------------
Targets failed build dependency check on system:
gpio netfilter
--------------------------------------------------------
Missing libraries system
-lmnl -lmount
--------------------------------------------------------
========================================================

Results from run on x86_64 system with aarch64-linux-gnu-gcc:
(trimmed detailed pass/fail list):
========================================================
Kselftest Dependency Check for [./kselftest_deps.sh aarch64-linux-gnu-gcc ]
results...
========================================================
Checked tests defining LDLIBS dependencies
--------------------------------------------------------
Total tests with Dependencies:
55 Pass: 41 Fail: 14
--------------------------------------------------------
Targets failed build dependency check on system:
bpf capabilities filesystems futex gpio intel_pstate membarrier memfd
mqueue net powerpc ptp rseq rtc timens timers vDSO vm
--------------------------------------------------------
--------------------------------------------------------
Targets failed build dependency check on system:
bpf capabilities gpio memfd mqueue net netfilter safesetid vm
--------------------------------------------------------
Missing libraries system
-lcap -lcap-ng -lelf -lfuse -lmnl -lmount -lnuma -lpopt -lz
--------------------------------------------------------
========================================================

Signed-off-by: Shuah Khan <[e-mail]>

tools/testing/selftests/gpio/Makefile

···
 # SPDX-License-Identifier: GPL-2.0
 
-MOUNT_CFLAGS := $(shell pkg-config --cflags mount 2>/dev/null)
-MOUNT_LDLIBS := $(shell pkg-config --libs mount 2>/dev/null)
-ifeq ($(MOUNT_LDLIBS),)
-MOUNT_LDLIBS := -lmount -I/usr/include/libmount
+VAR_CFLAGS := $(shell pkg-config --cflags mount 2>/dev/null)
+VAR_LDLIBS := $(shell pkg-config --libs mount 2>/dev/null)
+ifeq ($(VAR_LDLIBS),)
+VAR_LDLIBS := -lmount -I/usr/include/libmount
 endif
 
-CFLAGS += -O2 -g -std=gnu99 -Wall -I../../../../usr/include/ $(MOUNT_CFLAGS)
-LDLIBS += $(MOUNT_LDLIBS)
+CFLAGS += -O2 -g -std=gnu99 -Wall -I../../../../usr/include/ $(VAR_CFLAGS)
+LDLIBS += $(VAR_LDLIBS)
 
 TEST_PROGS := gpio-mockup.sh
 TEST_FILES := gpio-mockup-sysfs.sh

tools/testing/selftests/intel_pstate/Makefile

···
 # SPDX-License-Identifier: GPL-2.0
 CFLAGS := $(CFLAGS) -Wall -D_GNU_SOURCE
-LDLIBS := $(LDLIBS) -lm
+LDLIBS += -lm
 
 uname_M := $(shell uname -m 2>/dev/null || echo not)
 ARCH ?= $(shell echo $(uname_M) | sed -e s/i.86/x86/ -e s/x86_64/x86/)

tools/testing/selftests/kselftest_deps.sh

···
+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0
+# kselftest_deps.sh
+#
+# Checks for kselftest build dependencies on the build system.
+# Copyright (c) 2020 Shuah Khan <[e-mail]>
+#
+#
+
+usage()
+{
+
+echo -e "Usage: $0 -[p] <compiler> [test_name]\n"
+echo -e "\tkselftest_deps.sh [-p] gcc"
+echo -e "\tkselftest_deps.sh [-p] gcc vm"
+echo -e "\tkselftest_deps.sh [-p] aarch64-linux-gnu-gcc"
+echo -e "\tkselftest_deps.sh [-p] aarch64-linux-gnu-gcc vm\n"
+echo "- Should be run in selftests directory in the kernel repo."
+echo "- Checks if Kselftests can be built/cross-built on a system."
+echo "- Parses all test/sub-test Makefile to find library dependencies."
+echo "- Runs compile test on a trivial C file with LDLIBS specified"
+echo "  in the test Makefiles to identify missing library dependencies."
+echo "- Prints suggested target list for a system filtering out tests"
+echo "  failed the build dependency check from the TARGETS in Selftests"
+echo "  main Makefile when optional -p is specified."
+echo "- Prints pass/fail dependency check for each tests/sub-test."
+echo "- Prints pass/fail targets and libraries."
+echo "- Default: runs dependency checks on all tests."
+echo "- Optional test name can be specified to check dependencies for it."
+exit 1
+
+}
+
+# Start main()
+main()
+{
+
+base_dir=`pwd`
+# Make sure we're in the selftests top-level directory.
+if [ $(basename "$base_dir") !=  "selftests" ]; then
+	echo -e "\tPlease run $0 in"
+	echo -e "\ttools/testing/selftests directory ..."
+	exit 1
+fi
+
+print_targets=0
+
+while getopts "p" arg; do
+    case $arg in
+        p)
+		print_targets=1
+	shift;;
+    esac
+done
+
+if [ $# -eq 0 ]
+then
+	usage
+fi
+
+# Compiler
+CC=$1
+
+tmp_file=$(mktemp).c
+trap "rm -f $tmp_file.o $tmp_file $tmp_file.bin" EXIT
+#echo $tmp_file
+
+pass=$(mktemp).out
+trap "rm -f $pass" EXIT
+#echo $pass
+
+fail=$(mktemp).out
+trap "rm -f $fail" EXIT
+#echo $fail
+
+# Generate tmp source fire for compile test
+cat << "EOF" > $tmp_file
+int main()
+{
+}
+EOF
+
+# Save results
+total_cnt=0
+fail_trgts=()
+fail_libs=()
+fail_cnt=0
+pass_trgts=()
+pass_libs=()
+pass_cnt=0
+
+# Get all TARGETS from selftests Makefile
+targets=$(egrep "^TARGETS +|^TARGETS =" Makefile | cut -d "=" -f2)
+
+# Single test case
+if [ $# -eq 2 ]
+then
+	test=$2/Makefile
+
+	l1_test $test
+	l2_test $test
+	l3_test $test
+
+	print_results $1 $2
+	exit $?
+fi
+
+# Level 1: LDLIBS set static.
+#
+# Find all LDLIBS set statically for all executables built by a Makefile
+# and filter out VAR_LDLIBS to discard the following:
+# 	gpio/Makefile:LDLIBS += $(VAR_LDLIBS)
+# Append space at the end of the list to append more tests.
+
+l1_tests=$(grep -r --include=Makefile "^LDLIBS" | \
+		grep -v "VAR_LDLIBS" | awk -F: '{print $1}')
+
+# Level 2: LDLIBS set dynamically.
+#
+# Level 2
+# Some tests have multiple valid LDLIBS lines for individual sub-tests
+# that need dependency checks. Find them and append them to the tests
+# e.g: vm/Makefile:$(OUTPUT)/userfaultfd: LDLIBS += -lpthread
+# Filter out VAR_LDLIBS to discard the following:
+# 	memfd/Makefile:$(OUTPUT)/fuse_mnt: LDLIBS += $(VAR_LDLIBS)
+# Append space at the end of the list to append more tests.
+
+l2_tests=$(grep -r --include=Makefile ": LDLIBS" | \
+		grep -v "VAR_LDLIBS" | awk -F: '{print $1}')
+
+# Level 3
+# gpio,  memfd and others use pkg-config to find mount and fuse libs
+# respectively and save it in VAR_LDLIBS. If pkg-config doesn't find
+# any, VAR_LDLIBS set to default.
+# Use the default value and filter out pkg-config for dependency check.
+# e.g:
+# gpio/Makefile
+#	VAR_LDLIBS := $(shell pkg-config --libs mount) 2>/dev/null)
+# memfd/Makefile
+#	VAR_LDLIBS := $(shell pkg-config fuse --libs 2>/dev/null)
+
+l3_tests=$(grep -r --include=Makefile "^VAR_LDLIBS" | \
+		grep -v "pkg-config" | awk -F: '{print $1}')
+
+#echo $l1_tests
+#echo $l2_1_tests
+#echo $l3_tests
+
+all_tests
+print_results $1 $2
+
+exit $?
+}
+# end main()
+
+all_tests()
+{
+	for test in $l1_tests; do
+		l1_test $test
+	done
+
+	for test in $l2_tests; do
+		l2_test $test
+	done
+
+	for test in $l3_tests; do
+		l3_test $test
+	done
+}
+
+# Use same parsing used for l1_tests and pick libraries this time.
+l1_test()
+{
+	test_libs=$(grep --include=Makefile "^LDLIBS" $test | \
+			grep -v "VAR_LDLIBS" | \
+			sed -e 's/\:/ /' | \
+			sed -e 's/+/ /' | cut -d "=" -f 2)
+
+	check_libs $test $test_libs
+}
+
+# Use same parsing used for l2__tests and pick libraries this time.
+l2_test()
+{
+	test_libs=$(grep --include=Makefile ": LDLIBS" $test | \
+			grep -v "VAR_LDLIBS" | \
+			sed -e 's/\:/ /' | sed -e 's/+/ /' | \
+			cut -d "=" -f 2)
+
+	check_libs $test $test_libs
+}
+
+l3_test()
+{
+	test_libs=$(grep --include=Makefile "^VAR_LDLIBS" $test | \
+			grep -v "pkg-config" | sed -e 's/\:/ /' |
+			sed -e 's/+/ /' | cut -d "=" -f 2)
+
+	check_libs $test $test_libs
+}
+
+check_libs()
+{
+
+if [[ ! -z "${test_libs// }" ]]
+then
+
+	#echo $test_libs
+
+	for lib in $test_libs; do
+
+	let total_cnt+=1
+	$CC -o $tmp_file.bin $lib $tmp_file > /dev/null 2>&1
+	if [ $? -ne 0 ]; then
+		echo "FAIL: $test dependency check: $lib" >> $fail
+		let fail_cnt+=1
+		fail_libs+="$lib "
+		fail_target=$(echo "$test" | cut -d "/" -f1)
+		fail_trgts+="$fail_target "
+		targets=$(echo "$targets" | grep -v "$fail_target")
+	else
+		echo "PASS: $test dependency check passed $lib" >> $pass
+		let pass_cnt+=1
+		pass_libs+="$lib "
+		pass_trgts+="$(echo "$test" | cut -d "/" -f1) "
+	fi
+
+	done
+fi
+}
+
+print_results()
+{
+	echo -e "========================================================";
+	echo -e "Kselftest Dependency Check for [$0 $1 $2] results..."
+
+	if [ $print_targets -ne 0 ]
+	then
+	echo -e "Suggested Selftest Targets for your configuration:"
+	echo -e "$targets";
+	fi
+
+	echo -e "========================================================";
+	echo -e "Checked tests defining LDLIBS dependencies"
+	echo -e "--------------------------------------------------------";
+	echo -e "Total tests with Dependencies:"
+	echo -e "$total_cnt Pass: $pass_cnt Fail: $fail_cnt";
+
+	if [ $pass_cnt -ne 0 ]; then
+	echo -e "--------------------------------------------------------";
+	cat $pass
+	echo -e "--------------------------------------------------------";
+	echo -e "Targets passed build dependency check on system:"
+	echo -e "$(echo "$pass_trgts" | xargs -n1 | sort -u | xargs)"
+	fi
+
+	if [ $fail_cnt -ne 0 ]; then
+	echo -e "--------------------------------------------------------";
+	cat $fail
+	echo -e "--------------------------------------------------------";
+	echo -e "Targets failed build dependency check on system:"
+	echo -e "$(echo "$fail_trgts" | xargs -n1 | sort -u | xargs)"
+	echo -e "--------------------------------------------------------";
+	echo -e "Missing libraries system"
+	echo -e "$(echo "$fail_libs" | xargs -n1 | sort -u | xargs)"
+	fi
+
+	echo -e "--------------------------------------------------------";
+	echo -e "========================================================";
+}
+
+main "$@"

tools/testing/selftests/memfd/Makefile

···
 TEST_PROGS := run_fuse_test.sh run_hugetlbfs_test.sh
 TEST_GEN_FILES := fuse_test fuse_mnt
 
-fuse_mnt.o: CFLAGS += $(shell pkg-config fuse --cflags)
+VAR_CFLAGS := $(shell pkg-config fuse --cflags 2>/dev/null)
+ifeq ($(VAR_CFLAGS),)
+VAR_CFLAGS := -D_FILE_OFFSET_BITS=64 -I/usr/include/fuse
+endif
+
+VAR_LDLIBS := $(shell pkg-config fuse --libs 2>/dev/null)
+ifeq ($(VAR_LDLIBS),)
+VAR_LDLIBS := -lfuse -pthread
+endif
+
+fuse_mnt.o: CFLAGS += $(VAR_CFLAGS)
 
 include ../lib.mk
 
-$(OUTPUT)/fuse_mnt: LDLIBS += $(shell pkg-config fuse --libs)
+$(OUTPUT)/fuse_mnt: LDLIBS += $(VAR_LDLIBS)
 
 $(OUTPUT)/memfd_test: memfd_test.c common.c
 $(OUTPUT)/fuse_test: fuse_test.c common.c