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 <skhan@linuxfoundation.org>

1 files changed, 6 insertions, 6 deletions

diff --git a/tools/testing/selftests/gpio/Makefile b/tools/testing/selftests/gpio/Makefile
index 0bb80619db58..32bdc978a711 100644
--- a/tools/testing/selftests/gpio/Makefile
+++ b/tools/testing/selftests/gpio/Makefile
@@ -1,13 +1,13 @@
 # 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