[RFC PATCH 4/6] tools: build kernel selftests in tools_build

[Sasha Levin <sashal@kernel.org>]

Add a "Kernel selftests" sub-menu with one entry per selftests directory
that builds with only a C library and does not write into the source
tree. Each is built as "make kselftest-all" builds it, with KHDR_INCLUDES
pointing at the UAPI headers installed in the object tree, but by its own
make, so the selected ones build in parallel. Selftests whose Makefile
does not use KHDR_INCLUDES still build against the C library's copy of
the UAPI headers.

The selftests do not track header dependencies, so a selftest is built
again from scratch when its own directory, a header or makefile any
selftest may share, or a kernel source it includes directly (the vDSO
test includes the architecture's vDSO code) is newer than its last
build.

Selftests that need libraries beyond the C library, a vmlinux with BTF,
or a sanitizer runtime are left out for now.

Assisted-by: LLM
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 tools/Kconfig         | 239 ++++++++++++++++++++++++++++++++++++++++++
 tools/Makefile.kbuild | 100 ++++++++++++++++++
 2 files changed, 339 insertions(+)

diff --git a/tools/Kconfig b/tools/Kconfig
index 488f439592150..d713741782e22 100644
--- a/tools/Kconfig
+++ b/tools/Kconfig
@@ -84,4 +84,243 @@ config TOOLS_BUILD_USB
 	help
 	  Build tools/usb (testusb, ffs-test).
 
+menuconfig TOOLS_BUILD_SELFTESTS
+	bool "Kernel selftests"
+	help
+	  Build the selected targets under tools/testing/selftests, as
+	  "make kselftest-all" would, without running them.
+
+if TOOLS_BUILD_SELFTESTS
+
+config TOOLS_BUILD_SELFTESTS_ACCT
+	bool "acct"
+
+config TOOLS_BUILD_SELFTESTS_ALLOC_TAG
+	bool "alloc_tag"
+
+config TOOLS_BUILD_SELFTESTS_BREAKPOINTS
+	bool "breakpoints"
+
+config TOOLS_BUILD_SELFTESTS_CACHESTAT
+	bool "cachestat"
+
+config TOOLS_BUILD_SELFTESTS_CGROUP
+	bool "cgroup"
+
+config TOOLS_BUILD_SELFTESTS_CONNECTOR
+	bool "connector"
+
+config TOOLS_BUILD_SELFTESTS_CORE
+	bool "core"
+
+config TOOLS_BUILD_SELFTESTS_COREDUMP
+	bool "coredump"
+
+config TOOLS_BUILD_SELFTESTS_DAMON
+	bool "damon"
+
+config TOOLS_BUILD_SELFTESTS_DMABUF_HEAPS
+	bool "dmabuf-heaps"
+
+config TOOLS_BUILD_SELFTESTS_DRIVERS_DMA_BUF
+	bool "drivers/dma-buf"
+
+config TOOLS_BUILD_SELFTESTS_DRIVERS_NTSYNC
+	bool "drivers/ntsync"
+
+config TOOLS_BUILD_SELFTESTS_EFIVARFS
+	bool "efivarfs"
+
+config TOOLS_BUILD_SELFTESTS_FILELOCK
+	bool "filelock"
+
+config TOOLS_BUILD_SELFTESTS_FILESYSTEMS_BINDERFS
+	bool "filesystems/binderfs"
+
+config TOOLS_BUILD_SELFTESTS_FILESYSTEMS_EPOLL
+	bool "filesystems/epoll"
+
+config TOOLS_BUILD_SELFTESTS_FILESYSTEMS_EVENTFD
+	bool "filesystems/eventfd"
+
+config TOOLS_BUILD_SELFTESTS_FILESYSTEMS_FAILFS
+	bool "filesystems/failfs"
+
+config TOOLS_BUILD_SELFTESTS_FILESYSTEMS_FAT
+	bool "filesystems/fat"
+
+config TOOLS_BUILD_SELFTESTS_FILESYSTEMS_MNTNS_UNBINDABLE
+	bool "filesystems/mntns_unbindable"
+
+config TOOLS_BUILD_SELFTESTS_FILESYSTEMS_MOUNT_CYCLE
+	bool "filesystems/mount_cycle"
+
+config TOOLS_BUILD_SELFTESTS_FILESYSTEMS_NSFS
+	bool "filesystems/nsfs"
+
+config TOOLS_BUILD_SELFTESTS_FILESYSTEMS_UMOUNT_PROPAGATION
+	bool "filesystems/umount_propagation"
+
+config TOOLS_BUILD_SELFTESTS_FILESYSTEMS_XATTR
+	bool "filesystems/xattr"
+
+config TOOLS_BUILD_SELFTESTS_FIRMWARE
+	bool "firmware"
+
+config TOOLS_BUILD_SELFTESTS_FPU
+	bool "fpu"
+
+config TOOLS_BUILD_SELFTESTS_FTRACE
+	bool "ftrace"
+
+config TOOLS_BUILD_SELFTESTS_GPIO
+	bool "gpio"
+
+config TOOLS_BUILD_SELFTESTS_INTEL_PSTATE
+	bool "intel_pstate"
+	depends on X86
+
+config TOOLS_BUILD_SELFTESTS_IPC
+	bool "ipc"
+
+config TOOLS_BUILD_SELFTESTS_IR
+	bool "ir"
+
+config TOOLS_BUILD_SELFTESTS_KCMP
+	bool "kcmp"
+
+config TOOLS_BUILD_SELFTESTS_KEXEC
+	bool "kexec"
+	depends on X86_64
+
+config TOOLS_BUILD_SELFTESTS_KSELFTEST_HARNESS
+	bool "kselftest_harness"
+
+config TOOLS_BUILD_SELFTESTS_LSM
+	bool "lsm"
+
+config TOOLS_BUILD_SELFTESTS_MEDIA_TESTS
+	bool "media_tests"
+
+config TOOLS_BUILD_SELFTESTS_MEMBARRIER
+	bool "membarrier"
+
+config TOOLS_BUILD_SELFTESTS_MINCORE
+	bool "mincore"
+
+config TOOLS_BUILD_SELFTESTS_MOUNT
+	bool "mount"
+
+config TOOLS_BUILD_SELFTESTS_MOUNT_SETATTR
+	bool "mount_setattr"
+
+config TOOLS_BUILD_SELFTESTS_MOVE_MOUNT_SET_GROUP
+	bool "move_mount_set_group"
+
+config TOOLS_BUILD_SELFTESTS_MSEAL_SYSTEM_MAPPINGS
+	bool "mseal_system_mappings"
+
+config TOOLS_BUILD_SELFTESTS_NCI
+	bool "nci"
+
+config TOOLS_BUILD_SELFTESTS_NET_CAN
+	bool "net/can"
+
+config TOOLS_BUILD_SELFTESTS_NET_FORWARDING
+	bool "net/forwarding"
+
+config TOOLS_BUILD_SELFTESTS_NET_MPTCP
+	bool "net/mptcp"
+
+config TOOLS_BUILD_SELFTESTS_PCI_ENDPOINT
+	bool "pci_endpoint"
+
+config TOOLS_BUILD_SELFTESTS_PERF_EVENTS
+	bool "perf_events"
+
+config TOOLS_BUILD_SELFTESTS_PID_NAMESPACE
+	bool "pid_namespace"
+
+config TOOLS_BUILD_SELFTESTS_PIDFD
+	bool "pidfd"
+
+config TOOLS_BUILD_SELFTESTS_PIPE
+	bool "pipe"
+
+config TOOLS_BUILD_SELFTESTS_PROC
+	bool "proc"
+
+config TOOLS_BUILD_SELFTESTS_PTP
+	bool "ptp"
+
+config TOOLS_BUILD_SELFTESTS_PTRACE
+	bool "ptrace"
+
+config TOOLS_BUILD_SELFTESTS_RESCTRL
+	bool "resctrl"
+	depends on X86
+
+config TOOLS_BUILD_SELFTESTS_RING_BUFFER
+	bool "ring-buffer"
+
+config TOOLS_BUILD_SELFTESTS_RLIMITS
+	bool "rlimits"
+
+config TOOLS_BUILD_SELFTESTS_RSEQ
+	bool "rseq"
+
+config TOOLS_BUILD_SELFTESTS_RTC
+	bool "rtc"
+
+config TOOLS_BUILD_SELFTESTS_SCHED
+	bool "sched"
+
+config TOOLS_BUILD_SELFTESTS_SIGNAL
+	bool "signal"
+
+config TOOLS_BUILD_SELFTESTS_SIZE
+	bool "size"
+
+config TOOLS_BUILD_SELFTESTS_SPLICE
+	bool "splice"
+
+config TOOLS_BUILD_SELFTESTS_SYNC
+	bool "sync"
+
+config TOOLS_BUILD_SELFTESTS_SYSCALL_USER_DISPATCH
+	bool "syscall_user_dispatch"
+
+config TOOLS_BUILD_SELFTESTS_TDX
+	bool "tdx"
+	depends on X86
+
+config TOOLS_BUILD_SELFTESTS_THERMAL_INTEL_POWER_FLOOR
+	bool "thermal/intel/power_floor"
+	depends on X86
+
+config TOOLS_BUILD_SELFTESTS_THERMAL_INTEL_WORKLOAD_HINT
+	bool "thermal/intel/workload_hint"
+	depends on X86
+
+config TOOLS_BUILD_SELFTESTS_TIMENS
+	bool "timens"
+
+config TOOLS_BUILD_SELFTESTS_TMPFS
+	bool "tmpfs"
+
+config TOOLS_BUILD_SELFTESTS_USER_EVENTS
+	bool "user_events"
+
+config TOOLS_BUILD_SELFTESTS_VDSO
+	bool "vDSO"
+
+config TOOLS_BUILD_SELFTESTS_WATCHDOG
+	bool "watchdog"
+
+config TOOLS_BUILD_SELFTESTS_X86
+	bool "x86"
+	depends on X86
+
+endif # TOOLS_BUILD_SELFTESTS
+
 endif # TOOLS_BUILD
diff --git a/tools/Makefile.kbuild b/tools/Makefile.kbuild
index 62fd494253eca..c31347258d0a9 100644
--- a/tools/Makefile.kbuild
+++ b/tools/Makefile.kbuild
@@ -92,6 +92,106 @@ PHONY += perf
 perf: FORCE
 	$(call build,$(outdir)/perf,-C $(toolsdir)/perf -f Makefile.perf O=$(outdir)/perf $(perf-flags) $(perf-flags-y),,TOOLS_BUILD_PERF)
 
+# Selftests in tools/testing/selftests/<name>
+selftests-$(CONFIG_TOOLS_BUILD_SELFTESTS_ACCT)	+= acct
+selftests-$(CONFIG_TOOLS_BUILD_SELFTESTS_ALLOC_TAG)	+= alloc_tag
+selftests-$(CONFIG_TOOLS_BUILD_SELFTESTS_BREAKPOINTS)	+= breakpoints
+selftests-$(CONFIG_TOOLS_BUILD_SELFTESTS_CACHESTAT)	+= cachestat
+selftests-$(CONFIG_TOOLS_BUILD_SELFTESTS_CGROUP)	+= cgroup
+selftests-$(CONFIG_TOOLS_BUILD_SELFTESTS_CONNECTOR)	+= connector
+selftests-$(CONFIG_TOOLS_BUILD_SELFTESTS_CORE)	+= core
+selftests-$(CONFIG_TOOLS_BUILD_SELFTESTS_COREDUMP)	+= coredump
+selftests-$(CONFIG_TOOLS_BUILD_SELFTESTS_DAMON)	+= damon
+selftests-$(CONFIG_TOOLS_BUILD_SELFTESTS_DMABUF_HEAPS)	+= dmabuf-heaps
+selftests-$(CONFIG_TOOLS_BUILD_SELFTESTS_DRIVERS_DMA_BUF)	+= drivers/dma-buf
+selftests-$(CONFIG_TOOLS_BUILD_SELFTESTS_DRIVERS_NTSYNC)	+= drivers/ntsync
+selftests-$(CONFIG_TOOLS_BUILD_SELFTESTS_EFIVARFS)	+= efivarfs
+selftests-$(CONFIG_TOOLS_BUILD_SELFTESTS_FILELOCK)	+= filelock
+selftests-$(CONFIG_TOOLS_BUILD_SELFTESTS_FILESYSTEMS_BINDERFS)	+= filesystems/binderfs
+selftests-$(CONFIG_TOOLS_BUILD_SELFTESTS_FILESYSTEMS_EPOLL)	+= filesystems/epoll
+selftests-$(CONFIG_TOOLS_BUILD_SELFTESTS_FILESYSTEMS_EVENTFD)	+= filesystems/eventfd
+selftests-$(CONFIG_TOOLS_BUILD_SELFTESTS_FILESYSTEMS_FAILFS)	+= filesystems/failfs
+selftests-$(CONFIG_TOOLS_BUILD_SELFTESTS_FILESYSTEMS_FAT)	+= filesystems/fat
+selftests-$(CONFIG_TOOLS_BUILD_SELFTESTS_FILESYSTEMS_MNTNS_UNBINDABLE)	+= filesystems/mntns_unbindable
+selftests-$(CONFIG_TOOLS_BUILD_SELFTESTS_FILESYSTEMS_MOUNT_CYCLE)	+= filesystems/mount_cycle
+selftests-$(CONFIG_TOOLS_BUILD_SELFTESTS_FILESYSTEMS_NSFS)	+= filesystems/nsfs
+selftests-$(CONFIG_TOOLS_BUILD_SELFTESTS_FILESYSTEMS_UMOUNT_PROPAGATION)	+= filesystems/umount_propagation
+selftests-$(CONFIG_TOOLS_BUILD_SELFTESTS_FILESYSTEMS_XATTR)	+= filesystems/xattr
+selftests-$(CONFIG_TOOLS_BUILD_SELFTESTS_FIRMWARE)	+= firmware
+selftests-$(CONFIG_TOOLS_BUILD_SELFTESTS_FPU)	+= fpu
+selftests-$(CONFIG_TOOLS_BUILD_SELFTESTS_FTRACE)	+= ftrace
+selftests-$(CONFIG_TOOLS_BUILD_SELFTESTS_GPIO)	+= gpio
+selftests-$(CONFIG_TOOLS_BUILD_SELFTESTS_INTEL_PSTATE)	+= intel_pstate
+selftests-$(CONFIG_TOOLS_BUILD_SELFTESTS_IPC)	+= ipc
+selftests-$(CONFIG_TOOLS_BUILD_SELFTESTS_IR)	+= ir
+selftests-$(CONFIG_TOOLS_BUILD_SELFTESTS_KCMP)	+= kcmp
+selftests-$(CONFIG_TOOLS_BUILD_SELFTESTS_KEXEC)	+= kexec
+selftests-$(CONFIG_TOOLS_BUILD_SELFTESTS_KSELFTEST_HARNESS)	+= kselftest_harness
+selftests-$(CONFIG_TOOLS_BUILD_SELFTESTS_LSM)	+= lsm
+selftests-$(CONFIG_TOOLS_BUILD_SELFTESTS_MEDIA_TESTS)	+= media_tests
+selftests-$(CONFIG_TOOLS_BUILD_SELFTESTS_MEMBARRIER)	+= membarrier
+selftests-$(CONFIG_TOOLS_BUILD_SELFTESTS_MINCORE)	+= mincore
+selftests-$(CONFIG_TOOLS_BUILD_SELFTESTS_MOUNT)	+= mount
+selftests-$(CONFIG_TOOLS_BUILD_SELFTESTS_MOUNT_SETATTR)	+= mount_setattr
+selftests-$(CONFIG_TOOLS_BUILD_SELFTESTS_MOVE_MOUNT_SET_GROUP)	+= move_mount_set_group
+selftests-$(CONFIG_TOOLS_BUILD_SELFTESTS_MSEAL_SYSTEM_MAPPINGS)	+= mseal_system_mappings
+selftests-$(CONFIG_TOOLS_BUILD_SELFTESTS_NCI)	+= nci
+selftests-$(CONFIG_TOOLS_BUILD_SELFTESTS_NET_CAN)	+= net/can
+selftests-$(CONFIG_TOOLS_BUILD_SELFTESTS_NET_FORWARDING)	+= net/forwarding
+selftests-$(CONFIG_TOOLS_BUILD_SELFTESTS_NET_MPTCP)	+= net/mptcp
+selftests-$(CONFIG_TOOLS_BUILD_SELFTESTS_PCI_ENDPOINT)	+= pci_endpoint
+selftests-$(CONFIG_TOOLS_BUILD_SELFTESTS_PERF_EVENTS)	+= perf_events
+selftests-$(CONFIG_TOOLS_BUILD_SELFTESTS_PID_NAMESPACE)	+= pid_namespace
+selftests-$(CONFIG_TOOLS_BUILD_SELFTESTS_PIDFD)	+= pidfd
+selftests-$(CONFIG_TOOLS_BUILD_SELFTESTS_PIPE)	+= pipe
+selftests-$(CONFIG_TOOLS_BUILD_SELFTESTS_PROC)	+= proc
+selftests-$(CONFIG_TOOLS_BUILD_SELFTESTS_PTP)	+= ptp
+selftests-$(CONFIG_TOOLS_BUILD_SELFTESTS_PTRACE)	+= ptrace
+selftests-$(CONFIG_TOOLS_BUILD_SELFTESTS_RESCTRL)	+= resctrl
+selftests-$(CONFIG_TOOLS_BUILD_SELFTESTS_RING_BUFFER)	+= ring-buffer
+selftests-$(CONFIG_TOOLS_BUILD_SELFTESTS_RLIMITS)	+= rlimits
+selftests-$(CONFIG_TOOLS_BUILD_SELFTESTS_RSEQ)	+= rseq
+selftests-$(CONFIG_TOOLS_BUILD_SELFTESTS_RTC)	+= rtc
+selftests-$(CONFIG_TOOLS_BUILD_SELFTESTS_SCHED)	+= sched
+selftests-$(CONFIG_TOOLS_BUILD_SELFTESTS_SIGNAL)	+= signal
+selftests-$(CONFIG_TOOLS_BUILD_SELFTESTS_SIZE)	+= size
+selftests-$(CONFIG_TOOLS_BUILD_SELFTESTS_SPLICE)	+= splice
+selftests-$(CONFIG_TOOLS_BUILD_SELFTESTS_SYNC)	+= sync
+selftests-$(CONFIG_TOOLS_BUILD_SELFTESTS_SYSCALL_USER_DISPATCH)	+= syscall_user_dispatch
+selftests-$(CONFIG_TOOLS_BUILD_SELFTESTS_TDX)	+= tdx
+selftests-$(CONFIG_TOOLS_BUILD_SELFTESTS_THERMAL_INTEL_POWER_FLOOR)	+= thermal/intel/power_floor
+selftests-$(CONFIG_TOOLS_BUILD_SELFTESTS_THERMAL_INTEL_WORKLOAD_HINT)	+= thermal/intel/workload_hint
+selftests-$(CONFIG_TOOLS_BUILD_SELFTESTS_TIMENS)	+= timens
+selftests-$(CONFIG_TOOLS_BUILD_SELFTESTS_TMPFS)	+= tmpfs
+selftests-$(CONFIG_TOOLS_BUILD_SELFTESTS_USER_EVENTS)	+= user_events
+selftests-$(CONFIG_TOOLS_BUILD_SELFTESTS_VDSO)	+= vDSO
+selftests-$(CONFIG_TOOLS_BUILD_SELFTESTS_WATCHDOG)	+= watchdog
+selftests-$(CONFIG_TOOLS_BUILD_SELFTESTS_X86)	+= x86
+
+selftest-flags := CC='$(call escsq,$(tools-cc))' KHDR_INCLUDES='-isystem $(CURDIR)/usr/include'
+
+# Unlike tools/build, the selftests do not track header dependencies. A
+# selftest is built again from scratch when its own directory, a header or
+# makefile any selftest may share, or a kernel source it includes directly
+# is newer than its last build.
+selftest-shared := $(outdir)/selftests/.shared
+selftest-extra-vDSO := $(abs_srctree)/arch/$(SRCARCH)
+
+$(selftest-shared): FORCE
+	$(Q)mkdir -p $(@D); \
+	newest=$$(find $(CURDIR)/usr/include $(toolsdir)/include $(toolsdir)/testing/selftests \
+		-type f \( -name '*.h' -o -name '*.mk' -o -name Makefile \) -printf '%T@\n' | \
+		sort -n | tail -n 1); \
+	touch -d "@$${newest:-0}" $@
+
+selftest-targets := $(addprefix selftest-,$(selftests-y))
+
+__tools_build: $(selftest-targets)
+
+PHONY += $(selftest-targets)
+$(selftest-targets): selftest-%: $(selftest-shared) FORCE
+	$(call build,$(outdir)/selftests/$*,-C $(toolsdir)/testing/selftests/$* OUTPUT=$(outdir)/selftests/$* $(selftest-flags),$(selftest-shared) $(toolsdir)/testing/selftests/$* $(selftest-extra-$*),TOOLS_BUILD_SELFTESTS_$(shell echo $* | tr a-z/- A-Z__))
+
 PHONY += FORCE
 FORCE:
 
-- 
2.53.0