Merge tag 'kbuild-v4.15' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild

Pull Kbuild updates from Masahiro Yamada:
 "One of the most remarkable improvements in this cycle is, Kbuild is
  now able to cache the result of shell commands. Some variables are
  expensive to compute, for example, $(call cc-option,...) invokes the
  compiler. It is not efficient to redo this computation every time,
  even when we are not actually building anything. Kbuild creates a
  hidden file ".cache.mk" that contains invoked shell commands and their
  results. The speed-up should be noticeable.

  Summary:

   - Fix arch build issues (hexagon, sh)

   - Clean up various Makefiles and scripts

   - Fix wrong usage of {CFLAGS,LDFLAGS}_MODULE in arch Makefiles

   - Cache variables that are expensive to compute

   - Improve cc-ldopton and ld-option for Clang

   - Optimize output directory creation"

* tag 'kbuild-v4.15' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: (30 commits)
  kbuild: move coccicheck help from scripts/Makefile.help to top Makefile
  sh: decompressor: add shipped files to .gitignore
  frv: .gitignore: ignore vmlinux.lds
  selinux: remove unnecessary assignment to subdir-
  kbuild: specify FORCE in Makefile.headersinst as .PHONY target
  kbuild: remove redundant mkdir from ./Kbuild
  kbuild: optimize object directory creation for incremental build
  kbuild: create object directories simpler and faster
  kbuild: filter-out PHONY targets from "targets"
  kbuild: remove redundant $(wildcard ...) for cmd_files calculation
  kbuild: create directory for make cache only when necessary
  sh: select KBUILD_DEFCONFIG depending on ARCH
  kbuild: fix linker feature test macros when cross compiling with Clang
  kbuild: shrink .cache.mk when it exceeds 1000 lines
  kbuild: do not call cc-option before KBUILD_CFLAGS initialization
  kbuild: Cache a few more calls to the compiler
  kbuild: Add a cache for generated variables
  kbuild: add forward declaration of default target to Makefile.asm-generic
  kbuild: remove KBUILD_SUBDIR_ASFLAGS and KBUILD_SUBDIR_CCFLAGS
  hexagon/kbuild: replace CFLAGS_MODULE with KBUILD_CFLAGS_MODULE
  ...

8 files changed, 20 insertions, 16 deletions

diff --git a/arch/arm/Makefile b/arch/arm/Makefile
index def8824fc71c..80351e505fd5 100644
--- a/arch/arm/Makefile
+++ b/arch/arm/Makefile
@@ -16,11 +16,11 @@ LDFLAGS		:=
 LDFLAGS_vmlinux	:=-p --no-undefined -X --pic-veneer
 ifeq ($(CONFIG_CPU_ENDIAN_BE8),y)
 LDFLAGS_vmlinux	+= --be8
-LDFLAGS_MODULE	+= --be8
+KBUILD_LDFLAGS_MODULE	+= --be8
 endif
 
 ifeq ($(CONFIG_ARM_MODULE_PLTS),y)
-LDFLAGS_MODULE	+= -T $(srctree)/arch/arm/kernel/module.lds
+KBUILD_LDFLAGS_MODULE	+= -T $(srctree)/arch/arm/kernel/module.lds
 endif
 
 GZFLAGS		:=-9
@@ -122,7 +122,7 @@ CFLAGS_ISA	:=-mthumb $(AFLAGS_AUTOIT) $(AFLAGS_NOWARN)
 AFLAGS_ISA	:=$(CFLAGS_ISA) -Wa$(comma)-mthumb
 # Work around buggy relocation from gas if requested:
 ifeq ($(CONFIG_THUMB2_AVOID_R_ARM_THM_JUMP11),y)
-CFLAGS_MODULE	+=-fno-optimize-sibling-calls
+KBUILD_CFLAGS_MODULE	+=-fno-optimize-sibling-calls
 endif
 else
 CFLAGS_ISA	:=$(call cc-option,-marm,)
diff --git a/arch/c6x/Makefile b/arch/c6x/Makefile
index 6b0be670ddfa..6f6096ff05a4 100644
--- a/arch/c6x/Makefile
+++ b/arch/c6x/Makefile
@@ -12,7 +12,7 @@ cflags-y += -mno-dsbt -msdata=none -D__linux__
 
 cflags-$(CONFIG_C6X_BIG_KERNEL) += -mlong-calls
 
-CFLAGS_MODULE   += -mlong-calls -mno-dsbt -msdata=none
+KBUILD_CFLAGS_MODULE   += -mlong-calls -mno-dsbt -msdata=none
 
 CHECKFLAGS      +=
 
diff --git a/arch/frv/kernel/.gitignore b/arch/frv/kernel/.gitignore
new file mode 100644
index 000000000000..c5f676c3c224
--- /dev/null
+++ b/arch/frv/kernel/.gitignore
@@ -0,0 +1 @@
+vmlinux.lds
diff --git a/arch/hexagon/Makefile b/arch/hexagon/Makefile
index 48fe08230a80..2efaa18e995a 100644
--- a/arch/hexagon/Makefile
+++ b/arch/hexagon/Makefile
@@ -12,9 +12,9 @@ KBUILD_CFLAGS += -fno-short-enums
 
 # Modules must use either long-calls, or use pic/plt.
 # Use long-calls for now, it's easier.  And faster.
-# CFLAGS_MODULE += -fPIC
-# LDFLAGS_MODULE += -shared
-CFLAGS_MODULE += -mlong-calls
+# KBUILD_CFLAGS_MODULE += -fPIC
+# KBUILD_LDFLAGS_MODULE += -shared
+KBUILD_CFLAGS_MODULE += -mlong-calls
 
 cflags-y += $(call cc-option,-mv${CONFIG_HEXAGON_ARCH_VERSION})
 aflags-y += $(call cc-option,-mv${CONFIG_HEXAGON_ARCH_VERSION})
diff --git a/arch/hexagon/kernel/ptrace.c b/arch/hexagon/kernel/ptrace.c
index ecd75e2e8eb3..fa76493c1745 100644
--- a/arch/hexagon/kernel/ptrace.c
+++ b/arch/hexagon/kernel/ptrace.c
@@ -18,8 +18,6 @@
  * 02110-1301, USA.
  */
 
-#include <generated/compile.h>
-
 #include <linux/kernel.h>
 #include <linux/sched.h>
 #include <linux/sched/task_stack.h>
@@ -180,7 +178,7 @@ static const struct user_regset hexagon_regsets[] = {
 };
 
 static const struct user_regset_view hexagon_user_view = {
-	.name = UTS_MACHINE,
+	.name = "hexagon",
 	.e_machine = ELF_ARCH,
 	.ei_osabi = ELF_OSABI,
 	.regsets = hexagon_regsets,
diff --git a/arch/sh/Makefile b/arch/sh/Makefile
index 280bbff12102..65300193b99f 100644
--- a/arch/sh/Makefile
+++ b/arch/sh/Makefile
@@ -15,6 +15,12 @@ ifneq ($(SUBARCH),$(ARCH))
   endif
 endif
 
+ifeq ($(ARCH),sh)
+KBUILD_DEFCONFIG	:= shx3_defconfig
+else
+KBUILD_DEFCONFIG	:= cayman_defconfig
+endif
+
 isa-y					:= any
 isa-$(CONFIG_SH_DSP)			:= sh
 isa-$(CONFIG_CPU_SH2)			:= sh2
@@ -105,14 +111,12 @@ ifdef CONFIG_SUPERH32
 UTS_MACHINE		:= sh
 BITS			:= 32
 LDFLAGS_vmlinux		+= -e _stext
-KBUILD_DEFCONFIG	:= shx3_defconfig
 else
 UTS_MACHINE		:= sh64
 BITS			:= 64
 LDFLAGS_vmlinux		+= --defsym phys_stext=_stext-$(CONFIG_PAGE_OFFSET) \
 			   --defsym phys_stext_shmedia=phys_stext+1 \
 			   -e phys_stext_shmedia
-KBUILD_DEFCONFIG	:= cayman_defconfig
 endif
 
 ifdef CONFIG_CPU_LITTLE_ENDIAN
diff --git a/arch/sh/boot/compressed/.gitignore b/arch/sh/boot/compressed/.gitignore
index 2374a83d87b2..edff113f1b85 100644
--- a/arch/sh/boot/compressed/.gitignore
+++ b/arch/sh/boot/compressed/.gitignore
@@ -1 +1,6 @@
+ashiftrt.S
+ashldi3.c
+ashlsi3.S
+ashrsi3.S
+lshrsi3.S
 vmlinux.bin.*
diff --git a/arch/x86/entry/vdso/Makefile b/arch/x86/entry/vdso/Makefile
index c366c0adeb40..1943aebadede 100644
--- a/arch/x86/entry/vdso/Makefile
+++ b/arch/x86/entry/vdso/Makefile
@@ -130,10 +130,6 @@ $(obj)/vdsox32.so.dbg: $(src)/vdsox32.lds $(vobjx32s) FORCE
 CPPFLAGS_vdso32.lds = $(CPPFLAGS_vdso.lds)
 VDSO_LDFLAGS_vdso32.lds = -m32 -Wl,-m,elf_i386 -Wl,-soname=linux-gate.so.1
 
-# This makes sure the $(obj) subdirectory exists even though vdso32/
-# is not a kbuild sub-make subdirectory.
-override obj-dirs = $(dir $(obj)) $(obj)/vdso32/
-
 targets += vdso32/vdso32.lds
 targets += vdso32/note.o vdso32/system_call.o vdso32/sigreturn.o
 targets += vdso32/vclock_gettime.o