kbuild: remove head-y syntax

Kbuild puts the objects listed in head-y at the head of vmlinux.
Conventionally, we do this for head*.S, which contains the kernel entry
point.

A counter approach is to control the section order by the linker script.
Actually, the code marked as __HEAD goes into the ".head.text" section,
which is placed before the normal ".text" section.

I do not know if both of them are needed. From the build system
perspective, head-y is not mandatory. If you can achieve the proper code
placement by the linker script only, it would be cleaner.

I collected the current head-y objects into head-object-list.txt. It is
a whitelist. My hope is it will be reduced in the long run.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Reviewed-by: Nicolas Schier <nicolas@fjasle.eu>

csky: Move $(core-y) into arch/csky/Kbuild

Use the standard obj-y form to specify the sub-directories under
arch/csky/. Only leave core-y += arch/csky/$(CSKYABI)/ there.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Signed-off-by: Guo Ren <guoren@kernel.org>

csky: Remove unused core-y for dts

This line was used for embedding a DT into vmlinux.

Since commit c4c14c3bd177 ("csky: remove builtin-dtb Kbuild"),
DT for csky is just a separate blob.

It is covered by the generic rule in the top Makefile:

ifdef CONFIG_OF_EARLY_FLATTREE
all: dtbs
endif

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Signed-off-by: Guo Ren <guoren@linux.alibaba.com>

kbuild: use more subdir- for visiting subdirectories while cleaning

Documentation/kbuild/makefiles.rst suggests to use "archclean" for
cleaning arch/$(SRCARCH)/boot/, but it is not a hard requirement.

Since commit d92cc4d51643 ("kbuild: require all architectures to have
arch/$(SRCARCH)/Kbuild"), we can use the "subdir- += boot" trick for
all architectures. This can take advantage of the parallel option (-j)
for "make clean".

I also cleaned up the comments in arch/$(SRCARCH)/Makefile. The "archdep"
target no longer exists.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
Acked-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc)

csky: Fixup calltrace panic

The implementation of show_stack will panic with wrong fp:

addr = *fp++;

because the fp isn't checked properly.

The current implementations of show_stack, wchan and stack_trace
haven't been designed properly, so just deprecate them.

This patch is a reference to riscv's way, all codes are modified from
arm's. The patch is passed with:

- cat /proc/<pid>/stack
- cat /proc/<pid>/wchan
- echo c > /proc/sysrq-trigger

Signed-off-by: Guo Ren <guoren@linux.alibaba.com>

kconfig: make arch/*/configs/defconfig the default of KBUILD_DEFCONFIG

Until recently, if KBUILD_DEFCONFIG was not set by the arch Makefile,
the default path arch/*/defconfig was used.

The last users of the default are gone by the following commits:

- Commit f3e20ad67b4c ("s390: move arch/s390/defconfig to
arch/s390/configs/defconfig")

- Commit 986a13769c4b ("alpha: move arch/alpha/defconfig to
arch/alpha/configs/defconfig")

Let's set arch/*/configs/defconfig as a new default. This saves
KBUILD_DEFCONFIG for some architectures.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>

treewide: Add SPDX license identifier - Makefile/Kconfig

Add SPDX license identifiers to all Make/Kconfig files which:

- Have no license information of any form

These files fall under the project license, GPL v2 only. The resulting SPDX
license identifier is:

GPL-2.0-only

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

csky: Fixup vdsp&fpu issues in kernel

This fixup is continue to commit 35ff802af1c4 (csky: fixup remove
vdsp implement for kernel.) and in that patch I didn't finish the
job. We must forbid gcc to generate any vdsp & fpu instructions
and remove vdsp asm in memmove.S.

eg: For GCC it's -mcpu=ck860 and For AS it's -Wa,-mcpu=ck860fv

Signed-off-by: Guo Ren <ren_guo@c-sky.com>

csky: stacktrace supported.

The gcc option "-mbacktrace" will push fp(r8),lr into stack and we could
unwind the stack with:
fp = *fp
lr = (unsigned int *)fp[1]

Signed-off-by: Guo Ren <ren_guo@c-sky.com>

csky: use common dtb build rules

Remove the Kbuild rules in arch/csky and use common dtb build rules.

This modification is based on:

commit 37c8a5fafa3b ("kbuild: consolidate Devicetree dtb build rules")

Signed-off-by: Guo Ren <ren_guo@c-sky.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Acked-by: Arnd Bergmann <arnd@arndb.de>

csky: remove builtin-dtb Kbuild

Remove the builtin-dtb implementation in arch/csky.

Signed-off-by: Guo Ren <ren_guo@c-sky.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>

csky: Build infrastructure

This patch adds Makefile, Kconfig for build infrastructure.

Signed-off-by: Guo Ren <ren_guo@c-sky.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>