ARM: 8969/1: decompressor: simplify libfdt builds

Copying source files during the build time may not end up with
as clean code as expected.

lib/fdt*.c simply wrap scripts/dtc/libfdt/fdt*.c, and it works
nicely. Let's follow this approach for the arm decompressor, too.

Add four wrappers, arch/arm/boot/compressed/fdt*.c and remove
the Makefile messes. Another nice thing is we no longer need to
maintain the own libfdt_env.h because the decompressor can include
<linux/libfdt_env.h>.

There is a subtle problem when generated files are turned into
check-in files.

When you are doing a rebuild of an existing object tree with O=
option, there exists stale "shipped" copies that the old Makefile
implementation created. The build system ends up with compiling the
stale generated files because Make searches for prerequisites in the
current directory, i.e. $(objtree) first, and then the directory
listed in VPATH, i.e. $(srctree).

To mend this issue, I added the following code:

  ifdef building_out_of_srctree
  $(shell rm -f $(addprefix $(obj)/, fdt_rw.c fdt_ro.c fdt_wip.c fdt.c))
  endif

This will need to stay for a while because "git bisect" crossing this
commit, otherwise, would result in a build error.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
This commit is contained in:
Masahiro Yamada 2020-04-22 14:08:53 +01:00 committed by Russell King
parent 4f39467e52
commit 7ae4a78daa
8 changed files with 24 additions and 56 deletions

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@ -7,12 +7,3 @@ hyp-stub.S
piggy_data
vmlinux
vmlinux.lds
# borrowed libfdt files
fdt.c
fdt.h
fdt_ro.c
fdt_rw.c
fdt_wip.c
libfdt.h
libfdt_internal.h

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@ -76,29 +76,30 @@ compress-$(CONFIG_KERNEL_LZMA) = lzma
compress-$(CONFIG_KERNEL_XZ) = xzkern
compress-$(CONFIG_KERNEL_LZ4) = lz4
# Borrowed libfdt files for the ATAG compatibility mode
libfdt := fdt_rw.c fdt_ro.c fdt_wip.c fdt.c
libfdt_hdrs := fdt.h libfdt.h libfdt_internal.h
libfdt_objs := $(addsuffix .o, $(basename $(libfdt)))
$(addprefix $(obj)/,$(libfdt) $(libfdt_hdrs)): $(obj)/%: $(srctree)/scripts/dtc/libfdt/%
$(call cmd,shipped)
$(addprefix $(obj)/,$(libfdt_objs) atags_to_fdt.o): \
$(addprefix $(obj)/,$(libfdt_hdrs))
libfdt_objs := fdt_rw.o fdt_ro.o fdt_wip.o fdt.o
ifeq ($(CONFIG_ARM_ATAG_DTB_COMPAT),y)
OBJS += $(libfdt_objs) atags_to_fdt.o
endif
# -fstack-protector-strong triggers protection checks in this code,
# but it is being used too early to link to meaningful stack_chk logic.
nossp-flags-$(CONFIG_CC_HAS_STACKPROTECTOR_NONE) := -fno-stack-protector
$(foreach o, $(libfdt_objs) atags_to_fdt.o, \
$(eval CFLAGS_$(o) := -I $(srctree)/scripts/dtc/libfdt $(nossp-flags-y)))
# These were previously generated C files. When you are building the kernel
# with O=, make sure to remove the stale files in the output tree. Otherwise,
# the build system wrongly compiles the stale ones.
ifdef building_out_of_srctree
$(shell rm -f $(addprefix $(obj)/, fdt_rw.c fdt_ro.c fdt_wip.c fdt.c))
endif
targets := vmlinux vmlinux.lds piggy_data piggy.o \
lib1funcs.o ashldi3.o bswapsdi2.o \
head.o $(OBJS)
clean-files += piggy_data lib1funcs.S ashldi3.S bswapsdi2.S \
$(libfdt) $(libfdt_hdrs) hyp-stub.S
clean-files += piggy_data lib1funcs.S ashldi3.S bswapsdi2.S hyp-stub.S
KBUILD_CFLAGS += -DDISABLE_BRANCH_PROFILING
@ -107,15 +108,6 @@ ORIG_CFLAGS := $(KBUILD_CFLAGS)
KBUILD_CFLAGS = $(subst -pg, , $(ORIG_CFLAGS))
endif
# -fstack-protector-strong triggers protection checks in this code,
# but it is being used too early to link to meaningful stack_chk logic.
nossp-flags-$(CONFIG_CC_HAS_STACKPROTECTOR_NONE) := -fno-stack-protector
CFLAGS_atags_to_fdt.o := $(nossp-flags-y)
CFLAGS_fdt.o := $(nossp-flags-y)
CFLAGS_fdt_ro.o := $(nossp-flags-y)
CFLAGS_fdt_rw.o := $(nossp-flags-y)
CFLAGS_fdt_wip.o := $(nossp-flags-y)
ccflags-y := -fpic $(call cc-option,-mno-single-pic-base,) -fno-builtin \
-I$(obj) $(DISABLE_ARM_SSP_PER_TASK_PLUGIN)
asflags-y := -DZIMAGE

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@ -1,4 +1,5 @@
// SPDX-License-Identifier: GPL-2.0
#include <linux/libfdt_env.h>
#include <asm/setup.h>
#include <libfdt.h>

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@ -0,0 +1,2 @@
// SPDX-License-Identifier: GPL-2.0-only
#include "../../../../lib/fdt.c"

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@ -0,0 +1,2 @@
// SPDX-License-Identifier: GPL-2.0-only
#include "../../../../lib/fdt_ro.c"

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@ -0,0 +1,2 @@
// SPDX-License-Identifier: GPL-2.0-only
#include "../../../../lib/fdt_rw.c"

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@ -0,0 +1,2 @@
// SPDX-License-Identifier: GPL-2.0-only
#include "../../../../lib/fdt_wip.c"

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@ -1,24 +0,0 @@
/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _ARM_LIBFDT_ENV_H
#define _ARM_LIBFDT_ENV_H
#include <linux/limits.h>
#include <linux/types.h>
#include <linux/string.h>
#include <asm/byteorder.h>
#define INT32_MAX S32_MAX
#define UINT32_MAX U32_MAX
typedef __be16 fdt16_t;
typedef __be32 fdt32_t;
typedef __be64 fdt64_t;
#define fdt16_to_cpu(x) be16_to_cpu(x)
#define cpu_to_fdt16(x) cpu_to_be16(x)
#define fdt32_to_cpu(x) be32_to_cpu(x)
#define cpu_to_fdt32(x) cpu_to_be32(x)
#define fdt64_to_cpu(x) be64_to_cpu(x)
#define cpu_to_fdt64(x) cpu_to_be64(x)
#endif