diff options
| -rw-r--r-- | Config.in | 8 | ||||
| -rw-r--r-- | Makefile | 4 | ||||
| -rw-r--r-- | Makefile.flags | 20 | ||||
| -rw-r--r-- | scripts/Makefile.IMA | 6 | ||||
| -rw-r--r-- | scripts/Makefile.build | 4 |
5 files changed, 32 insertions, 10 deletions
@@ -262,6 +262,14 @@ config STATIC Most people will leave this set to 'N'. +config PIE + bool "Build BusyBox as a position independent executable" + default n + depends on !STATIC + help + (TODO: what is it and why/when is it useful?) + Most people will leave this set to 'N'. + config NOMMU bool "Force NOMMU build" default n @@ -315,6 +315,8 @@ AFLAGS_KERNEL = # Use LINUXINCLUDE when you must reference the include/ directory. # Needed to be compatible with the O= option CFLAGS := $(CFLAGS) +# Added only to final link stage of busybox binary +CFLAGS_busybox := $(CFLAGS_busybox) CPPFLAGS := $(CPPFLAGS) AFLAGS := $(AFLAGS) LDFLAGS := $(LDFLAGS) @@ -580,7 +582,7 @@ quiet_cmd_busybox__ ?= LINK $@ cmd_busybox__ ?= $(srctree)/scripts/trylink \ "$@" \ "$(CC)" \ - "$(CFLAGS)" \ + "$(CFLAGS) $(CFLAGS_busybox)" \ "$(LDFLAGS) $(EXTRA_LDFLAGS)" \ "$(core-y)" \ "$(libs-y)" \ diff --git a/Makefile.flags b/Makefile.flags index 9525889..1cfda26 100644 --- a/Makefile.flags +++ b/Makefile.flags @@ -50,17 +50,31 @@ ifeq ($(CONFIG_DEBUG),y) CFLAGS += $(call cc-option,-g) endif +# If arch/$(ARCH)/Makefile did not override it (with, say, -fPIC)... +ARCH_FPIC ?= -fpic +ARCH_FPIE ?= -fpie +ARCH_PIE ?= -pie + ifeq ($(CONFIG_BUILD_LIBBUSYBOX),y) # on i386: 14% smaller libbusybox.so # (code itself is 9% bigger, we save on relocs/PLT/GOT) -CFLAGS += -fpic +CFLAGS += $(ARCH_FPIC) # and another 4% reduction of libbusybox.so: # (external entry points must be marked EXTERNALLY_VISIBLE) CFLAGS += $(call cc-option,-fvisibility=hidden) endif ifeq ($(CONFIG_STATIC),y) -LDFLAGS += -static +CFLAGS_busybox += -static +endif + +ifeq ($(CONFIG_PIE),y) +CFLAGS_busybox += $(ARCH_PIE) +CFLAGS += $(ARCH_FPIE) +# No switch() jump tables. Code growth +1k, binary size down -12k +# due to reduced number of code pointers. +# (TODO: make overridable: some arches may want to not do this) +CFLAGS += $(call cc-option,-fno-jump-tables) endif LDLIBS += m crypt @@ -81,8 +95,6 @@ ifeq ($(CONFIG_DMALLOC),y) LDLIBS += dmalloc endif -#LDFLAGS += -nostdlib - LDFLAGS_ELF2FLT = -Wl,-elf2flt ifneq (,$(findstring $(LDFLAGS_ELF2FLT),$(LDFLAGS))) SKIP_STRIP = y diff --git a/scripts/Makefile.IMA b/scripts/Makefile.IMA index 988c6a6..a34db50 100644 --- a/scripts/Makefile.IMA +++ b/scripts/Makefile.IMA @@ -45,8 +45,8 @@ STRIP = $(CROSS_COMPILE)strip OBJCOPY = $(CROSS_COMPILE)objcopy OBJDUMP = $(CROSS_COMPILE)objdump -CFLAGS := $(CFLAGS) -CPPFLAGS+= -D"KBUILD_STR(s)=\#s" #-Q +CFLAGS := $(CFLAGS) +CPPFLAGS += -D"KBUILD_STR(s)=\#s" #-Q # We need some generic definitions include $(srctree)/scripts/Kbuild.include @@ -180,7 +180,7 @@ busybox_unstripped.o: $(usage_stuff) include/applet_tables.h include/autoconf.h busybox: busybox_unstripped.o $(srctree)/scripts/trylink \ busybox_unstripped \ - "$(CC)" \ + "$(CC) $(CFLAGS_busybox)" \ "$(CFLAGS)" \ "$(LDFLAGS)" \ "busybox_unstripped.o" \ diff --git a/scripts/Makefile.build b/scripts/Makefile.build index ddefea5..f343818 100644 --- a/scripts/Makefile.build +++ b/scripts/Makefile.build @@ -251,8 +251,8 @@ ifdef builtin-target quiet_cmd_link_o_target = LD $@ # If the list of objects to link is empty, just create an empty built-in.o cmd_link_o_target = $(if $(strip $(obj-y)),\ - $(LD) $(ld_flags) -r -o $@ $(filter $(obj-y), $^),\ - rm -f $@; $(AR) rcs $@) + $(LD) $(ld_flags) -r -o $@ $(filter $(obj-y), $^),\ + rm -f $@; $(AR) rcs $@) $(builtin-target): $(obj-y) FORCE $(call if_changed,link_o_target) |