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authorDenis Vlasenko <vda.linux@googlemail.com>2008-06-04 11:28:24 +0000
committerDenis Vlasenko <vda.linux@googlemail.com>2008-06-04 11:28:24 +0000
commit1da86d2f40f304d78b2ae4aac3b590b19adc7ce3 (patch)
tree6f2a87934ad24c0e640c6313d56d2e28d1e81185
parent1e93f3c5859aeebcca7c0480de2bd038defe8b1c (diff)
downloadbusybox-1da86d2f40f304d78b2ae4aac3b590b19adc7ce3.tar.gz
build system: add PIE build option
-rw-r--r--Config.in8
-rw-r--r--Makefile4
-rw-r--r--Makefile.flags20
-rw-r--r--scripts/Makefile.IMA6
-rw-r--r--scripts/Makefile.build4
5 files changed, 32 insertions, 10 deletions
diff --git a/Config.in b/Config.in
index a991b8a81..3b374967b 100644
--- a/Config.in
+++ b/Config.in
@@ -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
diff --git a/Makefile b/Makefile
index aad67a1a8..308ea42cd 100644
--- a/Makefile
+++ b/Makefile
@@ -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)" \
"$(libs-y)" \
diff --git a/Makefile.flags b/Makefile.flags
index 9525889c6..1cfda26ac 100644
--- a/Makefile.flags
+++ b/Makefile.flags
@@ -50,17 +50,31 @@ ifeq ($(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 988c6a6d1..a34db50f4 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 ddefea5a6..f343818b1 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)