1da86d2f4
Denis Vlasenko
2008-06-04
Subject
build system: add PIE build option
Binary
No binary (build failed)
Architecture & Compiler Flags
—
Build Log
(log yok)
Commit Diff GitHub →
Config.in +8 -0Makefile +3 -1Makefile.flags +16 -4scripts/Makefile.IMA +3 -3scripts/Makefile.build +2 -2
Config.in+8 -0
| @@ -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 | |
Makefile+3 -1
| @@ -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)" \ | |
| "$(libs-y)" \ | |
Makefile.flags+16 -4
| @@ -50,17 +50,31 @@ ifeq ($(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 | |
scripts/Makefile.IMA+3 -3
| @@ -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" \ | |
scripts/Makefile.build+2 -2
| @@ -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) | |