* [Qemu-devel] [PATCH v4 2/2] Build usermode targets as PIE
2009-09-04 12:28 [Qemu-devel] [PATCH v4 1/2] Do not link usermode targets with libhw*.a Kirill A. Shutemov
@ 2009-09-04 12:28 ` Kirill A. Shutemov
2009-09-04 9:58 ` Arnaud Patard
0 siblings, 1 reply; 5+ messages in thread
From: Kirill A. Shutemov @ 2009-09-04 12:28 UTC (permalink / raw)
To: qemu-devel
Cc: Paolo Bonzini, Riku Voipio, Juan Quintela, Kirill A. Shutemov,
Arnaud Patard, Paul Brook
Long since, qemu on i386 has a linking hack which produces an executable
which looks like PIE, but it always has text relocations since all
object files compiled without -fpie.
The best was to solve the issue is to build a true PIE.
v4:
- Add test for toolchain if it has proper PIE support
v3:
- One more pice of the hack was removed
- Description updated
v2:
- Add configure options do enable/disable PIE for usermode targets.
Disabling can be useful if you build uswing toolchain which has
broken PIE support. PIE for usermode targets enabled by default.
Signed-off-by: Kirill A. Shutemov <kirill@shutemov.name>
---
Makefile | 10 +---------
Makefile.target | 19 +++++++++++++++----
configure | 49 ++++++++++++++++++++++++++++++++++++++-----------
linux-user/main.c | 26 --------------------------
4 files changed, 54 insertions(+), 50 deletions(-)
diff --git a/Makefile b/Makefile
index bdac9b3..634ea81 100644
--- a/Makefile
+++ b/Makefile
@@ -39,8 +39,6 @@ subdir-%:
$(call quiet-command,$(MAKE) $(SUBDIR_MAKEFLAGS) -C $* V="$(V)" TARGET_DIR="$*/" all,)
$(filter %-softmmu,$(SUBDIR_RULES)): libqemu_common.a
-$(filter %-user,$(SUBDIR_RULES)): libqemu_user.a
-
ROMSUBDIR_RULES=$(patsubst %,romsubdir-%, $(ROMS))
romsubdir-%:
@@ -74,7 +72,7 @@ block-obj-y += $(addprefix block/, $(block-nested-y))
# CPUs and machines.
obj-y = $(block-obj-y)
-obj-y += readline.o console.o host-utils.o
+obj-y += readline.o console.o
obj-y += irq.o ptimer.o
obj-y += i2c.o smbus.o smbus_eeprom.o max7310.o max111x.o wm8750.o
@@ -161,12 +159,6 @@ bt-host.o: QEMU_CFLAGS += $(BLUEZ_CFLAGS)
libqemu_common.a: $(obj-y)
-#######################################################################
-# user-obj-y is code used by qemu userspace emulation
-user-obj-y = cutils.o cache-utils.o path.o envlist.o host-utils.o
-
-libqemu_user.a: $(user-obj-y)
-
######################################################################
qemu-img.o: qemu-img-cmds.h
diff --git a/Makefile.target b/Makefile.target
index f7d1919..f738617 100644
--- a/Makefile.target
+++ b/Makefile.target
@@ -31,7 +31,7 @@ all: $(PROGS)
#########################################################
# cpu emulator library
-libobj-y = exec.o translate-all.o cpu-exec.o translate.o
+libobj-y = exec.o translate-all.o cpu-exec.o translate.o host-utils.o
libobj-y += tcg/tcg.o tcg/tcg-runtime.o
libobj-$(CONFIG_SOFTFLOAT) += fpu/softfloat.o
libobj-$(CONFIG_NOSOFTFLOAT) += fpu/softfloat-native.o
@@ -80,9 +80,9 @@ ifdef CONFIG_LINUX_USER
VPATH+=:$(SRC_PATH)/linux-user:$(SRC_PATH)/linux-user/$(TARGET_ABI_DIR)
QEMU_CFLAGS+=-I$(SRC_PATH)/linux-user -I$(SRC_PATH)/linux-user/$(TARGET_ABI_DIR)
-
obj-y = main.o syscall.o strace.o mmap.o signal.o thunk.o \
elfload.o linuxload.o uaccess.o gdbstub.o gdbstub-xml.o
+obj-y += envlist.o path.o
obj-$(TARGET_HAS_BFLT) += flatload.o
obj-$(TARGET_HAS_ELFLOAD32) += elfload32.o
@@ -98,7 +98,7 @@ obj-arm-y += arm-semi.o
obj-m68k-y += m68k-sim.o m68k-semi.o
-ARLIBS=../libqemu_user.a libqemu.a
+ARLIBS=libqemu.a
endif #CONFIG_LINUX_USER
#########################################################
@@ -116,6 +116,7 @@ LIBS+=-lmx
obj-y = main.o commpage.o machload.o mmap.o signal.o syscall.o thunk.o \
gdbstub.o gdbstub-xml.o
+obj-y += envlist.o path.o
obj-i386-y += ioport-user.o
@@ -133,13 +134,23 @@ QEMU_CFLAGS+=-I$(SRC_PATH)/bsd-user -I$(SRC_PATH)/bsd-user/$(TARGET_ARCH)
obj-y = main.o bsdload.o elfload.o mmap.o signal.o strace.o syscall.o \
gdbstub.o gdbstub-xml.o uaccess.o
+obj-y += envlist.o path.o
obj-i386-y += ioport-user.o
-ARLIBS=libqemu.a ../libqemu_user.a
+ARLIBS=libqemu.a
endif #CONFIG_BSD_USER
+ifdef CONFIG_USER_ONLY
+# hack to compile with -fpie for *-user targets
+obj-y += cutils-user.o cache-utils-user.o
+cutils-user.c cache-utils-user.c:
+ @echo " LN $(TARGET_DIR)$@"
+ @ln -s $(SRC_PATH)/$(@:%-user.c=%.c) $@
+endif
+
+
#########################################################
# System emulator target
ifdef CONFIG_SOFTMMU
diff --git a/configure b/configure
index 0d0162a..4a6a9fb 100755
--- a/configure
+++ b/configure
@@ -221,6 +221,7 @@ kerneldir=""
aix="no"
blobs="yes"
pkgversion=""
+user_pie=""
# OS specific
if check_define __linux__ ; then
@@ -498,6 +499,10 @@ for opt do
;;
--disable-guest-base) guest_base="no"
;;
+ --enable-user-pie) user_pie="yes"
+ ;;
+ --disable-user-pie) user_pie="no"
+ ;;
--enable-uname-release=*) uname_release="$optarg"
;;
--sparc_cpu=*)
@@ -672,6 +677,8 @@ echo " --disable-bsd-user disable all BSD usermode emulation targets"
echo " --enable-guest-base enable GUEST_BASE support for usermode"
echo " emulation targets"
echo " --disable-guest-base disable GUEST_BASE support"
+echo " --enable-user-pie build usermode emulation targets as PIE"
+echo " --disable-user-pie do not build usermode emulation targets as PIE"
echo " --fmod-lib path to FMOD library"
echo " --fmod-inc path to FMOD includes"
echo " --oss-lib path to OSS library"
@@ -1538,6 +1545,29 @@ elif compile_prog "" "-lrt" ; then
LIBS="-lrt $LIBS"
fi
+##########################################
+# Can toolchain generate proper PIE
+cat > $TMPC <<EOF
+int main() {
+ static __thread int i = 0;
+ i++;
+ return 0;
+}
+EOF
+
+if test "$user_pie" != "no" ; then
+ if compile_prog "-fpie" "-pie -Wl,--fatal-warnings -Wl,--warn-shared-textrel"; then
+ user_pie="yes"
+ else
+ if test "$user_pie" = "yes"; then
+ echo "Toolchain has no proper PIE support"
+ exit 1
+ else
+ user_pie="no"
+ fi
+ fi
+fi
+
# Determine what linker flags to use to force archive inclusion
check_linker_flags()
{
@@ -1678,6 +1708,7 @@ echo "Documentation $docs"
echo "uname -r $uname_release"
echo "NPTL support $nptl"
echo "GUEST_BASE $guest_base"
+echo "PIE user targets $user_pie"
echo "vde support $vde"
echo "IO thread $io_thread"
echo "Linux AIO support $linux_aio"
@@ -2302,6 +2333,12 @@ if test "$target_softmmu" = "yes" ; then
esac
fi
+if test "$target_user_only" = "yes" -a "$static" = "no" -a \
+ "$user_pie" = "yes" ; then
+ cflags="-fpie $cflags"
+ ldflags="-pie $ldflags"
+fi
+
if test "$target_softmmu" = "yes" -a \( \
"$TARGET_ARCH" = "microblaze" -o \
"$TARGET_ARCH" = "cris" \) ; then
@@ -2323,16 +2360,6 @@ fi
linker_script="-Wl,-T../config-host.ld -Wl,-T,\$(SRC_PATH)/\$(ARCH).ld"
if test "$target_linux_user" = "yes" -o "$target_bsd_user" = "yes" ; then
case "$ARCH" in
- i386)
- if test "$gprof" = "yes" -o "$static" = "yes" ; then
- ldflags="$linker_script $ldflags"
- else
- # WARNING: this LDFLAGS is _very_ tricky : qemu is an ELF shared object
- # that the kernel ELF loader considers as an executable. I think this
- # is the simplest way to make it self virtualizable!
- ldflags="-Wl,-shared $ldflags"
- fi
- ;;
sparc)
# -static is used to avoid g1/g3 usage by the dynamic linker
ldflags="$linker_script -static $ldflags"
@@ -2340,7 +2367,7 @@ if test "$target_linux_user" = "yes" -o "$target_bsd_user" = "yes" ; then
ia64)
ldflags="-Wl,-G0 $linker_script -static $ldflags"
;;
- x86_64|ppc|ppc64|s390|sparc64|alpha|arm|m68k|mips|mips64)
+ i386|x86_64|ppc|ppc64|s390|sparc64|alpha|arm|m68k|mips|mips64)
ldflags="$linker_script $ldflags"
;;
esac
diff --git a/linux-user/main.c b/linux-user/main.c
index a628c01..81a1ada 100644
--- a/linux-user/main.c
+++ b/linux-user/main.c
@@ -48,32 +48,6 @@ int have_guest_base;
static const char *interp_prefix = CONFIG_QEMU_PREFIX;
const char *qemu_uname_release = CONFIG_UNAME_RELEASE;
-#if defined(__i386__) && !defined(CONFIG_STATIC)
-/* Force usage of an ELF interpreter even if it is an ELF shared
- object ! */
-const char interp[] __attribute__((section(".interp"))) = "/lib/ld-linux.so.2";
-#endif
-
-/* for recent libc, we add these dummy symbols which are not declared
- when generating a linked object (bug in ld ?) */
-#if (__GLIBC__ > 2 || (__GLIBC__ == 2 && __GLIBC_MINOR__ >= 3)) && !defined(CONFIG_STATIC)
-asm(".globl __preinit_array_start\n"
- ".globl __preinit_array_end\n"
- ".globl __init_array_start\n"
- ".globl __init_array_end\n"
- ".globl __fini_array_start\n"
- ".globl __fini_array_end\n"
- ".section \".rodata\"\n"
- "__preinit_array_start:\n"
- "__preinit_array_end:\n"
- "__init_array_start:\n"
- "__init_array_end:\n"
- "__fini_array_start:\n"
- "__fini_array_end:\n"
- ".long 0\n"
- ".previous\n");
-#endif
-
/* XXX: on x86 MAP_GROWSDOWN only works if ESP <= address + 32, so
we allocate a bigger stack. Need a better solution, for example
by remapping the process stack directly at the right place */
--
1.6.4.2
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