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linux/arch/x86_64/Makefile
Andi Kleen 2aae950b21 x86_64: Add vDSO for x86-64 with gettimeofday/clock_gettime/getcpu 
This implements new vDSO for x86-64.  The concept is similar
to the existing vDSOs on i386 and PPC.  x86-64 has had static
vsyscalls before,  but these are not flexible enough anymore.

A vDSO is a ELF shared library supplied by the kernel that is mapped into
user address space.  The vDSO mapping is randomized for each process
for security reasons.

Doing this was needed for clock_gettime, because clock_gettime
always needs a syscall fallback and having one at a fixed
address would have made buffer overflow exploits too easy to write.

The vdso can be disabled with vdso=0

It currently includes a new gettimeofday implemention and optimized
clock_gettime(). The gettimeofday implementation is slightly faster
than the one in the old vsyscall.  clock_gettime is significantly faster
than the syscall for CLOCK_MONOTONIC and CLOCK_REALTIME.

The new calls are generally faster than the old vsyscall.

Advantages over the old x86-64 vsyscalls:
- Extensible
- Randomized
- Cleaner
- Easier to virtualize (the old static address range previously causes
overhead e.g. for Xen because it has to create special page tables for it)

Weak points:
- glibc support still to be written

The VM interface is partly based on Ingo Molnar's i386 version.

Includes compile fix from Joachim Deguara

Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-07-21 18:37:08 -07:00

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Makefile
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#
# x86_64/Makefile
#
# This file is included by the global makefile so that you can add your own
# architecture-specific flags and dependencies. Remember to do have actions
# for "archclean" and "archdep" for cleaning up and making dependencies for
# this architecture
#
# This file is subject to the terms and conditions of the GNU General Public
# License. See the file "COPYING" in the main directory of this archive
# for more details.
#
# Copyright (C) 1994 by Linus Torvalds
#
# 19990713 Artur Skawina <skawina@geocities.com>
# Added '-march' and '-mpreferred-stack-boundary' support
# 20000913 Pavel Machek <pavel@suse.cz>
# Converted for x86_64 architecture
# 20010105 Andi Kleen, add IA32 compiler.
# ....and later removed it again....
#
# $Id: Makefile,v 1.31 2002/03/22 15:56:07 ak Exp $
LDFLAGS := -m elf_x86_64
OBJCOPYFLAGS := -O binary -R .note -R .comment -S
LDFLAGS_vmlinux :=
CHECKFLAGS += -D__x86_64__ -m64
cflags-y :=
cflags-kernel-y :=
cflags-$(CONFIG_MK8) += $(call cc-option,-march=k8)
cflags-$(CONFIG_MPSC) += $(call cc-option,-march=nocona)
# gcc doesn't support -march=core2 yet as of gcc 4.3, but I hope it
# will eventually. Use -mtune=generic as fallback
cflags-$(CONFIG_MCORE2) += \
$(call cc-option,-march=core2,$(call cc-option,-mtune=generic))
cflags-$(CONFIG_GENERIC_CPU) += $(call cc-option,-mtune=generic)
cflags-y += -m64
cflags-y += -mno-red-zone
cflags-y += -mcmodel=kernel
cflags-y += -pipe
cflags-y += -Wno-sign-compare
cflags-y += -fno-asynchronous-unwind-tables
ifneq ($(CONFIG_DEBUG_INFO),y)
# -fweb shrinks the kernel a bit, but the difference is very small
# it also messes up debugging, so don't use it for now.
#cflags-y += $(call cc-option,-fweb)
endif
# -funit-at-a-time shrinks the kernel .text considerably
# unfortunately it makes reading oopses harder.
cflags-y += $(call cc-option,-funit-at-a-time)
# prevent gcc from generating any FP code by mistake
cflags-y += $(call cc-option,-mno-sse -mno-mmx -mno-sse2 -mno-3dnow,)
# this works around some issues with generating unwind tables in older gccs
# newer gccs do it by default
cflags-y += -maccumulate-outgoing-args
# do binutils support CFI?
cflags-y += $(call as-instr,.cfi_startproc\n.cfi_endproc,-DCONFIG_AS_CFI=1,)
AFLAGS += $(call as-instr,.cfi_startproc\n.cfi_endproc,-DCONFIG_AS_CFI=1,)
# is .cfi_signal_frame supported too?
cflags-y += $(call as-instr,.cfi_startproc\n.cfi_signal_frame\n.cfi_endproc,-DCONFIG_AS_CFI_SIGNAL_FRAME=1,)
AFLAGS += $(call as-instr,.cfi_startproc\n.cfi_signal_frame\n.cfi_endproc,-DCONFIG_AS_CFI_SIGNAL_FRAME=1,)
cflags-$(CONFIG_CC_STACKPROTECTOR) += $(shell $(CONFIG_SHELL) $(srctree)/scripts/gcc-x86_64-has-stack-protector.sh "$(CC)" -fstack-protector )
cflags-$(CONFIG_CC_STACKPROTECTOR_ALL) += $(shell $(CONFIG_SHELL) $(srctree)/scripts/gcc-x86_64-has-stack-protector.sh "$(CC)" -fstack-protector-all )
CFLAGS += $(cflags-y)
CFLAGS_KERNEL += $(cflags-kernel-y)
AFLAGS += -m64
head-y := arch/x86_64/kernel/head.o arch/x86_64/kernel/head64.o arch/x86_64/kernel/init_task.o
libs-y += arch/x86_64/lib/
core-y += arch/x86_64/kernel/ \
arch/x86_64/mm/ \
arch/x86_64/crypto/ \
arch/x86_64/vdso/
core-$(CONFIG_IA32_EMULATION) += arch/x86_64/ia32/
drivers-$(CONFIG_PCI) += arch/x86_64/pci/
drivers-$(CONFIG_OPROFILE) += arch/x86_64/oprofile/
boot := arch/x86_64/boot
PHONY += bzImage bzlilo install archmrproper \
fdimage fdimage144 fdimage288 isoimage archclean
#Default target when executing "make"
all: bzImage
BOOTIMAGE := arch/x86_64/boot/bzImage
KBUILD_IMAGE := $(BOOTIMAGE)
bzImage: vmlinux
$(Q)$(MAKE) $(build)=$(boot) $(BOOTIMAGE)
bzlilo: vmlinux
$(Q)$(MAKE) $(build)=$(boot) BOOTIMAGE=$(BOOTIMAGE) zlilo
bzdisk: vmlinux
$(Q)$(MAKE) $(build)=$(boot) BOOTIMAGE=$(BOOTIMAGE) zdisk
fdimage fdimage144 fdimage288 isoimage: vmlinux
$(Q)$(MAKE) $(build)=$(boot) BOOTIMAGE=$(BOOTIMAGE) $@
install:
$(Q)$(MAKE) $(build)=$(boot) BOOTIMAGE=$(BOOTIMAGE) $@
archclean:
$(Q)$(MAKE) $(clean)=$(boot)
define archhelp
echo '* bzImage - Compressed kernel image (arch/$(ARCH)/boot/bzImage)'
echo ' install - Install kernel using'
echo ' (your) ~/bin/installkernel or'
echo ' (distribution) /sbin/installkernel or'
echo ' install to $$(INSTALL_PATH) and run lilo'
echo ' bzdisk - Create a boot floppy in /dev/fd0'
echo ' fdimage - Create a boot floppy image'
echo ' isoimage - Create a boot CD-ROM image'
endef
CLEAN_FILES += arch/$(ARCH)/boot/fdimage \
arch/$(ARCH)/boot/image.iso \
arch/$(ARCH)/boot/mtools.conf
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