um: implement a x86_64 vDSO

	setjmp.o signal.o stub.o stub_segv.o syscalls.o syscall_table.o \

	sysrq.o ksyms.o tls.o

obj-y += vdso/

subarch-obj-y = lib/csum-partial_64.o lib/memcpy_64.o lib/thunk_64.o \

		lib/rwsem.o

subarch-obj-$(CONFIG_MODULES) += kernel/module.o

#

# Building vDSO images for x86.

#

VDSO64-y		:= y

vdso-install-$(VDSO64-y)	+= vdso.so

# files to link into the vdso

vobjs-y := vdso-note.o um_vdso.o

# files to link into kernel

obj-$(VDSO64-y)			+= vdso.o vma.o

vobjs := $(foreach F,$(vobjs-y),$(obj)/$F)

$(obj)/vdso.o: $(obj)/vdso.so

targets += vdso.so vdso.so.dbg vdso.lds $(vobjs-y)

export CPPFLAGS_vdso.lds += -P -C

VDSO_LDFLAGS_vdso.lds = -m64 -Wl,-soname=linux-vdso.so.1 \

       -Wl,-z,max-page-size=4096 -Wl,-z,common-page-size=4096

$(obj)/vdso.o: $(src)/vdso.S $(obj)/vdso.so

$(obj)/vdso.so.dbg: $(src)/vdso.lds $(vobjs) FORCE

	$(call if_changed,vdso)

$(obj)/%.so: OBJCOPYFLAGS := -S

$(obj)/%.so: $(obj)/%.so.dbg FORCE

	$(call if_changed,objcopy)

#

# Don't omit frame pointers for ease of userspace debugging, but do

# optimize sibling calls.

#

CFL := $(PROFILING) -mcmodel=small -fPIC -O2 -fasynchronous-unwind-tables -m64 \

       $(filter -g%,$(KBUILD_CFLAGS)) $(call cc-option, -fno-stack-protector) \

       -fno-omit-frame-pointer -foptimize-sibling-calls

$(vobjs): KBUILD_CFLAGS += $(CFL)

#

# vDSO code runs in userspace and -pg doesn't help with profiling anyway.

#

CFLAGS_REMOVE_vdso-note.o = -pg

CFLAGS_REMOVE_um_vdso.o = -pg

targets += vdso-syms.lds

obj-$(VDSO64-y)			+= vdso-syms.lds

#

# Match symbols in the DSO that look like VDSO*; produce a file of constants.

#

sed-vdsosym := -e 's/^00*/0/' \

	-e 's/^\([0-9a-fA-F]*\) . \(VDSO[a-zA-Z0-9_]*\)$$/\2 = 0x\1;/p'

quiet_cmd_vdsosym = VDSOSYM $@

define cmd_vdsosym

	$(NM) $< | LC_ALL=C sed -n $(sed-vdsosym) | LC_ALL=C sort > $@

endef

$(obj)/%-syms.lds: $(obj)/%.so.dbg FORCE

	$(call if_changed,vdsosym)

#

# The DSO images are built using a special linker script.

#

quiet_cmd_vdso = VDSO    $@

      cmd_vdso = $(CC) -nostdlib -o $@ \

		       $(VDSO_LDFLAGS) $(VDSO_LDFLAGS_$(filter %.lds,$(^F))) \

		       -Wl,-T,$(filter %.lds,$^) $(filter %.o,$^) && \

		 sh $(srctree)/$(src)/checkundef.sh '$(NM)' '$@'

VDSO_LDFLAGS = -fPIC -shared $(call cc-ldoption, -Wl$(comma)--hash-style=sysv)

GCOV_PROFILE := n

#

# Install the unstripped copy of vdso*.so listed in $(vdso-install-y).

#

quiet_cmd_vdso_install = INSTALL $@

      cmd_vdso_install = cp $(obj)/$@.dbg $(MODLIB)/vdso/$@

$(vdso-install-y): %.so: $(obj)/%.so.dbg FORCE

	@mkdir -p $(MODLIB)/vdso

	$(call cmd,vdso_install)

PHONY += vdso_install $(vdso-install-y)

vdso_install: $(vdso-install-y)

#!/bin/sh

nm="$1"

file="$2"

$nm "$file" | grep '^ *U' > /dev/null 2>&1

if [ $? -eq 1 ]; then

    exit 0

else

    echo "$file: undefined symbols found" >&2

    exit 1

fi

/*

 * Copyright (C) 2011 Richard Weinberger <richrd@nod.at>

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License version 2 as

 * published by the Free Software Foundation.

 *

 * This vDSO turns all calls into a syscall so that UML can trap them.

 */

/* Disable profiling for userspace code */

#define DISABLE_BRANCH_PROFILING

#include <linux/time.h>

#include <linux/getcpu.h>

#include <asm/unistd.h>

int __vdso_clock_gettime(clockid_t clock, struct timespec *ts)

{

	long ret;

	asm("syscall" : "=a" (ret) :

		"0" (__NR_clock_gettime), "D" (clock), "S" (ts) : "memory");

	return ret;

}

int clock_gettime(clockid_t, struct timespec *)

	__attribute__((weak, alias("__vdso_clock_gettime")));

int __vdso_gettimeofday(struct timeval *tv, struct timezone *tz)

{

	long ret;

	asm("syscall" : "=a" (ret) :

		"0" (__NR_gettimeofday), "D" (tv), "S" (tz) : "memory");

	return ret;

}

int gettimeofday(struct timeval *, struct timezone *)

	__attribute__((weak, alias("__vdso_gettimeofday")));

time_t __vdso_time(time_t *t)

{

	long secs;

	asm volatile("syscall"

		: "=a" (secs)

		: "0" (__NR_time), "D" (t) : "cc", "r11", "cx", "memory");

	return secs;

}

int time(time_t *t) __attribute__((weak, alias("__vdso_time")));

long

__vdso_getcpu(unsigned *cpu, unsigned *node, struct getcpu_cache *unused)

{

	/*

	 * UML does not support SMP, we can cheat here. :)

	 */

	if (cpu)

		*cpu = 0;

	if (node)

		*node = 0;

	return 0;

}

long getcpu(unsigned *cpu, unsigned *node, struct getcpu_cache *tcache)

	__attribute__((weak, alias("__vdso_getcpu")));

/*

 * Linker script for vDSO.  This is an ELF shared object prelinked to

 * its virtual address, and with only one read-only segment.

 * This script controls its layout.

 */

SECTIONS

{

	. = VDSO_PRELINK + SIZEOF_HEADERS;

	.hash		: { *(.hash) }			:text

	.gnu.hash	: { *(.gnu.hash) }

	.dynsym		: { *(.dynsym) }

	.dynstr		: { *(.dynstr) }

	.gnu.version	: { *(.gnu.version) }

	.gnu.version_d	: { *(.gnu.version_d) }

	.gnu.version_r	: { *(.gnu.version_r) }

	.note		: { *(.note.*) }		:text	:note

	.eh_frame_hdr	: { *(.eh_frame_hdr) }		:text	:eh_frame_hdr

	.eh_frame	: { KEEP (*(.eh_frame)) }	:text

	.dynamic	: { *(.dynamic) }		:text	:dynamic

	.rodata		: { *(.rodata*) }		:text

	.data		: {

	      *(.data*)

	      *(.sdata*)

	      *(.got.plt) *(.got)

	      *(.gnu.linkonce.d.*)

	      *(.bss*)

	      *(.dynbss*)

	      *(.gnu.linkonce.b.*)

	}

	.altinstructions	: { *(.altinstructions) }

	.altinstr_replacement	: { *(.altinstr_replacement) }

	/*

	 * Align the actual code well away from the non-instruction data.

	 * This is the best thing for the I-cache.

	 */

	. = ALIGN(0x100);

	.text		: { *(.text*) }			:text	=0x90909090

}

/*

 * Very old versions of ld do not recognize this name token; use the constant.

 */

#define PT_GNU_EH_FRAME	0x6474e550

/*

 * We must supply the ELF program headers explicitly to get just one

 * PT_LOAD segment, and set the flags explicitly to make segments read-only.

 */

PHDRS

{

	text		PT_LOAD		FLAGS(5) FILEHDR PHDRS; /* PF_R|PF_X */

	dynamic		PT_DYNAMIC	FLAGS(4);		/* PF_R */

	note		PT_NOTE		FLAGS(4);		/* PF_R */

	eh_frame_hdr	PT_GNU_EH_FRAME;

}