x86 vDSO: vdso32 build

#

# x86-64 vDSO.

# Building vDSO images for x86.

#

VDSO64-$(CONFIG_X86_64)		:= y

VDSO32-$(CONFIG_X86_32)		:= y

VDSO32-$(CONFIG_COMPAT)		:= y

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

vdso-install-$(VDSO32-y)	+= $(vdso32-y:=.so)

# files to link into the vdso

vobjs-y := vdso-note.o vclock_gettime.o vgetcpu.o vvar.o

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

	$(call if_changed,vdsosym)

#

# Build multiple 32-bit vDSO images to choose from at boot time.

#

vdso32.so-$(CONFIG_X86_32)	+= int80

vdso32.so-$(VDSO32-y)		+= sysenter

CPPFLAGS_vdso32.lds = $(CPPFLAGS_vdso.lds)

VDSO_LDFLAGS_vdso32.lds = -m elf_i386 -Wl,-soname=linux-gate.so.1

# This makes sure the $(obj) subdirectory exists even though vdso32/

# is not a kbuild sub-make subdirectory.

override obj-dirs = $(dir $(obj)) $(obj)/vdso32/

targets += vdso32/vdso32.lds

targets += $(vdso32.so-y:%=vdso32-%.so.dbg) $(vdso32.so-y:%=vdso32-%.so)

targets += vdso32/note.o $(vdso32.so-y:%=vdso32/%.o)

extra-y	+= $(vdso32.so-y:%=vdso32-%.so)

KBUILD_AFLAGS_32 := $(filter-out -m64,$(KBUILD_AFLAGS))

$(vdso32.so-y:%=$(obj)/vdso32-%.so.dbg): KBUILD_AFLAGS = $(KBUILD_AFLAGS_32)

$(vdso32.so-y:%=$(obj)/vdso32-%.so.dbg): asflags-$(CONFIG_X86_64) += -m32

$(vdso32.so-y:%=$(obj)/vdso32-%.so.dbg): $(obj)/vdso32-%.so.dbg: FORCE \

					 $(obj)/vdso32/vdso32.lds \

					 $(obj)/vdso32/note.o \

					 $(obj)/vdso32/%.o

	$(call if_changed,vdso)

# Make vdso32-*-syms.lds from each image, and then make sure they match.

# The only difference should be that some do not define VDSO32_SYSENTER_RETURN.

targets += vdso32-syms.lds $(vdso32.so-y:%=vdso32-%-syms.lds)

quiet_cmd_vdso32sym = VDSOSYM $@

define cmd_vdso32sym

	if LC_ALL=C sort -u $(filter-out FORCE,$^) > $(@D)/.tmp_$(@F) && \

	   $(foreach H,$(filter-out FORCE,$^),\

		     if grep -q VDSO32_SYSENTER_RETURN $H; \

		     then diff -u $(@D)/.tmp_$(@F) $H; \

		     else sed /VDSO32_SYSENTER_RETURN/d $(@D)/.tmp_$(@F) | \

			  diff -u - $H; fi &&) : ;\

	then mv -f $(@D)/.tmp_$(@F) $@; \

	else rm -f $(@D)/.tmp_$(@F); exit 1; \

	fi

endef

$(obj)/vdso32-syms.lds: $(vdso32.so-y:%=$(obj)/vdso32-%-syms.lds) FORCE

	$(call if_changed,vdso32sym)

#

# 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,$(filter %.lds,$^) $(filter %.o,$^)

VDSO_LDFLAGS = -fPIC -shared $(call ld-option, -Wl$(comma)--hash-style=sysv)

#

# 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.so:

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

	@mkdir -p $(MODLIB)/vdso

	$(call cmd,vdso_install)

vdso_install: vdso.so

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

vdso_install: $(vdso-install-y)

/*

 * Linker script for 32-bit vDSO.

 * We #include the file to define the layout details.

 * Here we only choose the prelinked virtual address.

 *

 * This file defines the version script giving the user-exported symbols in

 * the DSO.  We can define local symbols here called VDSO* to make their

 * values visible using the asm-x86/vdso.h macros from the kernel proper.

 */

#define VDSO_PRELINK 0

#include "../vdso-layout.lds.S"

/* The ELF entry point can be used to set the AT_SYSINFO value.  */

ENTRY(__kernel_vsyscall);

/*

 * This controls what userland symbols we export from the vDSO.

 */

VERSION

{

	LINUX_2.5 {

	global:

		__kernel_vsyscall;

		__kernel_sigreturn;

		__kernel_rt_sigreturn;

	local: *;

	};

}

/*

 * Symbols we define here called VDSO* get their values into vdso32-syms.h.

 */

VDSO32_PRELINK		= VDSO_PRELINK;

VDSO32_vsyscall		= __kernel_vsyscall;

VDSO32_sigreturn	= __kernel_sigreturn;

VDSO32_rt_sigreturn	= __kernel_rt_sigreturn;