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Commit 1a21d4e0 authored by H. J. Lu's avatar H. J. Lu Committed by H. Peter Anvin
Browse files

x32: Add x32 VDSO support 



Add support for the x32 VDSO.  The x32 VDSO takes advantage of the
similarity between the x86-64 and the x32 ABIs to contain the same
content, only the container is different, as the x32 VDSO obviously is
an x32 shared object.

Signed-off-by: default avatarH. Peter Anvin <hpa@zytor.com>
parent 5fd92e65

arch/x86/vdso/.gitignore

+2 −0
Original line number Diff line number Diff line 
vdso.lds

vdso-syms.lds

vdsox32.lds

vdsox32-syms.lds

vdso32-syms.lds

vdso32-syscall-syms.lds

vdso32-sysenter-syms.lds

arch/x86/vdso/Makefile

+45 −1
Original line number Diff line number Diff line
@@ -3,21 +3,29 @@ 
#



VDSO64-$(CONFIG_X86_64)		:= y

VDSOX32-$(CONFIG_X86_X32_ABI)	:= y

VDSO32-$(CONFIG_X86_32)		:= y

VDSO32-$(CONFIG_COMPAT)		:= y



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

vdso-install-$(VDSOX32-y)	+= vdsox32.so

vdso-install-$(VDSO32-y)	+= $(vdso32-images)





# files to link into the vdso

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



vobjs-$(VDSOX32-y) += $(vobjx32s-compat)



# Filter out x32 objects.

vobj64s := $(filter-out $(vobjx32s-compat),$(vobjs-y))



# files to link into kernel

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

obj-$(VDSOX32-y)		+= vdsox32.o

obj-$(VDSO32-y)			+= vdso32.o vdso32-setup.o



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

vobjs := $(foreach F,$(vobj64s),$(obj)/$F)



$(obj)/vdso.o: $(obj)/vdso.so
@@ -72,6 +80,42 @@ endef 
$(obj)/%-syms.lds: $(obj)/%.so.dbg FORCE

	$(call if_changed,vdsosym)



#

# X32 processes use x32 vDSO to access 64bit kernel data.

#

# Build x32 vDSO image:

# 1. Compile x32 vDSO as 64bit.

# 2. Convert object files to x32.

# 3. Build x32 VDSO image with x32 objects, which contains 64bit codes

# so that it can reach 64bit address space with 64bit pointers.

#



targets += vdsox32-syms.lds

obj-$(VDSOX32-y)		+= vdsox32-syms.lds



CPPFLAGS_vdsox32.lds = $(CPPFLAGS_vdso.lds)

VDSO_LDFLAGS_vdsox32.lds = -Wl,-m,elf32_x86_64 \

			   -Wl,-soname=linux-vdso.so.1 \

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

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



vobjx32s-y := $(vobj64s:.o=-x32.o)

vobjx32s := $(foreach F,$(vobjx32s-y),$(obj)/$F)



# Convert 64bit object file to x32 for x32 vDSO.

quiet_cmd_x32 = X32     $@

      cmd_x32 = $(OBJCOPY) -O elf32-x86-64 $< $@



$(obj)/%-x32.o: $(obj)/%.o FORCE

	$(call if_changed,x32)



targets += vdsox32.so vdsox32.so.dbg vdsox32.lds $(vobjx32s-y)



$(obj)/vdsox32.o: $(src)/vdsox32.S $(obj)/vdsox32.so



$(obj)/vdsox32.so.dbg: $(src)/vdsox32.lds $(vobjx32s) FORCE

	$(call if_changed,vdso)



#

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

#

arch/x86/vdso/vdso32-setup.c

+6 −0
Original line number Diff line number Diff line
@@ -317,6 +317,12 @@ int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp) 
	int ret = 0;

	bool compat;



#ifdef CONFIG_X86_X32_ABI

	extern int x32_setup_additional_pages(struct linux_binprm *, int);

	if (test_thread_flag(TIF_X32))

		return x32_setup_additional_pages (bprm, uses_interp);

#endif



	if (vdso_enabled == VDSO_DISABLED)

		return 0;

arch/x86/vdso/vdsox32.S

0 → 100644
+22 −0
Original line number Diff line number Diff line 
#include <asm/page_types.h>

#include <linux/linkage.h>

#include <linux/init.h>



__PAGE_ALIGNED_DATA



	.globl vdsox32_start, vdsox32_end

	.align PAGE_SIZE

vdsox32_start:

	.incbin "arch/x86/vdso/vdsox32.so"

vdsox32_end:

	.align PAGE_SIZE /* extra data here leaks to userspace. */



.previous



	.globl vdsox32_pages

	.bss

	.align 8

	.type vdsox32_pages, @object

vdsox32_pages:

	.zero (vdsox32_end - vdsox32_start + PAGE_SIZE - 1) / PAGE_SIZE * 8

	.size vdsox32_pages, .-vdsox32_pages

arch/x86/vdso/vdsox32.lds.S

0 → 100644
+32 −0
Original line number Diff line number Diff line 
/*

 * Linker script for x32 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"



/*

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

 */

VERSION {

	LINUX_2.6 {

	global:

		clock_gettime;

		__vdso_clock_gettime;

		gettimeofday;

		__vdso_gettimeofday;

		getcpu;

		__vdso_getcpu;

		time;

		__vdso_time;

	local: *;

	};

}



VDSOX32_PRELINK = VDSO_PRELINK;