Commit b67e612c authored by Andy Lutomirski's avatar Andy Lutomirski Committed by H. Peter Anvin
Browse files

x86: Load the 32-bit vdso in place, just like the 64-bit vdsos 



This replaces a decent amount of incomprehensible and buggy code
with much more straightforward code.  It also brings the 32-bit vdso
more in line with the 64-bit vdsos, so maybe someday they can share
even more code.

This wastes a small amount of kernel .data and .text space, but it
avoids a couple of allocations on startup, so it should be more or
less a wash memory-wise.

Signed-off-by: default avatarAndy Lutomirski <luto@amacapital.net>
Cc: Stefani Seibold <stefani@seibold.net>
Link: http://lkml.kernel.org/r/b8093933fad09ce181edb08a61dcd5d2592e9814.1395352498.git.luto@amacapital.net


Signed-off-by: default avatarH. Peter Anvin <hpa@linux.intel.com>
parent 4e40112c

arch/x86/include/asm/vdso.h

+0 −8
Original line number Diff line number Diff line
@@ -25,14 +25,6 @@ extern const char VDSO32_PRELINK[]; 
extern void __user __kernel_sigreturn;

extern void __user __kernel_rt_sigreturn;



/*

 * These symbols are defined by vdso32.S to mark the bounds

 * of the ELF DSO images included therein.

 */

extern const char vdso32_int80_start, vdso32_int80_end;

extern const char vdso32_syscall_start, vdso32_syscall_end;

extern const char vdso32_sysenter_start, vdso32_sysenter_end;



void __init patch_vdso32(void *vdso, size_t len);



#endif /* _ASM_X86_VDSO_H */

arch/x86/vdso/vdso.S

+2 −20
Original line number Diff line number Diff line 
#include <asm/page_types.h>

#include <linux/linkage.h>

#include "vdso_image.h"



__PAGE_ALIGNED_DATA



	.globl vdso_start, vdso_end

	.align PAGE_SIZE

vdso_start:

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

vdso_end:

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



.previous



	.globl vdso_pages

	.bss

	.align 8

	.type vdso_pages, @object

vdso_pages:

	.zero (vdso_end - vdso_start + PAGE_SIZE - 1) / PAGE_SIZE * 8

	.size vdso_pages, .-vdso_pages
 
DEFINE_VDSO_IMAGE(vdso, "arch/x86/vdso/vdso.so")

arch/x86/vdso/vdso32-setup.c

+29 −21
Original line number Diff line number Diff line
@@ -29,6 +29,7 @@ 
#include <asm/fixmap.h>

#include <asm/hpet.h>

#include <asm/vvar.h>

#include "vdso_image.h"



#ifdef CONFIG_COMPAT_VDSO

#define VDSO_DEFAULT	0
@@ -41,6 +42,12 @@ 
#define arch_setup_additional_pages	syscall32_setup_pages

#endif



DECLARE_VDSO_IMAGE(vdso32_int80);

#ifdef CONFIG_COMPAT

DECLARE_VDSO_IMAGE(vdso32_syscall);

#endif

DECLARE_VDSO_IMAGE(vdso32_sysenter);



/*

 * Should the kernel map a VDSO page into processes and pass its

 * address down to glibc upon exec()?
@@ -71,7 +78,7 @@ EXPORT_SYMBOL_GPL(vdso_enabled); 
#endif



static struct page **vdso32_pages;

static unsigned int vdso32_size;

static unsigned vdso32_size;



#ifdef CONFIG_X86_64
@@ -117,31 +124,32 @@ void enable_sep_cpu(void) 


int __init sysenter_setup(void)

{

	void *vdso_pages;

	const void *vdso;

	size_t vdso_len;

	unsigned int i;

	char *vdso32_start, *vdso32_end;

	int npages, i;



#ifdef CONFIG_COMPAT

	if (vdso32_syscall()) {

		vdso = &vdso32_syscall_start;

		vdso_len = &vdso32_syscall_end - &vdso32_syscall_start;

	} else if (vdso32_sysenter()){

		vdso = &vdso32_sysenter_start;

		vdso_len = &vdso32_sysenter_end - &vdso32_sysenter_start;

		vdso32_start = vdso32_syscall_start;

		vdso32_end = vdso32_syscall_end;

		vdso32_pages = vdso32_syscall_pages;

	} else

#endif

	if (vdso32_sysenter()) {

		vdso32_start = vdso32_sysenter_start;

		vdso32_end = vdso32_sysenter_end;

		vdso32_pages = vdso32_sysenter_pages;

	} else {

		vdso = &vdso32_int80_start;

		vdso_len = &vdso32_int80_end - &vdso32_int80_start;

		vdso32_start = vdso32_int80_start;

		vdso32_end = vdso32_int80_end;

		vdso32_pages = vdso32_int80_pages;

	}



	vdso32_size = (vdso_len + PAGE_SIZE - 1) / PAGE_SIZE;

	vdso32_pages = kmalloc(sizeof(*vdso32_pages) * vdso32_size, GFP_ATOMIC);

	vdso_pages = kmalloc(VDSO_OFFSET(vdso32_size), GFP_ATOMIC);



	for(i = 0; i != vdso32_size; ++i)

		vdso32_pages[i] = virt_to_page(vdso_pages + VDSO_OFFSET(i));

	npages = ((vdso32_end - vdso32_start) + PAGE_SIZE - 1) / PAGE_SIZE;

	vdso32_size = npages << PAGE_SHIFT;

	for (i = 0; i < npages; i++)

		vdso32_pages[i] = virt_to_page(vdso32_start + i*PAGE_SIZE);



	memcpy(vdso_pages, vdso, vdso_len);

	patch_vdso32(vdso_pages, vdso_len);

	patch_vdso32(vdso32_start, vdso32_size);



	return 0;

}
@@ -177,7 +185,7 @@ int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp) 
	 */

	ret = install_special_mapping(mm,

			addr,

			VDSO_OFFSET(vdso32_size),

			vdso32_size,

			VM_READ|VM_EXEC|

			VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC,

			vdso32_pages);

arch/x86/vdso/vdso32.S

+4 −17
Original line number Diff line number Diff line 
#include <linux/init.h>

#include "vdso_image.h"



__INITDATA

DEFINE_VDSO_IMAGE(vdso32_int80, "arch/x86/vdso/vdso32-int80.so")



	.globl vdso32_int80_start, vdso32_int80_end

vdso32_int80_start:

	.incbin "arch/x86/vdso/vdso32-int80.so"

vdso32_int80_end:



	.globl vdso32_syscall_start, vdso32_syscall_end

vdso32_syscall_start:

#ifdef CONFIG_COMPAT

	.incbin "arch/x86/vdso/vdso32-syscall.so"

DEFINE_VDSO_IMAGE(vdso32_syscall, "arch/x86/vdso/vdso32-syscall.so")

#endif

vdso32_syscall_end:



	.globl vdso32_sysenter_start, vdso32_sysenter_end

vdso32_sysenter_start:

	.incbin "arch/x86/vdso/vdso32-sysenter.so"

vdso32_sysenter_end:



__FINIT
 
DEFINE_VDSO_IMAGE(vdso32_sysenter, "arch/x86/vdso/vdso32-sysenter.so")

arch/x86/vdso/vdso_image.h

0 → 100644
+30 −0
Original line number Diff line number Diff line 
#ifndef _VDSO_IMAGE_H

#define _VDSO_IMAGE_H



#include <asm/page_types.h>

#include <linux/linkage.h>



#define DEFINE_VDSO_IMAGE(symname, filename)				\

__PAGE_ALIGNED_DATA ;							\

	.globl symname##_start, symname##_end ;				\

	.align PAGE_SIZE ;						\

	symname##_start: ;						\

	.incbin filename ;						\

	symname##_end: ;						\

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

									\

.previous ;								\

									\

	.globl symname##_pages ;					\

	.bss ;								\

	.align 8 ;							\

	.type symname##_pages, @object ;				\

	symname##_pages: ;						\

	.zero (symname##_end - symname##_start + PAGE_SIZE - 1) / PAGE_SIZE * (BITS_PER_LONG / 8) ; \

	.size symname##_pages, .-symname##_pages



#define DECLARE_VDSO_IMAGE(symname)				\

	extern char symname##_start[], symname##_end[];		\

	extern struct page *symname##_pages[]



#endif /* _VDSO_IMAGE_H */

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