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

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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: Andy 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: H. Peter Anvin <hpa@linux.intel.com>
This commit is contained in:
Andy Lutomirski 2014-03-20 15:01:21 -07:00 committed by H. Peter Anvin
parent 4e40112c4f
commit b67e612cef
7 changed files with 70 additions and 91 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

8
arch/x86/include/asm/vdso.h
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@ -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 */

22
arch/x86/vdso/vdso.S
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@ -1,21 +1,3 @@
#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")

50
arch/x86/vdso/vdso32-setup.c
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@ -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);
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);
for(i = 0; i != vdso32_size; ++i)
vdso32_pages[i] = virt_to_page(vdso_pages + VDSO_OFFSET(i));
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);

21
arch/x86/vdso/vdso32.S
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@ -1,22 +1,9 @@
#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")

30
arch/x86/vdso/vdso_image.h Normal file
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@ -0,0 +1,30 @@
#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 */

22
arch/x86/vdso/vdsox32.S
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@ -1,21 +1,3 @@
#include <asm/page_types.h>
#include <linux/linkage.h>
#include "vdso_image.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
DEFINE_VDSO_IMAGE(vdsox32, "arch/x86/vdso/vdsox32.so")

8
arch/x86/vdso/vma.c
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@ -15,19 +15,17 @@
#include <asm/proto.h>
#include <asm/vdso.h>
#include <asm/page.h>
#include "vdso_image.h"
#if defined(CONFIG_X86_64)
unsigned int __read_mostly vdso_enabled = 1;
extern char vdso_start[], vdso_end[];
DECLARE_VDSO_IMAGE(vdso);
extern unsigned short vdso_sync_cpuid;
extern struct page *vdso_pages[];
static unsigned vdso_size;
#ifdef CONFIG_X86_X32_ABI
extern char vdsox32_start[], vdsox32_end[];
extern struct page *vdsox32_pages[];
DECLARE_VDSO_IMAGE(vdsox32);
static unsigned vdsox32_size;
#endif
#endif