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Merge branch 'x86-vdso-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip

Browse Source 
* 'x86-vdso-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  x86: vdso: Remove unused variable
  x86-64: Optimize vDSO time()
  x86-64: Add time to vDSO
  x86-64: Turn off -pg and turn on -foptimize-sibling-calls for vDSO
  x86-64: Move vread_tsc into a new file with sensible options
  x86-64: Vclock_gettime(CLOCK_MONOTONIC) can't ever see nsec < 0
  x86-64: Don't generate cmov in vread_tsc
  x86-64: Remove unnecessary barrier in vread_tsc
  x86-64: Clean up vdso/kernel shared variables
This commit is contained in:
Linus Torvalds 2011-05-26 12:19:31 -07:00
commit 14587a2a25
18 changed files with 202 additions and 185 deletions
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4
arch/x86/include/asm/tsc.h
View File

@ -51,6 +51,10 @@ extern int unsynchronized_tsc(void);
extern int check_tsc_unstable(void);
extern unsigned long native_calibrate_tsc(void);
#ifdef CONFIG_X86_64
extern cycles_t vread_tsc(void);
#endif
/*
* Boot-time check whether the TSCs are synchronized across
* all CPUs/cores:

14
arch/x86/include/asm/vdso.h
View File

@ -1,20 +1,6 @@
#ifndef _ASM_X86_VDSO_H
#define _ASM_X86_VDSO_H
#ifdef CONFIG_X86_64
extern const char VDSO64_PRELINK[];
/*
* Given a pointer to the vDSO image, find the pointer to VDSO64_name
* as that symbol is defined in the vDSO sources or linker script.
*/
#define VDSO64_SYMBOL(base, name) \
({ \
extern const char VDSO64_##name[]; \
(void *)(VDSO64_##name - VDSO64_PRELINK + (unsigned long)(base)); \
})
#endif
#if defined CONFIG_X86_32 || defined CONFIG_COMPAT
extern const char VDSO32_PRELINK[];

2
arch/x86/include/asm/vgtod.h
View File

@ -23,8 +23,6 @@ struct vsyscall_gtod_data {
struct timespec wall_to_monotonic;
struct timespec wall_time_coarse;
};
extern struct vsyscall_gtod_data __vsyscall_gtod_data
__section_vsyscall_gtod_data;
extern struct vsyscall_gtod_data vsyscall_gtod_data;
#endif /* _ASM_X86_VGTOD_H */

12
arch/x86/include/asm/vsyscall.h
View File

@ -16,27 +16,19 @@ enum vsyscall_num {
#ifdef __KERNEL__
#include <linux/seqlock.h>
#define __section_vgetcpu_mode __attribute__ ((unused, __section__ (".vgetcpu_mode"), aligned(16)))
#define __section_jiffies __attribute__ ((unused, __section__ (".jiffies"), aligned(16)))
/* Definitions for CONFIG_GENERIC_TIME definitions */
#define __section_vsyscall_gtod_data __attribute__ \
((unused, __section__ (".vsyscall_gtod_data"),aligned(16)))
#define __section_vsyscall_clock __attribute__ \
((unused, __section__ (".vsyscall_clock"),aligned(16)))
#define __vsyscall_fn \
__attribute__ ((unused, __section__(".vsyscall_fn"))) notrace
#define VGETCPU_RDTSCP 1
#define VGETCPU_LSL 2
extern int __vgetcpu_mode;
extern volatile unsigned long __jiffies;
/* kernel space (writeable) */
extern int vgetcpu_mode;
extern struct timezone sys_tz;
#include <asm/vvar.h>
extern void map_vsyscall(void);
#endif /* __KERNEL__ */

52
arch/x86/include/asm/vvar.h Normal file
View File

@ -0,0 +1,52 @@
/*
* vvar.h: Shared vDSO/kernel variable declarations
* Copyright (c) 2011 Andy Lutomirski
* Subject to the GNU General Public License, version 2
*
* A handful of variables are accessible (read-only) from userspace
* code in the vsyscall page and the vdso. They are declared here.
* Some other file must define them with DEFINE_VVAR.
*
* In normal kernel code, they are used like any other variable.
* In user code, they are accessed through the VVAR macro.
*
* Each of these variables lives in the vsyscall page, and each
* one needs a unique offset within the little piece of the page
* reserved for vvars. Specify that offset in DECLARE_VVAR.
* (There are 896 bytes available. If you mess up, the linker will
* catch it.)
*/
/* Offset of vars within vsyscall page */
#define VSYSCALL_VARS_OFFSET (3072 + 128)
#if defined(__VVAR_KERNEL_LDS)
/* The kernel linker script defines its own magic to put vvars in the
* right place.
*/
#define DECLARE_VVAR(offset, type, name) \
EMIT_VVAR(name, VSYSCALL_VARS_OFFSET + offset)
#else
#define DECLARE_VVAR(offset, type, name) \
static type const * const vvaraddr_ ## name = \
(void *)(VSYSCALL_START + VSYSCALL_VARS_OFFSET + (offset));
#define DEFINE_VVAR(type, name) \
type __vvar_ ## name \
__attribute__((section(".vsyscall_var_" #name), aligned(16)))
#define VVAR(name) (*vvaraddr_ ## name)
#endif
/* DECLARE_VVAR(offset, type, name) */
DECLARE_VVAR(0, volatile unsigned long, jiffies)
DECLARE_VVAR(8, int, vgetcpu_mode)
DECLARE_VVAR(128, struct vsyscall_gtod_data, vsyscall_gtod_data)
#undef DECLARE_VVAR
#undef VSYSCALL_VARS_OFFSET

8
arch/x86/kernel/Makefile
View File

@ -8,7 +8,6 @@ CPPFLAGS_vmlinux.lds += -U$(UTS_MACHINE)
ifdef CONFIG_FUNCTION_TRACER
# Do not profile debug and lowlevel utilities
CFLAGS_REMOVE_tsc.o = -pg
CFLAGS_REMOVE_rtc.o = -pg
CFLAGS_REMOVE_paravirt-spinlocks.o = -pg
CFLAGS_REMOVE_pvclock.o = -pg
@ -24,13 +23,16 @@ endif
nostackp := $(call cc-option, -fno-stack-protector)
CFLAGS_vsyscall_64.o := $(PROFILING) -g0 $(nostackp)
CFLAGS_hpet.o := $(nostackp)
CFLAGS_tsc.o := $(nostackp)
CFLAGS_vread_tsc_64.o := $(nostackp)
CFLAGS_paravirt.o := $(nostackp)
GCOV_PROFILE_vsyscall_64.o := n
GCOV_PROFILE_hpet.o := n
GCOV_PROFILE_tsc.o := n
GCOV_PROFILE_paravirt.o := n
# vread_tsc_64 is hot and should be fully optimized:
CFLAGS_REMOVE_vread_tsc_64.o = -pg -fno-optimize-sibling-calls
obj-y := process_$(BITS).o signal.o entry_$(BITS).o
obj-y += traps.o irq.o irq_$(BITS).o dumpstack_$(BITS).o
obj-y += time.o ioport.o ldt.o dumpstack.o
@ -39,7 +41,7 @@ obj-$(CONFIG_IRQ_WORK) += irq_work.o
obj-y += probe_roms.o
obj-$(CONFIG_X86_32) += sys_i386_32.o i386_ksyms_32.o
obj-$(CONFIG_X86_64) += sys_x86_64.o x8664_ksyms_64.o
obj-$(CONFIG_X86_64) += syscall_64.o vsyscall_64.o
obj-$(CONFIG_X86_64) += syscall_64.o vsyscall_64.o vread_tsc_64.o
obj-y += bootflag.o e820.o
obj-y += pci-dma.o quirks.o topology.o kdebugfs.o
obj-y += alternative.o i8253.o pci-nommu.o hw_breakpoint.o

2
arch/x86/kernel/time.c
View File

@ -23,7 +23,7 @@
#include <asm/time.h>
#ifdef CONFIG_X86_64
volatile unsigned long __jiffies __section_jiffies = INITIAL_JIFFIES;
DEFINE_VVAR(volatile unsigned long, jiffies) = INITIAL_JIFFIES;
#endif
unsigned long profile_pc(struct pt_regs *regs)

19
arch/x86/kernel/tsc.c
View File

@ -763,25 +763,6 @@ static cycle_t read_tsc(struct clocksource *cs)
ret : clocksource_tsc.cycle_last;
}
#ifdef CONFIG_X86_64
static cycle_t __vsyscall_fn vread_tsc(void)
{
cycle_t ret;
/*
* Surround the RDTSC by barriers, to make sure it's not
* speculated to outside the seqlock critical section and
* does not cause time warps:
*/
rdtsc_barrier();
ret = (cycle_t)vget_cycles();
rdtsc_barrier();
return ret >= __vsyscall_gtod_data.clock.cycle_last ?
ret : __vsyscall_gtod_data.clock.cycle_last;
}
#endif
static void resume_tsc(struct clocksource *cs)
{
clocksource_tsc.cycle_last = 0;

34
arch/x86/kernel/vmlinux.lds.S
View File

@ -161,6 +161,12 @@ SECTIONS
#define VVIRT_OFFSET (VSYSCALL_ADDR - __vsyscall_0)
#define VVIRT(x) (ADDR(x) - VVIRT_OFFSET)
#define EMIT_VVAR(x, offset) .vsyscall_var_ ## x \
ADDR(.vsyscall_0) + offset \
: AT(VLOAD(.vsyscall_var_ ## x)) { \
*(.vsyscall_var_ ## x) \
} \
x = VVIRT(.vsyscall_var_ ## x);
. = ALIGN(4096);
__vsyscall_0 = .;
@ -175,18 +181,6 @@ SECTIONS
*(.vsyscall_fn)
}
. = ALIGN(L1_CACHE_BYTES);
.vsyscall_gtod_data : AT(VLOAD(.vsyscall_gtod_data)) {
*(.vsyscall_gtod_data)
}
vsyscall_gtod_data = VVIRT(.vsyscall_gtod_data);
.vsyscall_clock : AT(VLOAD(.vsyscall_clock)) {
*(.vsyscall_clock)
}
vsyscall_clock = VVIRT(.vsyscall_clock);
.vsyscall_1 ADDR(.vsyscall_0) + 1024: AT(VLOAD(.vsyscall_1)) {
*(.vsyscall_1)
}
@ -194,21 +188,14 @@ SECTIONS
*(.vsyscall_2)
}
.vgetcpu_mode : AT(VLOAD(.vgetcpu_mode)) {
*(.vgetcpu_mode)
}
vgetcpu_mode = VVIRT(.vgetcpu_mode);
. = ALIGN(L1_CACHE_BYTES);
.jiffies : AT(VLOAD(.jiffies)) {
*(.jiffies)
}
jiffies = VVIRT(.jiffies);
.vsyscall_3 ADDR(.vsyscall_0) + 3072: AT(VLOAD(.vsyscall_3)) {
*(.vsyscall_3)
}
#define __VVAR_KERNEL_LDS
#include <asm/vvar.h>
#undef __VVAR_KERNEL_LDS
. = __vsyscall_0 + PAGE_SIZE;
#undef VSYSCALL_ADDR
@ -216,6 +203,7 @@ SECTIONS
#undef VLOAD
#undef VVIRT_OFFSET
#undef VVIRT
#undef EMIT_VVAR
#endif /* CONFIG_X86_64 */

36
arch/x86/kernel/vread_tsc_64.c Normal file
View File

@ -0,0 +1,36 @@
/* This code runs in userspace. */
#define DISABLE_BRANCH_PROFILING
#include <asm/vgtod.h>
notrace cycle_t __vsyscall_fn vread_tsc(void)
{
cycle_t ret;
u64 last;
/*
* Empirically, a fence (of type that depends on the CPU)
* before rdtsc is enough to ensure that rdtsc is ordered
* with respect to loads. The various CPU manuals are unclear
* as to whether rdtsc can be reordered with later loads,
* but no one has ever seen it happen.
*/
rdtsc_barrier();
ret = (cycle_t)vget_cycles();
last = VVAR(vsyscall_gtod_data).clock.cycle_last;
if (likely(ret >= last))
return ret;
/*
* GCC likes to generate cmov here, but this branch is extremely
* predictable (it's just a funciton of time and the likely is
* very likely) and there's a data dependence, so force GCC
* to generate a branch instead. I don't barrier() because
* we don't actually need a barrier, and if this function
* ever gets inlined it will generate worse code.
*/
asm volatile ("");
return last;
}

46
arch/x86/kernel/vsyscall_64.c
View File

@ -49,15 +49,8 @@
__attribute__ ((unused, __section__(".vsyscall_" #nr))) notrace
#define __syscall_clobber "r11","cx","memory"
/*
* vsyscall_gtod_data contains data that is :
* - readonly from vsyscalls
* - written by timer interrupt or systcl (/proc/sys/kernel/vsyscall64)
* Try to keep this structure as small as possible to avoid cache line ping pongs
*/
int __vgetcpu_mode __section_vgetcpu_mode;
struct vsyscall_gtod_data __vsyscall_gtod_data __section_vsyscall_gtod_data =
DEFINE_VVAR(int, vgetcpu_mode);
DEFINE_VVAR(struct vsyscall_gtod_data, vsyscall_gtod_data) =
{
.lock = __SEQLOCK_UNLOCKED(__vsyscall_gtod_data.lock),
.sysctl_enabled = 1,
@ -97,7 +90,7 @@ void update_vsyscall(struct timespec *wall_time, struct timespec *wtm,
*/
static __always_inline void do_get_tz(struct timezone * tz)
{
*tz = __vsyscall_gtod_data.sys_tz;
*tz = VVAR(vsyscall_gtod_data).sys_tz;
}
static __always_inline int gettimeofday(struct timeval *tv, struct timezone *tz)
@ -126,23 +119,24 @@ static __always_inline void do_vgettimeofday(struct timeval * tv)
unsigned long mult, shift, nsec;
cycle_t (*vread)(void);
do {
seq = read_seqbegin(&__vsyscall_gtod_data.lock);
seq = read_seqbegin(&VVAR(vsyscall_gtod_data).lock);
vread = __vsyscall_gtod_data.clock.vread;
if (unlikely(!__vsyscall_gtod_data.sysctl_enabled || !vread)) {
vread = VVAR(vsyscall_gtod_data).clock.vread;
if (unlikely(!VVAR(vsyscall_gtod_data).sysctl_enabled ||
!vread)) {
gettimeofday(tv,NULL);
return;
}
now = vread();
base = __vsyscall_gtod_data.clock.cycle_last;
mask = __vsyscall_gtod_data.clock.mask;
mult = __vsyscall_gtod_data.clock.mult;
shift = __vsyscall_gtod_data.clock.shift;
base = VVAR(vsyscall_gtod_data).clock.cycle_last;
mask = VVAR(vsyscall_gtod_data).clock.mask;
mult = VVAR(vsyscall_gtod_data).clock.mult;
shift = VVAR(vsyscall_gtod_data).clock.shift;
tv->tv_sec = __vsyscall_gtod_data.wall_time_sec;
nsec = __vsyscall_gtod_data.wall_time_nsec;
} while (read_seqretry(&__vsyscall_gtod_data.lock, seq));
tv->tv_sec = VVAR(vsyscall_gtod_data).wall_time_sec;
nsec = VVAR(vsyscall_gtod_data).wall_time_nsec;
} while (read_seqretry(&VVAR(vsyscall_gtod_data).lock, seq));
/* calculate interval: */
cycle_delta = (now - base) & mask;
@ -171,15 +165,15 @@ time_t __vsyscall(1) vtime(time_t *t)
{
unsigned seq;
time_t result;
if (unlikely(!__vsyscall_gtod_data.sysctl_enabled))
if (unlikely(!VVAR(vsyscall_gtod_data).sysctl_enabled))
return time_syscall(t);
do {
seq = read_seqbegin(&__vsyscall_gtod_data.lock);
seq = read_seqbegin(&VVAR(vsyscall_gtod_data).lock);
result = __vsyscall_gtod_data.wall_time_sec;
result = VVAR(vsyscall_gtod_data).wall_time_sec;
} while (read_seqretry(&__vsyscall_gtod_data.lock, seq));
} while (read_seqretry(&VVAR(vsyscall_gtod_data).lock, seq));
if (t)
*t = result;
@ -208,9 +202,9 @@ vgetcpu(unsigned *cpu, unsigned *node, struct getcpu_cache *tcache)
We do this here because otherwise user space would do it on
its own in a likely inferior way (no access to jiffies).
If you don't like it pass NULL. */
if (tcache && tcache->blob[0] == (j = __jiffies)) {
if (tcache && tcache->blob[0] == (j = VVAR(jiffies))) {
p = tcache->blob[1];
} else if (__vgetcpu_mode == VGETCPU_RDTSCP) {
} else if (VVAR(vgetcpu_mode) == VGETCPU_RDTSCP) {
/* Load per CPU data from RDTSCP */
native_read_tscp(&p);
} else {

17
arch/x86/vdso/Makefile
View File

@ -11,7 +11,7 @@ vdso-install-$(VDSO32-y) += $(vdso32-images)
# files to link into the vdso
vobjs-y := vdso-note.o vclock_gettime.o vgetcpu.o vvar.o
vobjs-y := vdso-note.o vclock_gettime.o vgetcpu.o
# files to link into kernel
obj-$(VDSO64-y) += vma.o vdso.o
@ -37,11 +37,24 @@ $(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)
$(filter -g%,$(KBUILD_CFLAGS)) $(call cc-option, -fno-stack-protector) \
-fno-omit-frame-pointer -foptimize-sibling-calls
$(vobjs): KBUILD_CFLAGS += $(CFL)
#
# vDSO code runs in userspace and -pg doesn't help with profiling anyway.
#
CFLAGS_REMOVE_vdso-note.o = -pg
CFLAGS_REMOVE_vclock_gettime.o = -pg
CFLAGS_REMOVE_vgetcpu.o = -pg
CFLAGS_REMOVE_vvar.o = -pg
targets += vdso-syms.lds
obj-$(VDSO64-y) += vdso-syms.lds

74
arch/x86/vdso/vclock_gettime.c
View File

@ -2,7 +2,7 @@
* Copyright 2006 Andi Kleen, SUSE Labs.
* Subject to the GNU Public License, v.2
*
* Fast user context implementation of clock_gettime and gettimeofday.
* Fast user context implementation of clock_gettime, gettimeofday, and time.
*
* The code should have no internal unresolved relocations.
* Check with readelf after changing.
@ -22,9 +22,8 @@
#include <asm/hpet.h>
#include <asm/unistd.h>
#include <asm/io.h>
#include "vextern.h"
#define gtod vdso_vsyscall_gtod_data
#define gtod (&VVAR(vsyscall_gtod_data))
notrace static long vdso_fallback_gettime(long clock, struct timespec *ts)
{
@ -56,22 +55,6 @@ notrace static noinline int do_realtime(struct timespec *ts)
return 0;
}
/* Copy of the version in kernel/time.c which we cannot directly access */
notrace static void
vset_normalized_timespec(struct timespec *ts, long sec, long nsec)
{
while (nsec >= NSEC_PER_SEC) {
nsec -= NSEC_PER_SEC;
++sec;
}
while (nsec < 0) {
nsec += NSEC_PER_SEC;
--sec;
}
ts->tv_sec = sec;
ts->tv_nsec = nsec;
}
notrace static noinline int do_monotonic(struct timespec *ts)
{
unsigned long seq, ns, secs;
@ -82,7 +65,17 @@ notrace static noinline int do_monotonic(struct timespec *ts)
secs += gtod->wall_to_monotonic.tv_sec;
ns += gtod->wall_to_monotonic.tv_nsec;
} while (unlikely(read_seqretry(&gtod->lock, seq)));
vset_normalized_timespec(ts, secs, ns);
/* wall_time_nsec, vgetns(), and wall_to_monotonic.tv_nsec
* are all guaranteed to be nonnegative.
*/
while (ns >= NSEC_PER_SEC) {
ns -= NSEC_PER_SEC;
++secs;
}
ts->tv_sec = secs;
ts->tv_nsec = ns;
return 0;
}
@ -107,7 +100,17 @@ notrace static noinline int do_monotonic_coarse(struct timespec *ts)
secs += gtod->wall_to_monotonic.tv_sec;
ns += gtod->wall_to_monotonic.tv_nsec;
} while (unlikely(read_seqretry(&gtod->lock, seq)));
vset_normalized_timespec(ts, secs, ns);
/* wall_time_nsec and wall_to_monotonic.tv_nsec are
* guaranteed to be between 0 and NSEC_PER_SEC.
*/
if (ns >= NSEC_PER_SEC) {
ns -= NSEC_PER_SEC;
++secs;
}
ts->tv_sec = secs;
ts->tv_nsec = ns;
return 0;
}
@ -157,3 +160,32 @@ notrace int __vdso_gettimeofday(struct timeval *tv, struct timezone *tz)
}
int gettimeofday(struct timeval *, struct timezone *)
__attribute__((weak, alias("__vdso_gettimeofday")));
/* This will break when the xtime seconds get inaccurate, but that is
* unlikely */
static __always_inline long time_syscall(long *t)
{
long secs;
asm volatile("syscall"
: "=a" (secs)
: "0" (__NR_time), "D" (t) : "cc", "r11", "cx", "memory");
return secs;
}
notrace time_t __vdso_time(time_t *t)
{
time_t result;
if (unlikely(!VVAR(vsyscall_gtod_data).sysctl_enabled))
return time_syscall(t);
/* This is atomic on x86_64 so we don't need any locks. */
result = ACCESS_ONCE(VVAR(vsyscall_gtod_data).wall_time_sec);
if (t)
*t = result;
return result;
}
int time(time_t *t)
__attribute__((weak, alias("__vdso_time")));

9
arch/x86/vdso/vdso.lds.S
View File

@ -23,15 +23,10 @@ VERSION {
__vdso_gettimeofday;
getcpu;
__vdso_getcpu;
time;
__vdso_time;
local: *;
};
}
VDSO64_PRELINK = VDSO_PRELINK;
/*
* Define VDSO64_x for each VEXTERN(x), for use via VDSO64_SYMBOL.
*/
#define VEXTERN(x) VDSO64_ ## x = vdso_ ## x;
#include "vextern.h"
#undef VEXTERN

16
arch/x86/vdso/vextern.h
View File

@ -1,16 +0,0 @@
#ifndef VEXTERN
#include <asm/vsyscall.h>
#define VEXTERN(x) \
extern typeof(x) *vdso_ ## x __attribute__((visibility("hidden")));
#endif
#define VMAGIC 0xfeedbabeabcdefabUL
/* Any kernel variables used in the vDSO must be exported in the main
kernel's vmlinux.lds.S/vsyscall.h/proper __section and
put into vextern.h and be referenced as a pointer with vdso prefix.
The main kernel later fills in the values. */
VEXTERN(jiffies)
VEXTERN(vgetcpu_mode)
VEXTERN(vsyscall_gtod_data)

3
arch/x86/vdso/vgetcpu.c
View File

@ -11,14 +11,13 @@
#include <linux/time.h>
#include <asm/vsyscall.h>
#include <asm/vgtod.h>
#include "vextern.h"
notrace long
__vdso_getcpu(unsigned *cpu, unsigned *node, struct getcpu_cache *unused)
{
unsigned int p;
if (*vdso_vgetcpu_mode == VGETCPU_RDTSCP) {
if (VVAR(vgetcpu_mode) == VGETCPU_RDTSCP) {
/* Load per CPU data from RDTSCP */
native_read_tscp(&p);
} else {

27
arch/x86/vdso/vma.c
View File

@ -15,9 +15,6 @@
#include <asm/proto.h>
#include <asm/vdso.h>
#include "vextern.h" /* Just for VMAGIC. */
#undef VEXTERN
unsigned int __read_mostly vdso_enabled = 1;
extern char vdso_start[], vdso_end[];
@ -26,20 +23,10 @@ extern unsigned short vdso_sync_cpuid;
static struct page **vdso_pages;
static unsigned vdso_size;
static inline void *var_ref(void *p, char *name)
{
if (*(void **)p != (void *)VMAGIC) {
printk("VDSO: variable %s broken\n", name);
vdso_enabled = 0;
}
return p;
}
static int __init init_vdso_vars(void)
{
int npages = (vdso_end - vdso_start + PAGE_SIZE - 1) / PAGE_SIZE;
int i;
char *vbase;
vdso_size = npages << PAGE_SHIFT;
vdso_pages = kmalloc(sizeof(struct page *) * npages, GFP_KERNEL);
@ -54,20 +41,6 @@ static int __init init_vdso_vars(void)
copy_page(page_address(p), vdso_start + i*PAGE_SIZE);
}
vbase = vmap(vdso_pages, npages, 0, PAGE_KERNEL);
if (!vbase)
goto oom;
if (memcmp(vbase, "\177ELF", 4)) {
printk("VDSO: I'm broken; not ELF\n");
vdso_enabled = 0;
}
#define VEXTERN(x) \
*(typeof(__ ## x) **) var_ref(VDSO64_SYMBOL(vbase, x), #x) = &__ ## x;
#include "vextern.h"
#undef VEXTERN
vunmap(vbase);
return 0;
oom:

12
arch/x86/vdso/vvar.c
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/* Define pointer to external vDSO variables.
These are part of the vDSO. The kernel fills in the real addresses
at boot time. This is done because when the vdso is linked the
kernel isn't yet and we don't know the final addresses. */
#include <linux/kernel.h>
#include <linux/time.h>
#include <asm/vsyscall.h>
#include <asm/timex.h>
#include <asm/vgtod.h>
#define VEXTERN(x) typeof (__ ## x) *const vdso_ ## x = (void *)VMAGIC;
#include "vextern.h"