linux/arch/x86_64/kernel/vsyscall.c

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/*
* linux/arch/x86_64/kernel/vsyscall.c
*
* Copyright (C) 2001 Andrea Arcangeli <andrea@suse.de> SuSE
* Copyright 2003 Andi Kleen, SuSE Labs.
*
* Thanks to hpa@transmeta.com for some useful hint.
* Special thanks to Ingo Molnar for his early experience with
* a different vsyscall implementation for Linux/IA32 and for the name.
*
* vsyscall 1 is located at -10Mbyte, vsyscall 2 is located
* at virtual address -10Mbyte+1024bytes etc... There are at max 4
* vsyscalls. One vsyscall can reserve more than 1 slot to avoid
* jumping out of line if necessary. We cannot add more with this
* mechanism because older kernels won't return -ENOSYS.
* If we want more than four we need a vDSO.
*
* Note: the concept clashes with user mode linux. If you use UML and
* want per guest time just set the kernel.vsyscall64 sysctl to 0.
*/
#include <linux/time.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/timer.h>
#include <linux/seqlock.h>
#include <linux/jiffies.h>
#include <linux/sysctl.h>
#include <linux/clocksource.h>
#include <linux/getcpu.h>
#include <linux/cpu.h>
#include <linux/smp.h>
#include <linux/notifier.h>
#include <asm/vsyscall.h>
#include <asm/pgtable.h>
#include <asm/page.h>
#include <asm/unistd.h>
#include <asm/fixmap.h>
#include <asm/errno.h>
#include <asm/io.h>
#include <asm/segment.h>
#include <asm/desc.h>
#include <asm/topology.h>
#define __vsyscall(nr) __attribute__ ((unused,__section__(".vsyscall_" #nr)))
#define __syscall_clobber "r11","rcx","memory"
[PATCH] x86: __pa and __pa_symbol address space separation Currently __pa_symbol is for use with symbols in the kernel address map and __pa is for use with pointers into the physical memory map. But the code is implemented so you can usually interchange the two. __pa which is much more common can be implemented much more cheaply if it is it doesn't have to worry about any other kernel address spaces. This is especially true with a relocatable kernel as __pa_symbol needs to peform an extra variable read to resolve the address. There is a third macro that is added for the vsyscall data __pa_vsymbol for finding the physical addesses of vsyscall pages. Most of this patch is simply sorting through the references to __pa or __pa_symbol and using the proper one. A little of it is continuing to use a physical address when we have it instead of recalculating it several times. swapper_pgd is now NULL. leave_mm now uses init_mm.pgd and init_mm.pgd is initialized at boot (instead of compile time) to the physmem virtual mapping of init_level4_pgd. The physical address changed. Except for the for EMPTY_ZERO page all of the remaining references to __pa_symbol appear to be during kernel initialization. So this should reduce the cost of __pa in the common case, even on a relocated kernel. As this is technically a semantic change we need to be on the lookout for anything I missed. But it works for me (tm). Signed-off-by: Eric W. Biederman <ebiederm@xmission.com> Signed-off-by: Vivek Goyal <vgoyal@in.ibm.com> Signed-off-by: Andi Kleen <ak@suse.de>
2007-05-02 17:27:07 +00:00
#define __pa_vsymbol(x) \
({unsigned long v; \
extern char __vsyscall_0; \
asm("" : "=r" (v) : "0" (x)); \
((v - VSYSCALL_FIRST_PAGE) + __pa_symbol(&__vsyscall_0)); })
/*
* vsyscall_gtod_data contains data that is :
* - readonly from vsyscalls
* - writen by timer interrupt or systcl (/proc/sys/kernel/vsyscall64)
* Try to keep this structure as small as possible to avoid cache line ping pongs
*/
struct vsyscall_gtod_data_t {
seqlock_t lock;
/* open coded 'struct timespec' */
time_t wall_time_sec;
u32 wall_time_nsec;
int sysctl_enabled;
struct timezone sys_tz;
struct { /* extract of a clocksource struct */
cycle_t (*vread)(void);
cycle_t cycle_last;
cycle_t mask;
u32 mult;
u32 shift;
} clock;
};
int __vgetcpu_mode __section_vgetcpu_mode;
struct vsyscall_gtod_data_t __vsyscall_gtod_data __section_vsyscall_gtod_data =
{
.lock = SEQLOCK_UNLOCKED,
.sysctl_enabled = 1,
};
void update_vsyscall(struct timespec *wall_time, struct clocksource *clock)
{
unsigned long flags;
write_seqlock_irqsave(&vsyscall_gtod_data.lock, flags);
/* copy vsyscall data */
vsyscall_gtod_data.clock.vread = clock->vread;
vsyscall_gtod_data.clock.cycle_last = clock->cycle_last;
vsyscall_gtod_data.clock.mask = clock->mask;
vsyscall_gtod_data.clock.mult = clock->mult;
vsyscall_gtod_data.clock.shift = clock->shift;
vsyscall_gtod_data.wall_time_sec = wall_time->tv_sec;
vsyscall_gtod_data.wall_time_nsec = wall_time->tv_nsec;
vsyscall_gtod_data.sys_tz = sys_tz;
write_sequnlock_irqrestore(&vsyscall_gtod_data.lock, flags);
}
/* RED-PEN may want to readd seq locking, but then the variable should be
* write-once.
*/
static __always_inline void do_get_tz(struct timezone * tz)
{
*tz = __vsyscall_gtod_data.sys_tz;
}
static __always_inline int gettimeofday(struct timeval *tv, struct timezone *tz)
{
int ret;
asm volatile("vsysc2: syscall"
: "=a" (ret)
: "0" (__NR_gettimeofday),"D" (tv),"S" (tz)
: __syscall_clobber );
return ret;
}
static __always_inline long time_syscall(long *t)
{
long secs;
asm volatile("vsysc1: syscall"
: "=a" (secs)
: "0" (__NR_time),"D" (t) : __syscall_clobber);
return secs;
}
static __always_inline void do_vgettimeofday(struct timeval * tv)
{
cycle_t now, base, mask, cycle_delta;
unsigned seq;
unsigned long mult, shift, nsec;
cycle_t (*vread)(void);
do {
seq = read_seqbegin(&__vsyscall_gtod_data.lock);
vread = __vsyscall_gtod_data.clock.vread;
if (unlikely(!__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;
tv->tv_sec = __vsyscall_gtod_data.wall_time_sec;
nsec = __vsyscall_gtod_data.wall_time_nsec;
} while (read_seqretry(&__vsyscall_gtod_data.lock, seq));
/* calculate interval: */
cycle_delta = (now - base) & mask;
/* convert to nsecs: */
nsec += (cycle_delta * mult) >> shift;
while (nsec >= NSEC_PER_SEC) {
tv->tv_sec += 1;
nsec -= NSEC_PER_SEC;
}
tv->tv_usec = nsec / NSEC_PER_USEC;
}
int __vsyscall(0) vgettimeofday(struct timeval * tv, struct timezone * tz)
{
if (tv)
do_vgettimeofday(tv);
if (tz)
do_get_tz(tz);
return 0;
}
/* This will break when the xtime seconds get inaccurate, but that is
* unlikely */
time_t __vsyscall(1) vtime(time_t *t)
{
time_t result;
if (unlikely(!__vsyscall_gtod_data.sysctl_enabled))
return time_syscall(t);
result = __vsyscall_gtod_data.wall_time_sec;
if (t)
*t = result;
return result;
}
/* Fast way to get current CPU and node.
This helps to do per node and per CPU caches in user space.
The result is not guaranteed without CPU affinity, but usually
works out because the scheduler tries to keep a thread on the same
CPU.
tcache must point to a two element sized long array.
All arguments can be NULL. */
long __vsyscall(2)
vgetcpu(unsigned *cpu, unsigned *node, struct getcpu_cache *tcache)
{
unsigned int dummy, p;
unsigned long j = 0;
/* Fast cache - only recompute value once per jiffies and avoid
relatively costly rdtscp/cpuid otherwise.
This works because the scheduler usually keeps the process
on the same CPU and this syscall doesn't guarantee its
results anyways.
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)) {
p = tcache->blob[1];
} else if (__vgetcpu_mode == VGETCPU_RDTSCP) {
/* Load per CPU data from RDTSCP */
rdtscp(dummy, dummy, p);
} else {
/* Load per CPU data from GDT */
asm("lsl %1,%0" : "=r" (p) : "r" (__PER_CPU_SEG));
}
if (tcache) {
tcache->blob[0] = j;
tcache->blob[1] = p;
}
if (cpu)
*cpu = p & 0xfff;
if (node)
*node = p >> 12;
return 0;
}
long __vsyscall(3) venosys_1(void)
{
return -ENOSYS;
}
#ifdef CONFIG_SYSCTL
#define SYSCALL 0x050f
#define NOP2 0x9090
/*
* NOP out syscall in vsyscall page when not needed.
*/
static int vsyscall_sysctl_change(ctl_table *ctl, int write, struct file * filp,
void __user *buffer, size_t *lenp, loff_t *ppos)
{
extern u16 vsysc1, vsysc2;
[PATCH] Add sparse annotation to vsyscall.c Fixes linux/arch/x86_64/kernel/vsyscall.c:276:7: warning: constant 0x0f40000000000 is so big it is long linux/arch/x86_64/kernel/vsyscall.c:80:14: warning: incorrect type in argument 1 (different address spaces) linux/arch/x86_64/kernel/vsyscall.c:80:14: expected void const volatile [noderef] *addr<asn:2> linux/arch/x86_64/kernel/vsyscall.c:80:14: got void *<noident> linux/arch/x86_64/kernel/vsyscall.c:200:7: warning: incorrect type in assignment (different address spaces) linux/arch/x86_64/kernel/vsyscall.c:200:7: expected unsigned short [usertype] *map1 linux/arch/x86_64/kernel/vsyscall.c:200:7: got void [noderef] *<asn:2> linux/arch/x86_64/kernel/vsyscall.c:203:7: warning: incorrect type in assignment (different address spaces) linux/arch/x86_64/kernel/vsyscall.c:203:7: expected unsigned short [usertype] *map2 linux/arch/x86_64/kernel/vsyscall.c:203:7: got void [noderef] *<asn:2> linux/arch/x86_64/kernel/vsyscall.c:215:10: warning: incorrect type in argument 1 (different address spaces) linux/arch/x86_64/kernel/vsyscall.c:215:10: expected void volatile [noderef] *addr<asn:2> linux/arch/x86_64/kernel/vsyscall.c:215:10: got unsigned short [usertype] *map2 linux/arch/x86_64/kernel/vsyscall.c:217:10: warning: incorrect type in argument 1 (different address spaces) linux/arch/x86_64/kernel/vsyscall.c:217:10: expected void volatile [noderef] *addr<asn:2> linux/arch/x86_64/kernel/vsyscall.c:217:10: got unsigned short [usertype] *map1 Signed-off-by: Andi Kleen <ak@suse.de>
2006-09-26 08:52:33 +00:00
u16 __iomem *map1;
u16 __iomem *map2;
int ret = proc_dointvec(ctl, write, filp, buffer, lenp, ppos);
if (!write)
return ret;
/* gcc has some trouble with __va(__pa()), so just do it this
way. */
[PATCH] x86: __pa and __pa_symbol address space separation Currently __pa_symbol is for use with symbols in the kernel address map and __pa is for use with pointers into the physical memory map. But the code is implemented so you can usually interchange the two. __pa which is much more common can be implemented much more cheaply if it is it doesn't have to worry about any other kernel address spaces. This is especially true with a relocatable kernel as __pa_symbol needs to peform an extra variable read to resolve the address. There is a third macro that is added for the vsyscall data __pa_vsymbol for finding the physical addesses of vsyscall pages. Most of this patch is simply sorting through the references to __pa or __pa_symbol and using the proper one. A little of it is continuing to use a physical address when we have it instead of recalculating it several times. swapper_pgd is now NULL. leave_mm now uses init_mm.pgd and init_mm.pgd is initialized at boot (instead of compile time) to the physmem virtual mapping of init_level4_pgd. The physical address changed. Except for the for EMPTY_ZERO page all of the remaining references to __pa_symbol appear to be during kernel initialization. So this should reduce the cost of __pa in the common case, even on a relocated kernel. As this is technically a semantic change we need to be on the lookout for anything I missed. But it works for me (tm). Signed-off-by: Eric W. Biederman <ebiederm@xmission.com> Signed-off-by: Vivek Goyal <vgoyal@in.ibm.com> Signed-off-by: Andi Kleen <ak@suse.de>
2007-05-02 17:27:07 +00:00
map1 = ioremap(__pa_vsymbol(&vsysc1), 2);
if (!map1)
return -ENOMEM;
[PATCH] x86: __pa and __pa_symbol address space separation Currently __pa_symbol is for use with symbols in the kernel address map and __pa is for use with pointers into the physical memory map. But the code is implemented so you can usually interchange the two. __pa which is much more common can be implemented much more cheaply if it is it doesn't have to worry about any other kernel address spaces. This is especially true with a relocatable kernel as __pa_symbol needs to peform an extra variable read to resolve the address. There is a third macro that is added for the vsyscall data __pa_vsymbol for finding the physical addesses of vsyscall pages. Most of this patch is simply sorting through the references to __pa or __pa_symbol and using the proper one. A little of it is continuing to use a physical address when we have it instead of recalculating it several times. swapper_pgd is now NULL. leave_mm now uses init_mm.pgd and init_mm.pgd is initialized at boot (instead of compile time) to the physmem virtual mapping of init_level4_pgd. The physical address changed. Except for the for EMPTY_ZERO page all of the remaining references to __pa_symbol appear to be during kernel initialization. So this should reduce the cost of __pa in the common case, even on a relocated kernel. As this is technically a semantic change we need to be on the lookout for anything I missed. But it works for me (tm). Signed-off-by: Eric W. Biederman <ebiederm@xmission.com> Signed-off-by: Vivek Goyal <vgoyal@in.ibm.com> Signed-off-by: Andi Kleen <ak@suse.de>
2007-05-02 17:27:07 +00:00
map2 = ioremap(__pa_vsymbol(&vsysc2), 2);
if (!map2) {
ret = -ENOMEM;
goto out;
}
if (!vsyscall_gtod_data.sysctl_enabled) {
[PATCH] Add sparse annotation to vsyscall.c Fixes linux/arch/x86_64/kernel/vsyscall.c:276:7: warning: constant 0x0f40000000000 is so big it is long linux/arch/x86_64/kernel/vsyscall.c:80:14: warning: incorrect type in argument 1 (different address spaces) linux/arch/x86_64/kernel/vsyscall.c:80:14: expected void const volatile [noderef] *addr<asn:2> linux/arch/x86_64/kernel/vsyscall.c:80:14: got void *<noident> linux/arch/x86_64/kernel/vsyscall.c:200:7: warning: incorrect type in assignment (different address spaces) linux/arch/x86_64/kernel/vsyscall.c:200:7: expected unsigned short [usertype] *map1 linux/arch/x86_64/kernel/vsyscall.c:200:7: got void [noderef] *<asn:2> linux/arch/x86_64/kernel/vsyscall.c:203:7: warning: incorrect type in assignment (different address spaces) linux/arch/x86_64/kernel/vsyscall.c:203:7: expected unsigned short [usertype] *map2 linux/arch/x86_64/kernel/vsyscall.c:203:7: got void [noderef] *<asn:2> linux/arch/x86_64/kernel/vsyscall.c:215:10: warning: incorrect type in argument 1 (different address spaces) linux/arch/x86_64/kernel/vsyscall.c:215:10: expected void volatile [noderef] *addr<asn:2> linux/arch/x86_64/kernel/vsyscall.c:215:10: got unsigned short [usertype] *map2 linux/arch/x86_64/kernel/vsyscall.c:217:10: warning: incorrect type in argument 1 (different address spaces) linux/arch/x86_64/kernel/vsyscall.c:217:10: expected void volatile [noderef] *addr<asn:2> linux/arch/x86_64/kernel/vsyscall.c:217:10: got unsigned short [usertype] *map1 Signed-off-by: Andi Kleen <ak@suse.de>
2006-09-26 08:52:33 +00:00
writew(SYSCALL, map1);
writew(SYSCALL, map2);
} else {
[PATCH] Add sparse annotation to vsyscall.c Fixes linux/arch/x86_64/kernel/vsyscall.c:276:7: warning: constant 0x0f40000000000 is so big it is long linux/arch/x86_64/kernel/vsyscall.c:80:14: warning: incorrect type in argument 1 (different address spaces) linux/arch/x86_64/kernel/vsyscall.c:80:14: expected void const volatile [noderef] *addr<asn:2> linux/arch/x86_64/kernel/vsyscall.c:80:14: got void *<noident> linux/arch/x86_64/kernel/vsyscall.c:200:7: warning: incorrect type in assignment (different address spaces) linux/arch/x86_64/kernel/vsyscall.c:200:7: expected unsigned short [usertype] *map1 linux/arch/x86_64/kernel/vsyscall.c:200:7: got void [noderef] *<asn:2> linux/arch/x86_64/kernel/vsyscall.c:203:7: warning: incorrect type in assignment (different address spaces) linux/arch/x86_64/kernel/vsyscall.c:203:7: expected unsigned short [usertype] *map2 linux/arch/x86_64/kernel/vsyscall.c:203:7: got void [noderef] *<asn:2> linux/arch/x86_64/kernel/vsyscall.c:215:10: warning: incorrect type in argument 1 (different address spaces) linux/arch/x86_64/kernel/vsyscall.c:215:10: expected void volatile [noderef] *addr<asn:2> linux/arch/x86_64/kernel/vsyscall.c:215:10: got unsigned short [usertype] *map2 linux/arch/x86_64/kernel/vsyscall.c:217:10: warning: incorrect type in argument 1 (different address spaces) linux/arch/x86_64/kernel/vsyscall.c:217:10: expected void volatile [noderef] *addr<asn:2> linux/arch/x86_64/kernel/vsyscall.c:217:10: got unsigned short [usertype] *map1 Signed-off-by: Andi Kleen <ak@suse.de>
2006-09-26 08:52:33 +00:00
writew(NOP2, map1);
writew(NOP2, map2);
}
iounmap(map2);
out:
iounmap(map1);
return ret;
}
static int vsyscall_sysctl_nostrat(ctl_table *t, int __user *name, int nlen,
void __user *oldval, size_t __user *oldlenp,
void __user *newval, size_t newlen)
{
return -ENOSYS;
}
static ctl_table kernel_table2[] = {
{ .ctl_name = 99, .procname = "vsyscall64",
.data = &vsyscall_gtod_data.sysctl_enabled, .maxlen = sizeof(int),
.mode = 0644,
.strategy = vsyscall_sysctl_nostrat,
.proc_handler = vsyscall_sysctl_change },
{}
};
static ctl_table kernel_root_table2[] = {
{ .ctl_name = CTL_KERN, .procname = "kernel", .mode = 0555,
.child = kernel_table2 },
{}
};
#endif
/* Assume __initcall executes before all user space. Hopefully kmod
doesn't violate that. We'll find out if it does. */
static void __cpuinit vsyscall_set_cpu(int cpu)
{
unsigned long *d;
unsigned long node = 0;
#ifdef CONFIG_NUMA
node = cpu_to_node[cpu];
#endif
if (cpu_has(&cpu_data[cpu], X86_FEATURE_RDTSCP))
write_rdtscp_aux((node << 12) | cpu);
/* Store cpu number in limit so that it can be loaded quickly
in user space in vgetcpu.
12 bits for the CPU and 8 bits for the node. */
d = (unsigned long *)(cpu_gdt(cpu) + GDT_ENTRY_PER_CPU);
*d = 0x0f40000000000ULL;
*d |= cpu;
*d |= (node & 0xf) << 12;
*d |= (node >> 4) << 48;
}
static void __cpuinit cpu_vsyscall_init(void *arg)
{
/* preemption should be already off */
vsyscall_set_cpu(raw_smp_processor_id());
}
static int __cpuinit
cpu_vsyscall_notifier(struct notifier_block *n, unsigned long action, void *arg)
{
long cpu = (long)arg;
if (action == CPU_ONLINE || action == CPU_ONLINE_FROZEN)
smp_call_function_single(cpu, cpu_vsyscall_init, NULL, 0, 1);
return NOTIFY_DONE;
}
static void __init map_vsyscall(void)
{
extern char __vsyscall_0;
unsigned long physaddr_page0 = __pa_symbol(&__vsyscall_0);
/* Note that VSYSCALL_MAPPED_PAGES must agree with the code below. */
__set_fixmap(VSYSCALL_FIRST_PAGE, physaddr_page0, PAGE_KERNEL_VSYSCALL);
}
static int __init vsyscall_init(void)
{
BUG_ON(((unsigned long) &vgettimeofday !=
VSYSCALL_ADDR(__NR_vgettimeofday)));
BUG_ON((unsigned long) &vtime != VSYSCALL_ADDR(__NR_vtime));
BUG_ON((VSYSCALL_ADDR(0) != __fix_to_virt(VSYSCALL_FIRST_PAGE)));
BUG_ON((unsigned long) &vgetcpu != VSYSCALL_ADDR(__NR_vgetcpu));
map_vsyscall();
#ifdef CONFIG_SYSCTL
[PATCH] sysctl: remove insert_at_head from register_sysctl The semantic effect of insert_at_head is that it would allow new registered sysctl entries to override existing sysctl entries of the same name. Which is pain for caching and the proc interface never implemented. I have done an audit and discovered that none of the current users of register_sysctl care as (excpet for directories) they do not register duplicate sysctl entries. So this patch simply removes the support for overriding existing entries in the sys_sysctl interface since no one uses it or cares and it makes future enhancments harder. Signed-off-by: Eric W. Biederman <ebiederm@xmission.com> Acked-by: Ralf Baechle <ralf@linux-mips.org> Acked-by: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Russell King <rmk@arm.linux.org.uk> Cc: David Howells <dhowells@redhat.com> Cc: "Luck, Tony" <tony.luck@intel.com> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Andi Kleen <ak@muc.de> Cc: Jens Axboe <axboe@kernel.dk> Cc: Corey Minyard <minyard@acm.org> Cc: Neil Brown <neilb@suse.de> Cc: "John W. Linville" <linville@tuxdriver.com> Cc: James Bottomley <James.Bottomley@steeleye.com> Cc: Jan Kara <jack@ucw.cz> Cc: Trond Myklebust <trond.myklebust@fys.uio.no> Cc: Mark Fasheh <mark.fasheh@oracle.com> Cc: David Chinner <dgc@sgi.com> Cc: "David S. Miller" <davem@davemloft.net> Cc: Patrick McHardy <kaber@trash.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-02-14 08:34:09 +00:00
register_sysctl_table(kernel_root_table2);
#endif
on_each_cpu(cpu_vsyscall_init, NULL, 0, 1);
hotcpu_notifier(cpu_vsyscall_notifier, 0);
return 0;
}
__initcall(vsyscall_init);