306 строки
7.7 KiB
C
306 строки
7.7 KiB
C
/*
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* linux/arch/x86_64/kernel/vsyscall.c
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*
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* Copyright (C) 2001 Andrea Arcangeli <andrea@suse.de> SuSE
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* Copyright 2003 Andi Kleen, SuSE Labs.
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*
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* Thanks to hpa@transmeta.com for some useful hint.
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* Special thanks to Ingo Molnar for his early experience with
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* a different vsyscall implementation for Linux/IA32 and for the name.
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*
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* vsyscall 1 is located at -10Mbyte, vsyscall 2 is located
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* at virtual address -10Mbyte+1024bytes etc... There are at max 4
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* vsyscalls. One vsyscall can reserve more than 1 slot to avoid
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* jumping out of line if necessary. We cannot add more with this
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* mechanism because older kernels won't return -ENOSYS.
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* If we want more than four we need a vDSO.
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*
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* Note: the concept clashes with user mode linux. If you use UML and
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* want per guest time just set the kernel.vsyscall64 sysctl to 0.
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*/
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#include <linux/time.h>
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#include <linux/init.h>
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#include <linux/kernel.h>
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#include <linux/timer.h>
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#include <linux/seqlock.h>
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#include <linux/jiffies.h>
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#include <linux/sysctl.h>
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#include <linux/getcpu.h>
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#include <asm/vsyscall.h>
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#include <asm/pgtable.h>
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#include <asm/page.h>
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#include <asm/fixmap.h>
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#include <asm/errno.h>
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#include <asm/io.h>
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#include <asm/segment.h>
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#include <asm/desc.h>
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#include <asm/topology.h>
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#define __vsyscall(nr) __attribute__ ((unused,__section__(".vsyscall_" #nr)))
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int __sysctl_vsyscall __section_sysctl_vsyscall = 1;
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seqlock_t __xtime_lock __section_xtime_lock = SEQLOCK_UNLOCKED;
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int __vgetcpu_mode __section_vgetcpu_mode;
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#include <asm/unistd.h>
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static __always_inline void timeval_normalize(struct timeval * tv)
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{
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time_t __sec;
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__sec = tv->tv_usec / 1000000;
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if (__sec) {
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tv->tv_usec %= 1000000;
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tv->tv_sec += __sec;
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}
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}
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static __always_inline void do_vgettimeofday(struct timeval * tv)
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{
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long sequence, t;
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unsigned long sec, usec;
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do {
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sequence = read_seqbegin(&__xtime_lock);
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sec = __xtime.tv_sec;
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usec = __xtime.tv_nsec / 1000;
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if (__vxtime.mode != VXTIME_HPET) {
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t = get_cycles_sync();
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if (t < __vxtime.last_tsc)
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t = __vxtime.last_tsc;
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usec += ((t - __vxtime.last_tsc) *
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__vxtime.tsc_quot) >> 32;
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/* See comment in x86_64 do_gettimeofday. */
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} else {
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usec += ((readl((void __iomem *)
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fix_to_virt(VSYSCALL_HPET) + 0xf0) -
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__vxtime.last) * __vxtime.quot) >> 32;
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}
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} while (read_seqretry(&__xtime_lock, sequence));
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tv->tv_sec = sec + usec / 1000000;
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tv->tv_usec = usec % 1000000;
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}
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/* RED-PEN may want to readd seq locking, but then the variable should be write-once. */
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static __always_inline void do_get_tz(struct timezone * tz)
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{
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*tz = __sys_tz;
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}
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static __always_inline int gettimeofday(struct timeval *tv, struct timezone *tz)
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{
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int ret;
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asm volatile("vsysc2: syscall"
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: "=a" (ret)
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: "0" (__NR_gettimeofday),"D" (tv),"S" (tz) : __syscall_clobber );
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return ret;
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}
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static __always_inline long time_syscall(long *t)
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{
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long secs;
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asm volatile("vsysc1: syscall"
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: "=a" (secs)
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: "0" (__NR_time),"D" (t) : __syscall_clobber);
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return secs;
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}
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int __vsyscall(0) vgettimeofday(struct timeval * tv, struct timezone * tz)
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{
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if (!__sysctl_vsyscall)
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return gettimeofday(tv,tz);
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if (tv)
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do_vgettimeofday(tv);
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if (tz)
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do_get_tz(tz);
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return 0;
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}
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/* This will break when the xtime seconds get inaccurate, but that is
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* unlikely */
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time_t __vsyscall(1) vtime(time_t *t)
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{
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if (!__sysctl_vsyscall)
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return time_syscall(t);
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else if (t)
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*t = __xtime.tv_sec;
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return __xtime.tv_sec;
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}
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/* Fast way to get current CPU and node.
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This helps to do per node and per CPU caches in user space.
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The result is not guaranteed without CPU affinity, but usually
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works out because the scheduler tries to keep a thread on the same
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CPU.
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tcache must point to a two element sized long array.
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All arguments can be NULL. */
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long __vsyscall(2)
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vgetcpu(unsigned *cpu, unsigned *node, struct getcpu_cache *tcache)
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{
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unsigned int dummy, p;
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unsigned long j = 0;
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/* Fast cache - only recompute value once per jiffies and avoid
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relatively costly rdtscp/cpuid otherwise.
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This works because the scheduler usually keeps the process
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on the same CPU and this syscall doesn't guarantee its
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results anyways.
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We do this here because otherwise user space would do it on
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its own in a likely inferior way (no access to jiffies).
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If you don't like it pass NULL. */
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if (tcache && tcache->blob[0] == (j = __jiffies)) {
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p = tcache->blob[1];
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} else if (__vgetcpu_mode == VGETCPU_RDTSCP) {
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/* Load per CPU data from RDTSCP */
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rdtscp(dummy, dummy, p);
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} else {
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/* Load per CPU data from GDT */
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asm("lsl %1,%0" : "=r" (p) : "r" (__PER_CPU_SEG));
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}
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if (tcache) {
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tcache->blob[0] = j;
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tcache->blob[1] = p;
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}
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if (cpu)
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*cpu = p & 0xfff;
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if (node)
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*node = p >> 12;
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return 0;
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}
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long __vsyscall(3) venosys_1(void)
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{
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return -ENOSYS;
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}
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#ifdef CONFIG_SYSCTL
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#define SYSCALL 0x050f
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#define NOP2 0x9090
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/*
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* NOP out syscall in vsyscall page when not needed.
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*/
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static int vsyscall_sysctl_change(ctl_table *ctl, int write, struct file * filp,
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void __user *buffer, size_t *lenp, loff_t *ppos)
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{
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extern u16 vsysc1, vsysc2;
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u16 __iomem *map1;
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u16 __iomem *map2;
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int ret = proc_dointvec(ctl, write, filp, buffer, lenp, ppos);
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if (!write)
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return ret;
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/* gcc has some trouble with __va(__pa()), so just do it this
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way. */
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map1 = ioremap(__pa_symbol(&vsysc1), 2);
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if (!map1)
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return -ENOMEM;
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map2 = ioremap(__pa_symbol(&vsysc2), 2);
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if (!map2) {
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ret = -ENOMEM;
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goto out;
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}
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if (!sysctl_vsyscall) {
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writew(SYSCALL, map1);
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writew(SYSCALL, map2);
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} else {
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writew(NOP2, map1);
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writew(NOP2, map2);
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}
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iounmap(map2);
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out:
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iounmap(map1);
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return ret;
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}
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static int vsyscall_sysctl_nostrat(ctl_table *t, int __user *name, int nlen,
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void __user *oldval, size_t __user *oldlenp,
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void __user *newval, size_t newlen,
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void **context)
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{
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return -ENOSYS;
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}
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static ctl_table kernel_table2[] = {
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{ .ctl_name = 99, .procname = "vsyscall64",
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.data = &sysctl_vsyscall, .maxlen = sizeof(int), .mode = 0644,
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.strategy = vsyscall_sysctl_nostrat,
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.proc_handler = vsyscall_sysctl_change },
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{ 0, }
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};
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static ctl_table kernel_root_table2[] = {
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{ .ctl_name = CTL_KERN, .procname = "kernel", .mode = 0555,
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.child = kernel_table2 },
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{ 0 },
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};
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#endif
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static void __cpuinit write_rdtscp_cb(void *info)
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{
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write_rdtscp_aux((unsigned long)info);
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}
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void __cpuinit vsyscall_set_cpu(int cpu)
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{
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unsigned long *d;
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unsigned long node = 0;
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#ifdef CONFIG_NUMA
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node = cpu_to_node[cpu];
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#endif
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if (cpu_has(&cpu_data[cpu], X86_FEATURE_RDTSCP)) {
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void *info = (void *)((node << 12) | cpu);
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/* Can happen on preemptive kernel */
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if (get_cpu() == cpu)
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write_rdtscp_cb(info);
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#ifdef CONFIG_SMP
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else {
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/* the notifier is unfortunately not executed on the
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target CPU */
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smp_call_function_single(cpu,write_rdtscp_cb,info,0,1);
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}
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#endif
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put_cpu();
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}
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/* Store cpu number in limit so that it can be loaded quickly
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in user space in vgetcpu.
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12 bits for the CPU and 8 bits for the node. */
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d = (unsigned long *)(cpu_gdt(cpu) + GDT_ENTRY_PER_CPU);
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*d = 0x0f40000000000ULL;
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*d |= cpu;
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*d |= (node & 0xf) << 12;
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*d |= (node >> 4) << 48;
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}
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static void __init map_vsyscall(void)
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{
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extern char __vsyscall_0;
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unsigned long physaddr_page0 = __pa_symbol(&__vsyscall_0);
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__set_fixmap(VSYSCALL_FIRST_PAGE, physaddr_page0, PAGE_KERNEL_VSYSCALL);
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}
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static int __init vsyscall_init(void)
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{
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BUG_ON(((unsigned long) &vgettimeofday !=
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VSYSCALL_ADDR(__NR_vgettimeofday)));
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BUG_ON((unsigned long) &vtime != VSYSCALL_ADDR(__NR_vtime));
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BUG_ON((VSYSCALL_ADDR(0) != __fix_to_virt(VSYSCALL_FIRST_PAGE)));
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BUG_ON((unsigned long) &vgetcpu != VSYSCALL_ADDR(__NR_vgetcpu));
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map_vsyscall();
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#ifdef CONFIG_SYSCTL
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register_sysctl_table(kernel_root_table2, 0);
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#endif
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return 0;
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}
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__initcall(vsyscall_init);
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