--- /dev/null
+/*
+ * 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 <asm/vsyscall.h>
+#include <asm/pgtable.h>
+#include <asm/page.h>
+#include <asm/fixmap.h>
+#include <asm/errno.h>
+#include <asm/io.h>
+
+#define __vsyscall(nr) __attribute__ ((unused,__section__(".vsyscall_" #nr)))
+
+int __sysctl_vsyscall __section_sysctl_vsyscall = 1;
+seqlock_t __xtime_lock __section_xtime_lock = SEQLOCK_UNLOCKED;
+
+#include <asm/unistd.h>
+
+static __always_inline void timeval_normalize(struct timeval * tv)
+{
+ time_t __sec;
+
+ __sec = tv->tv_usec / 1000000;
+ if (__sec) {
+ tv->tv_usec %= 1000000;
+ tv->tv_sec += __sec;
+ }
+}
+
+static __always_inline void do_vgettimeofday(struct timeval * tv)
+{
+ long sequence, t;
+ unsigned long sec, usec;
+
+ do {
+ sequence = read_seqbegin(&__xtime_lock);
+
+ sec = __xtime.tv_sec;
+ usec = (__xtime.tv_nsec / 1000) +
+ (__jiffies - __wall_jiffies) * (1000000 / HZ);
+
+ if (__vxtime.mode != VXTIME_HPET) {
+ t = get_cycles_sync();
+ if (t < __vxtime.last_tsc)
+ t = __vxtime.last_tsc;
+ usec += ((t - __vxtime.last_tsc) *
+ __vxtime.tsc_quot) >> 32;
+ /* See comment in x86_64 do_gettimeofday. */
+ } else {
+ usec += ((readl((void *)fix_to_virt(VSYSCALL_HPET) + 0xf0) -
+ __vxtime.last) * __vxtime.quot) >> 32;
+ }
+ } while (read_seqretry(&__xtime_lock, sequence));
+
+ tv->tv_sec = sec + usec / 1000000;
+ tv->tv_usec = usec % 1000000;
+}
+
+/* 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 = __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;
+}
+
+int __vsyscall(0) vgettimeofday(struct timeval * tv, struct timezone * tz)
+{
+ if (unlikely(!__sysctl_vsyscall))
+ return gettimeofday(tv,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)
+{
+ if (unlikely(!__sysctl_vsyscall))
+ return time_syscall(t);
+ else if (t)
+ *t = __xtime.tv_sec;
+ return __xtime.tv_sec;
+}
+
+long __vsyscall(2) venosys_0(void)
+{
+ return -ENOSYS;
+}
+
+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;
+ u16 *map1, *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. */
+ map1 = ioremap(__pa_symbol(&vsysc1), 2);
+ if (!map1)
+ return -ENOMEM;
+ map2 = ioremap(__pa_symbol(&vsysc2), 2);
+ if (!map2) {
+ ret = -ENOMEM;
+ goto out;
+ }
+ if (!sysctl_vsyscall) {
+ *map1 = SYSCALL;
+ *map2 = SYSCALL;
+ } else {
+ *map1 = NOP2;
+ *map2 = NOP2;
+ }
+ 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,
+ void **context)
+{
+ return -ENOSYS;
+}
+
+static ctl_table kernel_table2[] = {
+ { .ctl_name = 99, .procname = "vsyscall64",
+ .data = &sysctl_vsyscall, .maxlen = sizeof(int), .mode = 0644,
+ .strategy = vsyscall_sysctl_nostrat,
+ .proc_handler = vsyscall_sysctl_change },
+ { 0, }
+};
+
+static ctl_table kernel_root_table2[] = {
+ { .ctl_name = CTL_KERN, .procname = "kernel", .mode = 0555,
+ .child = kernel_table2 },
+ { 0 },
+};
+
+#endif
+
+static void __init map_vsyscall(void)
+{
+ extern char __vsyscall_0;
+ unsigned long physaddr_page0 = __pa_symbol(&__vsyscall_0);
+
+ __set_fixmap(VSYSCALL_FIRST_PAGE, physaddr_page0, PAGE_KERNEL_VSYSCALL);
+}
+
+#ifdef CONFIG_XEN
+static void __init map_vsyscall_user(void)
+{
+ extern void __set_fixmap_user(enum fixed_addresses, unsigned long, pgprot_t);
+ extern char __vsyscall_0;
+ unsigned long physaddr_page0 = __pa_symbol(&__vsyscall_0);
+
+ __set_fixmap_user(VSYSCALL_FIRST_PAGE, physaddr_page0, PAGE_KERNEL_VSYSCALL);
+}
+#endif
+
+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)));
+ map_vsyscall();
+#ifdef CONFIG_XEN
+ map_vsyscall_user();
+ sysctl_vsyscall = 0; /* disable vgettimeofay() */
+#endif
+#ifdef CONFIG_SYSCTL
+ register_sysctl_table(kernel_root_table2, 0);
+#endif
+ return 0;
+}
+
+__initcall(vsyscall_init);
git://git.onelab.eu / linux-2.6.git / blobdiff