diff options
Diffstat (limited to 'arch/x86_64/kernel/vsyscall.c')
| -rw-r--r-- | arch/x86_64/kernel/vsyscall.c | 225 |
1 files changed, 225 insertions, 0 deletions
diff --git a/arch/x86_64/kernel/vsyscall.c b/arch/x86_64/kernel/vsyscall.c new file mode 100644 index 00000000000..b4b8dc59663 --- /dev/null +++ b/arch/x86_64/kernel/vsyscall.c @@ -0,0 +1,225 @@ +/* + * 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))) +#define force_inline __attribute__((always_inline)) inline + +int __sysctl_vsyscall __section_sysctl_vsyscall = 1; +seqlock_t __xtime_lock __section_xtime_lock = SEQLOCK_UNLOCKED; + +#include <asm/unistd.h> + +static force_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 force_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_TSC) { + sync_core(); + rdtscll(t); + 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 force_inline void do_get_tz(struct timezone * tz) +{ + *tz = __sys_tz; +} + +static force_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 force_inline long time_syscall(long *t) +{ + long secs; + asm volatile("vsysc1: syscall" + : "=a" (secs) + : "0" (__NR_time),"D" (t) : __syscall_clobber); + return secs; +} + +static 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 */ +static 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; +} + +static long __vsyscall(2) venosys_0(void) +{ + return -ENOSYS; +} + +static 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); +} + +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(); + sysctl_vsyscall = 1; + register_sysctl_table(kernel_root_table2, 0); + return 0; +} + +__initcall(vsyscall_init); |