X-Git-Url: http://git.onelab.eu/?a=blobdiff_plain;f=arch%2Fx86_64%2Fkernel%2Fvsyscall-xen.c;fp=arch%2Fx86_64%2Fkernel%2Fvsyscall-xen.c;h=190834bfba28f5ae750badf378214cb086f61e66;hb=1db395853d4f30d6120458bd279ede1f882a8525;hp=0000000000000000000000000000000000000000;hpb=34a75f0025b9cf803b6a88db032e6ad6950c9313;p=linux-2.6.git diff --git a/arch/x86_64/kernel/vsyscall-xen.c b/arch/x86_64/kernel/vsyscall-xen.c new file mode 100644 index 000000000..190834bfb --- /dev/null +++ b/arch/x86_64/kernel/vsyscall-xen.c @@ -0,0 +1,239 @@ +/* + * linux/arch/x86_64/kernel/vsyscall.c + * + * Copyright (C) 2001 Andrea Arcangeli 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 +#include +#include +#include +#include +#include +#include + +#include +#include +#include +#include +#include +#include + +#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 + +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);