diff options
Diffstat (limited to 'arch/x86_64/kernel/vsyscall.c')
| -rw-r--r-- | arch/x86_64/kernel/vsyscall.c | 127 |
1 files changed, 75 insertions, 52 deletions
diff --git a/arch/x86_64/kernel/vsyscall.c b/arch/x86_64/kernel/vsyscall.c index 2433d6fc68b..180ff919eaf 100644 --- a/arch/x86_64/kernel/vsyscall.c +++ b/arch/x86_64/kernel/vsyscall.c @@ -26,6 +26,7 @@ #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> @@ -34,6 +35,7 @@ #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> @@ -44,56 +46,41 @@ #define __vsyscall(nr) __attribute__ ((unused,__section__(".vsyscall_" #nr))) #define __syscall_clobber "r11","rcx","memory" -int __sysctl_vsyscall __section_sysctl_vsyscall = 1; -seqlock_t __xtime_lock __section_xtime_lock = SEQLOCK_UNLOCKED; +struct vsyscall_gtod_data_t { + seqlock_t lock; + int sysctl_enabled; + struct timeval wall_time_tv; + struct timezone sys_tz; + cycle_t offset_base; + struct clocksource clock; +}; int __vgetcpu_mode __section_vgetcpu_mode; -#include <asm/unistd.h> - -static __always_inline void timeval_normalize(struct timeval * tv) +struct vsyscall_gtod_data_t __vsyscall_gtod_data __section_vsyscall_gtod_data = { - time_t __sec; - - __sec = tv->tv_usec / 1000000; - if (__sec) { - tv->tv_usec %= 1000000; - tv->tv_sec += __sec; - } -} + .lock = SEQLOCK_UNLOCKED, + .sysctl_enabled = 1, +}; -static __always_inline void do_vgettimeofday(struct timeval * tv) +void update_vsyscall(struct timespec *wall_time, struct clocksource *clock) { - long sequence, t; - unsigned long sec, usec; - - do { - sequence = read_seqbegin(&__xtime_lock); - - sec = __xtime.tv_sec; - usec = __xtime.tv_nsec / 1000; - - 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 __iomem *) - 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; + unsigned long flags; + + write_seqlock_irqsave(&vsyscall_gtod_data.lock, flags); + /* copy vsyscall data */ + vsyscall_gtod_data.clock = *clock; + vsyscall_gtod_data.wall_time_tv.tv_sec = wall_time->tv_sec; + vsyscall_gtod_data.wall_time_tv.tv_usec = wall_time->tv_nsec/1000; + 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. */ +/* 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; + *tz = __vsyscall_gtod_data.sys_tz; } static __always_inline int gettimeofday(struct timeval *tv, struct timezone *tz) @@ -101,7 +88,8 @@ 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 ); + : "0" (__NR_gettimeofday),"D" (tv),"S" (tz) + : __syscall_clobber ); return ret; } @@ -114,10 +102,44 @@ static __always_inline long time_syscall(long *t) return secs; } +static __always_inline void do_vgettimeofday(struct timeval * tv) +{ + cycle_t now, base, mask, cycle_delta; + unsigned long seq, mult, shift, nsec_delta; + 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,0); + 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 = __vsyscall_gtod_data.wall_time_tv; + + } while (read_seqretry(&__vsyscall_gtod_data.lock, seq)); + + /* calculate interval: */ + cycle_delta = (now - base) & mask; + /* convert to nsecs: */ + nsec_delta = (cycle_delta * mult) >> shift; + + /* convert to usecs and add to timespec: */ + tv->tv_usec += nsec_delta / NSEC_PER_USEC; + while (tv->tv_usec > USEC_PER_SEC) { + tv->tv_sec += 1; + tv->tv_usec -= USEC_PER_SEC; + } +} + int __vsyscall(0) vgettimeofday(struct timeval * tv, struct timezone * tz) { - if (!__sysctl_vsyscall) - return gettimeofday(tv,tz); if (tv) do_vgettimeofday(tv); if (tz) @@ -129,11 +151,11 @@ int __vsyscall(0) vgettimeofday(struct timeval * tv, struct timezone * tz) * unlikely */ time_t __vsyscall(1) vtime(time_t *t) { - if (!__sysctl_vsyscall) + if (unlikely(!__vsyscall_gtod_data.sysctl_enabled)) return time_syscall(t); else if (t) - *t = __xtime.tv_sec; - return __xtime.tv_sec; + *t = __vsyscall_gtod_data.wall_time_tv.tv_sec; + return __vsyscall_gtod_data.wall_time_tv.tv_sec; } /* Fast way to get current CPU and node. @@ -210,7 +232,7 @@ static int vsyscall_sysctl_change(ctl_table *ctl, int write, struct file * filp, ret = -ENOMEM; goto out; } - if (!sysctl_vsyscall) { + if (!vsyscall_gtod_data.sysctl_enabled) { writew(SYSCALL, map1); writew(SYSCALL, map2); } else { @@ -232,16 +254,17 @@ static int vsyscall_sysctl_nostrat(ctl_table *t, int __user *name, int nlen, static ctl_table kernel_table2[] = { { .ctl_name = 99, .procname = "vsyscall64", - .data = &sysctl_vsyscall, .maxlen = sizeof(int), .mode = 0644, + .data = &vsyscall_gtod_data.sysctl_enabled, .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 @@ -301,7 +324,7 @@ static int __init vsyscall_init(void) BUG_ON((unsigned long) &vgetcpu != VSYSCALL_ADDR(__NR_vgetcpu)); map_vsyscall(); #ifdef CONFIG_SYSCTL - register_sysctl_table(kernel_root_table2, 0); + register_sysctl_table(kernel_root_table2); #endif on_each_cpu(cpu_vsyscall_init, NULL, 0, 1); hotcpu_notifier(cpu_vsyscall_notifier, 0); |