diff options
Diffstat (limited to 'arch/x86_64/kernel/vsyscall.c')
| -rw-r--r-- | arch/x86_64/kernel/vsyscall.c | 68 |
1 files changed, 47 insertions, 21 deletions
diff --git a/arch/x86_64/kernel/vsyscall.c b/arch/x86_64/kernel/vsyscall.c index b43c698cf7d..dc32cef9619 100644 --- a/arch/x86_64/kernel/vsyscall.c +++ b/arch/x86_64/kernel/vsyscall.c @@ -45,14 +45,34 @@ #define __vsyscall(nr) __attribute__ ((unused,__section__(".vsyscall_" #nr))) #define __syscall_clobber "r11","rcx","memory" +#define __pa_vsymbol(x) \ + ({unsigned long v; \ + extern char __vsyscall_0; \ + asm("" : "=r" (v) : "0" (x)); \ + ((v - VSYSCALL_FIRST_PAGE) + __pa_symbol(&__vsyscall_0)); }) +/* + * vsyscall_gtod_data contains data that is : + * - readonly from vsyscalls + * - writen by timer interrupt or systcl (/proc/sys/kernel/vsyscall64) + * Try to keep this structure as small as possible to avoid cache line ping pongs + */ struct vsyscall_gtod_data_t { - seqlock_t lock; - int sysctl_enabled; - struct timeval wall_time_tv; + seqlock_t lock; + + /* open coded 'struct timespec' */ + time_t wall_time_sec; + u32 wall_time_nsec; + + int sysctl_enabled; struct timezone sys_tz; - cycle_t offset_base; - struct clocksource clock; + struct { /* extract of a clocksource struct */ + cycle_t (*vread)(void); + cycle_t cycle_last; + cycle_t mask; + u32 mult; + u32 shift; + } clock; }; int __vgetcpu_mode __section_vgetcpu_mode; @@ -68,9 +88,13 @@ void update_vsyscall(struct timespec *wall_time, struct clocksource *clock) 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.clock.vread = clock->vread; + vsyscall_gtod_data.clock.cycle_last = clock->cycle_last; + vsyscall_gtod_data.clock.mask = clock->mask; + vsyscall_gtod_data.clock.mult = clock->mult; + vsyscall_gtod_data.clock.shift = clock->shift; + vsyscall_gtod_data.wall_time_sec = wall_time->tv_sec; + vsyscall_gtod_data.wall_time_nsec = wall_time->tv_nsec; vsyscall_gtod_data.sys_tz = sys_tz; write_sequnlock_irqrestore(&vsyscall_gtod_data.lock, flags); } @@ -105,7 +129,8 @@ static __always_inline long time_syscall(long *t) static __always_inline void do_vgettimeofday(struct timeval * tv) { cycle_t now, base, mask, cycle_delta; - unsigned long seq, mult, shift, nsec_delta; + unsigned seq; + unsigned long mult, shift, nsec; cycle_t (*vread)(void); do { seq = read_seqbegin(&__vsyscall_gtod_data.lock); @@ -121,21 +146,20 @@ static __always_inline void do_vgettimeofday(struct timeval * tv) mult = __vsyscall_gtod_data.clock.mult; shift = __vsyscall_gtod_data.clock.shift; - *tv = __vsyscall_gtod_data.wall_time_tv; - + tv->tv_sec = __vsyscall_gtod_data.wall_time_sec; + nsec = __vsyscall_gtod_data.wall_time_nsec; } while (read_seqretry(&__vsyscall_gtod_data.lock, seq)); /* calculate interval: */ cycle_delta = (now - base) & mask; /* convert to nsecs: */ - nsec_delta = (cycle_delta * mult) >> shift; + nsec += (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) { + while (nsec >= NSEC_PER_SEC) { tv->tv_sec += 1; - tv->tv_usec -= USEC_PER_SEC; + nsec -= NSEC_PER_SEC; } + tv->tv_usec = nsec / NSEC_PER_USEC; } int __vsyscall(0) vgettimeofday(struct timeval * tv, struct timezone * tz) @@ -151,11 +175,13 @@ int __vsyscall(0) vgettimeofday(struct timeval * tv, struct timezone * tz) * unlikely */ time_t __vsyscall(1) vtime(time_t *t) { + time_t result; if (unlikely(!__vsyscall_gtod_data.sysctl_enabled)) return time_syscall(t); - else if (t) - *t = __vsyscall_gtod_data.wall_time_tv.tv_sec; - return __vsyscall_gtod_data.wall_time_tv.tv_sec; + result = __vsyscall_gtod_data.wall_time_sec; + if (t) + *t = result; + return result; } /* Fast way to get current CPU and node. @@ -224,10 +250,10 @@ static int vsyscall_sysctl_change(ctl_table *ctl, int write, struct file * filp, return ret; /* gcc has some trouble with __va(__pa()), so just do it this way. */ - map1 = ioremap(__pa_symbol(&vsysc1), 2); + map1 = ioremap(__pa_vsymbol(&vsysc1), 2); if (!map1) return -ENOMEM; - map2 = ioremap(__pa_symbol(&vsysc2), 2); + map2 = ioremap(__pa_vsymbol(&vsysc2), 2); if (!map2) { ret = -ENOMEM; goto out; |