diff options
author | Chris Metcalf <cmetcalf@tilera.com> | 2013-08-07 15:33:32 -0400 |
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committer | Chris Metcalf <cmetcalf@tilera.com> | 2013-08-13 16:26:21 -0400 |
commit | 4a556f4f56da3110b27e265b79f0e7582115445c (patch) | |
tree | f5af0b865c867160855e4722b49d7e850dddf944 /arch/tile/kernel/time.c | |
parent | 0c1d1917c547c8e787fb58e20e2de577453c980c (diff) | |
download | linux-4a556f4f56da3110b27e265b79f0e7582115445c.tar.bz2 |
tile: implement gettimeofday() via vDSO
This change creates the framework for vDSO calls, makes the existing
rt_sigreturn() mechanism use it, and adds a fast gettimeofday().
Now that we need to expose the vDSO address to userspace, we add
AT_SYSINFO_EHDR to the set of aux entries provided to userspace.
(You can disable any extra vDSO support by booting with vdso=0,
but the rt_sigreturn vDSO page will still be provided.)
Note that glibc has supported the tile vDSO since release 2.17.
Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>
Diffstat (limited to 'arch/tile/kernel/time.c')
-rw-r--r-- | arch/tile/kernel/time.c | 37 |
1 files changed, 36 insertions, 1 deletions
diff --git a/arch/tile/kernel/time.c b/arch/tile/kernel/time.c index 5ac397ec6986..36dc1e1bc0a0 100644 --- a/arch/tile/kernel/time.c +++ b/arch/tile/kernel/time.c @@ -23,8 +23,10 @@ #include <linux/smp.h> #include <linux/delay.h> #include <linux/module.h> +#include <linux/timekeeper_internal.h> #include <asm/irq_regs.h> #include <asm/traps.h> +#include <asm/vdso.h> #include <hv/hypervisor.h> #include <arch/interrupts.h> #include <arch/spr_def.h> @@ -110,7 +112,6 @@ void __init time_init(void) setup_tile_timer(); } - /* * Define the tile timer clock event device. The timer is driven by * the TILE_TIMER_CONTROL register, which consists of a 31-bit down @@ -237,3 +238,37 @@ cycles_t ns2cycles(unsigned long nsecs) struct clock_event_device *dev = &__raw_get_cpu_var(tile_timer); return ((u64)nsecs * dev->mult) >> dev->shift; } + +void update_vsyscall_tz(void) +{ + /* Userspace gettimeofday will spin while this value is odd. */ + ++vdso_data->tz_update_count; + smp_wmb(); + vdso_data->tz_minuteswest = sys_tz.tz_minuteswest; + vdso_data->tz_dsttime = sys_tz.tz_dsttime; + smp_wmb(); + ++vdso_data->tz_update_count; +} + +void update_vsyscall(struct timekeeper *tk) +{ + struct timespec wall_time = tk_xtime(tk); + struct timespec *wtm = &tk->wall_to_monotonic; + struct clocksource *clock = tk->clock; + + if (clock != &cycle_counter_cs) + return; + + /* Userspace gettimeofday will spin while this value is odd. */ + ++vdso_data->tb_update_count; + smp_wmb(); + vdso_data->xtime_tod_stamp = clock->cycle_last; + vdso_data->xtime_clock_sec = wall_time.tv_sec; + vdso_data->xtime_clock_nsec = wall_time.tv_nsec; + vdso_data->wtom_clock_sec = wtm->tv_sec; + vdso_data->wtom_clock_nsec = wtm->tv_nsec; + vdso_data->mult = clock->mult; + vdso_data->shift = clock->shift; + smp_wmb(); + ++vdso_data->tb_update_count; +} |