提交 595dc54a 编写于 作者: L Linus Torvalds

Merge branch 'x86-vdso-for-linus' of...

Merge branch 'x86-vdso-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip

* 'x86-vdso-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  x86: move rdtsc_barrier() into the TSC vread method
......@@ -710,7 +710,16 @@ static cycle_t read_tsc(struct clocksource *cs)
#ifdef CONFIG_X86_64
static cycle_t __vsyscall_fn vread_tsc(void)
{
cycle_t ret = (cycle_t)vget_cycles();
cycle_t ret;
/*
* Surround the RDTSC by barriers, to make sure it's not
* speculated to outside the seqlock critical section and
* does not cause time warps:
*/
rdtsc_barrier();
ret = (cycle_t)vget_cycles();
rdtsc_barrier();
return ret >= __vsyscall_gtod_data.clock.cycle_last ?
ret : __vsyscall_gtod_data.clock.cycle_last;
......
......@@ -132,15 +132,7 @@ static __always_inline void do_vgettimeofday(struct timeval * tv)
return;
}
/*
* Surround the RDTSC by barriers, to make sure it's not
* speculated to outside the seqlock critical section and
* does not cause time warps:
*/
rdtsc_barrier();
now = vread();
rdtsc_barrier();
base = __vsyscall_gtod_data.clock.cycle_last;
mask = __vsyscall_gtod_data.clock.mask;
mult = __vsyscall_gtod_data.clock.mult;
......
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