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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
This commit is contained in:
Linus Torvalds 2009-06-10 16:15:59 -07:00
parent 9b29e8228a 7d96fd41ca
commit 595dc54a1d
2 changed files with 10 additions and 9 deletions
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11
arch/x86/kernel/tsc.c
View File

@ -710,7 +710,16 @@ static cycle_t read_tsc(struct clocksource *cs)
#ifdef CONFIG_X86_64 #ifdef CONFIG_X86_64
static cycle_t __vsyscall_fn vread_tsc(void) 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 ? return ret >= __vsyscall_gtod_data.clock.cycle_last ?
ret : __vsyscall_gtod_data.clock.cycle_last; ret : __vsyscall_gtod_data.clock.cycle_last;

8
arch/x86/kernel/vsyscall_64.c
View File

@ -132,15 +132,7 @@ static __always_inline void do_vgettimeofday(struct timeval * tv)
return; 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(); now = vread();
rdtsc_barrier();
base = __vsyscall_gtod_data.clock.cycle_last; base = __vsyscall_gtod_data.clock.cycle_last;
mask = __vsyscall_gtod_data.clock.mask; mask = __vsyscall_gtod_data.clock.mask;
mult = __vsyscall_gtod_data.clock.mult; mult = __vsyscall_gtod_data.clock.mult;