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| author | Benjamin Herrenschmidt <benh@kernel.crashing.org> | 2009-06-12 16:53:38 +1000 |
|---|---|---|
| committer | Benjamin Herrenschmidt <benh@kernel.crashing.org> | 2009-06-12 16:53:38 +1000 |
| commit | bc47ab0241c7c86da4f5e5f82fbca7d45387c18d (patch) | |
| tree | b9c33ae8b6de43e44cc5fcbaa3e4a15f18a5ed42 /arch/x86/kernel/tsc.c | |
| parent | 37f9ef553bed630957e025504cdcbc76f5de49d5 (diff) | |
| parent | 8ebf975608aaebd7feb33d77f07ba21a6380e086 (diff) | |
Merge commit 'origin/master' into next
Manual merge of:
arch/powerpc/kernel/asm-offsets.c
Diffstat (limited to 'arch/x86/kernel/tsc.c')
| -rw-r--r-- | arch/x86/kernel/tsc.c | 19 |
1 files changed, 14 insertions, 5 deletions
diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c index d57de05dc43..3e1c057e98f 100644 --- a/arch/x86/kernel/tsc.c +++ b/arch/x86/kernel/tsc.c @@ -384,13 +384,13 @@ unsigned long native_calibrate_tsc(void) { u64 tsc1, tsc2, delta, ref1, ref2; unsigned long tsc_pit_min = ULONG_MAX, tsc_ref_min = ULONG_MAX; - unsigned long flags, latch, ms, fast_calibrate, tsc_khz; + unsigned long flags, latch, ms, fast_calibrate, hv_tsc_khz; int hpet = is_hpet_enabled(), i, loopmin; - tsc_khz = get_hypervisor_tsc_freq(); - if (tsc_khz) { + hv_tsc_khz = get_hypervisor_tsc_freq(); + if (hv_tsc_khz) { printk(KERN_INFO "TSC: Frequency read from the hypervisor\n"); - return tsc_khz; + return hv_tsc_khz; } local_irq_save(flags); @@ -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; |