x86: remove get_cycles_sync
rdtsc is now speculation-safe, so no need for the sync variants of
the APIs.
[ mingo@elte.hu: removed the nsec_barrier() complication. ]
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
diff --git a/arch/x86/kernel/time_64.c b/arch/x86/kernel/time_64.c
index 91d4d49..61b17f5 100644
--- a/arch/x86/kernel/time_64.c
+++ b/arch/x86/kernel/time_64.c
@@ -83,7 +83,7 @@
rdtscl(tsc_start);
do {
rdmsrl(MSR_K7_PERFCTR0 + i, pmc_now);
- tsc_now = get_cycles_sync();
+ tsc_now = get_cycles();
} while ((tsc_now - tsc_start) < TICK_COUNT);
local_irq_restore(flags);
diff --git a/arch/x86/kernel/tsc_64.c b/arch/x86/kernel/tsc_64.c
index 3723401..2cc55b7 100644
--- a/arch/x86/kernel/tsc_64.c
+++ b/arch/x86/kernel/tsc_64.c
@@ -181,12 +181,12 @@
int i;
for (i = 0; i < MAX_RETRIES; i++) {
- t1 = get_cycles_sync();
+ t1 = get_cycles();
if (hpet)
*hpet = hpet_readl(HPET_COUNTER) & 0xFFFFFFFF;
else
*pm = acpi_pm_read_early();
- t2 = get_cycles_sync();
+ t2 = get_cycles();
if ((t2 - t1) < SMI_TRESHOLD)
return t2;
}
@@ -210,9 +210,9 @@
outb(0xb0, 0x43);
outb((CLOCK_TICK_RATE / (1000 / 50)) & 0xff, 0x42);
outb((CLOCK_TICK_RATE / (1000 / 50)) >> 8, 0x42);
- tr1 = get_cycles_sync();
+ tr1 = get_cycles();
while ((inb(0x61) & 0x20) == 0);
- tr2 = get_cycles_sync();
+ tr2 = get_cycles();
tsc2 = tsc_read_refs(&pm2, hpet ? &hpet2 : NULL);
@@ -300,13 +300,13 @@
/* clock source code: */
static cycle_t read_tsc(void)
{
- cycle_t ret = (cycle_t)get_cycles_sync();
+ cycle_t ret = (cycle_t)get_cycles();
return ret;
}
static cycle_t __vsyscall_fn vread_tsc(void)
{
- cycle_t ret = (cycle_t)vget_cycles_sync();
+ cycle_t ret = (cycle_t)vget_cycles();
return ret;
}
diff --git a/arch/x86/kernel/tsc_sync.c b/arch/x86/kernel/tsc_sync.c
index 05d8f25..ace3405 100644
--- a/arch/x86/kernel/tsc_sync.c
+++ b/arch/x86/kernel/tsc_sync.c
@@ -46,7 +46,7 @@
cycles_t start, now, prev, end;
int i;
- start = get_cycles_sync();
+ start = get_cycles();
/*
* The measurement runs for 20 msecs:
*/
@@ -61,7 +61,7 @@
*/
__raw_spin_lock(&sync_lock);
prev = last_tsc;
- now = get_cycles_sync();
+ now = get_cycles();
last_tsc = now;
__raw_spin_unlock(&sync_lock);
diff --git a/include/asm-x86/tsc.h b/include/asm-x86/tsc.h
index 4013037..f51a50da 100644
--- a/include/asm-x86/tsc.h
+++ b/include/asm-x86/tsc.h
@@ -36,62 +36,18 @@
return ret;
}
-/* Like get_cycles, but make sure the CPU is synchronized. */
-static __always_inline cycles_t __get_cycles_sync(void)
+static inline cycles_t vget_cycles(void)
{
- unsigned long long ret;
- unsigned eax, edx;
-
/*
- * Use RDTSCP if possible; it is guaranteed to be synchronous
- * and doesn't cause a VMEXIT on Hypervisors
+ * We only do VDSOs on TSC capable CPUs, so this shouldnt
+ * access boot_cpu_data (which is not VDSO-safe):
*/
- alternative_io(ASM_NOP3, ".byte 0x0f,0x01,0xf9", X86_FEATURE_RDTSCP,
- ASM_OUTPUT2("=a" (eax), "=d" (edx)),
- "a" (0U), "d" (0U) : "ecx", "memory");
- ret = (((unsigned long long)edx) << 32) | ((unsigned long long)eax);
- if (ret)
- return ret;
-
- /*
- * Don't do an additional sync on CPUs where we know
- * RDTSC is already synchronous:
- */
- alternative_io("cpuid", ASM_NOP2, X86_FEATURE_SYNC_RDTSC,
- "=a" (eax), "0" (1) : "ebx","ecx","edx","memory");
-
- return 0;
-}
-
-static __always_inline cycles_t get_cycles_sync(void)
-{
- unsigned long long ret;
- ret = __get_cycles_sync();
- if (!ret)
- rdtscll(ret);
- return ret;
-}
-
-#ifdef CONFIG_PARAVIRT
-/*
- * For paravirt guests, some functionalities are executed through function
- * pointers in the various pvops structures.
- * These function pointers exist inside the kernel and can not
- * be accessed by user space. To avoid this, we make a copy of the
- * get_cycles_sync (called in kernel) but force the use of native_read_tsc.
- * Ideally, the guest should set up it's own clock and vread
- */
-static __always_inline long long vget_cycles_sync(void)
-{
- unsigned long long ret;
- ret = __get_cycles_sync();
- if (!ret)
- ret = native_read_tsc();
- return ret;
-}
-#else
-# define vget_cycles_sync() get_cycles_sync()
+#ifndef CONFIG_X86_TSC
+ if (!cpu_has_tsc)
+ return 0;
#endif
+ return (cycles_t) native_read_tsc();
+}
extern void tsc_init(void);
extern void mark_tsc_unstable(char *reason);