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 91d4d495904e4ecd3f7f97617db511b607f3c02b..61b17f5ec8678e9c6aa1fba63af1ded16ab8214f 100644 (file)
--- a/arch/x86/kernel/time_64.c
+++ b/arch/x86/kernel/time_64.c
@@ -83,7 +83,7 @@ unsigned long __init native_calculate_cpu_khz(void)
        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 3723401c459381dca4c102b971e0e03764c5f5bd..2cc55b726c224f3f40930f8125389fa43b26aa86 100644 (file)
--- a/arch/x86/kernel/tsc_64.c
+++ b/arch/x86/kernel/tsc_64.c
@@ -181,12 +181,12 @@ static unsigned long __init tsc_read_refs(unsigned long *pm,
        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 @@ void __init tsc_calibrate(void)
        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 @@ __setup("notsc", notsc_setup);
 /* 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 05d8f25de6ae41dcde81a48cc0c7015fe3fe3743..ace340524c01588e6c48921beb67169193d0679d 100644 (file)
--- a/arch/x86/kernel/tsc_sync.c
+++ b/arch/x86/kernel/tsc_sync.c
@@ -46,7 +46,7 @@ static __cpuinit void check_tsc_warp(void)
        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 @@ static __cpuinit void check_tsc_warp(void)
                 */
                __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 401303724130b047b861ae2b7f3b1eff3e17108b..f51a50da35aac186341211ba9b754df6ad38229f 100644 (file)
--- a/include/asm-x86/tsc.h
+++ b/include/asm-x86/tsc.h
@@ -36,62 +36,18 @@ static inline cycles_t get_cycles(void)
        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);