1 files changed, 293 insertions, 101 deletions

diff --git a/arch/x86/vdso/vclock_gettime.c b/arch/x86/vdso/vclock_gettime.c
index ee55754cc3c..9793322751e 100644
--- a/arch/x86/vdso/vclock_gettime.c
+++ b/arch/x86/vdso/vclock_gettime.c
@@ -2,132 +2,316 @@
  * Copyright 2006 Andi Kleen, SUSE Labs.
  * Subject to the GNU Public License, v.2
  *
- * Fast user context implementation of clock_gettime and gettimeofday.
+ * Fast user context implementation of clock_gettime, gettimeofday, and time.
+ *
+ * 32 Bit compat layer by Stefani Seibold <stefani@seibold.net>
+ *  sponsored by Rohde & Schwarz GmbH & Co. KG Munich/Germany
  *
  * The code should have no internal unresolved relocations.
  * Check with readelf after changing.
- * Also alternative() doesn't work.
  */
 
-/* Disable profiling for userspace code: */
-#define DISABLE_BRANCH_PROFILING
-
-#include <linux/kernel.h>
-#include <linux/posix-timers.h>
-#include <linux/time.h>
-#include <linux/string.h>
-#include <asm/vsyscall.h>
+#include <uapi/linux/time.h>
 #include <asm/vgtod.h>
-#include <asm/timex.h>
 #include <asm/hpet.h>
+#include <asm/vvar.h>
 #include <asm/unistd.h>
-#include <asm/io.h>
-#include "vextern.h"
+#include <asm/msr.h>
+#include <linux/math64.h>
+#include <linux/time.h>
+
+#define gtod (&VVAR(vsyscall_gtod_data))
+
+extern int __vdso_clock_gettime(clockid_t clock, struct timespec *ts);
+extern int __vdso_gettimeofday(struct timeval *tv, struct timezone *tz);
+extern time_t __vdso_time(time_t *t);
+
+#ifdef CONFIG_HPET_TIMER
+extern u8 hpet_page
+	__attribute__((visibility("hidden")));
+
+static notrace cycle_t vread_hpet(void)
+{
+	return *(const volatile u32 *)(&hpet_page + HPET_COUNTER);
+}
+#endif
+
+#ifndef BUILD_VDSO32
 
-#define gtod vdso_vsyscall_gtod_data
+#include <linux/kernel.h>
+#include <asm/vsyscall.h>
+#include <asm/fixmap.h>
+#include <asm/pvclock.h>
 
 notrace static long vdso_fallback_gettime(long clock, struct timespec *ts)
 {
 	long ret;
 	asm("syscall" : "=a" (ret) :
-	    "0" (__NR_clock_gettime),"D" (clock), "S" (ts) : "memory");
+	    "0" (__NR_clock_gettime), "D" (clock), "S" (ts) : "memory");
 	return ret;
 }
 
-notrace static inline long vgetns(void)
+notrace static long vdso_fallback_gtod(struct timeval *tv, struct timezone *tz)
 {
-	long v;
-	cycles_t (*vread)(void);
-	vread = gtod->clock.vread;
-	v = (vread() - gtod->clock.cycle_last) & gtod->clock.mask;
-	return (v * gtod->clock.mult) >> gtod->clock.shift;
+	long ret;
+
+	asm("syscall" : "=a" (ret) :
+	    "0" (__NR_gettimeofday), "D" (tv), "S" (tz) : "memory");
+	return ret;
 }
 
-notrace static noinline int do_realtime(struct timespec *ts)
+#ifdef CONFIG_PARAVIRT_CLOCK
+
+static notrace const struct pvclock_vsyscall_time_info *get_pvti(int cpu)
 {
-	unsigned long seq, ns;
+	const struct pvclock_vsyscall_time_info *pvti_base;
+	int idx = cpu / (PAGE_SIZE/PVTI_SIZE);
+	int offset = cpu % (PAGE_SIZE/PVTI_SIZE);
+
+	BUG_ON(PVCLOCK_FIXMAP_BEGIN + idx > PVCLOCK_FIXMAP_END);
+
+	pvti_base = (struct pvclock_vsyscall_time_info *)
+		    __fix_to_virt(PVCLOCK_FIXMAP_BEGIN+idx);
+
+	return &pvti_base[offset];
+}
+
+static notrace cycle_t vread_pvclock(int *mode)
+{
+	const struct pvclock_vsyscall_time_info *pvti;
+	cycle_t ret;
+	u64 last;
+	u32 version;
+	u8 flags;
+	unsigned cpu, cpu1;
+
+
+	/*
+	 * Note: hypervisor must guarantee that:
+	 * 1. cpu ID number maps 1:1 to per-CPU pvclock time info.
+	 * 2. that per-CPU pvclock time info is updated if the
+	 *    underlying CPU changes.
+	 * 3. that version is increased whenever underlying CPU
+	 *    changes.
+	 *
+	 */
 	do {
-		seq = read_seqbegin(&gtod->lock);
-		ts->tv_sec = gtod->wall_time_sec;
-		ts->tv_nsec = gtod->wall_time_nsec;
-		ns = vgetns();
-	} while (unlikely(read_seqretry(&gtod->lock, seq)));
-	timespec_add_ns(ts, ns);
+		cpu = __getcpu() & VGETCPU_CPU_MASK;
+		/* TODO: We can put vcpu id into higher bits of pvti.version.
+		 * This will save a couple of cycles by getting rid of
+		 * __getcpu() calls (Gleb).
+		 */
+
+		pvti = get_pvti(cpu);
+
+		version = __pvclock_read_cycles(&pvti->pvti, &ret, &flags);
+
+		/*
+		 * Test we're still on the cpu as well as the version.
+		 * We could have been migrated just after the first
+		 * vgetcpu but before fetching the version, so we
+		 * wouldn't notice a version change.
+		 */
+		cpu1 = __getcpu() & VGETCPU_CPU_MASK;
+	} while (unlikely(cpu != cpu1 ||
+			  (pvti->pvti.version & 1) ||
+			  pvti->pvti.version != version));
+
+	if (unlikely(!(flags & PVCLOCK_TSC_STABLE_BIT)))
+		*mode = VCLOCK_NONE;
+
+	/* refer to tsc.c read_tsc() comment for rationale */
+	last = gtod->cycle_last;
+
+	if (likely(ret >= last))
+		return ret;
+
+	return last;
+}
+#endif
+
+#else
+
+notrace static long vdso_fallback_gettime(long clock, struct timespec *ts)
+{
+	long ret;
+
+	asm(
+		"mov %%ebx, %%edx \n"
+		"mov %2, %%ebx \n"
+		"call __kernel_vsyscall \n"
+		"mov %%edx, %%ebx \n"
+		: "=a" (ret)
+		: "0" (__NR_clock_gettime), "g" (clock), "c" (ts)
+		: "memory", "edx");
+	return ret;
+}
+
+notrace static long vdso_fallback_gtod(struct timeval *tv, struct timezone *tz)
+{
+	long ret;
+
+	asm(
+		"mov %%ebx, %%edx \n"
+		"mov %2, %%ebx \n"
+		"call __kernel_vsyscall \n"
+		"mov %%edx, %%ebx \n"
+		: "=a" (ret)
+		: "0" (__NR_gettimeofday), "g" (tv), "c" (tz)
+		: "memory", "edx");
+	return ret;
+}
+
+#ifdef CONFIG_PARAVIRT_CLOCK
+
+static notrace cycle_t vread_pvclock(int *mode)
+{
+	*mode = VCLOCK_NONE;
 	return 0;
 }
+#endif
 
-/* Copy of the version in kernel/time.c which we cannot directly access */
-notrace static void
-vset_normalized_timespec(struct timespec *ts, long sec, long nsec)
+#endif
+
+notrace static cycle_t vread_tsc(void)
 {
-	while (nsec >= NSEC_PER_SEC) {
-		nsec -= NSEC_PER_SEC;
-		++sec;
-	}
-	while (nsec < 0) {
-		nsec += NSEC_PER_SEC;
-		--sec;
-	}
-	ts->tv_sec = sec;
-	ts->tv_nsec = nsec;
+	cycle_t ret;
+	u64 last;
+
+	/*
+	 * Empirically, a fence (of type that depends on the CPU)
+	 * before rdtsc is enough to ensure that rdtsc is ordered
+	 * with respect to loads.  The various CPU manuals are unclear
+	 * as to whether rdtsc can be reordered with later loads,
+	 * but no one has ever seen it happen.
+	 */
+	rdtsc_barrier();
+	ret = (cycle_t)__native_read_tsc();
+
+	last = gtod->cycle_last;
+
+	if (likely(ret >= last))
+		return ret;
+
+	/*
+	 * GCC likes to generate cmov here, but this branch is extremely
+	 * predictable (it's just a funciton of time and the likely is
+	 * very likely) and there's a data dependence, so force GCC
+	 * to generate a branch instead.  I don't barrier() because
+	 * we don't actually need a barrier, and if this function
+	 * ever gets inlined it will generate worse code.
+	 */
+	asm volatile ("");
+	return last;
 }
 
-notrace static noinline int do_monotonic(struct timespec *ts)
+notrace static inline u64 vgetsns(int *mode)
 {
-	unsigned long seq, ns, secs;
+	u64 v;
+	cycles_t cycles;
+
+	if (gtod->vclock_mode == VCLOCK_TSC)
+		cycles = vread_tsc();
+#ifdef CONFIG_HPET_TIMER
+	else if (gtod->vclock_mode == VCLOCK_HPET)
+		cycles = vread_hpet();
+#endif
+#ifdef CONFIG_PARAVIRT_CLOCK
+	else if (gtod->vclock_mode == VCLOCK_PVCLOCK)
+		cycles = vread_pvclock(mode);
+#endif
+	else
+		return 0;
+	v = (cycles - gtod->cycle_last) & gtod->mask;
+	return v * gtod->mult;
+}
+
+/* Code size doesn't matter (vdso is 4k anyway) and this is faster. */
+notrace static int __always_inline do_realtime(struct timespec *ts)
+{
+	unsigned long seq;
+	u64 ns;
+	int mode;
+
 	do {
-		seq = read_seqbegin(&gtod->lock);
-		secs = gtod->wall_time_sec;
-		ns = gtod->wall_time_nsec + vgetns();
-		secs += gtod->wall_to_monotonic.tv_sec;
-		ns += gtod->wall_to_monotonic.tv_nsec;
-	} while (unlikely(read_seqretry(&gtod->lock, seq)));
-	vset_normalized_timespec(ts, secs, ns);
-	return 0;
+		seq = gtod_read_begin(gtod);
+		mode = gtod->vclock_mode;
+		ts->tv_sec = gtod->wall_time_sec;
+		ns = gtod->wall_time_snsec;
+		ns += vgetsns(&mode);
+		ns >>= gtod->shift;
+	} while (unlikely(gtod_read_retry(gtod, seq)));
+
+	ts->tv_sec += __iter_div_u64_rem(ns, NSEC_PER_SEC, &ns);
+	ts->tv_nsec = ns;
+
+	return mode;
 }
 
-notrace static noinline int do_realtime_coarse(struct timespec *ts)
+notrace static int __always_inline do_monotonic(struct timespec *ts)
 {
 	unsigned long seq;
+	u64 ns;
+	int mode;
+
 	do {
-		seq = read_seqbegin(&gtod->lock);
-		ts->tv_sec = gtod->wall_time_coarse.tv_sec;
-		ts->tv_nsec = gtod->wall_time_coarse.tv_nsec;
-	} while (unlikely(read_seqretry(&gtod->lock, seq)));
-	return 0;
+		seq = gtod_read_begin(gtod);
+		mode = gtod->vclock_mode;
+		ts->tv_sec = gtod->monotonic_time_sec;
+		ns = gtod->monotonic_time_snsec;
+		ns += vgetsns(&mode);
+		ns >>= gtod->shift;
+	} while (unlikely(gtod_read_retry(gtod, seq)));
+
+	ts->tv_sec += __iter_div_u64_rem(ns, NSEC_PER_SEC, &ns);
+	ts->tv_nsec = ns;
+
+	return mode;
 }
 
-notrace static noinline int do_monotonic_coarse(struct timespec *ts)
+notrace static void do_realtime_coarse(struct timespec *ts)
 {
-	unsigned long seq, ns, secs;
+	unsigned long seq;
 	do {
-		seq = read_seqbegin(&gtod->lock);
-		secs = gtod->wall_time_coarse.tv_sec;
-		ns = gtod->wall_time_coarse.tv_nsec;
-		secs += gtod->wall_to_monotonic.tv_sec;
-		ns += gtod->wall_to_monotonic.tv_nsec;
-	} while (unlikely(read_seqretry(&gtod->lock, seq)));
-	vset_normalized_timespec(ts, secs, ns);
-	return 0;
+		seq = gtod_read_begin(gtod);
+		ts->tv_sec = gtod->wall_time_coarse_sec;
+		ts->tv_nsec = gtod->wall_time_coarse_nsec;
+	} while (unlikely(gtod_read_retry(gtod, seq)));
+}
+
+notrace static void do_monotonic_coarse(struct timespec *ts)
+{
+	unsigned long seq;
+	do {
+		seq = gtod_read_begin(gtod);
+		ts->tv_sec = gtod->monotonic_time_coarse_sec;
+		ts->tv_nsec = gtod->monotonic_time_coarse_nsec;
+	} while (unlikely(gtod_read_retry(gtod, seq)));
 }
 
 notrace int __vdso_clock_gettime(clockid_t clock, struct timespec *ts)
 {
-	if (likely(gtod->sysctl_enabled))
-		switch (clock) {
-		case CLOCK_REALTIME:
-			if (likely(gtod->clock.vread))
-				return do_realtime(ts);
-			break;
-		case CLOCK_MONOTONIC:
-			if (likely(gtod->clock.vread))
-				return do_monotonic(ts);
-			break;
-		case CLOCK_REALTIME_COARSE:
-			return do_realtime_coarse(ts);
-		case CLOCK_MONOTONIC_COARSE:
-			return do_monotonic_coarse(ts);
-		}
+	switch (clock) {
+	case CLOCK_REALTIME:
+		if (do_realtime(ts) == VCLOCK_NONE)
+			goto fallback;
+		break;
+	case CLOCK_MONOTONIC:
+		if (do_monotonic(ts) == VCLOCK_NONE)
+			goto fallback;
+		break;
+	case CLOCK_REALTIME_COARSE:
+		do_realtime_coarse(ts);
+		break;
+	case CLOCK_MONOTONIC_COARSE:
+		do_monotonic_coarse(ts);
+		break;
+	default:
+		goto fallback;
+	}
+
+	return 0;
+fallback:
 	return vdso_fallback_gettime(clock, ts);
 }
 int clock_gettime(clockid_t, struct timespec *)
@@ -135,25 +319,33 @@ int clock_gettime(clockid_t, struct timespec *)
 
 notrace int __vdso_gettimeofday(struct timeval *tv, struct timezone *tz)
 {
-	long ret;
-	if (likely(gtod->sysctl_enabled && gtod->clock.vread)) {
-		if (likely(tv != NULL)) {
-			BUILD_BUG_ON(offsetof(struct timeval, tv_usec) !=
-				     offsetof(struct timespec, tv_nsec) ||
-				     sizeof(*tv) != sizeof(struct timespec));
-			do_realtime((struct timespec *)tv);
-			tv->tv_usec /= 1000;
-		}
-		if (unlikely(tz != NULL)) {
-			/* Avoid memcpy. Some old compilers fail to inline it */
-			tz->tz_minuteswest = gtod->sys_tz.tz_minuteswest;
-			tz->tz_dsttime = gtod->sys_tz.tz_dsttime;
-		}
-		return 0;
+	if (likely(tv != NULL)) {
+		if (unlikely(do_realtime((struct timespec *)tv) == VCLOCK_NONE))
+			return vdso_fallback_gtod(tv, tz);
+		tv->tv_usec /= 1000;
 	}
-	asm("syscall" : "=a" (ret) :
-	    "0" (__NR_gettimeofday), "D" (tv), "S" (tz) : "memory");
-	return ret;
+	if (unlikely(tz != NULL)) {
+		tz->tz_minuteswest = gtod->tz_minuteswest;
+		tz->tz_dsttime = gtod->tz_dsttime;
+	}
+
+	return 0;
 }
 int gettimeofday(struct timeval *, struct timezone *)
 	__attribute__((weak, alias("__vdso_gettimeofday")));
+
+/*
+ * This will break when the xtime seconds get inaccurate, but that is
+ * unlikely
+ */
+notrace time_t __vdso_time(time_t *t)
+{
+	/* This is atomic on x86 so we don't need any locks. */
+	time_t result = ACCESS_ONCE(gtod->wall_time_sec);
+
+	if (t)
+		*t = result;
+	return result;
+}
+int time(time_t *t)
+	__attribute__((weak, alias("__vdso_time")));