From 24e4a8c3e8868874835b0f1ad6dd417341e99822 Mon Sep 17 00:00:00 2001 From: John Stultz Date: Wed, 16 Jul 2014 21:03:53 +0000 Subject: [PATCH] ktime: Kill non-scalar ktime_t implementation for 2038 The non-scalar ktime_t implementation is basically a timespec which has to be changed to support dates past 2038 on 32bit systems. This patch removes the non-scalar ktime_t implementation, forcing the scalar s64 nanosecond version on all architectures. This may have additional performance overhead on some 32bit systems when converting between ktime_t and timespec structures, however the majority of 32bit systems (arm and i386) were already using scalar ktime_t, so no performance regressions will be seen on those platforms. On affected platforms, I'm open to finding optimizations, including avoiding converting to timespecs where possible. [ tglx: We can now cleanup the ktime_t.tv64 mess, but thats a different issue and we can throw a coccinelle script at it ] Signed-off-by: John Stultz Signed-off-by: Thomas Gleixner Signed-off-by: John Stultz --- arch/arm/Kconfig | 1 - arch/hexagon/Kconfig | 1 - arch/s390/Kconfig | 1 - arch/x86/Kconfig | 1 - include/linux/ktime.h | 173 +------------------------------------- include/linux/time.h | 11 +-- kernel/time/Kconfig | 4 - kernel/time/hrtimer.c | 54 ------------ kernel/time/timekeeping.c | 7 +- 9 files changed, 7 insertions(+), 246 deletions(-) diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig index 05a71511ab3c..b9f6728331c8 100644 --- a/arch/arm/Kconfig +++ b/arch/arm/Kconfig @@ -64,7 +64,6 @@ config ARM select HAVE_UID16 select HAVE_VIRT_CPU_ACCOUNTING_GEN select IRQ_FORCED_THREADING - select KTIME_SCALAR select MODULES_USE_ELF_REL select NO_BOOTMEM select OLD_SIGACTION diff --git a/arch/hexagon/Kconfig b/arch/hexagon/Kconfig index 0fd6138f6203..4dc89d1f9c48 100644 --- a/arch/hexagon/Kconfig +++ b/arch/hexagon/Kconfig @@ -23,7 +23,6 @@ config HEXAGON select GENERIC_IOMAP select GENERIC_SMP_IDLE_THREAD select STACKTRACE_SUPPORT - select KTIME_SCALAR select GENERIC_CLOCKEVENTS select GENERIC_CLOCKEVENTS_BROADCAST select MODULES_USE_ELF_RELA diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig index bb63499fc5d3..1afc7a686702 100644 --- a/arch/s390/Kconfig +++ b/arch/s390/Kconfig @@ -137,7 +137,6 @@ config S390 select HAVE_SYSCALL_TRACEPOINTS select HAVE_UID16 if 32BIT select HAVE_VIRT_CPU_ACCOUNTING - select KTIME_SCALAR if 32BIT select MODULES_USE_ELF_RELA select NO_BOOTMEM select OLD_SIGACTION diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index a8f749ef0fdc..7fa17b5ce668 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -111,7 +111,6 @@ config X86 select ARCH_CLOCKSOURCE_DATA select GENERIC_CLOCKEVENTS_BROADCAST if X86_64 || (X86_32 && X86_LOCAL_APIC) select GENERIC_TIME_VSYSCALL - select KTIME_SCALAR if X86_32 select GENERIC_STRNCPY_FROM_USER select GENERIC_STRNLEN_USER select HAVE_CONTEXT_TRACKING if X86_64 diff --git a/include/linux/ktime.h b/include/linux/ktime.h index de9e46e6bcc9..fbc64f8481b7 100644 --- a/include/linux/ktime.h +++ b/include/linux/ktime.h @@ -27,43 +27,19 @@ /* * ktime_t: * - * On 64-bit CPUs a single 64-bit variable is used to store the hrtimers + * A single 64-bit variable is used to store the hrtimers * internal representation of time values in scalar nanoseconds. The * design plays out best on 64-bit CPUs, where most conversions are * NOPs and most arithmetic ktime_t operations are plain arithmetic * operations. * - * On 32-bit CPUs an optimized representation of the timespec structure - * is used to avoid expensive conversions from and to timespecs. The - * endian-aware order of the tv struct members is chosen to allow - * mathematical operations on the tv64 member of the union too, which - * for certain operations produces better code. - * - * For architectures with efficient support for 64/32-bit conversions the - * plain scalar nanosecond based representation can be selected by the - * config switch CONFIG_KTIME_SCALAR. */ union ktime { s64 tv64; -#if BITS_PER_LONG != 64 && !defined(CONFIG_KTIME_SCALAR) - struct { -# ifdef __BIG_ENDIAN - s32 sec, nsec; -# else - s32 nsec, sec; -# endif - } tv; -#endif }; typedef union ktime ktime_t; /* Kill this */ -/* - * ktime_t definitions when using the 64-bit scalar representation: - */ - -#if (BITS_PER_LONG == 64) || defined(CONFIG_KTIME_SCALAR) - /** * ktime_set - Set a ktime_t variable from a seconds/nanoseconds value * @secs: seconds to set @@ -123,153 +99,6 @@ static inline ktime_t timeval_to_ktime(struct timeval tv) /* Convert ktime_t to nanoseconds - NOP in the scalar storage format: */ #define ktime_to_ns(kt) ((kt).tv64) -#else /* !((BITS_PER_LONG == 64) || defined(CONFIG_KTIME_SCALAR)) */ - -/* - * Helper macros/inlines to get the ktime_t math right in the timespec - * representation. The macros are sometimes ugly - their actual use is - * pretty okay-ish, given the circumstances. We do all this for - * performance reasons. The pure scalar nsec_t based code was nice and - * simple, but created too many 64-bit / 32-bit conversions and divisions. - * - * Be especially aware that negative values are represented in a way - * that the tv.sec field is negative and the tv.nsec field is greater - * or equal to zero but less than nanoseconds per second. This is the - * same representation which is used by timespecs. - * - * tv.sec < 0 and 0 >= tv.nsec < NSEC_PER_SEC - */ - -/* Set a ktime_t variable to a value in sec/nsec representation: */ -static inline ktime_t ktime_set(const long secs, const unsigned long nsecs) -{ - return (ktime_t) { .tv = { .sec = secs, .nsec = nsecs } }; -} - -/** - * ktime_sub - subtract two ktime_t variables - * @lhs: minuend - * @rhs: subtrahend - * - * Return: The remainder of the subtraction. - */ -static inline ktime_t ktime_sub(const ktime_t lhs, const ktime_t rhs) -{ - ktime_t res; - - res.tv64 = lhs.tv64 - rhs.tv64; - if (res.tv.nsec < 0) - res.tv.nsec += NSEC_PER_SEC; - - return res; -} - -/** - * ktime_add - add two ktime_t variables - * @add1: addend1 - * @add2: addend2 - * - * Return: The sum of @add1 and @add2. - */ -static inline ktime_t ktime_add(const ktime_t add1, const ktime_t add2) -{ - ktime_t res; - - res.tv64 = add1.tv64 + add2.tv64; - /* - * performance trick: the (u32) -NSEC gives 0x00000000Fxxxxxxx - * so we subtract NSEC_PER_SEC and add 1 to the upper 32 bit. - * - * it's equivalent to: - * tv.nsec -= NSEC_PER_SEC - * tv.sec ++; - */ - if (res.tv.nsec >= NSEC_PER_SEC) - res.tv64 += (u32)-NSEC_PER_SEC; - - return res; -} - -/** - * ktime_add_ns - Add a scalar nanoseconds value to a ktime_t variable - * @kt: addend - * @nsec: the scalar nsec value to add - * - * Return: The sum of @kt and @nsec in ktime_t format. - */ -extern ktime_t ktime_add_ns(const ktime_t kt, u64 nsec); - -/** - * ktime_sub_ns - Subtract a scalar nanoseconds value from a ktime_t variable - * @kt: minuend - * @nsec: the scalar nsec value to subtract - * - * Return: The subtraction of @nsec from @kt in ktime_t format. - */ -extern ktime_t ktime_sub_ns(const ktime_t kt, u64 nsec); - -/** - * timespec_to_ktime - convert a timespec to ktime_t format - * @ts: the timespec variable to convert - * - * Return: A ktime_t variable with the converted timespec value. - */ -static inline ktime_t timespec_to_ktime(const struct timespec ts) -{ - return (ktime_t) { .tv = { .sec = (s32)ts.tv_sec, - .nsec = (s32)ts.tv_nsec } }; -} - -/** - * timeval_to_ktime - convert a timeval to ktime_t format - * @tv: the timeval variable to convert - * - * Return: A ktime_t variable with the converted timeval value. - */ -static inline ktime_t timeval_to_ktime(const struct timeval tv) -{ - return (ktime_t) { .tv = { .sec = (s32)tv.tv_sec, - .nsec = (s32)(tv.tv_usec * - NSEC_PER_USEC) } }; -} - -/** - * ktime_to_timespec - convert a ktime_t variable to timespec format - * @kt: the ktime_t variable to convert - * - * Return: The timespec representation of the ktime value. - */ -static inline struct timespec ktime_to_timespec(const ktime_t kt) -{ - return (struct timespec) { .tv_sec = (time_t) kt.tv.sec, - .tv_nsec = (long) kt.tv.nsec }; -} - -/** - * ktime_to_timeval - convert a ktime_t variable to timeval format - * @kt: the ktime_t variable to convert - * - * Return: The timeval representation of the ktime value. - */ -static inline struct timeval ktime_to_timeval(const ktime_t kt) -{ - return (struct timeval) { - .tv_sec = (time_t) kt.tv.sec, - .tv_usec = (suseconds_t) (kt.tv.nsec / NSEC_PER_USEC) }; -} - -/** - * ktime_to_ns - convert a ktime_t variable to scalar nanoseconds - * @kt: the ktime_t variable to convert - * - * Return: The scalar nanoseconds representation of @kt. - */ -static inline s64 ktime_to_ns(const ktime_t kt) -{ - return (s64) kt.tv.sec * NSEC_PER_SEC + kt.tv.nsec; -} - -#endif /* !((BITS_PER_LONG == 64) || defined(CONFIG_KTIME_SCALAR)) */ /** * ktime_equal - Compares two ktime_t variables to see if they are equal diff --git a/include/linux/time.h b/include/linux/time.h index f6d990d1c79a..129f0bd36a8d 100644 --- a/include/linux/time.h +++ b/include/linux/time.h @@ -19,6 +19,10 @@ extern struct timezone sys_tz; #define TIME_T_MAX (time_t)((1UL << ((sizeof(time_t) << 3) - 1)) - 1) +/* Located here for timespec_valid_strict */ +#define KTIME_MAX ((s64)~((u64)1 << 63)) +#define KTIME_SEC_MAX (KTIME_MAX / NSEC_PER_SEC) + static inline int timespec_equal(const struct timespec *a, const struct timespec *b) { @@ -84,13 +88,6 @@ static inline struct timespec timespec_sub(struct timespec lhs, return ts_delta; } -#define KTIME_MAX ((s64)~((u64)1 << 63)) -#if (BITS_PER_LONG == 64) -# define KTIME_SEC_MAX (KTIME_MAX / NSEC_PER_SEC) -#else -# define KTIME_SEC_MAX LONG_MAX -#endif - /* * Returns true if the timespec is norm, false if denorm: */ diff --git a/kernel/time/Kconfig b/kernel/time/Kconfig index f448513a45ed..feccfd888732 100644 --- a/kernel/time/Kconfig +++ b/kernel/time/Kconfig @@ -20,10 +20,6 @@ config GENERIC_TIME_VSYSCALL config GENERIC_TIME_VSYSCALL_OLD bool -# ktime_t scalar 64bit nsec representation -config KTIME_SCALAR - bool - # Old style timekeeping config ARCH_USES_GETTIMEOFFSET bool diff --git a/kernel/time/hrtimer.c b/kernel/time/hrtimer.c index 2f4ef8a1e5ff..19f211051c35 100644 --- a/kernel/time/hrtimer.c +++ b/kernel/time/hrtimer.c @@ -261,60 +261,6 @@ lock_hrtimer_base(const struct hrtimer *timer, unsigned long *flags) * too large for inlining: */ #if BITS_PER_LONG < 64 -# ifndef CONFIG_KTIME_SCALAR -/** - * ktime_add_ns - Add a scalar nanoseconds value to a ktime_t variable - * @kt: addend - * @nsec: the scalar nsec value to add - * - * Returns the sum of kt and nsec in ktime_t format - */ -ktime_t ktime_add_ns(const ktime_t kt, u64 nsec) -{ - ktime_t tmp; - - if (likely(nsec < NSEC_PER_SEC)) { - tmp.tv64 = nsec; - } else { - unsigned long rem = do_div(nsec, NSEC_PER_SEC); - - /* Make sure nsec fits into long */ - if (unlikely(nsec > KTIME_SEC_MAX)) - return (ktime_t){ .tv64 = KTIME_MAX }; - - tmp = ktime_set((long)nsec, rem); - } - - return ktime_add(kt, tmp); -} - -EXPORT_SYMBOL_GPL(ktime_add_ns); - -/** - * ktime_sub_ns - Subtract a scalar nanoseconds value from a ktime_t variable - * @kt: minuend - * @nsec: the scalar nsec value to subtract - * - * Returns the subtraction of @nsec from @kt in ktime_t format - */ -ktime_t ktime_sub_ns(const ktime_t kt, u64 nsec) -{ - ktime_t tmp; - - if (likely(nsec < NSEC_PER_SEC)) { - tmp.tv64 = nsec; - } else { - unsigned long rem = do_div(nsec, NSEC_PER_SEC); - - tmp = ktime_set((long)nsec, rem); - } - - return ktime_sub(kt, tmp); -} - -EXPORT_SYMBOL_GPL(ktime_sub_ns); -# endif /* !CONFIG_KTIME_SCALAR */ - /* * Divide a ktime value by a nanosecond value */ diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c index b94fa3652aaa..cafef242d8f9 100644 --- a/kernel/time/timekeeping.c +++ b/kernel/time/timekeeping.c @@ -344,11 +344,8 @@ ktime_t ktime_get(void) nsecs = timekeeping_get_ns(tk) + tk->wall_to_monotonic.tv_nsec; } while (read_seqcount_retry(&timekeeper_seq, seq)); - /* - * Use ktime_set/ktime_add_ns to create a proper ktime on - * 32-bit architectures without CONFIG_KTIME_SCALAR. - */ - return ktime_add_ns(ktime_set(secs, 0), nsecs); + + return ktime_set(secs, nsecs); } EXPORT_SYMBOL_GPL(ktime_get); -- 2.20.1