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linux-next/include/linux/ktime.h
John Stultz f7bcb70eba ktime: Fix ktime_divns to do signed division
It was noted that the 32bit implementation of ktime_divns()
was doing unsigned division and didn't properly handle
negative values.

And when a ktime helper was changed to utilize
ktime_divns, it caused a regression on some IR blasters.
See the following bugzilla for details:
  https://bugzilla.redhat.com/show_bug.cgi?id=1200353

This patch fixes the problem in ktime_divns by checking
and preserving the sign bit, and then reapplying it if
appropriate after the division, it also changes the return
type to a s64 to make it more obvious this is expected.

Nicolas also pointed out that negative dividers would
cause infinite loops on 32bit systems, negative dividers
is unlikely for users of this function, but out of caution
this patch adds checks for negative dividers for both
32-bit (BUG_ON) and 64-bit(WARN_ON) versions to make sure
no such use cases creep in.

[ tglx: Hand an u64 to do_div() to avoid the compiler warning ]

Fixes: 166afb6451 'ktime: Sanitize ktime_to_us/ms conversion'
Reported-and-tested-by: Trevor Cordes <trevor@tecnopolis.ca>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Josh Boyer <jwboyer@redhat.com>
Cc: One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk>
Cc: <stable@vger.kernel.org>
Link: http://lkml.kernel.org/r/1431118043-23452-1-git-send-email-john.stultz@linaro.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2015-05-13 10:19:35 +02:00

300 lines
7.3 KiB
C

/*
* include/linux/ktime.h
*
* ktime_t - nanosecond-resolution time format.
*
* Copyright(C) 2005, Thomas Gleixner <tglx@linutronix.de>
* Copyright(C) 2005, Red Hat, Inc., Ingo Molnar
*
* data type definitions, declarations, prototypes and macros.
*
* Started by: Thomas Gleixner and Ingo Molnar
*
* Credits:
*
* Roman Zippel provided the ideas and primary code snippets of
* the ktime_t union and further simplifications of the original
* code.
*
* For licencing details see kernel-base/COPYING
*/
#ifndef _LINUX_KTIME_H
#define _LINUX_KTIME_H
#include <linux/time.h>
#include <linux/jiffies.h>
/*
* ktime_t:
*
* 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.
*
*/
union ktime {
s64 tv64;
};
typedef union ktime ktime_t; /* Kill this */
/**
* ktime_set - Set a ktime_t variable from a seconds/nanoseconds value
* @secs: seconds to set
* @nsecs: nanoseconds to set
*
* Return: The ktime_t representation of the value.
*/
static inline ktime_t ktime_set(const s64 secs, const unsigned long nsecs)
{
if (unlikely(secs >= KTIME_SEC_MAX))
return (ktime_t){ .tv64 = KTIME_MAX };
return (ktime_t) { .tv64 = secs * NSEC_PER_SEC + (s64)nsecs };
}
/* Subtract two ktime_t variables. rem = lhs -rhs: */
#define ktime_sub(lhs, rhs) \
({ (ktime_t){ .tv64 = (lhs).tv64 - (rhs).tv64 }; })
/* Add two ktime_t variables. res = lhs + rhs: */
#define ktime_add(lhs, rhs) \
({ (ktime_t){ .tv64 = (lhs).tv64 + (rhs).tv64 }; })
/*
* Add a ktime_t variable and a scalar nanosecond value.
* res = kt + nsval:
*/
#define ktime_add_ns(kt, nsval) \
({ (ktime_t){ .tv64 = (kt).tv64 + (nsval) }; })
/*
* Subtract a scalar nanosecod from a ktime_t variable
* res = kt - nsval:
*/
#define ktime_sub_ns(kt, nsval) \
({ (ktime_t){ .tv64 = (kt).tv64 - (nsval) }; })
/* convert a timespec to ktime_t format: */
static inline ktime_t timespec_to_ktime(struct timespec ts)
{
return ktime_set(ts.tv_sec, ts.tv_nsec);
}
/* convert a timespec64 to ktime_t format: */
static inline ktime_t timespec64_to_ktime(struct timespec64 ts)
{
return ktime_set(ts.tv_sec, ts.tv_nsec);
}
/* convert a timeval to ktime_t format: */
static inline ktime_t timeval_to_ktime(struct timeval tv)
{
return ktime_set(tv.tv_sec, tv.tv_usec * NSEC_PER_USEC);
}
/* Map the ktime_t to timespec conversion to ns_to_timespec function */
#define ktime_to_timespec(kt) ns_to_timespec((kt).tv64)
/* Map the ktime_t to timespec conversion to ns_to_timespec function */
#define ktime_to_timespec64(kt) ns_to_timespec64((kt).tv64)
/* Map the ktime_t to timeval conversion to ns_to_timeval function */
#define ktime_to_timeval(kt) ns_to_timeval((kt).tv64)
/* Convert ktime_t to nanoseconds - NOP in the scalar storage format: */
#define ktime_to_ns(kt) ((kt).tv64)
/**
* ktime_equal - Compares two ktime_t variables to see if they are equal
* @cmp1: comparable1
* @cmp2: comparable2
*
* Compare two ktime_t variables.
*
* Return: 1 if equal.
*/
static inline int ktime_equal(const ktime_t cmp1, const ktime_t cmp2)
{
return cmp1.tv64 == cmp2.tv64;
}
/**
* ktime_compare - Compares two ktime_t variables for less, greater or equal
* @cmp1: comparable1
* @cmp2: comparable2
*
* Return: ...
* cmp1 < cmp2: return <0
* cmp1 == cmp2: return 0
* cmp1 > cmp2: return >0
*/
static inline int ktime_compare(const ktime_t cmp1, const ktime_t cmp2)
{
if (cmp1.tv64 < cmp2.tv64)
return -1;
if (cmp1.tv64 > cmp2.tv64)
return 1;
return 0;
}
/**
* ktime_after - Compare if a ktime_t value is bigger than another one.
* @cmp1: comparable1
* @cmp2: comparable2
*
* Return: true if cmp1 happened after cmp2.
*/
static inline bool ktime_after(const ktime_t cmp1, const ktime_t cmp2)
{
return ktime_compare(cmp1, cmp2) > 0;
}
/**
* ktime_before - Compare if a ktime_t value is smaller than another one.
* @cmp1: comparable1
* @cmp2: comparable2
*
* Return: true if cmp1 happened before cmp2.
*/
static inline bool ktime_before(const ktime_t cmp1, const ktime_t cmp2)
{
return ktime_compare(cmp1, cmp2) < 0;
}
#if BITS_PER_LONG < 64
extern s64 __ktime_divns(const ktime_t kt, s64 div);
static inline s64 ktime_divns(const ktime_t kt, s64 div)
{
/*
* Negative divisors could cause an inf loop,
* so bug out here.
*/
BUG_ON(div < 0);
if (__builtin_constant_p(div) && !(div >> 32)) {
s64 ns = kt.tv64;
u64 tmp = ns < 0 ? -ns : ns;
do_div(tmp, div);
return ns < 0 ? -tmp : tmp;
} else {
return __ktime_divns(kt, div);
}
}
#else /* BITS_PER_LONG < 64 */
static inline s64 ktime_divns(const ktime_t kt, s64 div)
{
/*
* 32-bit implementation cannot handle negative divisors,
* so catch them on 64bit as well.
*/
WARN_ON(div < 0);
return kt.tv64 / div;
}
#endif
static inline s64 ktime_to_us(const ktime_t kt)
{
return ktime_divns(kt, NSEC_PER_USEC);
}
static inline s64 ktime_to_ms(const ktime_t kt)
{
return ktime_divns(kt, NSEC_PER_MSEC);
}
static inline s64 ktime_us_delta(const ktime_t later, const ktime_t earlier)
{
return ktime_to_us(ktime_sub(later, earlier));
}
static inline s64 ktime_ms_delta(const ktime_t later, const ktime_t earlier)
{
return ktime_to_ms(ktime_sub(later, earlier));
}
static inline ktime_t ktime_add_us(const ktime_t kt, const u64 usec)
{
return ktime_add_ns(kt, usec * NSEC_PER_USEC);
}
static inline ktime_t ktime_add_ms(const ktime_t kt, const u64 msec)
{
return ktime_add_ns(kt, msec * NSEC_PER_MSEC);
}
static inline ktime_t ktime_sub_us(const ktime_t kt, const u64 usec)
{
return ktime_sub_ns(kt, usec * NSEC_PER_USEC);
}
extern ktime_t ktime_add_safe(const ktime_t lhs, const ktime_t rhs);
/**
* ktime_to_timespec_cond - convert a ktime_t variable to timespec
* format only if the variable contains data
* @kt: the ktime_t variable to convert
* @ts: the timespec variable to store the result in
*
* Return: %true if there was a successful conversion, %false if kt was 0.
*/
static inline __must_check bool ktime_to_timespec_cond(const ktime_t kt,
struct timespec *ts)
{
if (kt.tv64) {
*ts = ktime_to_timespec(kt);
return true;
} else {
return false;
}
}
/**
* ktime_to_timespec64_cond - convert a ktime_t variable to timespec64
* format only if the variable contains data
* @kt: the ktime_t variable to convert
* @ts: the timespec variable to store the result in
*
* Return: %true if there was a successful conversion, %false if kt was 0.
*/
static inline __must_check bool ktime_to_timespec64_cond(const ktime_t kt,
struct timespec64 *ts)
{
if (kt.tv64) {
*ts = ktime_to_timespec64(kt);
return true;
} else {
return false;
}
}
/*
* The resolution of the clocks. The resolution value is returned in
* the clock_getres() system call to give application programmers an
* idea of the (in)accuracy of timers. Timer values are rounded up to
* this resolution values.
*/
#define LOW_RES_NSEC TICK_NSEC
#define KTIME_LOW_RES (ktime_t){ .tv64 = LOW_RES_NSEC }
static inline ktime_t ns_to_ktime(u64 ns)
{
static const ktime_t ktime_zero = { .tv64 = 0 };
return ktime_add_ns(ktime_zero, ns);
}
static inline ktime_t ms_to_ktime(u64 ms)
{
static const ktime_t ktime_zero = { .tv64 = 0 };
return ktime_add_ms(ktime_zero, ms);
}
# include <linux/timekeeping.h>
#endif