Author: kib
Date: Fri Mar 6 14:43:13 2020
New Revision: 358702
URL: https://svnweb.freebsd.org/changeset/base/358702
Log:
MFC r357948:
Consolidate read code for timecounters and fix possible overflow in
bintime()/binuptime().
Modified:
stable/12/sys/kern/kern_tc.c
Directory Properties:
stable/12/ (props changed)
Modified: stable/12/sys/kern/kern_tc.c
==============================================================================
--- stable/12/sys/kern/kern_tc.c Fri Mar 6 14:24:10 2020
(r358701)
+++ stable/12/sys/kern/kern_tc.c Fri Mar 6 14:43:13 2020
(r358702)
@@ -72,6 +72,7 @@ struct timehands {
struct timecounter *th_counter;
int64_t th_adjustment;
uint64_t th_scale;
+ u_int th_large_delta;
u_int th_offset_count;
struct bintime th_offset;
struct bintime th_bintime;
@@ -87,6 +88,7 @@ static struct timehands ths[16] = {
[0] = {
.th_counter = &dummy_timecounter,
.th_scale = (uint64_t)-1 / 1000000,
+ .th_large_delta = 1000000,
.th_offset = { .sec = 1 },
.th_generation = 1,
},
@@ -201,23 +203,75 @@ tc_delta(struct timehands *th)
* the comment in <sys/time.h> for a description of these 12 functions.
*/
-#ifdef FFCLOCK
-void
-fbclock_binuptime(struct bintime *bt)
+static __inline void
+bintime_off(struct bintime *bt, u_int off)
{
struct timehands *th;
- unsigned int gen;
+ struct bintime *btp;
+ uint64_t scale, x;
+ u_int delta, gen, large_delta;
do {
th = timehands;
gen = atomic_load_acq_int(&th->th_generation);
- *bt = th->th_offset;
- bintime_addx(bt, th->th_scale * tc_delta(th));
+ btp = (struct bintime *)((vm_offset_t)th + off);
+ *bt = *btp;
+ scale = th->th_scale;
+ delta = tc_delta(th);
+ large_delta = th->th_large_delta;
atomic_thread_fence_acq();
} while (gen == 0 || gen != th->th_generation);
+
+ if (__predict_false(delta >= large_delta)) {
+ /* Avoid overflow for scale * delta. */
+ x = (scale >> 32) * delta;
+ bt->sec += x >> 32;
+ bintime_addx(bt, x << 32);
+ bintime_addx(bt, (scale & 0xffffffff) * delta);
+ } else {
+ bintime_addx(bt, scale * delta);
+ }
}
+#define GETTHBINTIME(dst, member)
\
+do { \
+ _Static_assert(_Generic(((struct timehands *)NULL)->member, \
+ struct bintime: 1, default: 0) == 1, \
+ "struct timehands member is not of struct bintime type"); \
+ bintime_off(dst, __offsetof(struct timehands, member)); \
+} while (0)
+static __inline void
+getthmember(void *out, size_t out_size, u_int off)
+{
+ struct timehands *th;
+ u_int gen;
+
+ do {
+ th = timehands;
+ gen = atomic_load_acq_int(&th->th_generation);
+ memcpy(out, (char *)th + off, out_size);
+ atomic_thread_fence_acq();
+ } while (gen == 0 || gen != th->th_generation);
+}
+#define GETTHMEMBER(dst, member)
\
+do { \
+ _Static_assert(_Generic(*dst, \
+ __typeof(((struct timehands *)NULL)->member): 1, \
+ default: 0) == 1, \
+ "*dst and struct timehands member have different types"); \
+ getthmember(dst, sizeof(*dst), __offsetof(struct timehands, \
+ member)); \
+} while (0)
+
+#ifdef FFCLOCK
void
+fbclock_binuptime(struct bintime *bt)
+{
+
+ GETTHBINTIME(bt, th_offset);
+}
+
+void
fbclock_nanouptime(struct timespec *tsp)
{
struct bintime bt;
@@ -238,16 +292,8 @@ fbclock_microuptime(struct timeval *tvp)
void
fbclock_bintime(struct bintime *bt)
{
- struct timehands *th;
- unsigned int gen;
- do {
- th = timehands;
- gen = atomic_load_acq_int(&th->th_generation);
- *bt = th->th_bintime;
- bintime_addx(bt, th->th_scale * tc_delta(th));
- atomic_thread_fence_acq();
- } while (gen == 0 || gen != th->th_generation);
+ GETTHBINTIME(bt, th_bintime);
}
void
@@ -271,100 +317,55 @@ fbclock_microtime(struct timeval *tvp)
void
fbclock_getbinuptime(struct bintime *bt)
{
- struct timehands *th;
- unsigned int gen;
- do {
- th = timehands;
- gen = atomic_load_acq_int(&th->th_generation);
- *bt = th->th_offset;
- atomic_thread_fence_acq();
- } while (gen == 0 || gen != th->th_generation);
+ GETTHMEMBER(bt, th_offset);
}
void
fbclock_getnanouptime(struct timespec *tsp)
{
- struct timehands *th;
- unsigned int gen;
+ struct bintime bt;
- do {
- th = timehands;
- gen = atomic_load_acq_int(&th->th_generation);
- bintime2timespec(&th->th_offset, tsp);
- atomic_thread_fence_acq();
- } while (gen == 0 || gen != th->th_generation);
+ GETTHMEMBER(&bt, th_offset);
+ bintime2timespec(&bt, tsp);
}
void
fbclock_getmicrouptime(struct timeval *tvp)
{
- struct timehands *th;
- unsigned int gen;
+ struct bintime bt;
- do {
- th = timehands;
- gen = atomic_load_acq_int(&th->th_generation);
- bintime2timeval(&th->th_offset, tvp);
- atomic_thread_fence_acq();
- } while (gen == 0 || gen != th->th_generation);
+ GETTHMEMBER(&bt, th_offset);
+ bintime2timeval(&bt, tvp);
}
void
fbclock_getbintime(struct bintime *bt)
{
- struct timehands *th;
- unsigned int gen;
- do {
- th = timehands;
- gen = atomic_load_acq_int(&th->th_generation);
- *bt = th->th_bintime;
- atomic_thread_fence_acq();
- } while (gen == 0 || gen != th->th_generation);
+ GETTHMEMBER(bt, th_bintime);
}
void
fbclock_getnanotime(struct timespec *tsp)
{
- struct timehands *th;
- unsigned int gen;
- do {
- th = timehands;
- gen = atomic_load_acq_int(&th->th_generation);
- *tsp = th->th_nanotime;
- atomic_thread_fence_acq();
- } while (gen == 0 || gen != th->th_generation);
+ GETTHMEMBER(tsp, th_nanotime);
}
void
fbclock_getmicrotime(struct timeval *tvp)
{
- struct timehands *th;
- unsigned int gen;
- do {
- th = timehands;
- gen = atomic_load_acq_int(&th->th_generation);
- *tvp = th->th_microtime;
- atomic_thread_fence_acq();
- } while (gen == 0 || gen != th->th_generation);
+ GETTHMEMBER(tvp, th_microtime);
}
#else /* !FFCLOCK */
+
void
binuptime(struct bintime *bt)
{
- struct timehands *th;
- u_int gen;
- do {
- th = timehands;
- gen = atomic_load_acq_int(&th->th_generation);
- *bt = th->th_offset;
- bintime_addx(bt, th->th_scale * tc_delta(th));
- atomic_thread_fence_acq();
- } while (gen == 0 || gen != th->th_generation);
+ GETTHBINTIME(bt, th_offset);
}
void
@@ -388,16 +389,8 @@ microuptime(struct timeval *tvp)
void
bintime(struct bintime *bt)
{
- struct timehands *th;
- u_int gen;
- do {
- th = timehands;
- gen = atomic_load_acq_int(&th->th_generation);
- *bt = th->th_bintime;
- bintime_addx(bt, th->th_scale * tc_delta(th));
- atomic_thread_fence_acq();
- } while (gen == 0 || gen != th->th_generation);
+ GETTHBINTIME(bt, th_bintime);
}
void
@@ -421,85 +414,47 @@ microtime(struct timeval *tvp)
void
getbinuptime(struct bintime *bt)
{
- struct timehands *th;
- u_int gen;
- do {
- th = timehands;
- gen = atomic_load_acq_int(&th->th_generation);
- *bt = th->th_offset;
- atomic_thread_fence_acq();
- } while (gen == 0 || gen != th->th_generation);
+ GETTHMEMBER(bt, th_offset);
}
void
getnanouptime(struct timespec *tsp)
{
- struct timehands *th;
- u_int gen;
+ struct bintime bt;
- do {
- th = timehands;
- gen = atomic_load_acq_int(&th->th_generation);
- bintime2timespec(&th->th_offset, tsp);
- atomic_thread_fence_acq();
- } while (gen == 0 || gen != th->th_generation);
+ GETTHMEMBER(&bt, th_offset);
+ bintime2timespec(&bt, tsp);
}
void
getmicrouptime(struct timeval *tvp)
{
- struct timehands *th;
- u_int gen;
+ struct bintime bt;
- do {
- th = timehands;
- gen = atomic_load_acq_int(&th->th_generation);
- bintime2timeval(&th->th_offset, tvp);
- atomic_thread_fence_acq();
- } while (gen == 0 || gen != th->th_generation);
+ GETTHMEMBER(&bt, th_offset);
+ bintime2timeval(&bt, tvp);
}
void
getbintime(struct bintime *bt)
{
- struct timehands *th;
- u_int gen;
- do {
- th = timehands;
- gen = atomic_load_acq_int(&th->th_generation);
- *bt = th->th_bintime;
- atomic_thread_fence_acq();
- } while (gen == 0 || gen != th->th_generation);
+ GETTHMEMBER(bt, th_bintime);
}
void
getnanotime(struct timespec *tsp)
{
- struct timehands *th;
- u_int gen;
- do {
- th = timehands;
- gen = atomic_load_acq_int(&th->th_generation);
- *tsp = th->th_nanotime;
- atomic_thread_fence_acq();
- } while (gen == 0 || gen != th->th_generation);
+ GETTHMEMBER(tsp, th_nanotime);
}
void
getmicrotime(struct timeval *tvp)
{
- struct timehands *th;
- u_int gen;
- do {
- th = timehands;
- gen = atomic_load_acq_int(&th->th_generation);
- *tvp = th->th_microtime;
- atomic_thread_fence_acq();
- } while (gen == 0 || gen != th->th_generation);
+ GETTHMEMBER(tvp, th_microtime);
}
#endif /* FFCLOCK */
@@ -515,15 +470,8 @@ getboottime(struct timeval *boottime)
void
getboottimebin(struct bintime *boottimebin)
{
- struct timehands *th;
- u_int gen;
- do {
- th = timehands;
- gen = atomic_load_acq_int(&th->th_generation);
- *boottimebin = th->th_boottime;
- atomic_thread_fence_acq();
- } while (gen == 0 || gen != th->th_generation);
+ GETTHMEMBER(boottimebin, th_boottime);
}
#ifdef FFCLOCK
@@ -1039,15 +987,8 @@ getmicrotime(struct timeval *tvp)
void
dtrace_getnanotime(struct timespec *tsp)
{
- struct timehands *th;
- u_int gen;
- do {
- th = timehands;
- gen = atomic_load_acq_int(&th->th_generation);
- *tsp = th->th_nanotime;
- atomic_thread_fence_acq();
- } while (gen == 0 || gen != th->th_generation);
+ GETTHMEMBER(tsp, th_nanotime);
}
/*
@@ -1465,6 +1406,7 @@ tc_windup(struct bintime *new_boottimebin)
scale += (th->th_adjustment / 1024) * 2199;
scale /= th->th_counter->tc_frequency;
th->th_scale = scale * 2;
+ th->th_large_delta = MIN(((uint64_t)1 << 63) / scale, UINT_MAX);
/*
* Now that the struct timehands is again consistent, set the new
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