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Subject[PATCH v6 04/10] lib: time handling (kernel glue code)
Date
timer related (internal) functions such as add_timer(),
do_gettimeofday() of kernel are trivially reimplemented
for libos. these eventually call the functions registered by lib_init()
API.

Signed-off-by: Hajime Tazaki <thehajime@gmail.com>
---
arch/lib/hrtimer.c | 117 ++++++++++++++++++
arch/lib/tasklet-hrtimer.c | 57 +++++++++
arch/lib/time.c | 116 ++++++++++++++++++
arch/lib/timer.c | 299 +++++++++++++++++++++++++++++++++++++++++++++
4 files changed, 589 insertions(+)
create mode 100644 arch/lib/hrtimer.c
create mode 100644 arch/lib/tasklet-hrtimer.c
create mode 100644 arch/lib/time.c
create mode 100644 arch/lib/timer.c

diff --git a/arch/lib/hrtimer.c b/arch/lib/hrtimer.c
new file mode 100644
index 000000000000..6a99bad6c5b7
--- /dev/null
+++ b/arch/lib/hrtimer.c
@@ -0,0 +1,117 @@
+/*
+ * glue code for library version of Linux kernel
+ * Copyright (c) 2015 INRIA, Hajime Tazaki
+ *
+ * Author: Mathieu Lacage <mathieu.lacage@gmail.com>
+ * Hajime Tazaki <tazaki@sfc.wide.ad.jp>
+ */
+
+#include <linux/hrtimer.h>
+#include "sim-assert.h"
+#include "sim.h"
+
+/**
+ * hrtimer_init - initialize a timer to the given clock
+ * @timer: the timer to be initialized
+ * @clock_id: the clock to be used
+ * @mode: timer mode abs/rel
+ */
+void hrtimer_init(struct hrtimer *timer, clockid_t clock_id,
+ enum hrtimer_mode mode)
+{
+ memset(timer, 0, sizeof(*timer));
+}
+static void trampoline(void *context)
+{
+ struct hrtimer *timer = context;
+ enum hrtimer_restart restart = timer->function(timer);
+
+ if (restart == HRTIMER_RESTART) {
+ void *event =
+ lib_event_schedule_ns(ktime_to_ns(timer->_softexpires),
+ &trampoline, timer);
+ timer->base = event;
+ } else {
+ /* mark as completed. */
+ timer->base = 0;
+ }
+}
+/**
+ * hrtimer_start_range_ns - (re)start an hrtimer on the current CPU
+ * @timer: the timer to be added
+ * @tim: expiry time
+ * @delta_ns: "slack" range for the timer
+ * @mode: expiry mode: absolute (HRTIMER_ABS) or relative (HRTIMER_REL)
+ *
+ * Returns:
+ * 0 on success
+ * 1 when the timer was active
+ */
+int __hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim,
+ unsigned long delta_ns,
+ const enum hrtimer_mode mode,
+ int wakeup)
+{
+ int ret = hrtimer_cancel(timer);
+ s64 ns = ktime_to_ns(tim);
+ void *event;
+
+ if (mode == HRTIMER_MODE_ABS)
+ ns -= lib_current_ns();
+ timer->_softexpires = ns_to_ktime(ns);
+ event = lib_event_schedule_ns(ns, &trampoline, timer);
+ timer->base = event;
+ return ret;
+}
+/**
+ * hrtimer_try_to_cancel - try to deactivate a timer
+ * @timer: hrtimer to stop
+ *
+ * Returns:
+ * 0 when the timer was not active
+ * 1 when the timer was active
+ * -1 when the timer is currently excuting the callback function and
+ * cannot be stopped
+ */
+int hrtimer_try_to_cancel(struct hrtimer *timer)
+{
+ /* Note: we cannot return -1 from this function.
+ see comment in hrtimer_cancel. */
+ if (timer->base == 0)
+ /* timer was not active yet */
+ return 1;
+ lib_event_cancel(timer->base);
+ timer->base = 0;
+ return 0;
+}
+/**
+ * hrtimer_cancel - cancel a timer and wait for the handler to finish.
+ * @timer: the timer to be cancelled
+ *
+ * Returns:
+ * 0 when the timer was not active
+ * 1 when the timer was active
+ */
+int hrtimer_cancel(struct hrtimer *timer)
+{
+ /* Note: because we assume a uniprocessor non-interruptible */
+ /* system when running in the kernel, we know that the timer */
+ /* is not running when we execute this code, so, know that */
+ /* try_to_cancel cannot return -1 and we don't need to retry */
+ /* the cancel later to wait for the handler to finish. */
+ int ret = hrtimer_try_to_cancel(timer);
+
+ lib_assert(ret >= 0);
+ return ret;
+}
+void hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim,
+ unsigned long delta_ns, const enum hrtimer_mode mode)
+{
+ __hrtimer_start_range_ns(timer, tim, delta_ns, mode, 1);
+}
+
+int hrtimer_get_res(const clockid_t which_clock, struct timespec *tp)
+{
+ *tp = ns_to_timespec(1);
+ return 0;
+}
diff --git a/arch/lib/tasklet-hrtimer.c b/arch/lib/tasklet-hrtimer.c
new file mode 100644
index 000000000000..fef4902d4938
--- /dev/null
+++ b/arch/lib/tasklet-hrtimer.c
@@ -0,0 +1,57 @@
+/*
+ * glue code for library version of Linux kernel
+ * Copyright (c) 2015 INRIA, Hajime Tazaki
+ *
+ * Author: Mathieu Lacage <mathieu.lacage@gmail.com>
+ * Hajime Tazaki <tazaki@sfc.wide.ad.jp>
+ */
+
+#include <linux/interrupt.h>
+#include "sim.h"
+#include "sim-assert.h"
+
+static enum hrtimer_restart __hrtimer_tasklet_trampoline(struct hrtimer *timer)
+{
+ struct tasklet_hrtimer *ttimer =
+ container_of(timer, struct tasklet_hrtimer, timer);
+
+ tasklet_schedule(&ttimer->tasklet);
+ return HRTIMER_NORESTART;
+}
+static void __tasklet_hrtimer_trampoline(unsigned long data)
+{
+ struct tasklet_hrtimer *ttimer = (void *)data;
+ enum hrtimer_restart restart;
+
+ restart = ttimer->function(&ttimer->timer);
+ if (restart != HRTIMER_NORESTART)
+ hrtimer_restart(&ttimer->timer);
+}
+/**
+ * tasklet_hrtimer_init - Init a tasklet/hrtimer combo for softirq callbacks
+ * @ttimer: tasklet_hrtimer which is initialized
+ * @function: hrtimer callback function which gets called from softirq context
+ * @which_clock: clock id (CLOCK_MONOTONIC/CLOCK_REALTIME)
+ * @mode: hrtimer mode (HRTIMER_MODE_ABS/HRTIMER_MODE_REL)
+ */
+void tasklet_hrtimer_init(struct tasklet_hrtimer *ttimer,
+ enum hrtimer_restart (*function)(struct hrtimer *),
+ clockid_t which_clock, enum hrtimer_mode mode)
+{
+ hrtimer_init(&ttimer->timer, which_clock, mode);
+ ttimer->timer.function = __hrtimer_tasklet_trampoline;
+ tasklet_init(&ttimer->tasklet, __tasklet_hrtimer_trampoline,
+ (unsigned long)ttimer);
+ ttimer->function = function;
+}
+
+void __tasklet_hi_schedule(struct tasklet_struct *t)
+{
+ /* Note: no need to set TASKLET_STATE_SCHED because
+ it is set by caller. */
+ lib_assert(t->next == 0);
+ /* run the tasklet at the next immediately available opportunity. */
+ void *event =
+ lib_event_schedule_ns(0, (void *)&t->func, (void *)t->data);
+ t->next = event;
+}
diff --git a/arch/lib/time.c b/arch/lib/time.c
new file mode 100644
index 000000000000..bc119843e0fd
--- /dev/null
+++ b/arch/lib/time.c
@@ -0,0 +1,116 @@
+/*
+ * glue code for library version of Linux kernel
+ * Copyright (c) 2015 INRIA, Hajime Tazaki
+ *
+ * Author: Mathieu Lacage <mathieu.lacage@gmail.com>
+ * Hajime Tazaki <tazaki@sfc.wide.ad.jp>
+ */
+
+#include <linux/time.h>
+#include <linux/errno.h>
+#include <linux/timex.h>
+#include <linux/ktime.h>
+#include "sim.h"
+#include "sim-assert.h"
+
+unsigned long volatile jiffies = INITIAL_JIFFIES;
+u64 jiffies_64 = INITIAL_JIFFIES;
+
+struct timespec xtime;
+seqlock_t xtime_lock;
+/* accessed from wrap_clock from do_sys_settimeofday.
+ We don't call the latter so we should never access this variable. */
+struct timespec wall_to_monotonic;
+
+uint64_t ns_to_jiffies(uint64_t ns)
+{
+ do_div(ns, (1000000000 / HZ));
+ return ns;
+}
+
+void lib_update_jiffies(void)
+{
+ jiffies = ns_to_jiffies(lib_current_ns());
+ jiffies_64 = ns_to_jiffies(lib_current_ns());
+}
+
+/* copied from kernel/time/hrtimeer.c */
+#if BITS_PER_LONG < 64
+/*
+ * Divide a ktime value by a nanosecond value
+ */
+s64 __ktime_divns(const ktime_t kt, s64 div)
+{
+ int sft = 0;
+ s64 dclc;
+ u64 tmp;
+
+ dclc = ktime_to_ns(kt);
+ tmp = dclc < 0 ? -dclc : dclc;
+
+ /* Make sure the divisor is less than 2^32: */
+ while (div >> 32) {
+ sft++;
+ div >>= 1;
+ }
+ tmp >>= sft;
+ do_div(tmp, (unsigned long) div);
+ return dclc < 0 ? -tmp : tmp;
+}
+#endif /* BITS_PER_LONG >= 64 */
+
+static unsigned long
+round_jiffies_common(unsigned long j,
+ bool force_up)
+{
+ int rem;
+ unsigned long original = j;
+
+ rem = j % HZ;
+ if (rem < HZ / 4 && !force_up) /* round down */
+ j = j - rem;
+ else /* round up */
+ j = j - rem + HZ;
+ if (j <= jiffies) /* rounding ate our timeout entirely; */
+ return original;
+ return j;
+}
+unsigned long round_jiffies(unsigned long j)
+{
+ return round_jiffies_common(j, false);
+}
+unsigned long round_jiffies_relative(unsigned long j)
+{
+ unsigned long j0 = jiffies;
+
+ /* Use j0 because jiffies might change while we run */
+ return round_jiffies_common(j + j0, false) - j0;
+}
+unsigned long round_jiffies_up(unsigned long j)
+{
+ return round_jiffies_common(j, true);
+}
+static void msleep_trampoline(void *context)
+{
+ struct SimTask *task = context;
+
+ lib_task_wakeup(task);
+}
+void msleep(unsigned int msecs)
+{
+ lib_event_schedule_ns(((__u64)msecs) * 1000000, &msleep_trampoline,
+ lib_task_current());
+ lib_task_wait();
+}
+
+void read_persistent_clock(struct timespec *ts)
+{
+ u64 nsecs = lib_current_ns();
+
+ set_normalized_timespec(ts, nsecs / NSEC_PER_SEC,
+ nsecs % NSEC_PER_SEC);
+}
+
+void __init time_init(void)
+{
+}
diff --git a/arch/lib/timer.c b/arch/lib/timer.c
new file mode 100644
index 000000000000..d290e3721841
--- /dev/null
+++ b/arch/lib/timer.c
@@ -0,0 +1,299 @@
+/*
+ * glue code for library version of Linux kernel
+ * Copyright (c) 2015 INRIA, Hajime Tazaki
+ *
+ * Author: Mathieu Lacage <mathieu.lacage@gmail.com>
+ * Hajime Tazaki <tazaki@sfc.wide.ad.jp>
+ */
+
+#include <linux/timer.h>
+#include <linux/interrupt.h>
+#include <linux/hash.h>
+#include <linux/hashtable.h>
+
+#include "sim-assert.h"
+#include "sim.h"
+
+static DEFINE_HASHTABLE(lib_timers_hashtable, 9);
+struct lib_timer {
+ struct timer_list *timer;
+ struct hlist_node t_hash;
+ void *event;
+};
+
+static int hash(struct timer_list *timer)
+{
+ return hash_32(hash32_ptr(timer), HASH_BITS(lib_timers_hashtable));
+}
+
+static struct lib_timer *__lib_timers_find(struct hlist_head *head,
+ struct timer_list *timer)
+{
+ struct lib_timer *l_timer;
+
+ hlist_for_each_entry(l_timer, head, t_hash) {
+ if (l_timer->timer == timer)
+ return l_timer;
+ }
+ return NULL;
+}
+
+static struct lib_timer *lib_timer_find(struct timer_list *timer)
+{
+ struct hlist_head *head;
+
+ head = &lib_timers_hashtable[hash(timer)];
+ return __lib_timers_find(head, timer);
+}
+
+/**
+ * init_timer_key - initialize a timer
+ * @timer: the timer to be initialized
+ * @name: name of the timer
+ * @key: lockdep class key of the fake lock used for tracking timer
+ * sync lock dependencies
+ *
+ * init_timer_key() must be done to a timer prior calling *any* of the
+ * other timer functions.
+ */
+void init_timer_key(struct timer_list *timer,
+ unsigned int flags,
+ const char *name,
+ struct lock_class_key *key)
+{
+ /**
+ * Note: name and key are used for debugging. We ignore them
+ * unconditionally.
+ * Note: we do not initialize the lockdep map either because we
+ * don't care.
+ * and, finally, we never care about the base field either.
+ *
+ * So, for now, we have a timer which is marked as "not started"
+ * thanks to its entry.pprev field set to NULL (timer_pending
+ * will return 0)
+ */
+ timer->entry.pprev = NULL;
+}
+
+struct hlist_head g_expired_events;
+struct hlist_head g_pending_events;
+
+static void run_timer_softirq(struct softirq_action *h)
+{
+ while (!hlist_empty(&g_expired_events)) {
+ struct timer_list *timer =
+ hlist_entry((&g_expired_events)->first,
+ struct timer_list, entry);
+ void (*fn)(unsigned long);
+ unsigned long data;
+ struct lib_timer *l_timer = lib_timer_find(timer);
+
+ fn = timer->function;
+ data = timer->data;
+ lib_assert(l_timer->event == 0);
+
+ hlist_del(&timer->entry);
+ timer->entry.pprev = NULL;
+ fn(data);
+ }
+}
+
+static void ensure_softirq_opened(void)
+{
+ static bool opened = false;
+
+ if (opened)
+ return;
+ opened = true;
+ open_softirq(TIMER_SOFTIRQ, run_timer_softirq);
+}
+static void timer_trampoline(void *context)
+{
+ struct timer_list *timer;
+ struct lib_timer *l_timer;
+
+ ensure_softirq_opened();
+ timer = context;
+
+ l_timer = lib_timer_find(timer);
+ if (l_timer)
+ l_timer->event = NULL;
+
+ if (timer->entry.pprev != 0)
+ hlist_del(&timer->entry);
+
+ timer->entry.pprev = NULL;
+ hlist_add_head(&timer->entry, &g_expired_events);
+ raise_softirq(TIMER_SOFTIRQ);
+}
+/**
+ * add_timer - start a timer
+ * @timer: the timer to be added
+ *
+ * The kernel will do a ->function(->data) callback from the
+ * timer interrupt at the ->expires point in the future. The
+ * current time is 'jiffies'.
+ *
+ * The timer's ->expires, ->function (and if the handler uses it, ->data)
+ * fields must be set prior calling this function.
+ *
+ * Timers with an ->expires field in the past will be executed in the next
+ * timer tick.
+ */
+void add_timer(struct timer_list *timer)
+{
+ __u64 delay_ns = 0;
+ struct hlist_head *head;
+
+ lib_assert(!timer_pending(timer));
+ if (timer->expires <= jiffies)
+ delay_ns = (1000000000 / HZ); /* next tick. */
+ else
+ delay_ns =
+ ((__u64)timer->expires *
+ (1000000000 / HZ)) - lib_current_ns();
+ void *event = lib_event_schedule_ns(delay_ns, &timer_trampoline, timer);
+
+ /* store the external event in the hash table */
+ /* to be able to retrieve it from del_timer */
+ head = &lib_timers_hashtable[hash(timer)];
+ if (!__lib_timers_find(head, timer)) {
+ struct lib_timer *l_timer;
+
+ l_timer = lib_malloc(sizeof(struct lib_timer));
+ l_timer->timer = timer;
+ l_timer->event = event;
+ hlist_add_head(&l_timer->t_hash, head);
+ }
+
+ /* finally, store timer in list of pending events. */
+ hlist_add_head(&timer->entry, &g_pending_events);
+}
+/**
+ * del_timer - deactive a timer.
+ * @timer: the timer to be deactivated
+ *
+ * del_timer() deactivates a timer - this works on both active and inactive
+ * timers.
+ *
+ * The function returns whether it has deactivated a pending timer or not.
+ * (ie. del_timer() of an inactive timer returns 0, del_timer() of an
+ * active timer returns 1.)
+ */
+int del_timer(struct timer_list *timer)
+{
+ int retval;
+ struct lib_timer *l_timer;
+
+ if (timer->entry.pprev == NULL)
+ return 0;
+
+ l_timer = lib_timer_find(timer);
+ if (l_timer != NULL && l_timer->event != NULL) {
+ lib_event_cancel(l_timer->event);
+
+ if (l_timer->t_hash.next != LIST_POISON1) {
+ hlist_del(&l_timer->t_hash);
+ lib_free(l_timer);
+ }
+ retval = 1;
+ } else {
+ retval = 0;
+ }
+
+ if (timer->entry.next != LIST_POISON1)
+ hlist_del(&timer->entry);
+ timer->entry.pprev = NULL;
+ return retval;
+}
+
+/* ////////////////////// */
+
+void init_timer_deferrable_key(struct timer_list *timer,
+ const char *name,
+ struct lock_class_key *key)
+{
+ /**
+ * From lwn.net:
+ * Timers which are initialized in this fashion will be
+ * recognized as deferrable by the kernel. They will not
+ * be considered when the kernel makes its "when should
+ * the next timer interrupt be?" decision. When the system
+ * is busy these timers will fire at the scheduled time. When
+ * things are idle, instead, they will simply wait until
+ * something more important wakes up the processor.
+ *
+ * Note: Our implementation of deferrable timers uses
+ * non-deferrable timers for simplicity.
+ */
+ init_timer_key(timer, 0, name, key);
+}
+/**
+ * add_timer_on - start a timer on a particular CPU
+ * @timer: the timer to be added
+ * @cpu: the CPU to start it on
+ *
+ * This is not very scalable on SMP. Double adds are not possible.
+ */
+void add_timer_on(struct timer_list *timer, int cpu)
+{
+ /* we ignore the cpu: we have only one. */
+ add_timer(timer);
+}
+/**
+ * mod_timer - modify a timer's timeout
+ * @timer: the timer to be modified
+ * @expires: new timeout in jiffies
+ *
+ * mod_timer() is a more efficient way to update the expire field of an
+ * active timer (if the timer is inactive it will be activated)
+ *
+ * mod_timer(timer, expires) is equivalent to:
+ *
+ * del_timer(timer); timer->expires = expires; add_timer(timer);
+ *
+ * Note that if there are multiple unserialized concurrent users of the
+ * same timer, then mod_timer() is the only safe way to modify the timeout,
+ * since add_timer() cannot modify an already running timer.
+ *
+ * The function returns whether it has modified a pending timer or not.
+ * (ie. mod_timer() of an inactive timer returns 0, mod_timer() of an
+ * active timer returns 1.)
+ */
+int mod_timer(struct timer_list *timer, unsigned long expires)
+{
+ int ret;
+
+ /* common optimization stolen from kernel */
+ if (timer_pending(timer) && timer->expires == expires)
+ return 1;
+
+ ret = del_timer(timer);
+ timer->expires = expires;
+ add_timer(timer);
+ return ret;
+}
+/**
+ * mod_timer_pending - modify a pending timer's timeout
+ * @timer: the pending timer to be modified
+ * @expires: new timeout in jiffies
+ *
+ * mod_timer_pending() is the same for pending timers as mod_timer(),
+ * but will not re-activate and modify already deleted timers.
+ *
+ * It is useful for unserialized use of timers.
+ */
+int mod_timer_pending(struct timer_list *timer, unsigned long expires)
+{
+ if (timer_pending(timer))
+ return 0;
+ return mod_timer(timer, expires);
+}
+
+int mod_timer_pinned(struct timer_list *timer, unsigned long expires)
+{
+ if (timer->expires == expires && timer_pending(timer))
+ return 1;
+
+ return mod_timer(timer, expires);
+}
--
2.1.0


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