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Signed-off-by: Philippe Gerum <rpm@xenomai.org>

Signed-off-by: Philippe Gerum <rpm@xenomai.org>

Signed-off-by: Philippe Gerum <rpm@xenomai.org>

We may be running a SMP kernel on a uniprocessor machine whose
interrupt controller supports no IPI. We should attempt to hook IPIs
only if the hardware can support multiple CPUs, otherwise it is
unneeded and poised to fail.
Signed-off-by: Philippe Gerum <rpm@xenomai.org>

Signed-off-by: Philippe Gerum <rpm@xenomai.org>

We have only very few syscalls, prefer a plain switch to a pointer
indirection which ends up being fairly costly due to exploit
mitigations.
Signed-off-by: Philippe Gerum <rpm@xenomai.org>

Signed-off-by: Philippe Gerum <rpm@xenomai.org>

Signed-off-by: Philippe Gerum <rpm@xenomai.org>

EVL_HIGH_PERCPU_CONCURRENCY optimizes the implementation for
applications with many real-time threads running concurrently on any
given CPU core (typically when eight or more threads may be sharing a
single CPU core). This is a combination of the scalable scheduler and
rb-tree timer indexing as a single configuration switch, since both
aspects are normally coupled.

If the application system runs only a few EVL threads per CPU core,
then this option should be turned off, in order to minimize the cache
footprint of the queuing operations performed by the scheduler and
timer subsystems. Otherwise, it should be turned on in order to have
constant-time queuing operations for a large number of runnable
threads and outstanding timers.
Signed-off-by: Philippe Gerum <rpm@xenomai.org>

For applications with only few runnable tasks at any point in time, a
linear queue ordering the latter for scheduling delivers better
performance on low-end systems due to smaller CPU cache footprints,
compared to the multi-level queue used by the scalable scheduler.

Allow users to select between lightning-fast and scalable scheduler
implementation depending on the runtime profile of the application.
Signed-off-by: Philippe Gerum <rpm@xenomai.org>

# Please enter the commit message for your changes. Lines starting
# with '#' will be ignored, and an empty message aborts the commit.
#
# On branch evl/master
# Your branch is ahead of 'origin/evl/master' by 2 commits.
#   (use "git push" to publish your local commits)
#
# Changes to be committed:
#	modified:   include/evl/sched.h
#	modified:   include/evl/sched/queue.h
#	modified:   include/evl/sched/tp.h
#	modified:   include/evl/sched/weak.h
#	modified:   kernel/evl/Kconfig
#	modified:   kernel/evl/sched/core.c
#
# Untracked files:
#	include/trace/events/mm.h
#

Signed-off-by: Philippe Gerum <rpm@xenomai.org>

Add (back) the ability to index timers either in a rb-tree or linked
to a basic linked list.

The latter delivers lower latency to applications systems with very
few active timers at any point in time (typically less than 10 active
timers, e.g. not more than a couple of timed loops, very few timed
syscalls).
Signed-off-by: Philippe Gerum <rpm@xenomai.org>

Signed-off-by: Philippe Gerum <rpm@xenomai.org>

The pipelined interrupt entry code must always run the common work
loop before returning to user mode on the in-band stage, including
after the preempted task was demoted from oob to in-band context as a
result of handling the incoming IRQ.

Failing to do so may cause in-band work to be left pending in this
particular case, like _TIF_RETUSER and other _TIF_WORK conditions.

This bug caused the smokey 'gdb' test to fail on x86:
https://xenomai.org/pipermail/xenomai/2021-March/044522.html

Signed-off-by: Philippe Gerum <rpm@xenomai.org>

Since #ae18ad28

, MAX_RT_PRIO should be used instead.
Signed-off-by: Philippe Gerum <rpm@xenomai.org>

A process is now marked for COW-breaking on fork() upon the first call
to dovetail_init_altsched(), and must ensure its memory is locked via
a call to mlockall(MCL_CURRENT|MCL_FUTURE) as usual.

As a result, force_commit_memory() became pointless and was removed
from the Dovetail interface.
Signed-off-by: Philippe Gerum <rpm@xenomai.org>

evl/factory.h is included more than once, remove the one that isn't
necessary.
Signed-off-by: Zhang Kun <zhangkun@cdjrlc.com>

Signed-off-by: Philippe Gerum <rpm@xenomai.org>

Signed-off-by: Philippe Gerum <rpm@xenomai.org>

Signed-off-by: Philippe Gerum <rpm@xenomai.org>

An EVL lock is now distinct from a hard lock in that it tracks and
disables preemption in the core when held.

Such spinlock may be useful when only EVL threads running out-of-band
can contend for the lock, to the exclusion of out-of-band IRQ
handlers. In this case, disabling preemption before attempting to grab
the lock may be substituted to disabling hard irqs.

There are gotchas when using such type of lock from the in-band
context, see comments in evl/lock.h.
Signed-off-by: Philippe Gerum <rpm@xenomai.org>

Very short sections of code outside of any hot path are protected by
such lock. Therefore we would not generally benefit from the
preemption disabling feature we are going to add to the EVL-specific
spinlock. Make it a hard lock to clarify the intent.
Signed-off-by: Philippe Gerum <rpm@xenomai.org>

For the most part, the gate lock is nested with a wait queue hard lock
- which requires hard irqs to be off - to access the protected
sections. Therefore we would not benefit in the common case from the
preemption disabling feature we are going to add to the EVL-specific
spinlock. Make it a hard lock to clarify the intent.
Signed-off-by: Philippe Gerum <rpm@xenomai.org>

For the most part, a thread hard lock - which requires hard irqs to be
off - is nested with the mutex lock to access the protected
sections. Therefore we would not benefit in the common case from the
preemption disabling feature we are going to add to the EVL-specific
spinlock. Make it a hard lock to clarify the intent.
Signed-off-by: Philippe Gerum <rpm@xenomai.org>

Sleeping voluntarily with EVL preemption disabled is a bug. Add the
proper assertion to detect this.
Signed-off-by: Philippe Gerum <rpm@xenomai.org>

Given the semantics of an evl_flag, disabling preemption manually
around the evl_raise_flag(to_flag) -> evl_wait_flag(from_flag)
sequence does not make sense.
Signed-off-by: Philippe Gerum <rpm@xenomai.org>

The subscriber lock is shared between both execution stages, but
accessed from the in-band stage for the most part, which implies
disabling hard irqs while holding it. Meanwhile, out-of-band IRQs and
EVL threads may compete for the observable lock, which would require
hard irqs to be disabled while holding it.  Therefore we would not
generally benefit from the preemption disabling feature we are going
to add to the EVL-specific spinlock in any case. Make these hard locks
to clarify the intent.
Signed-off-by: Philippe Gerum <rpm@xenomai.org>

The data protected by the inbound (oob -> in-band traffic) buffer lock
is frequently accessed from the in-band stage by design, where hard
irqs should be disabled. Conversely, the out-of-band sections are
short enough to bear with interrupt-free execution. Therefore we would
not generally benefit from the preemption disabling feature we are
going to add to the EVL-specific spinlock. Make it a hard lock to
clarify the intent.
Signed-off-by: Philippe Gerum <rpm@xenomai.org>

Out-of-band IRQs and EVL thread contexts would usually compete for
such lock, which would require hard irqs to be disabled while holding
it. Therefore we would not generally benefit from the preemption
disabling feature we are going to add to the EVL-specific
spinlock. Make it a hard lock to clarify the intent.
Signed-off-by: Philippe Gerum <rpm@xenomai.org>

The data protected by the file table lock is frequently accessed from
the in-band stage where holding it with hard irqs off is
required. Therefore we would not benefit in the common case from the
preemption disabling feature we are going to add to the EVL-specific
spinlock. Make it a hard lock to clarify the intent.
Signed-off-by: Philippe Gerum <rpm@xenomai.org>

Now that the inclusion hell is fixed with evl/wait.h, we may include
it into mm_info.h, for defining the ptsync barrier statically into the
out-of-band mm state.
Signed-off-by: Philippe Gerum <rpm@xenomai.org>

Signed-off-by: Philippe Gerum <rpm@xenomai.org>

Out-of-band IRQs and EVL thread contexts would usually compete for
such lock, which would require hard irqs to be disabled while holding
it. Therefore we would not generally benefit from the preemption
disabling feature we are going to add to the EVL-specific
spinlock. Make it a hard lock to clarify the intent.
Signed-off-by: Philippe Gerum <rpm@xenomai.org>

Out-of-band IRQs and EVL thread contexts may compete for such lock,
which would require hard irqs to be disabled while holding it.
Therefore we would not benefit from the preemption disabling feature
we are going to add to the EVL-specific spinlock. Make it a hard lock
to clarify the intent.
Signed-off-by: Philippe Gerum <rpm@xenomai.org>

Out-of-band IRQs and EVL thread contexts may compete for such lock,
which would require hard irqs to be disabled while holding it.
Therefore we would not benefit from the preemption disabling feature
we are going to add to the EVL-specific spinlock. Make it a hard lock
to clarify the intent.
Signed-off-by: Philippe Gerum <rpm@xenomai.org>

We don't actually need to rely on the oob stall bit, provided hard
irqs are off in the deemed interrupt-free sections, because the latter
is sufficient as long as the code does not traverse a pipeline
synchronization point (sync_current_irq_stage()) while holding a lock,
which would be in and of itself a bug in the first place.

Remove the stall/unstall operations from the evl_spinlock
implementation, fixing the few locations which were still testing the
oob stall bit.

The oob stall bit is still set by Dovetail on entry to IRQ handlers,
which is ok: we will neither use nor affect it anymore, only relying
on hard disabled irqs.

This temporary alignment of the evl_spinlock on the hard spinlock is a
first step to revisit the lock types in the core, before the
evl_spinlock is changed again to manage the preemption count.
Signed-off-by: Philippe Gerum <rpm@xenomai.org>

Checking the oob stall bit in __evl_enable_preempt() to block the
rescheduling is obsolete. It relates to a nested locking construct
which is long gone, when the evl_spinlock managed the preemption count
and the big lock was still in, i.e.:

lock_irqsave(&ugly_big_lock, flags)  /* stall bit raised */
	evl_spin_lock(&inner_lock);  /* +1 preempt */
	   wake_up_high_prio_thread();
	evl_spin_unlock(&inner_lock); /* -1 preempt == 0, NO schedule because stalled */
unlock_irqrestore(&ugly_big_lock, flags) /* stall bit restored */

This was a way to prevent a rescheduling to take place inadvertently
while holding the big lock.
Signed-off-by: Philippe Gerum <rpm@xenomai.org>

Signed-off-by: Philippe Gerum <rpm@xenomai.org>

This is a simple synchronization mechanism allowing an in-band caller
to pass a point in the code making sure that no out-of-band operations
which might traverse the same crossing are in flight.

Out-of-band callers delimit the danger zone by down-ing and up-ing the
barrier at the crossing, the in-band code should ask for passing the
crossing.

CAUTION: the caller must guarantee that evl_down_crossing() cannot be
invoked _after_ evl_pass_crossing() is entered for a given crossing.
Signed-off-by: Philippe Gerum <rpm@xenomai.org>

Returns the current kthread descriptor or NULL if another thread
context is running. CAUTION: does not account for IRQ context.
Signed-off-by: Philippe Gerum <rpm@xenomai.org>