linux.git/arch/um/kernel/time.c, branch v5.10.258

um: time-travel: fix time-travel-start option

2024-08-19T03:41:03+00:00

[ Upstream commit 7d0a8a490aa3a2a82de8826aaf1dfa38575cb77a ]

We need to have the = as part of the option so that the
value can be parsed properly. Also document that it must
be given in nanoseconds, not seconds.

Fixes: 065038706f77 ("um: Support time travel mode")
Link: https://patch.msgid.link/20240417102744.14b9a9d4eba0.Ib22e9136513126b2099d932650f55f193120cd97@changeid
Signed-off-by: Johannes Berg 
Signed-off-by: Sasha Levin

um: Fix time-travel mode

2020-12-30T10:54:17+00:00

commit ff9632d2a66512436d616ef4c380a0e73f748db1 upstream.

Since the time-travel rework, basic time-travel mode hasn't worked
properly, but there's no longer a need for this WARN_ON() so just
remove it and thereby fix things.

Cc: stable@vger.kernel.org
Fixes: 4b786e24ca80 ("um: time-travel: Rewrite as an event scheduler")
Signed-off-by: Johannes Berg 
Signed-off-by: Richard Weinberger 
Signed-off-by: Greg Kroah-Hartman

um: time-travel: Return the sequence number in ACK messages

2020-10-11T21:13:27+00:00

For external time travel, the protocol says to return the
incoming sequence number in the ACK message to aid debugging,
so do that.

Signed-off-by: Johannes Berg 
Acked-By: Anton Ivanov 
Signed-off-by: Richard Weinberger

um: time-travel: Fix IRQ handling in time_travel_handle_message()

2020-10-11T21:13:20+00:00

As the comment here indicates, we need to do the polling in the
idle loop without blocking interrupts, since interrupts can be
vhost-user messages that we must process even while in our idle
loop.

I don't know why I explained one thing and implemented another,
but we have indeed observed random hangs due to this, depending
on the timing of the messages.

Fixes: 88ce64249233 ("um: Implement time-travel=ext")
Signed-off-by: Johannes Berg 
Acked-By: Anton Ivanov 
Signed-off-by: Richard Weinberger

um: Implement ndelay/udelay in time-travel mode

2020-03-29T21:29:52+00:00

In external or inf-cpu time-travel mode, ndelay/udelay currently
just waste CPU time since the simulation time doesn't advance.
Implement them properly in this case.

Note that the "if (time_travel_mode == ...)" parts compile out
if CONFIG_UML_TIME_TRAVEL_SUPPORT isn't set, time_travel_mode is
defined to TT_MODE_OFF in that case.

Signed-off-by: Johannes Berg 
Signed-off-by: Richard Weinberger

um: Implement time-travel=ext

2020-03-29T21:29:08+00:00

This implements synchronized time-travel mode which - using a special
application on a unix socket - lets multiple machines take part in a
time-travelling simulation together.

The protocol for the unix domain socket is defined in the new file
include/uapi/linux/um_timetravel.h.

Signed-off-by: Johannes Berg 
Signed-off-by: Richard Weinberger

um: time-travel: Rewrite as an event scheduler

2020-03-29T21:28:51+00:00

Instead of tracking all the various timer configurations,
modify the time-travel mode to have an event scheduler and
use a timer event on the scheduler to handle the different
timer configurations.

This doesn't change the function right now, but it prepares
the code for having different kinds of events in the future
(i.e. interrupts coming from other devices that are part of
co-simulation.)

While at it, also move time_travel_sleep() to time.c to
reduce the externally visible API surface.

Also, we really should mark time-travel as incompatible with
SMP, even if UML doesn't support SMP yet.

Finally, I noticed a bug while developing this - if we move
time forward due to consuming time while reading the clock,
we might move across the next event and that would cause us
to go backward in time when we then handle that event. Fix
that by invoking the whole event machine in this case, but
in order to simplify this, make reading the clock only cost
something when interrupts are not disabled. Otherwise, we'd
have to hook into the interrupt delivery machinery etc. and
that's somewhat intrusive.

Signed-off-by: Johannes Berg 
Signed-off-by: Richard Weinberger

um: Move timer-internal.h to non-shared

2020-03-29T21:28:43+00:00

This file isn't really shared, it's only used on the kernel side,
not on the user side. Remove the include from the user-side and
move the file to a better place.

While at it, rename it to time-internal.h, it's not really just
timers but all kinds of things related to timekeeping.

Signed-off-by: Johannes Berg 
Signed-off-by: Richard Weinberger

um: Add SPDX headers to files in arch/um/kernel/

2019-09-15T19:37:17+00:00

Convert files to use SPDX header. All files are licensed under the
GPLv2.

Signed-off-by: Alex Dewar 
Signed-off-by: Richard Weinberger

um: time-travel: Restrict time update in IRQ handler

2019-09-15T19:37:13+00:00

We currently do the time updates in the timer handler, even if
we just call the timer handler ourselves. In basic mode we must
in fact do it there since otherwise the OS timer signal won't
move time forward, but in inf-cpu mode we don't need to, and
it's harder to understand.

Restrict the update there to basic mode, adding a comment, and
do it before calling the timer_handler() in inf-cpu mode.

Signed-off-by: Johannes Berg 
Signed-off-by: Richard Weinberger