The detection works very similarly to how we detect a mouse wheel, just
another magical sequence of "set sample rate" requests to the mouse
followed by an ID check.
If we OOM during a CoW fault and fail to allocate a new page for the
writing process, just leave the original VMObject alone so everyone
else can keep using it.
Since a Region is basically a view into a potentially larger VMObject,
it was always necessary to include the Region starting offset when
accessing its underlying physical pages.
Until now, you had to do that manually, but this patch adds a simple
Region::physical_page() for read-only access and a physical_page_slot()
when you want a mutable reference to the RefPtr<PhysicalPage> itself.
A lot of code is simplified by making use of this.
Previously we blindly just called update_next_timer_due() when
ever we modified the timer list. Since we know the list is sorted
this is a bit wasteful, and we can do better.
This change refactors the code so we only update the next due time
when necessary. In places where it was possible the code was modified
to directly modify the next due time, instead of having to go to the
front of the list to fetch it.
The public consumers of the timer API shouldn't need to know
the how timer id's are tracked internally. Expose a typedef
instead to allow the internal implementation to be protected
from potential churn in the future.
It's also just good API design.
Utilize the new Thread::wait_on timeout parameter to implement
timeout support for FUTEX_WAIT.
As we compute the relative time from the user specified absolute
time, we try to delay that computation as long as possible before
we call into Thread::wait_on(..). To enable this a small bit of
refactoring was done pull futex_queue fetching out and timeout fetch
and calculation separation.
This change plumbs a new optional timeout option to wait_on.
The timeout is enabled by enqueing a timer on the timer queue
while we are waiting. We can then see if we were woken up or
timed out by checking if we are still on the wait queue or not.
The current API of add_timer makes it hard to use as
you are forced to do a bunch of time arithmetic at the
caller. Ideally we would have overloads for common time
types like timespec or timeval to keep the API as straight
forward as possible. This change moves us in that direction.
While I'm here, we should really also use the machines actual
ticks per second, instead of the OPTIMAL_TICKS_PER_SECOND_RATE.
This is a special case that was previously not implemented.
The idea is that you can dispatch a signal to all other processes
the calling process has access to.
There was some minor refactoring to make the self signal logic
into a function so it could easily be easily re-used from do_killall.
Previously, when returning from a pthread's start_routine, we would
segfault. Now we instead implicitly call pthread_exit as specified in
the standard.
pthread_create now creates a thread running the new
pthread_create_helper, which properly manages the calling and exiting
of the start_routine supplied to pthread_create. To accomplish this,
the thread's stack initialization has been moved out of
sys$create_thread and into the userspace function create_thread.
A Lock can now be held either in shared or exclusive mode. Multiple threads can
hold the same lock in shared mode at one time, but if any thread holds the lock
in exclusive mode, no other thread can hold it at the same time in either mode.
The next commit is going to make it bigger again by increasing the size of Lock,
so make use of bitfields to make sure FileDescription still fits into 64 bytes,
and so can still be allocated with the SlabAllocator.
We don't need a wrapper Function object that just forwards the timer
callback to the scheduler tick function. It already has the same
signature, so we can just plug it in directly. :^)
Same with the clock updating function.
The IOAPIC manual states that "Interrupt Mask-R/W. When this bit is 1,
the interrupt signal is masked. Edge-sensitive interrupts signaled on
a masked interrupt pin are ignored." - Therefore we have to ensure that
we disable interrupts globally with cli(), but also to ensure that we
invoke enable_irq() before sending the hardware command that generates
an IRQ almost immediately.
First, before this change, specifying 'force_pio' in the kernel
commandline was meaningless because we nevertheless set the DMA flag to
be enabled.
Also, we had a problem in which we used IO::repeated_out16() in PIO
write method. This might work on buggy emulators, but I suspect that on
real hardware this code will fail.
The most difficult problem was to restore the PIO read operation.
Apparently, it seems that we can't use IO::repeated_in16() here because
it will read zeroed data. Currently we rely on a simple loop that
invokes IO::in16() to a buffer. Also, the interrupt handling stage in
the PIO read method is moved to be handled inside the loop of reading
the requested sectors.
POSIX says, "Conforming applications should not assume that the returned
contents of the symbolic link are null-terminated."
If we do include the null terminator into the returning string, Python
believes it to actually be a part of the returned name, and gets unhappy
about that later. This suggests other systems Python runs in don't include
it, so let's do that too.
Also, make our userspace support non-null-terminated realpath().
Output address validation should be done for the tracer's address space
and not the tracee's.
Also use copy_to_user() instead of copy_from_user(). The two are really
identical at the moment, but maybe we can add some assertions to make
sure we're doing what we think we're doing.
Thanks to Sergey for spotting these!
We currently only care about debug exceptions that are triggered
by the single-step execution mode.
The debug exception is translated to a SIGTRAP, which can be caught
and handled by the tracing thread.
