current value. It is believed that the change is the real fix for the
issue which was covered over by the r252683.
With the current code, if the interrupt handler sets it_need between
read and consequent reset, the update could be lost and
ithread_execute_handlers() would not be called in response to the lost
update.
The r252683 could have hide the issue since at the moment of commit,
atomic_load_acq_int() did locked cmpxchg on the variable, which puts
the cache line into the exclusive owned state and clears store
buffers. Then the immediate store of zero has very high chance of
reusing the exclusive state of the cache line and make the load and
store sequence operate as atomic swap.
For now, add the acq+rel fence immediately after the swap, to not
disturb current (but excessive) ordering. Acquire is needed for the
ih_need reads after the load, while release does not serve a useful
purpose [*].
Reviewed by: alc
Noted by: alc [*]
Discussed with: bde
Tested by: pho
Sponsored by: The FreeBSD Foundation
MFC after: 2 weeks
Identify current CPU. This is necessary to setup
affinity registers and to provide support for
runtime chip identification.
Reviewed by: andrew
Obtained from: Semihalf
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D3095
We can map these system calls directly to the FreeBSD counterparts. The
other filesystem related system calls will be sent out for review
separately, as they are a bit more complex to get right.
an if_ixv instance can now set at creation time, and the receive ring
tail pointer is correctly initialized (previously, things still worked
because the receive ring tail pointer was being fixed up as a side
effect of other activity).
Differential Revision: https://reviews.freebsd.org/D2922
Reviewed by: erj, gnn
Approved by: jmallett (mentor)
Sponsored by: Norse Corp, Inc.
I performed the commit on a different system as where I wrote the
change. After pulling in the change from Phabricator, I didn't notice
that a single chunk did not apply.
Approved by: secteam (implicit, as intended change was approved)
Pointy hat to: me
The random_get() system call works similar to getentropy()/getrandom()
on OpenBSD/Linux. It fills a buffer with random data.
This change introduces a new function, read_random_uio(), that is used
to implement read() on the random devices. We can call into this
function from within the CloudABI compatibility layer.
Approved by: secteam
Reviewed by: jmg, markm, wblock
Obtained from: https://github.com/NuxiNL/freebsd
Differential Revision: https://reviews.freebsd.org/D3053
The first system call is used to set the user TLS address. Right now
this system call is invoked by the C library for both the initial thread
and additional threads unconditionally, but in the future we'll only
call this if the architecture does not support this. On recent x86-64
CPUs we could use the WRFSBASE instruction.
This system call was erroneously placed in sys/compat/cloudabi64, even
though it does not depend on any pointer size dependent datastructure.
Move it to the right place.
Obtained from: https://github.com/NuxiNL/freebsd
