Providing these in freebsd32.h facilitates local testing/measuring of the
structs rather than forcing one to locally recreate them. Sanity checking
offsets/sizes remains in kern_umtx.c where these are typically used.
This patch takes advantage of the consolidation that happened to provide two
flags that can be used with the native _umtx_op(2): UMTX_OP___32BIT and
UMTX_OP__I386.
UMTX_OP__32BIT iindicates that we are being provided with 32-bit structures.
Note that this flag alone indicates a 64bit time_t, since this is the
majority case.
UMTX_OP__I386 has been provided so that we can emulate i386 as well,
regardless of whether the host is amd64 or not.
Both imply a different set of copyops in sysumtx_op. freebsd32__umtx_op
simply ignores the flags, since it's already doing a 32-bit operation and
it's unlikely we'll be running an emulator under compat32. Future work
could consider it, but the author sees little benefit.
This will be used by qemu-bsd-user to pass on all _umtx_op calls to the
native interface as long as the host/target endianness matches, effectively
eliminating most if not all of the remaining unresolved deadlocks for most.
This version changed a fair amount from what was under review, mostly in
response to refactoring of the prereq reorganization and battle-testing
it with qemu-bsd-user. The main changes are as follows:
1.) The i386 flag got renamed to omit '32BIT' since this is redundant.
2.) The flags are now properly handled on 32-bit platforms to emulate other
32-bit platforms.
3.) Robust list handling was fixed, and the 32-bit functionality that was
previously gated by COMPAT_FREEBSD32 is now unconditional.
4.) Robust list handling was also improved, including the error reported
when a process has already registered 32-bit ABI lists and also
detecting if native robust lists have already been registered. Both
scenarios now return EBUSY rather than EINVAL, because the input is
technically valid but we're too busy with another ABI's lists.
libsysdecode/kdump/truss support will go into review soon-ish, along with
the associated manpage update.
Reviewed by: kib (earlier version)
MFC after: 3 weeks
There is no point in dynamic registration, umtx hook is there always.
Reviewed by: mjg
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
Differential revision: https://reviews.freebsd.org/D27303
A copy-pasto left us copying in 24-bytes at the address of the rb pointer
instead of the intended target.
Reported by: sigsys@gmail.com
Sighing: kevans
One of the last shifts inadvertently moved these static assertions out of a
COMPAT_FREEBSD32 block, which the relevant definitions are limited to.
Fix it.
Pointy hat: kevans
All of the compat32 variants are substantially the same, save for
copyin/copyout (mostly). Apply the same kind of technique used with kevent
here by having the syscall routines supply a umtx_copyops describing the
operations needed.
umtx_copyops carries the bare minimum needed- size of timespec and
_umtx_time are used for determining if copyout is needed in the sem2_wait
case.
Reviewed by: kib
MFC after: 1 week
Differential Revision: https://reviews.freebsd.org/D27222
Specifically, if we're waking up some value n > BATCH_SIZE, then the
copyin(9) is wrong on the second iteration due to upp being the wrong type.
upp is currently a uint32_t**, so upp + pos advances it by twice as many
elements as it should (host pointer size vs. compat32 pointer size).
Fix it by just making upp a uint32_t*; it's still technically a double
pointer, but the distinction doesn't matter all that much here since we're
just doing arithmetic on it.
Add a test case that demonstrates the problem, placed with the libthr tests
since one messing with _umtx_op should be running these tests. Running under
compat32, the new test case will hang as threads after the first 128 get
missed in the wake. it's not immediately clear how to hit it in practice,
since pthread_cond_broadcast() uses a smaller (sleepq batch?) size observed
to be around ~50 -- I did not spend much time digging into it.
The uintptr_t change makes no functional difference, but i've tossed it in
since it's more accurate (semantically).
Reported by: Andrew Gierth (andrew_tao173.riddles.org.uk, inspection)
Reviewed by: kib
MFC after: 1 week
Differential Revision: https://reviews.freebsd.org/D27231
This works for amd64, but none others -- drop it, because we already have a
proper definition in sys/compat/freebsd32/freebsd32.h that correctly uses
time32_t.
MFC after: 1 week
Created with shm_open2(SHM_LARGEPAGE) and then configured with
FIOSSHMLPGCNF ioctl, largepages posix shared memory objects guarantee
that all userspace mappings of it are served by superpage non-managed
mappings.
Only amd64 for now, both 2M and 1G superpages can be requested, the
later requires CPU feature.
Reviewed by: markj
Tested by: pho
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
Differential revision: https://reviews.freebsd.org/D24652
r357614 added CTLFLAG_NEEDGIANT to make it easier to find nodes that are
still not MPSAFE (or already are but aren’t properly marked).
Use it in preparation for a general review of all nodes.
This is non-functional change that adds annotations to SYSCTL_NODE and
SYSCTL_PROC nodes using one of the soon-to-be-required flags.
Mark all obvious cases as MPSAFE. All entries that haven't been marked
as MPSAFE before are by default marked as NEEDGIANT
Approved by: kib (mentor, blanket)
Commented by: kib, gallatin, melifaro
Differential Revision: https://reviews.freebsd.org/D23718
and make it usable outside of kern_umtx.c. To be used in several
future changes.
Discussed with: markj
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
The check for P_SINGLE_EXIT was shadowed by the (P_SHOULDSTOP || traced) check.
Reported by: bdrewery (might be)
Reviewed by: markj
Tested by: pho
MFC after: 1 week
Sponsored by: The FreeBSD Foundation
Differential revision: https://reviews.freebsd.org/D21124
In particular, restart should be only done when the failure is
transient. For this, recheck the count1 value after the operation.
Note that do_sem_wait() is older usem interface.
Reported and tested by: bdrewery
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
If umtxq_check_susp() indicates an exit, we should clean the resources
before returning. Do it by breaking out of the loop and relying on
post-loop cleanup.
Reviewed by: markj
Tested by: pho
Sponsored by: The FreeBSD Foundation
MFC after: 12 days
Differential revision: https://reviews.freebsd.org/D20949
After r349951, the return code must be checked instead of old == new
comparision.
Reviewed by: markj
Tested by: pho
Sponsored by: The FreeBSD Foundation
MFC after: 12 days
Differential revision: https://reviews.freebsd.org/D20949
Casueword(9) on ll/sc architectures must be prepared for userspace
constantly modifying the same cache line as containing the CAS word,
and not loop infinitely. Otherwise, rogue userspace livelocks the
kernel.
To fix the issue, change casueword(9) interface to return new value 1
indicating that either comparision or store failed, instead of relying
on the oldval == *oldvalp comparison. The primitive no longer retries
the operation if it failed spuriously. Modify callers of
casueword(9), all in kern_umtx.c, to handle retries, and react to
stops and requests to terminate between retries.
On x86, despite cmpxchg should not return spurious failures, we can
take advantage of the new interface and just return PSL.ZF.
Reviewed by: andrew (arm64, previous version), markj
Tested by: pho
Reported by: https://xenbits.xen.org/xsa/advisory-295.txt
Sponsored by: The FreeBSD Foundation
MFC after: 2 weeks
Differential revision: https://reviews.freebsd.org/D20772
- there is no need to take the process lock to iterate the thread
list after single-threading is enforced
- typically there are no mutexes to clean up (testable without taking
the global umtx lock)
- typically there is no need to adjust the priority (testable without
taking thread lock)
Reviewed by: kib
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D20160
The timespecadd(3) family of macros were imported from NetBSD back in
r35029. However, they were initially guarded by #ifdef _KERNEL. In the
meantime, we have grown at least 28 syscalls that use timespecs in some
way, leading many programs both inside and outside of the base system to
redefine those macros. It's better just to make the definitions public.
Our kernel currently defines two-argument versions of timespecadd and
timespecsub. NetBSD, OpenBSD, and FreeDesktop.org's libbsd, however, define
three-argument versions. Solaris also defines a three-argument version, but
only in its kernel. This revision changes our definition to match the
common three-argument version.
Bump _FreeBSD_version due to the breaking KPI change.
Discussed with: cem, jilles, ian, bde
Differential Revision: https://reviews.freebsd.org/D14725
opt_compat.h is mentioned in nearly 180 files. In-progress network
driver compabibility improvements may add over 100 more so this is
closer to "just about everywhere" than "only some files" per the
guidance in sys/conf/options.
Keep COMPAT_LINUX32 in opt_compat.h as it is confined to a subset of
sys/compat/linux/*.c. A fake _COMPAT_LINUX option ensure opt_compat.h
is created on all architectures.
Move COMPAT_LINUXKPI to opt_dontuse.h as it is only used to control the
set of compiled files.
Reviewed by: kib, cem, jhb, jtl
Sponsored by: DARPA, AFRL
Differential Revision: https://reviews.freebsd.org/D14941
Non-NULL timeouts where copied in improperly and could produce failures
due to incompatible data structures.
Reviewed by: kib
MFC after: 3 days
Sponsored by: DARPA, AFRL
Differential Revision: https://reviews.freebsd.org/D14587
Mainly focus on files that use BSD 2-Clause license, however the tool I
was using misidentified many licenses so this was mostly a manual - error
prone - task.
The Software Package Data Exchange (SPDX) group provides a specification
to make it easier for automated tools to detect and summarize well known
opensource licenses. We are gradually adopting the specification, noting
that the tags are considered only advisory and do not, in any way,
superceed or replace the license texts.
POSIX 2008 says this about clock_settime(2):
If the value of the CLOCK_REALTIME clock is set via clock_settime(),
the new value of the clock shall be used to determine the time
of expiration for absolute time services based upon the
CLOCK_REALTIME clock. This applies to the time at which armed
absolute timers expire. If the absolute time requested at the
invocation of such a time service is before the new value of
the clock, the time service shall expire immediately as if the
clock had reached the requested time normally.
Setting the value of the CLOCK_REALTIME clock via clock_settime()
shall have no effect on threads that are blocked waiting for
a relative time service based upon this clock, including the
nanosleep() function; nor on the expiration of relative timers
based upon this clock. Consequently, these time services shall
expire when the requested relative interval elapses, independently
of the new or old value of the clock.
When the real-time clock is adjusted, such as by clock_settime(3),
wake any threads sleeping until an absolute real-clock time.
Such a sleep is indicated by a non-zero td_rtcgen. The sleep functions
will set that field to zero and return zero to tell the caller
to reevaluate its sleep duration based on the new value of the clock.
At present, this affects the following functions:
pthread_cond_timedwait(3)
pthread_mutex_timedlock(3)
pthread_rwlock_timedrdlock(3)
pthread_rwlock_timedwrlock(3)
sem_timedwait(3)
sem_clockwait_np(3)
I'm working on adding clock_nanosleep(2), which will also be affected.
Reported by: Sebastian Huber <sebastian.huber@embedded-brains.de>
Reviewed by: jhb, kib
MFC after: 2 weeks
Relnotes: yes
Sponsored by: Dell EMC
Differential Revision: https://reviews.freebsd.org/D9791
This function allows the caller to specify the reference clock
and choose between absolute and relative mode. In relative mode,
the remaining time can be returned.
The API is similar to clock_nanosleep(3). Thanks to Ed Schouten
for that suggestion.
While I'm here, reduce the sleep time in the semaphore "child"
test to greatly reduce its runtime. Also add a reasonable timeout.
Reviewed by: ed (userland)
MFC after: 2 weeks
Relnotes: yes
Sponsored by: Dell EMC
Differential Revision: https://reviews.freebsd.org/D9656
The default (512) wastes quite a bit of space which doesn't really buy
us much on highly embedded systems which don't take a lot of locks in
parallel.
This makes it at least build time configurable so people can experiment.
obliterate possible error from sleep with errors from
umtxq_check_susp(), when looping to clear URWLOCK_{READ,WRITE}_WAITERS.
Noted and reviewed by: vangyzen
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
If there was some error, e.g. the sleep was interrupted, as in the
referenced PR, do_rw_rdlock() did not cleared URWLOCK_READ_WAITERS.
Since unlock only wakes up write waiters when there is no read
waiters, for URWLOCK_PREFER_READER kind of locks, the result was
missed wakeups for writers.
In particular, the most visible victims are ld-elf.so locks in
processes which loaded libthr, because rtld locks are urwlocks in
prefer-reader mode. Normal rwlocks fall into prefer-reader mode only
if thread already owns rw lock in read mode, which is not typical and
correspondingly less visible. In the PR, unowned rtld bind lock was
waited for in the process where only one thread was left alive.
Note that do_rw_wrlock() correctly clears URWLOCK_WRITE_WAITERS in
case of errors.
Reported and tested by: longwitz@incore.de
PR: 211947
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
If the caller of sem_post() wakes up a thread sleeping via sem_wait()
before it clears the has_waiters flag, the caller of sem_wait() has no way of
knowing when it is safe to destroy the semaphore and reuse the memory. This is
because the caller of sem_post() may be interrupted between the wake step and
the clearing of has_waiters. It will then write into the has_waiters flag in
userspace after being preempted for some unknown amount of time.
Reviewed by: jhb, kib, vangyzen
Approved by: kib (mentor), vangyzen (mentor)
MFC after: 2 weeks
Sponsored by: Dell Inc.
Differential Revision: https://reviews.freebsd.org/D7505
intention of the POSIX IEEE Std 1003.1TM-2008/Cor 1-2013.
A robust mutex is guaranteed to be cleared by the system upon either
thread or process owner termination while the mutex is held. The next
mutex locker is then notified about inconsistent mutex state and can
execute (or abandon) corrective actions.
The patch mostly consists of small changes here and there, adding
neccessary checks for the inconsistent and abandoned conditions into
existing paths. Additionally, the thread exit handler was extended to
iterate over the userspace-maintained list of owned robust mutexes,
unlocking and marking as terminated each of them.
The list of owned robust mutexes cannot be maintained atomically
synchronous with the mutex lock state (it is possible in kernel, but
is too expensive). Instead, for the duration of lock or unlock
operation, the current mutex is remembered in a special slot that is
also checked by the kernel at thread termination.
Kernel must be aware about the per-thread location of the heads of
robust mutex lists and the current active mutex slot. When a thread
touches a robust mutex for the first time, a new umtx op syscall is
issued which informs about location of lists heads.
The umtx sleep queues for PP and PI mutexes are split between
non-robust and robust.
Somewhat unrelated changes in the patch:
1. Style.
2. The fix for proper tdfind() call use in umtxq_sleep_pi() for shared
pi mutexes.
3. Removal of the userspace struct pthread_mutex m_owner field.
4. The sysctl kern.ipc.umtx_vnode_persistent is added, which controls
the lifetime of the shared mutex associated with a vnode' page.
Reviewed by: jilles (previous version, supposedly the objection was fixed)
Discussed with: brooks, Martin Simmons <martin@lispworks.com> (some aspects)
Tested by: pho
Sponsored by: The FreeBSD Foundation
breaking the ABI. Special value is stored in the lock pointer to
indicate shared lock, and offline page in the shared memory is
allocated to store the actual lock.
Reviewed by: vangyzen (previous version)
Discussed with: deischen, emaste, jhb, rwatson,
Martin Simmons <martin@lispworks.com>
Tested by: pho
Sponsored by: The FreeBSD Foundation
self-documented, and eases addition of new ops.
For the similar reasons, eliminate UMTX_OP_MAX. nitems() handles the
only use of the symbol.
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
It looks like umtx_key_get() has the addition and subtraction the wrong
way around, meaning that it fails to match in certain cases. This causes
the cloudlibc unit tests to deadlock in certain cases.
Reviewed by: kib
Differential Revision: https://reviews.freebsd.org/D3287
in this area and by the Clang static analyzer.
Remove some dead assignments.
Fix a typo in a panic string.
Use umtx_pi_disown() instead of duplicate code.
Use an existing variable instead of curthread.
Approved by: kib (mentor)
MFC after: 3 days
Sponsored by: Dell Inc
currently a spin lock. Apparently, the only reason for this is that
umtx_thread_exit() is called under the process spinlock, which put the
requirement on the umtx_lock. Note that the witness static order list
is wrong for the umtx_lock, umtx_lock is explicitely before any thread
lock, so it is also before sleepq locks.
Change umtx_lock to be the sleepable mutex. For the reason above, the
calls to umtx_thread_exit() are moved from thread_exit() earlier in
each caller, when the process spin lock is not yet taken.
Discussed with: jhb
Tested by: pho (previous version)
Sponsored by: The FreeBSD Foundation
MFC after: 3 weeks
