Priority ceiling semaphores (in contrast to MrsP semaphores) have only
one priority ceiling which is defined for the home scheduler of the task
which created the semaphore. Always check during a semaphore seize that
the home scheduler of the calling task is equal to this scheduler.
This avoids a scheduler mismatch if the semphore is acquired after the
calling thread blocked on the semaphore.
This change is a slight performance optimization for systems with a slow
64-bit division.
The th->th_scale and th->th_large_delta values only depend on the
timecounter frequency and the th->th_adjustment. The timecounter
frequency of a timehand only changes when a new timecounter is activated
for the timehand. The th->th_adjustment is only changed by the NTP
second update. The NTP second update is not done for every call of
tc_windup().
Move the code block to recalculate the scaling factor and
the large delta of a timehand to the new helper function
recalculate_scaling_factor_and_large_delta().
Call recalculate_scaling_factor_and_large_delta() when a new timecounter
is activated and a NTP second update occurred.
MFC after: 1 week
Timecounter registration is dynamic, i.e., there is no requirement that
timecounters must be registered during single-threaded boot. Loadable
drivers may in principle register timecounters (which can be switched to
automatically). Timecounters cannot be unregistered, though this could
be implemented.
Registered timecounters belong to a global linked list. Add a mutex to
synchronize insertions and the traversals done by (mpsafe) sysctl
handlers. No functional change intended.
Reviewed by: imp, kib
MFC after: 2 weeks
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D32511
FreeBSD Foundation sys/ copyrights
These ones were unambiguous cases where the Foundation was the only
listed copyright holder (in the associated license block).
Sponsored by: The FreeBSD Foundation
In FreeBSD, the current time is computed from uptime + boottime. Uptime
is a continuous, smooth function that's monotonically increasing. To
effect changes to the current time, boottime is adjusted. boottime is
mutable and shouldn't be cached against future need. Document the
current implementation, with the caveat that we may stop stepping
boottime on resume in the future and will step uptime instead (noted in
the commit message, but not in the code).
Sponsored by: Netflix
Reviewed by: phk, rpokala
Differential Revision: https://reviews.freebsd.org/D30116
on freebsd/arm64:
- Implement a dtrace_getnanouptime(), matching the existing
dtrace_getnanotime(), to avoid DTrace calling out to a potentially
instrumentable function.
(These should probably both be under KDTRACE_HOOKS. Also, it's not clear
to me that they are correct implementations for the DTrace thread time
functions they are used in .. fixes for another commit.)
- Don't allow FBT to instrument functions involved in EL1 exception handling
that are involved in FBT trap processing: handle_el1h_sync() and
do_el1h_sync().
- Don't allow FBT to instrument DDB and KDB functions, as that makes it
rather harder to debug FBT problems.
Prior to these changes, use of FBT on FreeBSD/arm64 rapidly led to kernel
panics due to recursion in DTrace.
Reliable FBT on FreeBSD/arm64 is reliant on another change from @andrew to
have the aarch64 instrumentor more carefully check that instructions it
replaces are against the stack pointer, which can otherwise lead to memory
corruption. That change remains under review.
MFC after: 2 weeks
Reviewed by: andrew, kp, markj (earlier version), jrtc27 (earlier version)
Differential revision: https://reviews.freebsd.org/D27766
to warm timecounters.
It seems that second call does not add any useful state change for all
implemented timecounters.
Discussed with: bde
Sponsored by: The FreeBSD Foundation
MFC after: 3 weeks
or CTLFLAG_NEEDGIANT (17 of many)
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 fix possible overflow in bintime()/binuptime().
The algorithm to read the consistent snapshot of current timehand is
repeated in each accessor, including the details proper rollup
detection and synchronization with the writer. In fact there are only
two different kind of readers: one for bintime()/binuptime() which has
to do the in-place calculation, and another kind which fetches some
member from struct timehand.
Extract the logic into type-checked macros, GETTHBINTIME() for bintime
calculation, and GETTHMEMBER() for safe read of a structure' member.
This way, the synchronization is only written in bintime_off() and
getthmember().
In bintime_off(), use overflow-safe calculation of th_scale *
delta(timecounter). In tc_windup, pre-calculate the min delta value
which overflows and require slow algorithm, into the new timehands
th_large_delta member.
This part with overflow fix was written by Bruce Evans.
Reported by: Mark Millard <marklmi@yahoo.com> (the overflow issue)
Tested by: pho
Discussed with: emaste
Sponsored by: The FreeBSD Foundation (kib)
MFC after: 3 weeks
On arm64 (and possible other architectures) we are unable to use static
DPCPU data in kernel modules. This is because the compiler will generate
PC-relative accesses, however the runtime-linker expects to be able to
relocate these.
In preparation to fix this create two macros depending on if the data is
global or static.
Reviewed by: bz, emaste, markj
Sponsored by: ABT Systems Ltd
Differential Revision: https://reviews.freebsd.org/D16140
to opt_global.h.
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
In this case volatile qualifiers enusre that a compiler does not
optimize the accesses out.
Reviewed by: alc, jhb
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
Differential revision: https://reviews.freebsd.org/D13534
This patch set replaces the CPU budget algorithm enumeration with a set of CPU
budget operations which implement a particular CPU budget algorithm. This
helps to hide the CPU budget algorithm implementation details from the general
thread handling. The CPU budget callouts are turned into CPU budget
operations. This slightly reduces the size of the thread control block.
All schedulers used the default scheduler tick implementation. The tick
scheduler operation is removed and the CPU budget operations are directly used
in _Watchdog_Tick() if the executing thread uses a CPU budget algorithm. This
is performance improvement for all threads which do not use a CPU budget
algorithm (default behaviour).
This fix came from Code Inspector, flagged by one of the analysis that
was done.
This test code is compiled only but better to address the issues so
future static analysis reports will not include it.
Debug events should be masked at least until after the first context
switch and should usually be masked until a debugger is attached for
application debugging.
The existing code is functional but inccorrect and blindly modifies the
other masking bits. It is important to preserve those other bits since
they control masking of important system events.
Certain input parameters for MMU mapping operations could cause an
infinite recursion if block end boundaries didn't align to 4k. This
ensures that recursion descent does not exceed 2 levels and instead
rounds up to the nearest 4k block if necessary.
This moves the AArch64 MMU memory type definitions into cpukit for use
by libdebugger since remapping of memory is required to insert software
breakpoints.
The N used in the breakpoint and watchpoint register names is intended
to be an integer between 0 and 15 (inclusive) and will not compile when
used as is. This adds the accessors necessary to access all of these
breakpoint and watchpoint registers.
This adds a confdef option allowing an application to request mapping
machine exceptions to POSIX signals. This is required for some languages
such as Ada.
