User pending bit should not be set if kernel did not noted a pending signal.
Reviewed by: markj
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D28089
Instead of trying to maintain pg_jobc counter on each process group
update (and sometimes before), just calculate the counter when needed.
Still, for the benefit of the signal delivery code, explicitly mark
orphaned groups as such with the new process group flag.
This way we prevent bugs in the corner cases where updates to the counter
were missed due to complicated configuration of p_pptr/p_opptr/real_parent
(debugger).
Since we need to iterate over all children of the process on exit, this
change mostly affects the process group entry and leave, where we need
to iterate all process group members to detect orpaned status.
(For MFC, keep pg_jobc around but unused).
Reported by: jhb
Reviewed by: jilles
Tested by: pho
MFC after: 2 weeks
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D27871
Check td_flags for relevant AST requests lock-less. This opens the
race slightly wider where sig_intr() returns false negative, but might
be it is worth it.
Requested by: mjg
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
It gives the answer would the thread sleep according to current state
of signals and suspensions. Of course the answer is racy and allows
for false-negatives (no sleep when signal is delivered after process
lock is dropped). Also the answer might change due to signal
rescheduling among threads in multi-threaded process.
Still it is the best approximation I can provide, to answering the
question was the thread interrupted.
Reviewed by: markj
Tested by: pho, rmacklem
Sponsored by: The FreeBSD Foundation
MFC after: 2 weeks
Differential revision: https://reviews.freebsd.org/D26628
- Extract suspension check into sig_ast_checksusp() helper.
- Extract signal check and calculation of the interruption errno into
sig_ast_needsigchk() helper.
The helpers are moved to kern_sig.c which is the proper place for
signal-related code.
Improve control flow in sleepq_catch_signals(), to handle ret == 0
(can sleep) and ret != 0 (interrupted) only once, by separating
checking code into sleepq_check_ast_sq_locked(), which return value is
interpreted at single location.
Reviewed by: markj
Tested by: pho
Sponsored by: The FreeBSD Foundation
MFC after: 2 weeks
Differential revision: https://reviews.freebsd.org/D26628
While rare, encountering an unimplemented system call early in init is
catastrophic and difficult to debug. Even after a SIGSYS handler is
registered, such configurations are problematic. As such, always report
such events for pid 1 (following kern.lognosys if non-zero).
Reviewed by: kevans, imp
Obtained from: CheriBSD (plus suggestions from kevans)
MFC after: 1 week
Sponsored by: DARPA
Differential Revision: https://reviews.freebsd.org/D26288
Consider this scenario:
- kern.corefile=/var/coredumps/%N.%U.%I.core
- multiple processes with the same name crash at the same time
It's possible that one process selects existing file N as oldvp while it
keeps looking for an unused file number. Another process scans through
files and stumbles upon N. That process would be blocked on the vnode
lock while holding the directory vnode exclusively locked. The first
process would, thus, get blocked on the directory's vnode lock.
More generally, holding a file's vnode lock (oldvp) while trying to lock
its directory (for the next lookup) is a violation of the vnode locking
order.
I have observed this deadlock in the wild.
So, the change to keep oldvp "opened" but unlocked and to lock it again
only if it's to be returned as the result.
As kib noted, an alternative would be to keep the directory locked and
to use VOP_LOOKUP directly for scanning through existing core files.
Reviewed by: kib
MFC after: 2 weeks
Differential Revision: https://reviews.freebsd.org/D25027
If single-threaded process receives a signal during critical section
established by sigfastblock(2) word, unblock did not caused signal
delivery because sigfastblock(SIGFASTBLOCK_UNBLOCK) failed to request
ast handling of the pending signals.
Set TDF_ASTPENDING | TDF_NEEDSIGCHK on unblock or when kernel forces
end of sigfastblock critical section, to cause syscall exit to recheck
and deliver any signal pending.
Reported by: corydoras@ridiculousfish.com
PR: 246385
Sponsored by: The FreeBSD Foundation
Modern debuggers and process tracers use ptrace() rather than procfs
for debugging. ptrace() has a supserset of functionality available
via procfs and new debugging features are only added to ptrace().
While the two debugging services share some fields in struct proc,
they each use dedicated fields and separate code. This results in
extra complexity to support a feature that hasn't been enabled in the
default install for several years.
PR: 244939 (exp-run)
Reviewed by: kib, mjg (earlier version)
Relnotes: yes
Differential Revision: https://reviews.freebsd.org/D23837
When clearing sigfastblock, either by sigfastblock(UNSETPTR) call or
implicitly on execve(2), kernel must check for pending signals and
reschedule them if needed.
E.g. on execve, all other threads are terminated, and current thread
fast block pointer is cleaned. If any signal was left pending, it can
now be delivered to the current thread, and we should prepare for
ast() on return to userspace to notice the signals.
Reported and tested by: pho
Sponsored by: The FreeBSD Foundation
It was used after sigfastblock_setpend() call in in ast() when current
thread fast-blocks signals. Add a flag to sigfastblock_setpend() to
request reschedule, and remove the direct use of the function from
subr_trap.c
Tested by: pho
Sponsored by: The FreeBSD Foundation
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
Quiet a variety of Wwrite-strings warnings in sys/kern at low-impact
sites. This patch avoids addressing certain others which would need to
plumb const through structure definitions.
Reviewed by: kib, markj
Differential Revision: https://reviews.freebsd.org/D23798
On machines with SMAP, fueword executes two serializing instructions
which can be seen in microbenchmarks.
As a measure to restore microbenchmark numbers, only read the word on
the attempt to deliver signal in ast(). If the word is set, signal is
not delivered and word is kept, preventing interruption of
interruptible sleeps by signals until userspace calls
sigfastblock(UNBLOCK) which clears the word.
This way, the spurious EINTR that userspace can see while in critical
section is on first interruptible sleep, if a signal is pending, and
on signal posting. It is believed that it is not important for rtld
and lbithr critical sections. It might be visible for the application
code e.g. for the callback of dl_iterate_phdr(3), but again the belief
is that the non-compliance is acceptable. Most important is that the
retry of the sleeping syscall does not interrupt unless additional
signal is posted.
For now I added the knob kern.sigfastblock_fetch_always to enable the
word read on syscall entry to be able to diagnose possible issues due
to spurious EINTR.
While there, do some code restructuting to have all sigfastblock()
handling located in kern_sig.c.
Reviewed by: jeff
Discussed with: mjg
Tested by: pho
Sponsored by: The FreeBSD Foundation
Differential revision: https://reviews.freebsd.org/D23622
A new syscall sigfastblock(2) is added which registers a uint32_t
variable as containing the count of blocks for signal delivery. Its
content is read by kernel on each syscall entry and on AST processing,
non-zero count of blocks is interpreted same as the signal mask
blocking all signals.
The biggest downside of the feature that I see is that memory
corruption that affects the registered fast sigblock location, would
cause quite strange application misbehavior. For instance, the process
would be immune to ^C (but killable by SIGKILL).
With consumers (rtld and libthr added), benchmarks do not show a
slow-down of the syscalls in micro-measurements, and macro benchmarks
like buildworld do not demonstrate a difference. Part of the reason is
that buildworld time is dominated by compiler, and clang already links
to libthr. On the other hand, small utilities typically used by shell
scripts have the total number of syscalls cut by half.
The syscall is not exported from the stable libc version namespace on
purpose. It is intended to be used only by our C runtime
implementation internals.
Tested by: pho
Disscussed with: cem, emaste, jilles
Sponsored by: The FreeBSD Foundation
Differential revision: https://reviews.freebsd.org/D12773
Filesystems which want to use it in limited capacity can employ the
VOP_UNLOCK_FLAGS macro.
Reviewed by: kib (previous version)
Differential Revision: https://reviews.freebsd.org/D21427
Eliminate recursion from most thread_lock consumers. Return from
sched_add() without the thread_lock held. This eliminates unnecessary
atomics and lock word loads as well as reducing the hold time for
scheduler locks. This will eventually allow for lockless remote adds.
Discussed with: kib
Reviewed by: jhb
Tested by: pho
Differential Revision: https://reviews.freebsd.org/D22626
As mandated by POSIX. Also clarify the kill(2) manpage.
While there, restructure the code in killpg1() to use helper which
keeps overall state of the process list iteration in the killpg1_ctx
structued, later used to infer the error returned.
Reported by: amdmi3
Reviewed by: jilles
Sponsored by: The FreeBSD Foundation
MFC after: 2 weeks
Differential revision: https://reviews.freebsd.org/D22621
When RFSPAWN is passed, rfork exhibits vfork(2) semantics but also resets
signal handlers in the child during creation to avoid a point of corruption
of parent state from the child.
This flag will be used by posix_spawn(3) to handle potential signal issues.
Reviewed by: jilles, kib
Differential Revision: https://reviews.freebsd.org/D19058
Add format capability to core file names to include signal
that generated the core. This can help various validation workflows
where all cores should not be considered equally (SIGQUIT is often
intentional and not an error unlike SIGSEGV or SIGBUS)
Submitted by: David Leimbach (leimy2k@gmail.com)
Reviewed by: markj
MFC after: 1 week
Relnotes: sysctl kern.corefile can now include the signal number
Sponsored by: Dell EMC Isilon
Differential Revision: https://reviews.freebsd.org/D20970
into existing files for sugid processes.
Despite using real user id pronounces the intent, it actually breaks
suid coredumps, while not making any difference for non-sugid
processes. The reason for the breakage is that non-existent core file
is created with the effective uid (unless weird hacks like SUIDDIR are
configured).
Then, if user enabled kern.sugid_coredump, core dumping should not
overwrite core files owned by effective uid, but we cannot pretend to
use real uid for dumping.
PR: 68905
admbugs: 358
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
PT_ATTACH was consumed.
In particular, do not clear TDP_FSTP in ptracestop() if td_wchan is
non-NULL. Leave it to sleepq_catch_signal() to clear and convert zero
return code to EINTR.
Otherwise, per submitter report, if the PT_ATTACH SIGSTOP was
delivered right after the thread was added to the sleepqueue but not
yet really sleep, and cursig() caused debugger attach, the thread
sleeps instead of returning to the userspace boundary with EINTR.
PR: 231445
Reported by: Efi Weiss <valmarelox@gmail.com>
Reviewed by: markj
Sponsored by: The FreeBSD Foundation
MFC after: 2 weeks
Differential revision: https://reviews.freebsd.org/D20381
Contrary to the comments, it was never used by core dumps or
debuggers. Instead, it used to hold the signal code of a pending
signal, but that was replaced by the 'ksi_code' member of ksiginfo_t
when signal information was reworked in 7.0.
Reviewed by: kib
Differential Revision: https://reviews.freebsd.org/D20047
Kernel now includes jail ID when logging a process exit. jid is 0 for unjailed
processes.
Submitted by: Marie Helene Kvello-Aune <freebsd@mhka.no>
Relnotes: yes
Sponsored by: Modirum MDPay
Differential Revision: https://reviews.freebsd.org/D18618
Once a signal's siginfo was copied to 'td_si' as part of the signal
exchange in issignal(), it was never cleared. This caused future
thread events that are reported as SIGTRAP events without signal
information to report the stale siginfo in 'td_si'. For example, if a
debugger created a new process and used SIGSTOP to stop it after
PT_ATTACH, future system call entry / exit events would set PL_FLAG_SI
with the SIGSTOP siginfo in pl_siginfo. This broke 'catch syscall' in
current versions of gdb as it assumed PL_FLAG_SI with SIGTRAP
indicates a breakpoint or single step trap.
Reviewed by: kib
MFC after: 1 week
Differential Revision: https://reviews.freebsd.org/D18487
Avoid relying on unsigned overflow for the test.
Simplify expressions to avoid duplicate check for the range.
Style.
Add herald comment.
Reviewed by: jhb
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
Differential revision: https://reviews.freebsd.org/D18361
Swapped-out process that is WKILLED must be swapped in as soon as
possible. The reason is that such process can be killed by OOM and
its pages can be only freed if the process exits. To exit, the kernel
stack of the process must be mapped.
When allocating pages for the stack of the WKILLED process on swap in,
use VM_ALLOC_SYSTEM requests to increase the chance of the allocation
to succeed.
Add counter of the swapped out processes to avoid unneeded iteration
over the allprocs list when there is no work to do, reducing the
allproc_lock ownership.
Reviewed by: alc, markj (previous version)
Tested by: pho
Sponsored by: The FreeBSD Foundation
MFC after: 2 weeks
Differential revision: https://reviews.freebsd.org/D16489
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
The '%I' format in the kern.corefile sysctl limits the number of
core files that a process can generate to the number stored in the
debug.ncores sysctl. The '%I' format is replaced by the single digit
index. Previously, if all indexes were taken the kernel would overwrite
only a core file with the highest index in a filename.
Currently the system will create a new core file if there is a free
index or if all slots are taken it will overwrite the oldest one.
Reviewed by: kib(code), bcr (updating)
Differential Revision: https://reviews.freebsd.org/D15991
Differential Revision: https://reviews.freebsd.org/D16084
We have a problem with vn_fullpath_global when the file exists. Work
around it by printing the full path if the core file name starts with /,
or current working directory followed by the filename if not.
Sponsored by: Netflix
Differential Review: https://reviews.freebsd.org/D16026
An RFSTOPPED thread can't clean TDB_STOPATFORK, which is done in the
fork_return() in its context, so parent is stuck forever. Triggered
when trying to ptrace linux process. Instead of waiting for the new
thread to clear TDB_STOPATFORK, tag it as traced and reparent to the
debugger in do_fork(), and let it only notify the debugger when run.
Submitted by: Yanko Yankulov <yanko.yankulov@gmail.com>
Reviewed by: jhb
MFC after: 1 week
X-MFC-Note: keep p_dbgwait placeholder intact
Differential revision: https://reviews.freebsd.org/D15857
- Add macros to allow preinitialization of cap_rights_t.
- Convert most commonly used code paths to use preinitialized cap_rights_t.
A 3.6% speedup in fstat was measured with this change.
Reported by: mjg
Reviewed by: oshogbo
Approved by: sbruno
MFC after: 1 month
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
