- Copy stable/10 (r259064) to releng/10.0 as part of the
10.0-RELEASE cycle.
- Update __FreeBSD_version [1]
- Set branch name to -RC1

[1] 10.0-CURRENT __FreeBSD_version value ended at '55', so
start releng/10.0 at '100' so the branch is started with
a value ending in zero.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Partially revert r195702. Deferring stops is now implemented via a set of
calls to toggle TDF_SBDRY rather than passing PBDRY to individual sleep
calls.
- Remove the stop_allowed parameters from cursig() and issignal().
issignal() checks TDF_SBDRY directly.
- Remove the PBDRY and SLEEPQ_STOP_ON_BDRY flags.

Further refine the handling of stop signals in the NFS client. The
changes in r246417 were incomplete as they did not add explicit calls to
sigdeferstop() around all the places that previously passed SBDRY to
_sleep(). In addition, nfs_getcacheblk() could trigger a write RPC from
getblk() resulting in sigdeferstop() recursing. Rather than manually
deferring stop signals in specific places, change the VFS_*() and VOP_*()
methods to defer stop signals for filesystems which request this behavior
via a new VFCF_SBDRY flag. Note that this has to be a VFC flag rather than
a MNTK flag so that it works properly with VFS_MOUNT() when the mount is
not yet fully constructed. For now, only the NFS clients are set this new
flag in VFS_SET().

A few other related changes:
- Add an assertion to ensure that TDF_SBDRY doesn't leak to userland.
- When a lookup request uses VOP_READLINK() to follow a symlink, mark
the request as being on behalf of the thread performing the lookup
(cnp_thread) rather than using a NULL thread pointer. This causes
NFS to properly handle signals during this VOP on an interruptible
mount.

PR: kern/176179
Reported by: Russell Cattelan (sigdeferstop() recursion)
Reviewed by: kib
MFC after: 1 month

Rework the handling of stop signals in the NFS client. The changes in
195702, 195703, and 195821 prevented a thread from suspending while holding
locks inside of NFS by forcing the thread to fail sleeps with EINTR or
ERESTART but defer the thread suspension to the user boundary. However,
this had the effect that stopping a process during an NFS request could
abort the request and trigger EINTR errors that were visible to userland
processes (previously the thread would have suspended and completed the
request once it was resumed).

This change instead effectively masks stop signals while in the NFS client.
It uses the existing TDF_SBDRY flag to effect this since SIGSTOP cannot
be masked directly. Also, instead of setting PBDRY on individual sleeps,
the NFS client now sets the TDF_SBDRY flag around each NFS request and
stop signals are masked for all sleeps during that region (the previous
change missed sleeps in lockmgr locks). The end result is that stop
signals sent to threads performing an NFS request are completely
ignored until after the NFS request has finished processing and the
thread prepares to return to userland. This restores the behavior of
stop signals being transparent to userland processes while still
preventing threads from suspending while holding NFS locks.

Reviewed by: kib
MFC after: 1 month

In order to maximize the re-usability of kernel code in user space this
patch modifies makesyscalls.sh to prefix all of the non-compatibility
calls (e.g. not linux_, freebsd32_) with sys_ and updates the kernel
entry points and all places in the code that use them. It also
fixes an additional name space collision between the kernel function
psignal and the libc function of the same name by renaming the kernel
psignal kern_psignal(). By introducing this change now we will ease future
MFCs that change syscalls.

Reviewed by: rwatson
Approved by: re (bz)

Create a global thread hash table to speed up thread lookup, use
rwlock to protect the table. In old code, thread lookup is done with
process lock held, to find a thread, kernel has to iterate through
process and thread list, this is quite inefficient.
With this change, test shows in extreme case performance is
dramatically improved.

Earlier patch was reviewed by: jhb, julian

- Various style and whitespace fixes.
- Make sugid_coredump and kern_logsigexit private to kern_sig.c.

Submitted by: bde (partially)
MFC after: 1 month

Move prototypes for kern_sigtimedwait() and kern_sigprocmask() to
<sys/syscallsubr.h> where all other kern_<syscall> prototypes live.

Sort function prototypes (since I didn't manage to insert tdksignal()
correctly).

Tweak the in-kernel API for sending signals to threads:
- Rename tdsignal() to tdsendsignal() and make it private to kern_sig.c.
- Add tdsignal() and tdksignal() routines that mirror psignal() and
pksignal() except that they accept a thread as an argument instead of
a process. They send a signal to a specific thread rather than to an
individual process.

Reviewed by: kib

Staticise sigqueue manipulation functions used only in kern_sig.c.

MFC after: 1 week

When traced process is about to receive the signal, the process is
stopped and debugger may modify or drop the signal. After the changes to
keep process-targeted signals on the process sigqueue, another thread
may note the old signal on the queue and act before the thread removes
changed or dropped signal from the process queue. Since process is
traced, it usually gets stopped. Or, if the same signal is delivered
while process was stopped, the thread may erronously remove it,
intending to remove the original signal.

Remove the signal from the queue before notifying the debugger. Restore
the siginfo to the head of sigqueue when signal is allowed to be
delivered to the debugee, using newly introduced KSI_HEAD ksiginfo_t
flag. This preserves required order of delivery. Always restore the
unchanged signal on the curthread sigqueue, not to the process queue,
since the thread is about to get it anyway, because sigmask cannot be
changed.

Handle failure of reinserting the siginfo into the queue by falling
back to sq_kill method, calling sigqueue_add with NULL ksi.

If debugger changed the signal to be delivered, use sigqueue_add()
with NULL ksi instead of only setting sq_signals bit.

Reported by: Gardner Bell <gbell72 rogers com>
Analyzed and first version of fix by: Tijl Coosemans <tijl coosemans org>
PR: 142757
Reviewed by: davidxu
MFC after: 2 weeks

Implement sighold, sigignore, sigpause, sigrelse, sigset functions
from SUSv4 XSI. Note that the functions are obsoleted, and only
provided to ease porting from System V-like systems. Since sigpause
already exists in compat with different interface, XSI sigpause is
named xsi_sigpause.

Reviewed by: davidxu
MFC after: 3 weeks

Among signal generation syscalls, only sigqueue(2) is allowed by POSIX
to fail due to lack of resources to queue siginfo. Add KSI_SIGQ flag
that allows sigqueue_add() to fail while trying to allocate memory for
new siginfo. When the flag is not set, behaviour is the same as for
KSI_TRAP: if memory cannot be allocated, set bit in sq_kill. KSI_TRAP is
kept to preserve KBI.

Add SI_KERNEL si_code, to be used in siginfo.si_code when signal is
generated by kernel. Deliver siginfo when signal is generated by kill(2)
family of syscalls (SI_USER with properly filled si_uid and si_pid), or
by kernel (SI_KERNEL, mostly job control or SIGIO). Since KSI_SIGQ flag
is not set for the ksi, low memory condition cause old behaviour.

Keep psignal(9) KBI intact, but modify it to generate SI_KERNEL
si_code. Pgsignal(9) and gsignal(9) now take ksi explicitely. Add
pksignal(9) that behaves like psignal but takes ksi, and ddb kill
command implemented as pksignal(..., ksi = NULL) to not do allocation
while in debugger.

While there, remove some register specifiers and use ANSI C prototypes.

Reviewed by: davidxu
MFC after: 1 month

In r198506, kern_sigsuspend() started doing cursig/postsig loop to make
sure that a signal was delivered to the thread before returning from
syscall. Signal delivery puts new return frame on the user stack, and
modifies trap frame to enter signal handler. As a consequence, syscall
return code sets EINTR as error return for signal frame, instead of the
syscall return.

Also, for ia64, due to different registers layout for those two kind of
frames, usermode sigsegfaulted when returned from signal handler.

Use newly-introduced cpu_set_syscall_retval(9) to set syscall result,
and return EJUSTRETURN from kern_sigsuspend() to prevent syscall return
code from modifying this frame [1].

Another issue is that pending SIGCONT might be cancelled by SIGSTOP,
causing postsig() not to deliver any catched signal [2]. Modify
postsig() to return 1 if signal was posted, and 0 otherwise, and use
this in the kern_sigsuspend loop.

Proposed by: marcel [1]
Noted by: davidxu [2]
Reviewed by: marcel, davidxu
MFC after: 1 month

Trapsignal() and postsig() call kern_sigprocmask() with both process
lock and curproc->p_sigacts->ps_mtx. Reschedule_signals may need to have
ps_mtx locked to decide and wakeup a thread, causing recursion on the
mutex.

Inform kern_sigprocmask() and reschedule_signals() about lock state
of the ps_mtx by new flag SIGPROCMASK_PS_LOCKED to avoid recursion.

Reported and tested by: keramida
MFC after: 1 month

In kern_sigsuspend(), better manipulate thread signal mask using
kern_sigprocmask() to properly notify other possible candidate threads
for signal delivery.

Since sigsuspend() shall only return to usermode after a signal was
delivered, do cursig/postsig loop immediately after waiting for
signal, repeating the wait if wakeup was spurious due to race with
other thread fetching signal from the process queue before us. Add
thread_suspend_check() call to allow the thread to be stopped or killed
while in loop.

Modify last argument of kern_sigprocmask() from boolean to flags,
allowing the function to be called with locked proc. Convertion of the
callers that supplied 1 to the old argument will be done in the next
commit, and due to SIGPROCMASK_OLD value equial to 1, code is formally
correct in between.

Reviewed by: davidxu
Tested by: pho
MFC after: 1 month

Currently, when signal is delivered to the process and there is a thread
not blocking the signal, signal is placed on the thread sigqueue. If
the selected thread is in kernel executing thr_exit() or sigprocmask()
syscalls, then signal might be not delivered to usermode for arbitrary
amount of time, and for exiting thread it is lost.

Put process-directed signals to the process queue unconditionally,
selecting the thread to deliver the signal only by the thread returning
to usermode, since only then the thread can handle delivery of signal
reliably. For exiting thread or thread that has blocked some signals,
check whether the newly blocked signal is queued for the process, and
try to find a thread to wakeup for delivery, in reschedule_signal(). For
exiting thread, assume that all signals are blocked.

Change cursig() and postsig() to look both into the thread and process
signal queues. When there is a signal that thread returning to usermode
could consume, TDF_NEEDSIGCHK flag is not neccessary set now. Do
unlocked read of p_siglist and p_pendingcnt to check for queued signals.

Note that thread that has a signal unblocked might get spurious wakeup
and EINTR from the interruptible system call now, due to the possibility
of being selected by reschedule_signals(), while other thread returned
to usermode earlier and removed the signal from process queue. This
should not cause compliance issues, since the thread has not blocked a
signal and thus should be ready to receive it anyway.

Reported by: Justin Teller <justin.teller gmail com>
Reviewed by: davidxu, jilles
MFC after: 1 month

Add new msleep(9) flag PBDY that shall be specified together with
PCATCH, to indicate that thread shall not be stopped upon receipt of
SIGSTOP until it reaches the kernel->usermode boundary.

Also change thread_single(SINGLE_NO_EXIT) to only stop threads at
the user boundary unconditionally.

Tested by: pho
Reviewed by: jhb
Approved by: re (kensmith)

Fix for the panic("vm_thread_new: kstack allocation failed") and
silent NULL pointer dereference in the i386 and sparc64 pmap_pinit()
when the kmem_alloc_nofault() failed to allocate address space. Both
functions now return error instead of panicing or dereferencing NULL.

As consequence, vmspace_exec() and vmspace_unshare() returns the errno
int. struct vmspace arg was added to vm_forkproc() to avoid dealing
with failed allocation when most of the fork1() job is already done.

The kernel stack for the thread is now set up in the thread_alloc(),
that itself may return NULL. Also, allocation of the first process
thread is performed in the fork1() to properly deal with stack
allocation failure. proc_linkup() is separated into proc_linkup()
called from fork1(), and proc_linkup0(), that is used to set up the
kernel process (was known as swapper).

In collaboration with: Peter Holm
Reviewed by: jhb

Move some declaration of 32-bit signal structures into file
freebsd32-signal.h, implement sigtimedwait and sigwaitinfo system calls.

Add signal set sq_kill to sigqueue structure, the member saves all
signals sent by kill() syscall, without this, a signal sent by
sigqueue() can cause a signal sent by kill() to be lost.

Sync with signal.h.

Add support for queueing SIGCHLD same as other UNIX systems did.

For each child process whose status has been changed, a SIGCHLD instance
is queued, if the signal is stilling pending, and process changed status
several times, signal information is updated to reflect latest process
status. If wait() returns because the status of a child process is
available, pending SIGCHLD signal associated with the child process is
discarded. Any other pending SIGCHLD signals remain pending.

The signal information is allocated at the same time when proc structure
is allocated, if process signal queue is fully filled or there is a memory
shortage, it can still send the signal to process.

There is a booting time tunable kern.sigqueue.queue_sigchild which
can control the behavior, setting it to zero disables the SIGCHLD queueing
feature, the tunable will be removed if the function is proved that it is
stable enough.

Tested on: i386 (SMP and UP)

Cleanup some signal interfaces. Now the tdsignal function accepts
both proc pointer and thread pointer, if thread pointer is NULL,
tdsignal automatically finds a thread, otherwise it sends signal
to given thread.
Add utility function psignal_event to send a realtime sigevent
to a process according to the delivery requirement specified in
struct sigevent.

Fix sigevent's POSIX incompatible problem by adding member fields
sigev_notify_function and sigev_notify_attributes. AIO syscalls
use sigevent, so they have to be adjusted.

Reviewed by: alc

1. Make ksiginfo_alloc and ksiginfo_free public.
2. Introduce flags KSI_EXT and KSI_INS. The flag KSI_EXT allows a ksiginfo
to be managed by outside code, the KSI_INS indicates sigqueue_add should
directly insert passed ksiginfo into queue other than copy it.

1. Change prototype of trapsignal and sendsig to use ksiginfo_t *, most
changes in MD code are trivial, before this change, trapsignal and
sendsig use discrete parameters, now they uses member fields of
ksiginfo_t structure. For sendsig, this change allows us to pass
POSIX realtime signal value to user code.

2. Remove cpu_thread_siginfo, it is no longer needed because we now always
generate ksiginfo_t data and feed it to libpthread.

3. Add p_sigqueue to proc structure to hold shared signals which were
blocked by all threads in the proc.

4. Add td_sigqueue to thread structure to hold all signals delivered to
thread.

5. i386 and amd64 now return POSIX standard si_code, other arches will
be fixed.

6. In this sigqueue implementation, pending signal set is kept as before,
an extra siginfo list holds additional siginfo_t data for signals.
kernel code uses psignal() still behavior as before, it won't be failed
even under memory pressure, only exception is when deleting a signal,
we should call sigqueue_delete to remove signal from sigqueue but
not SIGDELSET. Current there is no kernel code will deliver a signal
with additional data, so kernel should be as stable as before,
a ksiginfo can carry more information, for example, allow signal to
be delivered but throw away siginfo data if memory is not enough.
SIGKILL and SIGSTOP have fast path in sigqueue_add, because they can
not be caught or masked.
The sigqueue() syscall allows user code to queue a signal to target
process, if resource is unavailable, EAGAIN will be returned as
specification said.
Just before thread exits, signal queue memory will be freed by
sigqueue_flush.
Current, all signals are allowed to be queued, not only realtime signals.

Earlier patch reviewed by: jhb, deischen
Tested on: i386, amd64

Add ksiginfo_t which is a wrapper of siginfo_t but allows us to carry
more information which should not be in siginfo_t.

Reviewed by: jhb, deischen

/* -> /*- for license, minor formatting changes

Add code to support debugging threaded process.

1. Add tm_lwpid into kse_thr_mailbox to indicate which kernel
thread current user thread is running on. Add tm_dflags into
kse_thr_mailbox, the flags is written by debugger, it tells
UTS and kernel what should be done when the process is being
debugged, current, there two flags TMDF_SSTEP and TMDF_DONOTRUNUSER.

TMDF_SSTEP is used to tell kernel to turn on single stepping,
or turn off if it is not set.

TMDF_DONOTRUNUSER is used to tell kernel to schedule upcall
whenever possible, to UTS, it means do not run the user thread
until debugger clears it, this behaviour is necessary because
gdb wants to resume only one thread when the thread's pc is
at a breakpoint, and thread needs to go forward, in order to
avoid other threads sneak pass the breakpoints, it needs to remove
breakpoint, only wants one thread to go. Also, add km_lwp to
kse_mailbox, the lwp id is copied to kse_thr_mailbox at context
switch time when process is not being debugged, so when process
is attached, debugger can map kernel thread to user thread.

2. Add p_xthread to proc strcuture and td_xsig to thread structure.
p_xthread is used by a thread when it wants to report event
to debugger, every thread can set the pointer, especially, when
it is used in ptracestop, it is the last thread reporting event
will win the race. Every thread has a td_xsig to exchange signal
with debugger, thread uses TDF_XSIG flag to indicate it is reporting
signal to debugger, if the flag is not cleared, thread will keep
retrying until it is cleared by debugger, p_xthread may be
used by debugger to indicate CURRENT thread. The p_xstat is still
in proc structure to keep wait() to work, in future, we may
just use td_xsig.

3. Add TDF_DBSUSPEND flag, the flag is used by debugger to suspend
a thread. When process stops, debugger can set the flag for
thread, thread will check the flag in thread_suspend_check,
enters a loop, unless it is cleared by debugger, process is
detached or process is existing. The flag is also checked in
ptracestop, so debugger can temporarily suspend a thread even
if the thread wants to exchange signal.

4. Current, in ptrace, we always resume all threads, but if a thread
has already a TDF_DBSUSPEND flag set by debugger, it won't run.

Encouraged by: marcel, julian, deischen

Remove advertising clause from University of California Regent's license,
per letter dated July 22, 1999.

Approved by: core

If a thread masks all its signal, in cursig(), no signal will be exchanged
with debugger, so testing P_TRACED in SIGPENDING is useless. This test also
is the culprit which causes lots of 'failed to set signal flags properly for
ast()' to be printed on console which is just a false complaint.

Move some tracing related code into its own function as it will
be needed for system call related ptrace functionality I plan
to commit soon.

Signals sent specifically to a particular thread must
be delivered to that thread, regardless of whether it
has it masked or not.

Previously, if the targeted thread had the signal masked,
it would be put on the processes' siglist. If
another thread has the signal umasked or unmasks it before
the target, then the thread it was intended for would never
receive it.

This patch attempts to solve the problem by requiring callers
of tdsignal() to say whether the signal is for the thread or
for the process. If it is for the process, then normal processing
occurs and any thread that has it unmasked can receive it.
But if it is destined for a specific thread, it is put on
that thread's pending list regardless of whether it is currently
masked or not.

The new behaviour still needs more work, though. If the signal
is reposted for some reason it is always posted back to the
thread that handled it because the information regarding the
target of the signal has been lost by then.

Reviewed by: jdp, jeff, bde (style)

Add <sys/queue.h> to unbreak world.

Approved by: re (scottl)

- Merge struct procsig with struct sigacts.
- Move struct sigacts out of the u-area and malloc() it using the
M_SUBPROC malloc bucket.
- Add a small sigacts_*() API for managing sigacts structures: sigacts_alloc(),
sigacts_free(), sigacts_copy(), sigacts_share(), and sigacts_shared().
- Remove the p_sigignore, p_sigacts, and p_sigcatch macros.
- Add a mutex to struct sigacts that protects all the members of the struct.
- Add sigacts locking.
- Remove Giant from nosys(), kill(), killpg(), and kern_sigaction() now
that sigacts is locked.
- Several in-kernel functions such as psignal(), tdsignal(), trapsignal(),
and thread_stopped() are now MP safe.

Reviewed by: arch@
Approved by: re (rwatson)

Make issignal() private to kern_sig.c since it is only called from cursig()
and cursig() is now a function rather than a macro.

Style fixes to struct sigacts member comments. Sort function prototypes.

- Define sigwait, sigtimedwait, and sigwaitinfo in terms of
kern_sigtimedwait() which is capable of supporting all of their semantics.
- These should be POSIX compliant but more careful review is needed before
we announce this.

- Move p->p_sigmask to td->td_sigmask. Signal masks will be per thread with
a follow on commit to kern_sig.c
- signotify() now operates on a thread since unmasked pending signals are
stored in the thread.
- PS_NEEDSIGCHK moves to TDF_NEEDSIGCHK.

- Change trapsignal() to accept a thread and not a proc.
- Change all consumers to pass in a thread.

Right now this does not cause any functional changes but it will be important
later when signals can be delivered to specific threads.

Split 4.x and 5.x signal handling so that we can keep 4.x signal
handling clean and functional as 5.x evolves. This allows some of the
nasty bandaids in the 5.x codepaths to be unwound.

Encapsulate 4.x signal handling under COMPAT_FREEBSD4 (there is an
anti-foot-shooting measure in place, 5.x folks need this for a while) and
finish encapsulating the older stuff under COMPAT_43. Since the ancient
stuff is required on alpha (longjmp(3) passes a 'struct osigcontext *'
to the current sigreturn(2), instead of the 'ucontext_t *' that sigreturn
is supposed to take), add a compile time check to prevent foot shooting
there too. Add uniform COMPAT_43 stubs for ia64/sparc64/powerpc.

Tested on: i386, alpha, ia64. Compiled on sparc64 (a few days ago).
Approved by: re

Put parentheses around function-like macros to shut up warnings.

Part 1 of KSE-III

The ability to schedule multiple threads per process
(one one cpu) by making ALL system calls optionally asynchronous.
to come: ia64 and power-pc patches, patches for gdb, test program (in tools)

Reviewed by: Almost everyone who counts
(at various times, peter, jhb, matt, alfred, mini, bernd,
and a cast of thousands)

NOTE: this is still Beta code, and contains lots of debugging stuff.
expect slight instability in signals..

CURSIG() is not a macro so rename it cursig().

Obtained from: KSE tree

Redo the sigio locking.

Turn the sigio sx into a mutex.

Sigio lock is really only needed to protect interrupts from dereferencing
the sigio pointer in an object when the sigio itself is being destroyed.

In order to do this in the most unintrusive manner change pgsigio's
sigio * argument into a **, that way we can lock internally to the
function.

Revert the change of #includes in sys/filedesc.h and sys/socketvar.h.

Requested by: bde

Since locking sigio_lock is usually followed by calling pgsigio(),
move the declaration of sigio_lock and the definitions of SIGIO_*() to
sys/signalvar.h.

While I am here, sort include files alphabetically, where possible.

Moved signal handling and rescheduling from userret() to ast() so that
they aren't in the usual path of execution for syscalls and traps.
The main complication for this is that we have to set flags to control
ast() everywhere that changes the signal mask.

Avoid locking in userret() in most of the remaining cases.

Submitted by: luoqi (first part only, long ago, reorganized by me)
Reminded by: dillon

Optimized the check for unmasked pending signals in CURSIG() using a new
inline function sigsetmasked() and a new macro SIGPENDING(). CURSIG()
will soon be moved out of the normal path of execution for syscalls and
traps. Then its efficiency will be less important but the new interfaces
will be useful for checking for unmasked pending signals in more places.

Submitted by: luoqi (long ago, in a slightly different form)

Assert that sched_lock is not held in CURSIG().

Remove __P

Use struct __ucontext in prototypes and associated functions instead of
ucontext_t. Forward declare struct __ucontext in <sys/signal.h> and
remove reliance on <sys/ucontext.h> being included.

While I'm here, also hide osigcontext types from userland; suggested
by bde.

Namespace pollution noticed by: Kevin Day <toasty@shell.dragondata.com>

KSE Milestone 2
Note ALL MODULES MUST BE RECOMPILED
make the kernel aware that there are smaller units of scheduling than the
process. (but only allow one thread per process at this time).
This is functionally equivalent to teh previousl -current except
that there is a thread associated with each process.

Sorry john! (your next MFC will be a doosie!)

Reviewed by: peter@freebsd.org, dillon@freebsd.org

X-MFC after: ha ha ha ha

style(9) the structure definitions.

Forced commit; Previous commit was to remove check_sigacts() that was
added with the linuxthreads commit but appears to have never been used.

*** empty log message ***

Declare sigexit() as non-returning.

Fixed some style bugs.

Uninlined CURSIG() and unpolluted <sys/signalvar.h>. CURSIG() had become
very bloated, first with 128-bit sigset_t's, then with locking in the
SMP case, then with locking in all cases. The space bloat was probably
also time bloat, partly because the fast path through CURSIG() was
pessimized by the sigset_t changes. This change speeds up lmbench's
pipe-based latency benchmark by 4% on a Celeron. <sys/signalvar.h>
had become very polluted to support the bloat.

Major update to the way synchronization is done in the kernel. Highlights
include:

* Mutual exclusion is used instead of spl*(). See mutex(9). (Note: The
alpha port is still in transition and currently uses both.)

* Per-CPU idle processes.

* Interrupts are run in their own separate kernel threads and can be
preempted (i386 only).

Partially contributed by: BSDi (BSD/OS)
Submissions by (at least): cp, dfr, dillon, grog, jake, jhb, sheldonh

fix warning, declare function static.

Reviewed by: dfr

Functions may be static and __inline, but not extern and __inline. This
should fix broken no-"-O" kernel builds.

The SMP cleanup commit broke UP compiles. Make UP compiles work again.

Commit major SMP cleanups and move the BGL (big giant lock) in the
syscall path inward. A system call may select whether it needs the MP
lock or not (the default being that it does need it).

A great deal of conditional SMP code for various deadended experiments
has been removed. 'cil' and 'cml' have been removed entirely, and the
locking around the cpl has been removed. The conditional
separately-locked fast-interrupt code has been removed, meaning that
interrupts must hold the CPL now (but they pretty much had to anyway).
Another reason for doing this is that the original separate-lock for
interrupts just doesn't apply to the interrupt thread mechanism being
contemplated.

Modifications to the cpl may now ONLY occur while holding the MP
lock. For example, if an otherwise MP safe syscall needs to mess with
the cpl, it must hold the MP lock for the duration and must (as usual)
save/restore the cpl in a nested fashion.

This is precursor work for the real meat coming later: avoiding having
to hold the MP lock for common syscalls and I/O's and interrupt threads.
It is expected that the spl mechanisms and new interrupt threading
mechanisms will be able to run in tandem, allowing a slow piecemeal
transition to occur.

This patch should result in a moderate performance improvement due to
the considerable amount of code that has been removed from the critical
path, especially the simplification of the spl*() calls. The real
performance gains will come later.

Approved by: jkh
Reviewed by: current, bde (exception.s)
Some work taken from: luoqi's patch

Fix lots of warnings caused by __sigisempty and __sigseteq being externs
and later static inlines. Perhaps these should be #ifdef _KERNEL?

Use 'static __inline', not 'extern __inline', for __sigisempty() and
__sigseteq().

Submitted by: luoqi

Change #ifdef KERNEL to #ifdef _KERNEL in the public headers. "KERNEL"
is an application space macro and the applications are supposed to be free
to use it as they please (but cannot). This is consistant with the other
BSD's who made this change quite some time ago. More commits to come.

Revive ps_usertramp, it's still referenced by COMPAT_SUNOS code.

Reviewed by: bde

Move SIG_HOLD back to signalvar.h.

Fix style bugs and comments while I'm here.

Submitted by: bde

Add a per-signal flag to mark handlers registered with osigaction, so we
can provide the correct context to each signal handler.

Fix broken sigsuspend(): don't use p_oldsigmask as a flag, use SAS_OLDMASK
as we did before the linuxthreads support merge (submitted by bde).

Move ps_sigstk from to p_sigacts to the main proc structure since signal
stack should not be shared among threads.

Move SAS_OLDMASK and SAS_ALTSTACK flags from sigacts::ps_flags to proc::p_flag.
Move PS_NOCLDSTOP and PS_NOCLDWAIT flags from proc::p_flag to procsig::ps_flag.

Reviewed by: marcel, jdp, bde

sigset_t change (part 2 of 5)
-----------------------------

The core of the signalling code has been rewritten to operate
on the new sigset_t. No methodological changes have been made.
Most references to a sigset_t object are through macros (see
signalvar.h) to create a level of abstraction and to provide
a basis for further improvements.

The NSIG constant has not been changed to reflect the maximum
number of signals possible. The reason is that it breaks
programs (especially shells) which assume that all signals
have a non-null name in sys_signame. See src/bin/sh/trap.c
for an example. Instead _SIG_MAXSIG has been introduced to
hold the maximum signal possible with the new sigset_t.

struct sigprop has been moved from signalvar.h to kern_sig.c
because a) it is only used there, and b) access must be done
though function sigprop(). The latter because the table doesn't
holds properties for all signals, but only for the first NSIG
signals.

signal.h has been reorganized to make reading easier and to
add the new and/or modified structures. The "old" structures
are moved to signalvar.h to prevent namespace polution.

Especially the coda filesystem suffers from the change, because
it contained lines like (p->p_sigmask == SIGIO), which is easy
to do for integral types, but not for compound types.

NOTE: kdump (and port linux_kdump) must be recompiled.

Thanks to Garrett Wollman and Daniel Eischen for pressing the
importance of changing sigreturn as well.

General cleanup of core-dumping code.

Submitted by: Sean Fagan,

$Id$ -> $FreeBSD$

expand_name:
use pid_t and uid_t in the declaration as that is what we are passed
fix printf formatters accordingly.

Reviewed by: green

Implement SA_SIGINFO for i386. Thanks to Bruce Evans for much more
than a review, this was a nice puzzle.

This is supposed to be binary and source compatible with older
applications that access the old FreeBSD-style three arguments to a
signal handler.

Except those applications that access hidden signal handler arguments
bejond the documented third one. If you have applications that do,
please let me know so that we take the opportunity to provide the
functionality they need in a documented manner.

Also except application that use 'struct sigframe' directly. You need
to recompile gdb and doscmd. `make world` is recommended.

Example program that demonstrates how SA_SIGINFO and old-style FreeBSD
handlers (with their three args) may be used in the same process is at
http://www3.cons.org/tmp/fbsd-siginfo.c

Programs that use the old FreeBSD-style three arguments are easy to
change to SA_SIGINFO (although they don't need to, since the old style
will still work):

Old args to signal handler:
void handler_sn(int sig, int code, struct sigcontext *scp)

New args:
void handler_si(int sig, siginfo_t *si, void *third)
where:
old:code == new:second->si_code
old:scp == &(new:si->si_scp) /* Passed by value! */

The latter is also pointed to by new:third, but accessing via
si->si_scp is preferred because it is type-save.

FreeBSD implementation notes:
- This is just the framework to make the interface POSIX compatible.
For now, no additional functionality is provided. This is supposed
to happen now, starting with floating point values.
- We don't use 'sigcontext_t.si_value' for now (POSIX meant it for
realtime-related values).
- Documentation will be updated when new functionality is added and
the exact arguments passed are determined. The comments in
sys/signal.h are meant to be useful.

Reviewed by: BDE

Enable Linux threads support by default.
This takes the conditionals out of the code that has been tested by
various people for a while.
ps and friends (libkvm) will need a recompile as some proc structure
changes are made.

Submitted by: "Richard Seaman, Jr." <dick@tar.com>

Changes to the LINUX_THREADS support to only allocate extra memory for
shared signal handling when there is shared signal handling being
used.

This removes the main objection to making the shared signal handling
a standard ability in rfork() and friends and 'unconditionalising'
this code. (i.e. the allocation of an extra 328 bytes per process).

Signal handling information remains in the U area until such a time as
it's reference count would be incremented to > 1. At that point a new
struct is malloc'd and maintained in KVM so that it can be shared between
the processes (threads) using it.

A function to check the reference count and move the struct back to the U
area when it drops back to 1 is also supplied. Signal information is
therefore now swapable for all processes that are not sharing that
information with other processes. THis should addres the concerns raised
by Garrett and others.

Submitted by: "Richard Seaman, Jr." <dick@tar.com>

Reviewed by: Luoqi Chen, Jordan Hubbard
Submitted by: "Richard Seaman, Jr." <lists@tar.com>
Obtained from: linux :-)

Code to allow Linux Threads to run under FreeBSD.

By default not enabled
This code is dependent on the conditional
COMPAT_LINUX_THREADS (suggested by Garret)
This is not yet a 'real' option but will be within some number of hours.

Installed the second patch attached to kern/7899 with some changes suggested
by bde, a few other tweaks to get the patch to apply cleanly again and
some improvements to the comments.

This change closes some fairly minor security holes associated with
F_SETOWN, fixes a few bugs, and removes some limitations that F_SETOWN
had on tty devices. For more details, see the description on the PR.

Because this patch increases the size of the proc and pgrp structures,
it is necessary to re-install the includes and recompile libkvm,
the vinum lkm, fstat, gcore, gdb, ipfilter, ps, top, and w.

PR: kern/7899
Reviewed by: bde, elvind

Add provisions for variant core dump file formats, depending on the
object format of the executable being dumped. This is the first
step toward producing ELF core dumps in the proper format. I will
commit the code to generate the ELF core dumps Real Soon Now. In
the meantime, ELF executables won't dump core at all. That is
probably no less useful than dumping a.out-style core dumps as they
have done until now.

Submitted by: Alex <garbanzo@hooked.net> (with very minor changes by me)

Moved some #includes from <sys/param.h> nearer to where they are actually
used.

Forward declare more structs that are used in prototypes here - don't
depend on <sys/types.h> forward declaring common ones.

remove global prototype for setsigvec(). It's static inside kern_sig.c
and causes redundant declaration warnings.

Back out part 1 of the MCFH that changed $Id$ to $FreeBSD$. We are not
ready for it yet.

Make the long-awaited change from $Id$ to $FreeBSD$

This will make a number of things easier in the future, as well as (finally!)
avoiding the Id-smashing problem which has plagued developers for so long.

Boy, I'm glad we're not using sup anymore. This update would have been
insane otherwise.

re-add the ps_signodefer. The interaction between SA_NODEFER and the
sa_mask was "non intuitive" and broke another of bde's test cases.

Actually implement SA_RESETHAND - some of the sigaction code recognised it
but didn't actually do anything with it (*blush*).

This should fix bde's test case where the test program set SA_RESETHAND
and when reading it back, it was gone.

Tweak/optimize SA_NODEFER so that the implementation is a little simpler
and does not incur (slight) overhead for every signal at delivery time.

Merge in Lite2: add function prototypes
remove bogus function prototype for issig()---no such function
fix comment
Lite2 changed type of ps_code from int to long. We change it to u_long
to make it consistent w/ its usage in kern_sig.c.
Did not accept type change to ps_addr field. Delete it instead as it is
not used anywhere.
Reviewed by: davidg & bde

Mega-commit for Linux emulator update.. This has been stress tested under
netscape-2.0 for Linux running all the Java stuff. The scrollbars are now
working, at least on my machine. (whew! :-)

I'm uncomfortable with the size of this commit, but it's too
inter-dependant to easily seperate out.

The main changes:

COMPAT_LINUX is *GONE*. Most of the code has been moved out of the i386
machine dependent section into the linux emulator itself. The int 0x80
syscall code was almost identical to the lcall 7,0 code and a minor tweak
allows them to both be used with the same C code. All kernels can now
just modload the lkm and it'll DTRT without having to rebuild the kernel
first. Like IBCS2, you can statically compile it in with "options LINUX".

A pile of new syscalls implemented, including getdents(), llseek(),
readv(), writev(), msync(), personality(). The Linux-ELF libraries want
to use some of these.

linux_select() now obeys Linux semantics, ie: returns the time remaining
of the timeout value rather than leaving it the original value.

Quite a few bugs removed, including incorrect arguments being used in
syscalls.. eg: mixups between passing the sigset as an int, vs passing
it as a pointer and doing a copyin(), missing return values, unhandled
cases, SIOC* ioctls, etc.

The build for the code has changed. i386/conf/files now knows how
to build linux_genassym and generate linux_assym.h on the fly.

Supporting changes elsewhere in the kernel:

The user-mode signal trampoline has moved from the U area to immediately
below the top of the stack (below PS_STRINGS). This allows the different
binary emulations to have their own signal trampoline code (which gets rid
of the hardwired syscall 103 (sigreturn on BSD, syslog on Linux)) and so
that the emulator can provide the exact "struct sigcontext *" argument to
the program's signal handlers.

The sigstack's "ss_flags" now uses SS_DISABLE and SS_ONSTACK flags, which
have the same values as the re-used SA_DISABLE and SA_ONSTACK which are
intended for sigaction only. This enables the support of a SA_RESETHAND
flag to sigaction to implement the gross SYSV and Linux SA_ONESHOT signal
semantics where the signal handler is reset when it's triggered.

makesyscalls.sh no longer appends the struct sysentvec on the end of the
generated init_sysent.c code. It's a lot saner to have it in a seperate
file rather than trying to update the structure inside the awk script. :-)

At exec time, the dozen bytes or so of signal trampoline code are copied
to the top of the user's stack, rather than obtaining the trampoline code
the old way by getting a clone of the parent's user area. This allows
Linux and native binaries to freely exec each other without getting
trampolines mixed up.

Improved killproc() log message and made it and the other similar message
tolerant of p_ucred being invalid. Starting using killproc() where
appropriate.

A Major staticize sweep. Generates a couple of warnings that I'll deal
with later.
A number of unused vars removed.
A number of unused procs removed or #ifdefed.

Moved the prototype for setsigvec() from kern_sig.c to signalvar.h.

Completed function pointer declarations.

Implement SA_NODEFER sa_flag for sigaction():
Add SA_NODEFER define to signal.h
Add ps_nodefer field to struct sigacts in signalvar.h.
Add code to kern_sig.c to handle SA_NODEFER.

If flag is set, when the signal is delivered, it is not masked automatically
from receiving the same signal again.

Reviewed by: wollman, bde

Add and move declarations to fix all of the warnings from `gcc -Wimplicit'
(except in netccitt, netiso and netns) and most of the warnings from
`gcc -Wnested-externs'. Fix all the bugs found. There were no serious
ones.

Prototypes, prototypes and even more prototypes. Not quite done yet, but
getting closer all the time.

While in the real world, I had a bad case of being swapped out for a lot of
cycles. While waiting there I added a lot of the extra ()'s I have, (I have
never used LISP to any extent). So I compiled the kernel with -Wall and
shut up a lot of "suggest you add ()'s", removed a bunch of unused var's
and added a couple of declarations here and there. Having a lap-top is
highly recommended. My kernel still runs, yell at me if you kernel breaks.

Added $Id$

This commit was generated by cvs2svn to compensate for changes in r1541,
which included commits to RCS files with non-trunk default branches.

BSD 4.4 Lite Kernel Sources