When no fixed address is given in a shmat() request, pass a hint address
to vm_map_find() that is less likely to be outside of addressable memory
for 32-bit processes: just past the end of the larges

When no fixed address is given in a shmat() request, pass a hint address
to vm_map_find() that is less likely to be outside of addressable memory
for 32-bit processes: just past the end of the largest possible heap.
This is the same hint that mmap() uses.

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Add missing #include <sys/module.h>

Correct a reference counting bug in shmat(2). If vm_map_find(9)
failed, the reference count for the virtual memory object referenced
by the specified shared memory segment would have been erroneousl

Correct a reference counting bug in shmat(2). If vm_map_find(9)
failed, the reference count for the virtual memory object referenced
by the specified shared memory segment would have been erroneously
incremented.

Reported by: Joost Pol <joost@pine.nl>

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Slight whitespace consistency improvement:
Trim trailing whitespace.
Remove unmatched " " before ")".

Back out the following revisions:

1.36 +73 -60 src/sys/compat/linux/linux_ipc.c
1.83 +102 -48 src/sys/kern/sysv_shm.c
1.8 +4 -0 src/sys/sys/syscallsubr.h

That change was i

Back out the following revisions:

1.36 +73 -60 src/sys/compat/linux/linux_ipc.c
1.83 +102 -48 src/sys/kern/sysv_shm.c
1.8 +4 -0 src/sys/sys/syscallsubr.h

That change was intended to support vmware3, but
wantrem parameter is useless because vmware3 uses SYSV shared memory
to talk with X server and X server is native application.
The patch worked because check for wantrem was not valid
(wantrem and SHMSEG_REMOVED was never checked for SHMSEG_ALLOCATED segments).

Add kern.ipc.shm_allow_removed (integer, rw) sysctl (default 0) which when set
to 1 allows to return removed segments in
shm_find_segment_by_shmid() and shm_find_segment_by_shmidx().

MFC after: 1 week

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Change all SYSCTLS which are readonly and have a related TUNABLE
from CTLFLAG_RD to CTLFLAG_RDTUN so that sysctl(8) can provide
more useful error messages.

Update some argument-documenting comments to match reality.

Add an explicit range check to those same arguments to reduce risk of
cardiac arrest in future code readers.

Consistently use the BSD u_int and u_short instead of the SYSV uint and
ushort. In most of these files, there was a mixture of both styles and
this change just makes them self-consistent.

Requested

Consistently use the BSD u_int and u_short instead of the SYSV uint and
ushort. In most of these files, there was a mixture of both styles and
this change just makes them self-consistent.

Requested by: bde (kern_ktrace.c)

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Use __FBSDID().

Change the semantics of sysv shm emulation to take a additional
argument to the functions shm{at,ctl}1 and shm_find_segment_by_shmid{x}.
The BSD semantics didn't allow the usage of shared segment aft

Change the semantics of sysv shm emulation to take a additional
argument to the functions shm{at,ctl}1 and shm_find_segment_by_shmid{x}.
The BSD semantics didn't allow the usage of shared segment after
being marked for removal through IPC_RMID.

The patch involves the following functions:
- shmat
- shmctl
- shm_find_segment_by_shmid
- shm_find_segment_by_shmidx
- linux_shmat
- linux_shmctl

Submitted by: Orlando Bassotto <orlando.bassotto@ieo-research.it>
Reviewed by: marcel

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Lock some manipulations of the vm object's flags.

Back out M_* changes, per decision of the TRB.

Approved by: trb

Fix logic in loop so it actually executes.

Pointed out by: fjoe

prevent overflow in shminfo.shmmax

Bring shm functions closer the the opengroup standards.

PR: 47469
Submitted by: Craig Rodrigues <rodrigc@attbi.com>

Remove M_TRYWAIT/M_WAITOK/M_WAIT. Callers should use 0.
Merge M_NOWAIT/M_DONTWAIT into a single flag M_NOWAIT.

It is possible for an active aio to prevent shared memory from being
dereferenced when a process exits due to the vmspace ref-count being
bumped. Change shmexit() and shmexit_myhook() to take a vmsp

It is possible for an active aio to prevent shared memory from being
dereferenced when a process exits due to the vmspace ref-count being
bumped. Change shmexit() and shmexit_myhook() to take a vmspace instead
of a process and call it in vmspace_dofree(). This way if it is missed
in exit1()'s early-resource-free it will still be caught when the zombie is
reaped.

Also fix a potential race in shmexit_myhook() by NULLing out
vmspace->vm_shm prior to calling shm_delete_mapping() and free().

MFC after: 7 days

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Lock the vm object when performing back-to-back vm_object_clear_flag() and
vm_object_set_flag().

return foo -> return (foo)

Change struct vmspace->vm_shm from void * to struct shmmap_state *, this
removes the need for casts in several cases.

Remove caddr_t.

Remove __P.

- Use td_ucred for jail checks.
- Move jail checks and some other checks involving constants and stack
variables out from under Giant. This isn't perfectly safe atm because
jail_sysvipc_allowed

- Use td_ucred for jail checks.
- Move jail checks and some other checks involving constants and stack
variables out from under Giant. This isn't perfectly safe atm because
jail_sysvipc_allowed is read w/o a lock meaning that its value could be
stale. This global variable will soon become a per-jail flag, however,
at which time it will either not need a lock or will use the prison lock.

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Simple p_ucred -> td_ucred changes to start using the per-thread ucred
reference.

Make AIO a loadable module.

Remove the explicit call to aio_proc_rundown() from exit1(), instead AIO
will use at_exit(9).

Add functions at_exec(9), rm_at_exec(9) which function nearly the
same as a

Make AIO a loadable module.

Remove the explicit call to aio_proc_rundown() from exit1(), instead AIO
will use at_exit(9).

Add functions at_exec(9), rm_at_exec(9) which function nearly the
same as at_exec(9) and rm_at_exec(9), these functions are called
on behalf of modules at the time of execve(2) after the image
activator has run.

Use a modified version of tegge's suggestion via at_exec(9) to close
an exploitable race in AIO.

Fix SYSCALL_MODULE_HELPER such that it's archetecuterally neutral,
the problem was that one had to pass it a paramater indicating the
number of arguments which were actually the number of "int". Fix
it by using an inline version of the AS macro against the syscall
arguments. (AS should be available globally but we'll get to that
later.)

Add a primative system for dynamically adding kqueue ops, it's really
not as sophisticated as it should be, but I'll discuss with jlemon when
he's around.

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