to read strings completely to know the actual size.
As a side effect it fixes the issue with kern.proc.args and kern.proc.env
sysctls, which didn't return the size of available data when calling
sysctl(3) with the NULL argument for oldp.
Note, in get_ps_strings(), which does actual work for proc_getargv() and
proc_getenvv(), we still have a safety limit on the size of data read in
case of a corrupted procces stack.
Suggested by: kib
MFC after: 3 days
This function updates path string to vnode's full global path and checks
the size of the new path string against the pathlen argument.
In vfs_domount(), sys_unmount() and kern_jail_set() this new function
is used to update the supplied path argument to the respective global path.
Unbreaks jailed zfs(8) with enforce_statfs set to 1.
Reviewed by: kib
MFC after: 1 month
On amd64, link_elf_obj.c must specify KERNBASE rather than
VM_MIN_KERNEL_ADDRESS to vm_map_find() because kernel loadable
modules must be mapped for execution in the same upper region
of the kernel map as the kernel code and data segments.
For MIPS32 KERNBASE lies below KVA area (it's less than
VM_MIN_KERNEL_ADDRESS) so basically vm_map_find got whole
KVA to look through. On MIPS64 it's not the case because
KERNBASE is set to the very end of XKSEG, well out of KVA
bounds, so vm_map_find always fails. We should use
VM_MIN_KERNEL_ADDRESS as a base for vm_map_find.
Details obtained from: alc@
The vfs_busy() is after covered vnode lock in the global lock order, but
since quotaon() does recursive VFS call to open quota file, we usually
end up locking covered vnode after mp is busied in sys_quotactl().
Change the interface of VFS_QUOTACTL(), requiring that mp was unbusied
by fs code, and do not try to pick up vfs_busy() reference in ufs quotaon,
esp. if vfs_busy cannot succeed due to unmount being performed.
Reported and tested by: pho
MFC after: 1 week
operation on POSIX shared memory objects and tmpfs. Previously, neither of
these modules correctly handled the case in which the new size of the object
or file was not a multiple of the page size. Specifically, they did not
handle partial page truncation of data stored on swap. As a result, stale
data might later be returned to an application.
Interestingly, a data inconsistency was less likely to occur under tmpfs
than POSIX shared memory objects. The reason being that a different mistake
by the tmpfs truncation operation helped avoid a data inconsistency. If the
data was still resident in memory in a PG_CACHED page, then the tmpfs
truncation operation would reactivate that page, zero the truncated portion,
and leave the page pinned in memory. More precisely, the benevolent error
was that the truncation operation didn't add the reactivated page to any of
the paging queues, effectively pinning the page. This page would remain
pinned until the file was destroyed or the page was read or written. With
this change, the page is now added to the inactive queue.
Discussed with: jhb
Reviewed by: kib (an earlier version)
MFC after: 3 weeks
The wrong structure happened to work since the only argument used was
the vnode which is in the same place in both VOP_SETATTR() and the two
extattr VOPs.
MFC after: 3 days
- Only initialize the per-cpu switchticks and switchtime in sched_throw()
for the very first context switch on APs during boot. This avoids a
small gap between the middle of thread_exit() and sched_throw() where
time is not accounted to any thread.
- In thread_exit(), update the timestamp bookkeeping to track the changes
to mi_switch() introduced by td_rux so that the code once again matches
the comment claiming it is mimicing mi_switch(). Specifically, only
update the per-thread stats directly and depend on ruxagg() to update
p_rux rather than adjusting p_rux directly. While here, move the
timestamp bookkeeping as late in the function as possible.
Reviewed by: bde, kib
MFC after: 1 week
It seems strchr() and strrchr() are used more often than index() and
rindex(). Therefore, simply migrate all kernel code to use it.
For the XFS code, remove an empty line to make the code identical to
the code in the Linux kernel.
at SCHED_PRI_RANGE to prevent overflows in the priority value. This can
happen due to irregularities with clock interrupts under certain
virtualization environments.
Tested by: Larry Rosenman ler lerctr org
MFC after: 2 weeks
sysclock_getsnapshot() function allows the caller to obtain a snapshot of all
the system clock and timecounter state required to create time stamps at a later
point. The sysclock_snap2bintime() function converts a previously obtained
snapshot into a bintime time stamp according to the specified flags e.g. which
system clock, uptime vs absolute time, etc.
These KPIs enable useful functionality, including direct comparison of the
feedback and feed-forward system clocks and generation of multiple time stamps
with different formats from a single timecounter read.
Committed on behalf of Julien Ridoux and Darryl Veitch from the University of
Melbourne, Australia, as part of the FreeBSD Foundation funded "Feed-Forward
Clock Synchronization Algorithms" project.
For more information, see http://www.synclab.org/radclock/
In collaboration with: Julien Ridoux (jridoux at unimelb edu au)
these to trigger a NOTE_ATTRIB EVFILT_VNODE kevent when the extended
attributes of a vnode are changed.
Note that OS X already implements this behavior.
Reviewed by: rwatson
MFC after: 2 weeks
With the previous code, if the range of priorities for timeshare batch
threads was greater than RQ_NQS, then the threads with low priorities in
the part of the range above RQ_NQS would be scheduled to the run-queues
as if they had high priorities at the beginning of the range.
In other words, threads with a nice level of +N could be scheduled as
if they had a nice level of -M.
Reported by: George Mitchell <george@m5p.com>
Reviewed by: jhb
Tested by: George Mitchell <george@m5p.com> (earlier version)
MFC after: 1 week
locate a process calling pfind() and do some additional checks like
p_candebug(). To reduce this code duplication a new function pget() is
introduced and used.
As the function may be useful not only in kern_proc.c it is in the
kernel name space.
Suggested by: kib
Reviewed by: kib
MFC after: 2 weeks
This is intended as a replacement for libkern's gets and mostly borrows
its implementation. It uses cngrab/cnungrab to delimit kernel's access
to console input.
Note: libkern's gets obviously doesn't share any bits of implementation
iwth libc's gets. They also have different APIs and the former doesn't
have the overflow problems of the latter.
Inspired by: bde
MFC after: 2 months
At the moment grab and ungrab methods of all console drivers are no-ops.
Current intended meaning of the calls is that the kernel takes control of
console input. In the future the semantics may be extended to mean that
the calling thread takes full ownership of the console (e.g. console
output from other threads could be suspended).
Inspired by: bde
MFC after: 2 months
case where a kevent would not fire on a regular file if an application read
to EOF and then seeked backwards into the file.
Reviewed by: kib
MFC after: 2 weeks
The reverse direction of a pipe is lazily allocated on the first write in
that direction (because pipes are usually used in one direction only). A
special case is needed to ensure the pipe appears writable before the first
write because there are 0 bytes of pending data in 0 bytes of buffer space
at that point, leaving 0 bytes of data that can be written with the normal
code.
Note that the first write returns [ENOMEM] if kern.ipc.maxpipekva is
exceeded and does not block or return [EAGAIN], so selecting true for write
is correct even in that case.
PR: kern/93685
Submitted by: gianni
MFC after: 2 weeks
objects created by shm_open(2) into the kernel's address space. This
provides a convenient way for creating shared memory buffers between
userland and the kernel without requiring custom character devices.
Historical behavior of letting other CPUs merily go on is a default for
time being. The new behavior can be switched on via
kern.stop_scheduler_on_panic tunable and sysctl.
Stopping of the CPUs has (at least) the following benefits:
- more of the system state at panic time is preserved intact
- threads and interrupts do not interfere with dumping of the system
state
Only one thread runs uninterrupted after panic if stop_scheduler_on_panic
is set. That thread might call code that is also used in normal context
and that code might use locks to prevent concurrent execution of certain
parts. Those locks might be held by the stopped threads and would never
be released. To work around this issue, it was decided that instead of
explicit checks for panic context, we would rather put those checks
inside the locking primitives.
This change has substantial portions written and re-written by attilio
and kib at various times. Other changes are heavily based on the ideas
and patches submitted by jhb and mdf. bde has provided many insights
into the details and history of the current code.
The new behavior may cause problems for systems that use a USB keyboard
for interfacing with system console. This is because of some unusual
locking patterns in the ukbd code which have to be used because on one
hand ukbd is below syscons, but on the other hand it has to interface
with other usb code that uses regular mutexes/Giant for its concurrency
protection. Dumping to USB-connected disks may also be affected.
PR: amd64/139614 (at least)
In cooperation with: attilio, jhb, kib, mdf
Discussed with: arch@, bde
Tested by: Eugene Grosbein <eugen@grosbein.net>,
gnn,
Steven Hartland <killing@multiplay.co.uk>,
glebius,
Andrew Boyer <aboyer@averesystems.com>
(various versions of the patch)
MFC after: 3 months (or never)
thread_free(newtd). This to avoid a possible page fault in
cpu_thread_clean() as seen on amd64 with syscall fuzzing.
Reviewed by: kib
MFC after: 1 week
of vm_kmem_size that may occur if the system administrator has specified a
vm.vm_kmem_size tunable value that exceeds the hard cap.
PR: 162741
Submitted by: Adam McDougall
Reviewed by: bde@
MFC after: 3 weeks
Optimize for the case, by lazily allocating the pipe inode number at the
fstat(2) time. If alloc_unr(9) returns failure, do not fail fstat(2), since
uses of inode numbers are even rare then fstat(2), but provide zero inode
forever. Note that alloc_unr() failure is unlikely due to total number
of pipes in the system limited by the number of file descriptors.
Based on the submission by: gianni
MFC after: 2 weeks
Citing jilles:
If we are ever going to do ASLR, the AUXV information tells an attacker
where the stack, executable and RTLD are located, which defeats much of
the point of randomizing the addresses in the first place.
Given that the AUXV information seems to be used by debuggers only anyway,
I think it would be good to move it to p_candebug() now.
The full virtual memory maps (KERN_PROC_VMMAP, procstat -v) are already
under p_candebug().
Suggested by: jilles
Discussed with: rwatson
MFC after: 1 week
