reudundant complicated checks and additional locking required only for
anonymous memory. Introduce vm_object_allocate_anon() to create these
objects. DEFAULT and SWAP objects now have the correct settings for
non-anonymous consumers and so individual consumers need not modify the
default flags to create super-pages and avoid ONEMAPPING/NOSPLIT.
Reviewed by: alc, dougm, kib, markj
Tested by: pho
Differential Revision: https://reviews.freebsd.org/D22119
Co-mingling two things here:
* Addressing some feedback from Konstantin and Kyle re: jail,
capability mode, and a few other things
* Adding audit support as promised.
The audit support change includes a partial refresh of OpenBSM from
upstream, where the change to add shm_rename has already been
accepted. Matthew doesn't plan to work on refreshing anything else to
support audit for those new event types.
Submitted by: Matthew Bryan <matthew.bryan@isilon.com>
Reviewed by: kib
Relnotes: Yes
Sponsored by: Dell EMC Isilon
Differential Revision: https://reviews.freebsd.org/D22083
Atomics are used for page busy and valid state when the shared busy is
held. The details of the locking protocol and valid and dirty
synchronization are in the updated vm_page.h comments.
Reviewed by: kib, markj
Tested by: pho
Sponsored by: Netflix, Intel
Differential Revision: https://reviews.freebsd.org/D21594
This is the first in a series of patches that promotes the page busy field
to a first class lock that no longer requires the object lock for
consistency.
Reviewed by: kib, markj
Tested by: pho
Sponsored by: Netflix, Intel
Differential Revision: https://reviews.freebsd.org/D21548
kern_shm_open2(), since conception, completely fails to pass the mode along
to kern_shm_open(). This breaks most uses of it.
Add tests alongside this that actually check the mode of the returned
files.
PR: 240934 [pulseaudio breakage]
Reported by: ler, Andrew Gierth [postgres breakage]
Diagnosed by: Andrew Gierth (great catch)
Tested by: ler, tmunro
Pointy hat to: kevans
Add an atomic shm rename operation, similar in spirit to a file
rename. Atomically unlink an shm from a source path and link it to a
destination path. If an existing shm is linked at the destination
path, unlink it as part of the same atomic operation. The caller needs
the same permissions as shm_unlink to the shm being renamed, and the
same permissions for the shm at the destination which is being
unlinked, if it exists. If those fail, EACCES is returned, as with the
other shm_* syscalls.
truss support is included; audit support will come later.
This commit includes only the implementation; the sysent-generated
bits will come in a follow-on commit.
Submitted by: Matthew Bryan <matthew.bryan@isilon.com>
Reviewed by: jilles (earlier revision)
Reviewed by: brueffer (manpages, earlier revision)
Relnotes: yes
Sponsored by: Dell EMC Isilon
Differential Revision: https://reviews.freebsd.org/D21423
shm_open2 allows a little more flexibility than the original shm_open.
shm_open2 doesn't enforce CLOEXEC on its callers, and it has a separate
shmflag argument that can be expanded later. Currently the only shmflag is
to allow file sealing on the returned fd.
shm_open and memfd_create will both be implemented in libc to use this new
syscall.
__FreeBSD_version is bumped to indicate the presence.
Reviewed by: kib, markj
Differential Revision: https://reviews.freebsd.org/D21393
Now that flags may be set on posixshm, add an argument to kern_shm_open()
for the initial seals. To maintain past behavior where callers of
shm_open(2) are guaranteed to not have any seals applied to the fd they're
given, apply F_SEAL_SEAL for existing callers of kern_shm_open. A special
flag could be opened later for shm_open(2) to indicate that sealing should
be allowed.
We currently restrict initial seals to F_SEAL_SEAL. We cannot error out if
F_SEAL_SEAL is re-applied, as this would easily break shm_open() twice to a
shmfd that already existed. A note's been added about the assumptions we've
made here as a hint towards anyone wanting to allow other seals to be
applied at creation.
Reviewed by: kib, markj
Differential Revision: https://reviews.freebsd.org/D21392
File sealing applies protections against certain actions
(currently: write, growth, shrink) at the inode level. New fileops are added
to accommodate seals - EINVAL is returned by fcntl(2) if they are not
implemented.
Reviewed by: markj, kib
Differential Revision: https://reviews.freebsd.org/D21391
- VM_ALLOC_NOCREAT will grab without creating a page.
- vm_page_grab_valid() will grab and page in if necessary.
- vm_page_busy_acquire() automates some busy acquire loops.
Discussed with: alc, kib, markj
Tested by: pho (part of larger branch)
Sponsored by: Netflix
Differential Revision: https://reviews.freebsd.org/D21546
There are several mechanisms by which a vm_page reference is held,
preventing the page from being freed back to the page allocator. In
particular, holding the page's object lock is sufficient to prevent the
page from being freed; holding the busy lock or a wiring is sufficent as
well. These references are protected by the page lock, which must
therefore be acquired for many per-page operations. This results in
false sharing since the page locks are external to the vm_page
structures themselves and each lock protects multiple structures.
Transition to using an atomically updated per-page reference counter.
The object's reference is counted using a flag bit in the counter. A
second flag bit is used to atomically block new references via
pmap_extract_and_hold() while removing managed mappings of a page.
Thus, the reference count of a page is guaranteed not to increase if the
page is unbusied, unmapped, and the object's write lock is held. As
a consequence of this, the page lock no longer protects a page's
identity; operations which move pages between objects are now
synchronized solely by the objects' locks.
The vm_page_wire() and vm_page_unwire() KPIs are changed. The former
requires that either the object lock or the busy lock is held. The
latter no longer has a return value and may free the page if it releases
the last reference to that page. vm_page_unwire_noq() behaves the same
as before; the caller is responsible for checking its return value and
freeing or enqueuing the page as appropriate. vm_page_wire_mapped() is
introduced for use in pmap_extract_and_hold(). It fails if the page is
concurrently being unmapped, typically triggering a fallback to the
fault handler. vm_page_wire() no longer requires the page lock and
vm_page_unwire() now internally acquires the page lock when releasing
the last wiring of a page (since the page lock still protects a page's
queue state). In particular, synchronization details are no longer
leaked into the caller.
The change excises the page lock from several frequently executed code
paths. In particular, vm_object_terminate() no longer bounces between
page locks as it releases an object's pages, and direct I/O and
sendfile(SF_NOCACHE) completions no longer require the page lock. In
these latter cases we now get linear scalability in the common scenario
where different threads are operating on different files.
__FreeBSD_version is bumped. The DRM ports have been updated to
accomodate the KPI changes.
Reviewed by: jeff (earlier version)
Tested by: gallatin (earlier version), pho
Sponsored by: Netflix
Differential Revision: https://reviews.freebsd.org/D20486
r351650 switched posixshm to using OBJT_SWAP for shm_object
r351795 added support to the swap_pager for tracking writeable mappings
Take advantage of this and start tracking writeable mappings; fd sealing
will use this to reject a seal on writing with EBUSY if any such mapping
exist.
Reviewed by: kib, markj
Differential Revision: https://reviews.freebsd.org/D21456
Future changes to posixshm will start tracking writeable mappings in order
to support file sealing. Tracking writeable mappings for an OBJT_DEFAULT
object is complicated as it may be swapped out and converted to an
OBJT_SWAP. One may generically add this tracking for vm_object, but this is
difficult to do without increasing memory footprint of vm_object and blowing
up memory usage by a significant amount.
On the other hand, the swap pager can be expanded to track writeable
mappings without increasing vm_object size. This change is currently in
D21456. Switch over to OBJT_SWAP in advance of the other changes to the
swap pager and posixshm.
uiomove_object_page() and exec_map_first_page() would previously wire a
page after having grabbed it. Ask vm_page_grab() to perform the wiring
instead: this removes some redundant code, and is cheaper in the case
where the requested page is not resident since the page allocator can be
asked to initialize the page as wired, whereas a separate vm_page_wire()
call requires the page lock.
In vm_imgact_hold_page(), use vm_page_unwire_noq() instead of
vm_page_unwire(PQ_NONE). The latter ensures that the page is dequeued
before returning, but this is unnecessary since vm_page_free() will
trigger a batched dequeue of the page.
Reviewed by: alc, kib
Tested by: pho (part of a larger patch)
MFC after: 1 week
Sponsored by: Netflix
Differential Revision: https://reviews.freebsd.org/D21440
The motivation for this change is to allow wrappers around shm to be written
that don't set CLOEXEC. kern_shm_open currently accepts O_CLOEXEC but sets
it unconditionally. kern_shm_open is used by the shm_open(2) syscall, which
is mandated by POSIX to set CLOEXEC, and CloudABI's sys_fd_create1().
Presumably O_CLOEXEC is intended in the latter caller, but it's unclear from
the context.
sys_shm_open() now unconditionally sets O_CLOEXEC to meet POSIX
requirements, and a comment has been dropped in to kern_fd_open() to explain
the situation and add a pointer to where O_CLOEXEC setting is maintained for
shm_open(2) correctness. CloudABI's sys_fd_create1() also unconditionally
sets O_CLOEXEC to match previous behavior.
This also has the side-effect of making flags correctly reflect the
O_CLOEXEC status on this fd for the rest of kern_shm_open(), but a
glance-over leads me to believe that it didn't really matter.
Reviewed by: kib, markj
MFC after: 1 week
Differential Revision: https://reviews.freebsd.org/D21119
The hold_count and wire_count fields of struct vm_page are separate
reference counters with similar semantics. The remaining essential
differences are that holds are not counted as a reference with respect
to LRU, and holds have an implicit free-on-last unhold semantic whereas
vm_page_unwire() callers must explicitly determine whether to free the
page once the last reference to the page is released.
This change removes the KPIs which directly manipulate hold_count.
Functions such as vm_fault_quick_hold_pages() now return wired pages
instead. Since r328977 the overhead of maintaining LRU for wired pages
is lower, and in many cases vm_fault_quick_hold_pages() callers would
swap holds for wirings on the returned pages anyway, so with this change
we remove a number of page lock acquisitions.
No functional change is intended. __FreeBSD_version is bumped.
Reviewed by: alc, kib
Discussed with: jeff
Discussed with: jhb, np (cxgbe)
Tested by: pho (previous version)
Sponsored by: Netflix
Differential Revision: https://reviews.freebsd.org/D19247
The sysctl provides the listing on named linked posix shared memory
segments existing in the system.
Reuse shm_fill_kinfo() for filling individual struct kinfo_file.
Remove unneeded lock around reading of shmfd->shm_mode.
Reviewed by: jilles, tmunro
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
Differential revision: https://reviews.freebsd.org/D20258
Unless there are transient references to the object, the ref count is
equal to the number of the shared memory segment mappings plus one.
Reviewed by: jilles, tmunro
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
Differential revision: https://reviews.freebsd.org/D20258
They have no effect, as with filesystem file descriptors.
This improves compatibility with some existing userspace code.
Submitted by: Greg V <greg@unrelenting.technology>
Reviewed by: kib
MFC after: 1 week
Differential Revision: https://reviews.freebsd.org/D19330
Mainly focus on files that use BSD 2-Clause license, however the tool I
was using misidentified many licenses so this was mostly a manual - error
prone - task.
The Software Package Data Exchange (SPDX) group provides a specification
to make it easier for automated tools to detect and summarize well known
opensource licenses. We are gradually adopting the specification, noting
that the tags are considered only advisory and do not, in any way,
superceed or replace the license texts.
similar to the kernel memory allocator.
This simplifies NUMA allocation because the domain will be known at wait
time and races between failure and sleeping are eliminated. This also
reduces boilerplate code and simplifies callers.
A wait primitive is supplied for uma zones for similar reasons. This
eliminates some non-specific VM_WAIT calls in favor of more explicit
sleeps that may be satisfied without new pages.
Reviewed by: alc, kib, markj
Tested by: pho
Sponsored by: Netflix, Dell/EMC Isilon
Previously, uiomove_object_page() would maintain LRU by requeuing the
accessed page. This involves acquiring one of the heavily contended page
queue locks. Moreover, it is unnecessarily expensive for pages in the
active queue.
As of r254304 the page daemon continually performs a slow scan of the
active queue, with the effect that unreferenced pages are gradually
moved to the inactive queue, from which they can be reclaimed. Prior to
that revision, the active queue was scanned only during shortages of
free and inactive pages, meaning that unreferenced pages could get
"stuck" in the queue. Thus, tmpfs was required to use the inactive queue
and requeue pages in order to maintain LRU. Now that this is no longer
the case, tmpfs I/O operations can use the active queue and avoid the
page queue locks in most cases, instead setting PGA_REFERENCED on
referenced pages to provide pseudo-LRU.
Reviewed by: alc (previous version)
MFC after: 2 weeks
This requires minor changes to the audit framework to allow capturing
paths that are not filesystem paths (i.e., will not be canonicalised
relative to the process current working directory and/or filesystem
root).
Obtained from: TrustedBSD Project
MFC after: 3 weeks
Sponsored by: DARPA, AFRL
vm_pindex_t's into a vm_ooffset_t.
The length given to shm_dotruncate() must never be negative. Assert this.
Tidy up a comment.
Reviewed by: kib
MFC after: 1 week
For regular files and posix shared memory, POSIX requires that
[offset, offset + size) range is legitimate. At the maping time,
check that offset is not negative. Allowing negative offsets might
expose the data that filesystem put into vm_object for internal use,
esp. due to OFF_TO_IDX() signess treatment. Fault handler verifies
that the mapped range is valid, assuming that mmap(2) checked that
arithmetic gives no undefined results.
For device mappings, leave the semantic of negative offsets to the
driver. Correct object page index calculation to not erronously
propagate sign.
In either case, disallow overflow of offset + size.
Update mmap(2) man page to explain the requirement of the range
validity, and behaviour when the range becomes invalid after mapping.
Reported and tested by: royger (previous version)
Reviewed by: alc
Sponsored by: The FreeBSD Foundation
MFC after: 2 weeks
truncation, immediately queue the page for asynchronous laundering rather
than making the page pass through inactive queue first.
Reviewed by: kib, markj
not remove user-space visible fields from vm_cnt or all of the references to
cached pages from comments. Those changes will come later.)
Reviewed by: kib, markj
Tested by: pho
Sponsored by: Dell EMC Isilon
Differential Revision: https://reviews.freebsd.org/D8497
While reading the code, I noticed that shm_read() returns without unlocking
foffset and rangelock if mac_posixshm_check_read() rejects the read.
Reviewed by: kib, jhb, rwatson
Approved by: re (gjb)
MFC after: 1 week
Differential Revision: https://reviews.freebsd.org/D6927
name to the object's "path". While the objects don't have real path
names, it's a filesystem-like namespace, which allows jails to be
kept to their own space, but still allows the system / jail parent to
access a jail's IPC.
PR: 208082
breaking the ABI. Special value is stored in the lock pointer to
indicate shared lock, and offline page in the shared memory is
allocated to store the actual lock.
Reviewed by: vangyzen (previous version)
Discussed with: deischen, emaste, jhb, rwatson,
Martin Simmons <martin@lispworks.com>
Tested by: pho
Sponsored by: The FreeBSD Foundation
o With new KPI consumers can request contiguous ranges of pages, and
unlike before, all pages will be kept busied on return, like it was
done before with the 'reqpage' only. Now the reqpage goes away. With
new interface it is easier to implement code protected from race
conditions.
Such arrayed requests for now should be preceeded by a call to
vm_pager_haspage() to make sure that request is possible. This
could be improved later, making vm_pager_haspage() obsolete.
Strenghtening the promises on the business of the array of pages
allows us to remove such hacks as swp_pager_free_nrpage() and
vm_pager_free_nonreq().
o New KPI accepts two integer pointers that may optionally point at
values for read ahead and read behind, that a pager may do, if it
can. These pages are completely owned by pager, and not controlled
by the caller.
This shifts the UFS-specific readahead logic from vm_fault.c, which
should be file system agnostic, into vnode_pager.c. It also removes
one VOP_BMAP() request per hard fault.
Discussed with: kib, alc, jeff, scottl
Sponsored by: Nginx, Inc.
Sponsored by: Netflix
This allows you to specify the capabilities that the new file descriptor
should have. This allows us to create shared memory objects that only
have the rights we're interested in.
The idea behind restricting the rights is that it makes it a lot easier
for CloudABI to get consistent behaviour across different operating
systems. We only need to make sure that a shared memory implementation
consistently implements the operations that are whitelisted.
Approved by: kib
Obtained from: https://github.com/NuxiNL/freebsd
in the requested array, then it is responsible for disposition of previous
page and is responsible for updating the entry in the requested array.
Now consumers of KPI do not need to re-lookup the pages after call to
vm_pager_get_pages().
Reviewed by: kib
Sponsored by: Netflix
Sponsored by: Nginx, Inc.
logic is now placed in the mmap hook implementation rather than requiring
it to be placed in sys/vm/vm_mmap.c. This hook allows new file types to
support mmap() as well as potentially allowing mmap() for existing file
types that do not currently support any mapping.
The vm_mmap() function is now split up into two functions. A new
vm_mmap_object() function handles the "back half" of vm_mmap() and accepts
a referenced VM object to map rather than a (handle, handle_type) tuple.
vm_mmap() is now reduced to converting a (handle, handle_type) tuple to a
a VM object and then calling vm_mmap_object() to handle the actual mapping.
The vm_mmap() function remains for use by other parts of the kernel
(e.g. device drivers and exec) but now only supports mapping vnodes,
character devices, and anonymous memory.
The mmap() system call invokes vm_mmap_object() directly with a NULL object
for anonymous mappings. For mappings using a file descriptor, the
descriptors fo_mmap() hook is invoked instead. The fo_mmap() hook is
responsible for performing type-specific checks and adjustments to
arguments as well as possibly modifying mapping parameters such as flags
or the object offset. The fo_mmap() hook routines then call
vm_mmap_object() to handle the actual mapping.
The fo_mmap() hook is optional. If it is not set, then fo_mmap() will
fail with ENODEV. A fo_mmap() hook is implemented for regular files,
character devices, and shared memory objects (created via shm_open()).
While here, consistently use the VM_PROT_* constants for the vm_prot_t
type for the 'prot' variable passed to vm_mmap() and vm_mmap_object()
as well as the vm_mmap_vnode() and vm_mmap_cdev() helper routines.
Previously some places were using the mmap()-specific PROT_* constants
instead. While this happens to work because PROT_xx == VM_PROT_xx,
using VM_PROT_* is more correct.
Differential Revision: https://reviews.freebsd.org/D2658
Reviewed by: alc (glanced over), kib
MFC after: 1 month
Sponsored by: Chelsio
the page size, len is the total transfer length, which may be larger
than zero_region.
Reported and tested by: clusteradm (gjb)
Sponsored by: The FreeBSD Foundation
X-MFC-With: r281442
Check whether the page being requested is either resident or on swap. If
not, read from the zero_region instead of instantiating an unnecessary page.
This avoids consuming memory for sparse files on tmpfs, when they are read
by applications that do not use SEEK_HOLE/SEEK_DATA (which is most of them).
Reviewed by: kib
MFC after: 1 week
Sponsored by: Spectra Logic
struct kinfo_file.
- Move the various fill_*_info() methods out of kern_descrip.c and into the
various file type implementations.
- Rework the support for kinfo_ofile to generate a suitable kinfo_file object
for each file and then convert that to a kinfo_ofile structure rather than
keeping a second, different set of code that directly manipulates
type-specific file information.
- Remove the shm_path() and ksem_info() layering violations.
Differential Revision: https://reviews.freebsd.org/D775
Reviewed by: kib, glebius (earlier version)
- Add invfo_rdwr() (for read and write), invfo_ioctl(), invfo_poll(),
and invfo_kqfilter() for use by file types that do not support the
respective operations. Home-grown versions of invfo_poll() were
universally broken (they returned an errno value, invfo_poll()
uses poll_no_poll() to return an appropriate event mask). Home-grown
ioctl routines also tended to return an incorrect errno (invfo_ioctl
returns ENOTTY).
- Use the invfo_*() functions instead of local versions for
unsupported file operations.
- Reorder fileops members to match the order in the structure definition
to make it easier to spot missing members.
- Add several missing methods to linuxfileops used by the OFED shim
layer: fo_write(), fo_truncate(), fo_kqfilter(), and fo_stat(). Most
of these used invfo_*(), but a dummy fo_stat() implementation was
added.
