Now that OBJT_DEFAULT objects can't be instantiated, we can simplify
checks of the form object->type == OBJT_DEFAULT || (object->flags &
OBJ_SWAP) != 0. No functional change intended.
Reviewed by: alc, kib
Tested by: pho
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D35788
In preparation for removing OBJT_DEFAULT, eliminate some stale/unhelpful
comments from vm_mmap(), and remove an unused case. In particular, the
remaining callers of vm_mmap() in the tree do not specify OBJT_DEFAULT.
It's much more common to use vm_map_find() to map an object into user
memory, so rather than adjusting vm_mmap() to handle OBJT_SWAP objects,
let's further discourage its use and simply remove OBJT_DEFAULT
handling.
Reviewed by: dougm, alc, kib
MFC after: 2 weeks
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D35778
Commit 4b8365d752 introduced the ability to dynamically register
VM object types, for use by tmpfs, which creates swap-backed objects.
As a part of this, checks for such objects changed from
object->type == OBJT_DEFAULT || object->type == OBJT_SWAP
to
object->type == OBJT_DEFAULT || (object->flags & OBJ_SWAP) != 0
In particular, objects of type OBJT_DEFAULT do not have OBJ_SWAP set;
the swap pager sets this flag when converting from OBJT_DEFAULT to
OBJT_SWAP.
A few of these checks are done without the object lock held. It turns
out that this can result in false negatives since the swap pager
converts objects like so:
object->type = OBJT_SWAP;
object->flags |= OBJ_SWAP;
Fix the problem by adding explicit tests for OBJT_SWAP objects in
unlocked checks.
PR: 258932
Fixes: 4b8365d752 ("Add OBJT_SWAP_TMPFS pager")
Reported by: bdrewery
Reviewed by: kib
MFC after: 2 weeks
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D35470
This more clearly differentiates system call arguments from integer
registers and return values. On current architectures it has no effect,
but on architectures where pointers are not integers (CHERI) and may
not even share registers (CHERI-MIPS) it is necessiary to differentiate
between system call arguments (syscallarg_t) and integer register values
(register_t).
Obtained from: CheriBSD
Reviewed by: imp, kib
Differential Revision: https://reviews.freebsd.org/D33780
Missed issues in truss on at least armv7 and powerpcspe need to be
resolved before recommit.
This reverts commit 3889fb8af0.
This reverts commit 1544e0f5d1.
This more clearly differentiates system call arguments from integer
registers and return values. On current architectures it has no effect,
but on architectures where pointers are not integers (CHERI) and may
not even share registers (CHERI-MIPS) it is necessiary to differentiate
between system call arguments (syscallarg_t) and integer register values
(register_t).
Obtained from: CheriBSD
Reviewed by: imp, kib
Differential Revision: https://reviews.freebsd.org/D33780
4.3 BSD's mmap took an int len and long pos. Reject negative lengths
and in freebsd32 sign-extend pos correctly rather than mis-handling
negative positions as large positive ones.
Reviewed by: kib
This is OBJT_SWAP pager, specialized for tmpfs. Right now, both swap pager
and generic vm code have to explicitly handle swap objects which are tmpfs
vnode v_object, in the special ways. Replace (almost) all such places with
proper methods.
Since VM still needs a notion of the 'swap object', regardless of its
use, add yet another type-classification flag OBJ_SWAP. Set it in
vm_object_allocate() where other type-class flags are set.
This change almost completely eliminates the knowledge of tmpfs from VM,
and opens a way to make OBJT_SWAP_TMPFS loadable from tmpfs.ko.
Reviewed by: markj
Tested by: pho
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
Differential revision: https://reviews.freebsd.org/D30070
Replace all uses of kern_mmap with kern_mmap_req move the old kern_mmap.
Reand rename kern_mmap_req to kern_mmap .
The helper saved some code churn initially, but having multiple
interfaces is sub-optimal.
Obtained from: CheriBSD
Reviewed by: kib
Differential Revision: https://reviews.freebsd.org/D28292
This prevents a situation where other thread modifies map entries
permissions between setting max_prot, then relocking, then setting prot,
confusing the operation outcome. E.g. you can get an error that is not
possible if operation is performed atomic.
Also enable setting rwx for max_prot even if map does not allow to set
effective rwx protection.
Reviewed by: brooks, markj (previous version)
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D28117
Created with shm_open2(SHM_LARGEPAGE) and then configured with
FIOSSHMLPGCNF ioctl, largepages posix shared memory objects guarantee
that all userspace mappings of it are served by superpage non-managed
mappings.
Only amd64 for now, both 2M and 1G superpages can be requested, the
later requires CPU feature.
Reviewed by: markj
Tested by: pho
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
Differential revision: https://reviews.freebsd.org/D24652
Currently we use a single bit to indicate whether the virtual page is
part of a superpage. To support a forthcoming implementation of
non-transparent 1GB superpages, it is useful to provide more detailed
information about large page sizes.
The change converts MINCORE_SUPER into a mask for MINCORE_PSIND(psind)
values, indicating a mapping of size psind, where psind is an index into
the pagesizes array returned by getpagesizes(3), which in turn comes
from the hw.pagesizes sysctl. MINCORE_PSIND(1) is equal to the old
value of MINCORE_SUPER.
For now, two bits are used to record the page size, permitting values
of MAXPAGESIZES up to 4.
Reviewed by: alc, kib
Sponsored by: Juniper Networks, Inc.
Sponsored by: Klara, Inc.
Differential Revision: https://reviews.freebsd.org/D26238
FreeBSD madvise(2) directly. While some of the flag values match,
most don't.
PR: kern/230160
Reported by: markj
Reviewed by: markj
Discussed with: brooks, kib
MFC after: 2 weeks
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D25272
Functions which take untrusted user ranges must validate against the
bounds of the map, and also check for wraparound. Instead of having the
same logic duplicated in a number of places, add a function to check.
Reviewed by: dougm, kib
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
Differential Revision: https://reviews.freebsd.org/D25328
As with r361769 (man page), PROT_* are properly called protections, not
permissions.
MFC after: 1 week
MFC with: r361769
Sponsored by: The FreeBSD Foundation
This presents an extensible interface to the generic mmap(2)
implementation via a struct pointer intended to use a designated
initializer or compount literal. We take advantage of the mandatory
zeroing of fields not listed in the initializer.
Remove kern_mmap_fpcheck() and use kern_mmap_req().
The motivation for this change is a desire to keep the core
implementation from growing an ever-increasing number of arguments
that must be specified in the correct order for the lowest-level
implementations. In CheriBSD we have already added two more arguments.
Reviewed by: kib
Discussed with: kevans
Obtained from: CheriBSD
Sponsored by: DARPA, AFRL
Differential Revision: https://reviews.freebsd.org/D23164
From POSIX,
[ENOTSUP]
The implementation does not support the combination of accesses
requested in the prot argument.
This fits the case that prot contains permissions which are not a subset
of prot_max.
Reviewed by: brooks, cem
Relnotes: Yes
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D23843
Linux mmap rejects mmap() on a write-only file with EACCES.
linux_mmap_common currently does a fun dance to grab the fp associated with
the passed in fd, validates it, then drops the reference and calls into
kern_mmap(). Doing so is perhaps both fragile and premature; there's still
plenty of chance for the request to get rejected with a more appropriate
error, and it's prone to a race where the file we ultimately mmap has
changed after it drops its referenced.
This change alleviates the need to do this by providing a kern_mmap variant
that allows the caller to inspect the fp just before calling into the fileop
layer. The callback takes flags, prot, and maxprot as one could imagine
scenarios where any of these, in conjunction with the file itself, may
influence a caller's decision.
The file type check in the linux compat layer has been removed; EINVAL is
seemingly not an appropriate response to the file not being a vnode or
device. The fileop layer will reject the operation with ENODEV if it's not
supported, which more closely matches the common linux description of
mmap(2) return values.
If we discover that we're allowing an mmap() on a file type that Linux
normally wouldn't, we should restrict those explicitly.
Reviewed by: kib
MFC after: 1 week
Differential Revision: https://reviews.freebsd.org/D22977
This is a 32-bit structure embedded in each vm_page, consisting mostly
of page queue state. The use of a structure makes it easy to store a
snapshot of a page's queue state in a stack variable and use cmpset
loops to update that state without requiring the page lock.
This change merely adds the structure and updates references to atomic
state fields. No functional change intended.
Reviewed by: alc, jeff, kib
Sponsored by: Netflix, Intel
Differential Revision: https://reviews.freebsd.org/D22650
unset until the object is recycled so this check is stable. Now that we
can acquire the ref without a lock it is not necessary to group these
operations and we can avoid it entirely in many cases.
Reviewed by: kib, markj
Differential Revision: https://reviews.freebsd.org/D22565
around entry->{next,prev} when those are used for ordered list
traversal, and use those wrapper functions everywhere. Where the next
field is used for maintaining a stack of deferred operations, #define
defer_next to make that different usage clearer, and then use the
'right' pointer instead of 'next' for that purpose.
Approved by: markj
Tested by: pho (as part of a larger patch)
Differential Revision: https://reviews.freebsd.org/D22347
After r352110 the page lock no longer protects a page's identity, so
there is no purpose in locking the page in pmap_mincore(). Instead,
if vm.mincore_mapped is set to the non-default value of 0, re-lookup
the page after acquiring its object lock, which holds the page's
identity stable.
The change removes the last callers of vm_page_pa_tryrelock(), so
remove it.
Reviewed by: kib
Sponsored by: Netflix
Differential Revision: https://reviews.freebsd.org/D21823
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
- Remove a dead variable from the amd64 pmap_extract_and_hold().
- Fix grammar in the vm_page_wire man page.
Reported by: alc
Reviewed by: alc, kib
Sponsored by: Netflix
Differential Revision: https://reviews.freebsd.org/D21639
Currently writemapping accounting is only done for vnode_pager which does
some accounting on the underlying vnode.
Extend this to allow accounting to be possible for any of the pager types.
New pageops are added to update/release writecount that need to be
implemented for any pager wishing to do said accounting, and we implement
these methods now for both vnode_pager (unchanged) and swap_pager.
The primary motivation for this is to allow other systems with OBJT_SWAP
objects to check if their objects have any write mappings and reject
operations with EBUSY if so. posixshm will be the first to do so in order to
reject adding write seals to the shmfd if any writable mappings exist.
Reviewed by: kib, markj
Differential Revision: https://reviews.freebsd.org/D21456
feature bit.
In particular, allocate the bit to opt-out the image from implicit
PROTMAX enablement. Provide procctl(2) verbs to set and query
implicit PROTMAX handling. The knobs mimic the same per-image flag
and per-process controls for ASLR.
Reviewed by: emaste, markj (previous version)
Discussed with: brooks
Sponsored by: The FreeBSD Foundation
Differential revision: https://reviews.freebsd.org/D20795
A new macro PROT_MAX() alters a protection value so it can be OR'd with
a regular protection value to specify the maximum permissions. If
present, these flags specify the maximum permissions.
While these flags are non-portable, they can be used in portable code
with simple ifdefs to expand PROT_MAX() to 0.
This change allows (e.g.) a region that must be writable during run-time
linking or JIT code generation to be made permanently read+execute after
writes are complete. This complements W^X protections allowing more
precise control by the programmer.
This change alters mprotect argument checking and returns an error when
unhandled protection flags are set. This differs from POSIX (in that
POSIX only specifies an error), but is the documented behavior on Linux
and more closely matches historical mmap behavior.
In addition to explicit setting of the maximum permissions, an
experimental sysctl vm.imply_prot_max causes mmap to assume that the
initial permissions requested should be the maximum when the sysctl is
set to 1. PROT_NONE mappings are excluded from this for compatibility
with rtld and other consumers that use such mappings to reserve
address space before mapping contents into part of the reservation. A
final version this is expected to provide per-binary and per-process
opt-in/out options and this sysctl will go away in its current form.
As such it is undocumented.
Reviewed by: emaste, kib (prior version), markj
Additional suggestions from: alc
Obtained from: CheriBSD
Sponsored by: DARPA, AFRL
Differential Revision: https://reviews.freebsd.org/D18880
This change rights that comparison.
Reported by: pho
Approved by: markj (mentor)
MFC after: 3 days
Differential Revision: https://reviews.freebsd.org/D20595
for both the lower and upper bound modifications. Change the error returned
to ENOMEM. Rename the parameter size to len and make size a local variable
that stores the value of len after it has been modified.
This addresses concerns expressed by Bruce Evans after r348843.
Reported by: brde@optusnet.com.au
Reviewed by: kib, markj (mentors)
MFC after: 3 days
Relnotes: yes
Differential Revision: https://reviews.freebsd.org/D20592
32-bit machine, a len parameter just a few bytes short of 4G, rounded
up to a page boundary and hitting zero then, is not okay. Return
failure in that case.
Reported by: pho
Reviewed by: alc, kib (mentor)
Tested by: pho
Differential Revision: https://reviews.freebsd.org/D20580
Historically we have not distinguished between kernel wirings and user
wirings for accounting purposes. User wirings (via mlock(2)) were
subject to a global limit on the number of wired pages, so if large
swaths of physical memory were wired by the kernel, as happens with
the ZFS ARC among other things, the limit could be exceeded, causing
user wirings to fail.
The change adds a new counter, v_user_wire_count, which counts the
number of virtual pages wired by user processes via mlock(2) and
mlockall(2). Only user-wired pages are subject to the system-wide
limit which helps provide some safety against deadlocks. In
particular, while sources of kernel wirings typically support some
backpressure mechanism, there is no way to reclaim user-wired pages
shorting of killing the wiring process. The limit is exported as
vm.max_user_wired, renamed from vm.max_wired, and changed from u_int
to u_long.
The choice to count virtual user-wired pages rather than physical
pages was done for simplicity. There are mechanisms that can cause
user-wired mappings to be destroyed while maintaining a wiring of
the backing physical page; these make it difficult to accurately
track user wirings at the physical page layer.
The change also closes some holes which allowed user wirings to succeed
even when they would cause the system limit to be exceeded. For
instance, mmap() may now fail with ENOMEM in a process that has called
mlockall(MCL_FUTURE) if the new mapping would cause the user wiring
limit to be exceeded.
Note that bhyve -S is subject to the user wiring limit, which defaults
to 1/3 of physical RAM. Users that wish to exceed the limit must tune
vm.max_user_wired.
Reviewed by: kib, ngie (mlock() test changes)
Tested by: pho (earlier version)
MFC after: 45 days
Sponsored by: Netflix
Differential Revision: https://reviews.freebsd.org/D19908
kern_execve() locks text vnode exclusive to be able to set and clear
VV_TEXT flag. VV_TEXT is mutually exclusive with the v_writecount > 0
condition.
The change removes VV_TEXT, replacing it with the condition
v_writecount <= -1, and puts v_writecount under the vnode interlock.
Each text reference decrements v_writecount. To clear the text
reference when the segment is unmapped, it is recorded in the
vm_map_entry backed by the text file as MAP_ENTRY_VN_TEXT flag, and
v_writecount is incremented on the map entry removal
The operations like VOP_ADD_WRITECOUNT() and VOP_SET_TEXT() check that
v_writecount does not contradict the desired change. vn_writecheck()
is now racy and its use was eliminated everywhere except access.
Atomic check for writeability and increment of v_writecount is
performed by the VOP. vn_truncate() now increments v_writecount
around VOP_SETATTR() call, lack of which is arguably a bug on its own.
nullfs bypasses v_writecount to the lower vnode always, so nullfs
vnode has its own v_writecount correct, and lower vnode gets all
references, since object->handle is always lower vnode.
On the text vnode' vm object dealloc, the v_writecount value is reset
to zero, and deadfs vop_unset_text short-circuit the operation.
Reclamation of lowervp always reclaims all nullfs vnodes referencing
lowervp first, so no stray references are left.
Reviewed by: markj, trasz
Tested by: mjg, pho
Sponsored by: The FreeBSD Foundation
MFC after: 1 month
Differential revision: https://reviews.freebsd.org/D19923
It is currently re-declared in sys/sysent.h which is a wrong place for
MD variable. Which causes redeclaration error with gcc when
sys/sysent.h and machine/md_var.h are included both.
Remove it from sys/sysent.h and instead include machine/md_var.h when
needed, under #ifdef for both i386 and amd64.
Reported and tested by: bde
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
from the local mapping.
Enable the setting by default.
The article behind the change: https://arxiv.org/abs/1901.01161
Reviewed by: markj
Discussed with: emaste
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
Differential revision: https://reviews.freebsd.org/D18764
Have ogetkerninfo, ogetpagesize, ogethostname, osethostname, and oaccept
declare o<foo>_args structs rather than non-compat ones. Due to a
failure to use NOARGS in most cases this adds only one new declaration.
No changes required in freebsd32 as only ogetpagesize() is implemented
and it has a 32-bit specific implementation.
Reviewed by: kib
Sponsored by: DARPA, AFRL
Differential Revision: https://reviews.freebsd.org/D15816
Limits can be safely obtained with lim_cur from the thread. racct is compiled
in but disabled by default. Note that racct enablement is a boot-only tunable.
This eliminates second most common place of taking the lock while pkg building.
While here don't take the lock in mlockall either.
Reviewed by: kib
Approved by: re (gjb)
Differential Revision: https://reviews.freebsd.org/D17210
