Bump date for nvme(4) and nvd(4).

MFC after:	3 days
Fix my last commit, flags rather than flag... duh.

MFC after: 2 days
Implement RTC CMOS nvram. Init some fields that are used
by FreeBSD and UEFI.
Tested with nvram(4).

Reviewed by:	neel
MFamd64 r253140:
Clear m->object for the page taken from the delayed free list in
pmap_pv_reclaim().

Noted by:	alc
Explicitely panic instead of possibly doing undefined things when
ptelist KVA is exhausted.  Currently this cannot happen, the added
panic serves as assert.

Discussed with:	alc
Sponsored by:	The FreeBSD Foundation
Do not invalidate page of the B_NOCACHE buffer or buffer after an I/O
error if any user wired mappings exist.  Doing the invalidation
destroys the user wiring.

The change is the temporal measure to close the bug, the more proper
fix is to delegate the invalidation of the page to upper layers
always.

Reported and tested by:	pho
Reviewed by:	alc
Sponsored by:	The FreeBSD Foundation
MFC after:	2 weeks
In the vm_page_set_invalid() function, do not assert that the page is
not busy, since its only caller brelse() can legitimately call it on
busy page.  This happens for VOP_PUTPAGES() on filesystems that use
buffers and which VOP_WRITE() method marked the buffer containing page
as non-cacheable.

Reported and tested by:	pho
Reviewed by:	alc
Sponsored by:	The FreeBSD Foundation
MFC after:	2 weeks
Never remove user-wired pages from an object when doing
msync(MS_INVALIDATE).  The vm_fault_copy_entry() requires that object
range which corresponds to the user-wired vm_map_entry, is always
fully populated.

Add OBJPR_NOTWIRED flag for vm_object_page_remove() to request the
preserving behaviour, use it when calling vm_object_page_remove() from
vm_object_sync().

Reported and tested by:	pho
Reviewed by:	alc
Sponsored by:	The FreeBSD Foundation
MFC after:	2 weeks
The mlockall() or VM_MAP_WIRE_HOLESOK does not interact properly with
parallel creation of the map entries, e.g. by mmap() or stack growing.
It also breaks when other entry is wired in parallel.

The vm_map_wire() iterates over the map entries in the region, and
assumes that map entries it finds are marked as in transition before,
also that any entry marked as in transition, are marked by the current
invocation of vm_map_wire().  This is not true for new entries in the
holes.

Add the thread owner of the MAP_ENTRY_IN_TRANSITION flag to struct
vm_map_entry.  In vm_map_wire() and vm_map_unwire(), only process the
entries which transition owner is the current thread.

Reported and tested by:	pho
Reviewed by:	alc
Sponsored by:	The FreeBSD Foundation
MFC after:	2 weeks
The vm_fault() should not be allowed to proceed on the map entry which
is being wired now.  The entry wired count is changed to non-zero in
advance, before the map lock is dropped.  This makes the vm_fault() to
perceive the entry as wired, and breaks the fragment which moves the
wire count from the shadowed page, to the upper page, making the code
unwiring non-wired page.

On the other hand, the vm_fault() calls from vm_fault_wire() should be
allowed to proceed, so only drain MAP_ENTRY_IN_TRANSITION from
vm_fault() when wiring_thread is not current.

Reported and tested by:	pho
Reviewed by:	alc
Sponsored by:	The FreeBSD Foundation
MFC after:	2 weeks
Fix style issues, a typo in "kern.ipc.nmbufs" and correctly plave and
expose the value of the tunable maxmbufmem as "kern.ipc.maxmbufmem"
through sysctl.

Reported by:	smh
MFC after:	1 day
Make use of the fact that uma_zone_set_max(9) already returns the
rounded limit making a call to uma_zone_get_max(9) unnecessary.

MFC after:	1 day
SipHash is a cryptographically strong pseudo-random function (a.k.a. keyed
hash function) optimized for speed on short messages returning a 64bit hash/
digest value.

SipHash is simpler and much faster than other secure MACs and competitive
in speed with popular non-cryptographic hash functions.  It uses a 128-bit
key without the hidden cost of a key expansion step.  SipHash iterates a
simple round function consisting of four additions, four xors, and six
rotations, interleaved with xors of message blocks for a pre-defined number
of compression and finalization rounds.  The absence of  secret load/store
addresses or secret branch conditions avoid timing attacks.  No state is
shared between messages.  Hashing is deterministic and doesn't use nonces.
It is not susceptible to length extension attacks.

Target applications include network traffic authentication, message
authentication (MAC) and hash-tables protection against hash-flooding
denial-of-service attacks.

The number of update/finalization rounds is defined during initialization:

 SipHash24_Init() for the fast and reasonable strong version.
 SipHash48_Init() for the strong version (half as fast).

SipHash usage is similar to other hash functions:

 struct SIPHASH_CTX ctx;
 char *k = "16bytes long key"
 char *s = "string";
 uint64_t h = 0;
 SipHash24_Init(&ctx);
 SipHash_SetKey(&ctx, k);
 SipHash_Update(&ctx, s, strlen(s));
 SipHash_Final(&h, &ctx);  /* or */
 h = SipHash_End(&ctx);    /* or */
 h = SipHash24(&ctx, k, s, strlen(s));

It was designed by Jean-Philippe Aumasson and Daniel J. Bernstein and
is described in the paper "SipHash: a fast short-input PRF", 2012.09.18:
 https://131002.net/siphash/siphash.pdf
 Permanent ID: b9a943a805fbfc6fde808af9fc0ecdfa

Implemented by:	andre (based on the paper)
Reviewed by:	cperciva
Fix a poorly worded comment in nvme(4).

MFC after:	3 days
Improve SYN cookies by encoding the MSS, WSCALE (window scaling) and SACK
information into the ISN (initial sequence number) without the additional
use of timestamp bits and switching to the very fast and cryptographically
strong SipHash-2-4 MAC hash algorithm to protect the SYN cookie against
forgeries.

The purpose of SYN cookies is to encode all necessary session state in
the 32 bits of our initial sequence number to avoid storing any information
locally in memory.  This is especially important when under heavy spoofed
SYN attacks where we would either run out of memory or the syncache would
fill with bogus connection attempts swamping out legitimate connections.

The original SYN cookies method only stored an indexed MSS values in the
cookie.  This isn't sufficient anymore and breaks down in the presence of
WSCALE information which is only exchanged during SYN and SYN-ACK.  If we
can't keep track of it then we may severely underestimate the available
send or receive window. This is compounded with large windows whose size
information on the TCP segment header is even lower numerically.  A number
of years back SYN cookies were extended to store the additional state in
the TCP timestamp fields, if available on a connection.  While timestamps
are common among the BSD, Linux and other *nix systems Windows never enabled
them by default and thus are not present for the vast majority of clients
seen on the Internet.

The common parameters used on TCP sessions have changed quite a bit since
SYN cookies very invented some 17 years ago.  Today we have a lot more
bandwidth available making the use window scaling almost mandatory.  Also
SACK has become standard making recovering from packet loss much more
efficient.

This change moves all necessary information into the ISS removing the need
for timestamps.  Both the MSS (16 bits) and send WSCALE (4 bits) are stored
in 3 bit indexed form together with a single bit for SACK.  While this is
significantly less than the original range, it is sufficient to encode all
common values with minimal rounding.

The MSS depends on the MTU of the path and with the dominance of ethernet
the main value seen is around 1460 bytes.  Encapsulations for DSL lines
and some other overheads reduce it by a few more bytes for many connections
seen.  Rounding down to the next lower value in some cases isn't a problem
as we send only slightly more packets for the same amount of data.

The send WSCALE index is bit more tricky as rounding down under-estimates
the available send space available towards the remote host, however a small
number values dominate and are carefully selected again.

The receive WSCALE isn't encoded at all but recalculated based on the local
receive socket buffer size when a valid SYN cookie returns.  A listen socket
buffer size is unlikely to change while active.

The index values for MSS and WSCALE are selected for minimal rounding errors
based on large traffic surveys.  These values have to be periodically
validated against newer traffic surveys adjusting the arrays tcp_sc_msstab[]
and tcp_sc_wstab[] if necessary.

In addition the hash MAC to protect the SYN cookies is changed from MD5
to SipHash-2-4, a much faster and cryptographically secure algorithm.

Reviewed by:	dwmalone
Tested by:	Fabian Keil <fk@fabiankeil.de>
Fix const propagation issues to make GCC happy.

Submitted by:	Michael Butler <imb@protected-networks.net>
Cleanups to math.h that prevent namespace conflicts with C++.

Reviewed by:	bde
MFC after:	3 days
Attach to the 4x10G T540-CR card.
Fix some typoes in math.h cleanup.
When swap pager allocates metadata in the pagedaemon context, allow it
to drain the reserve.  This was broken in r243040, causing deadlock.
Note that VM_WAIT call in case of uma_zalloc() failure from pagedaemon
would only wait for the v_pageout_free_min anyway.

Reported and tested by:	pho
Reviewed by:	alc
Sponsored by:	The FreeBSD Foundation