sys: Remove ancient SCCS tags.

Remove ancient SCCS tags from the tree, automated scripting, with two
minor fixup to keep things compiling. All the common forms in the tree
were removed with a perl script.

Sponsored by: Netflix

sys: Remove $FreeBSD$: one-line .h pattern

Remove /^\s*\*+\s*\$FreeBSD\$.*$\n/

i386 4/4G split.

The change makes the user and kernel address spaces on i386
independent, giving each almost the full 4G of usable virtual addresses
except for one PDE at top used for trampoline and per-CPU trampoline
stacks, and system structures that must be always mapped, namely IDT,
GDT, common TSS and LDT, and process-private TSS and LDT if allocated.

By using 1:1 mapping for the kernel text and data, it appeared
possible to eliminate assembler part of the locore.S which bootstraps
initial page table and KPTmap. The code is rewritten in C and moved
into the pmap_cold(). The comment in vmparam.h explains the KVA
layout.

There is no PCID mechanism available in protected mode, so each
kernel/user switch forth and back completely flushes the TLB, except
for the trampoline PTD region. The TLB invalidations for userspace
becomes trivial, because IPI handlers switch page tables. On the other
hand, context switches no longer need to reload %cr3.

copyout(9) was rewritten to use vm_fault_quick_hold(). An issue for
new copyout(9) is compatibility with wiring user buffers around sysctl
handlers. This explains two kind of locks for copyout ptes and
accounting of the vslock() calls. The vm_fault_quick_hold() AKA slow
path, is only tried after the 'fast path' failed, which temporary
changes mapping to the userspace and copies the data to/from small
per-cpu buffer in the trampoline. If a page fault occurs during the
copy, it is short-circuit by exception.s to not even reach C code.

The change was motivated by the need to implement the Meltdown
mitigation, but instead of KPTI the full split is done. The i386
architecture already shows the sizing problems, in particular, it is
impossible to link clang and lld with debugging. I expect that the
issues due to the virtual address space limits would only exaggerate
and the split gives more liveness to the platform.

Tested by: pho
Discussed with: bde
Sponsored by: The FreeBSD Foundation
MFC after: 1 month
Differential revision: https://reviews.freebsd.org/D14633

sys: further adoption of SPDX licensing ID tags.

Mainly focus on files that use BSD 3-Clause license.

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.

Special thanks to Wind River for providing access to "The Duke of
Highlander" tool: an older (2014) run over FreeBSD tree was useful as a
starting point.

Renumber copyright clause 4

Renumber cluase 4 to 3, per what everybody else did when BSD granted
them permission to remove clause 3. My insistance on keeping the same
numbering for legal reasons is too pedantic, so give up on that point.

Submitted by: Jan Schaumann <jschauma@stevens.edu>
Pull Request: https://github.com/freebsd/freebsd/pull/96

Remove support for Xen PV domU kernels. Support for HVM domU kernels
remains. Xen is planning to phase out support for PV upstream since it
is harder to maintain and has more overhead. Modern x86 CPUs include
virtualization extensions that support HVM guests instead of PV guests.
In addition, the PV code was i386 only and not as well maintained recently
as the HVM code.
- Remove the i386-only NATIVE option that was used to disable certain
components for PV kernels. These components are now standard as they
are on amd64.
- Remove !XENHVM bits from PV drivers.
- Remove various shims required for XEN (e.g. PT_UPDATES_FLUSH, LOAD_CR3,
etc.)
- Remove duplicate copy of <xen/features.h>.
- Remove unused, i386-only xenstored.h.

Differential Revision: https://reviews.freebsd.org/D2362
Reviewed by: royger
Tested by: royger (i386/amd64 HVM domU and amd64 PVH dom0)
Relnotes: yes

Move userland bits (and some common kernel bits) from amd64 and i386
segments.h to a new x86 segments.h.

Add __packed attribute to some structs (just to be sure).
Also make it clear that i386 GDT and LDT entries are used in ia64 code.

Resort the IDT_DTRACE_RET constant after it was changed to be less than
IDT_SYSCALL.

Fix the DTrace pid return trap interrupt vector. Previously we were using
31, but that vector is reserved.

Without this fix, running dtrace -p <pid> would either cause the target
process to crash or the kernel to page fault.

Obtained from: rpaulo
MFC after: 3days

Make i386_set_ldt work on i386/XEN, step 5/5.

When cleaning up a thread, reset its LDT to the default LDT.

Note: Casting the LDT pointer to an int and storing it in pc_currentldt is
wildly bogus, but is harmless since pc_currentldt is a write-only variable.

MFC after: 3 days

A new jail(8) with a configuration file, to replace the work currently done
by /etc/rc.d/jail.

Register an interrupt vector for DTrace return probes. There is some
code missing in lapic to make sure that we don't overwrite this entry,
but this will be done on a sequent commit.

Sponsored by: The FreeBSD Foundation

MFamd64:
Add USD_GETBASE(), USD_SETBASE(), USD_GETLIMIT() and USD_SETLIMIT().

- Import the HEAD csup code which is the basis for the cvsmode work.

Integrate support for xen in to i386 common code.

MFC after: 1 month

Change the segment limits to 4GB, we set the user accessible bit on all
of the kernel address space already. Intel recommend this anyway, because
using a non-4GB limit adds an additional clock cycle to address generation.
We were able to install 4GB segments into the LDT, so any limits we imposed
on %cs and %ds were academic anyway. More importantly, this allows us to
make a page in the kernel readable to user applications, for holding things
like the signal trampoline and other fun things.

Move the user %cs/%ds segments from the LDT to the GDT. There was no good
reason for them to be there anyway. The old LDT entries are still there
but we can now relax the restriction that prevented users from emptying
the default LDT entries.

Putting user and kernel %cs and %ds together allows us to access the fast
sysenter/sysexit/syscall/sysret instructions. syscall/sysret in particular
require that the user/kernel segments be laid out this way. Reserve a slot
specifically for NDIS while here.

Create two user controllable slots in the GDT that are context switched
with the (kernel) thread. This allows user applications to set two
user privilige selectors to arbitary values. Create
i386_set_fsbase(void *base) and friends. (get/set, fs/gs). For i386,
%gs is used by tls and the thread libraries and this means that user
processes no longer have to have the cost of having a custom LDT, and
we will no longer to do a ldt switch when activating a kthread/ithread in
the usual case any more.

In other words, we can now set the base address for %fs and %gs to arbitary
addresses without the pain of messing with ldt segments.

Remove advertising clause from University of California Regent's
license, per letter dated July 22, 1999 and email from Peter Wemm,
Alan Cox and Robert Watson.

Approved by: core, peter, alc, rwatson

- Always use 256 IDT entries since it is now a runtime decison as to how
many entries we use.
- Add a constant IDT_IO_INTS for the first IDT entry used for device
interrupts.

Always export r_gdt and r_idt and give them extern declarations in
machine/segments.h.

Add constants for entries in the IDT and use those instead of magic
numbers.

Remove BDE_DEBUGGER.

Discussed with: bde

ISMEMSDP(), IS286GDP(), IS386GDP(), ISGDP(), ISSDP() and ISSYSSDP() are
not used anywhere anymore.

use __packed, rather than __attribute__((packed)).

Create inlines for ltr(sel), lldt(sel), lidt(addr) rather than
functions that have one instruction.

Fixed some style bugs in the removal of __P(()). The main ones were
not removing tabs before "__P((", and not outdenting continuation lines
to preserve non-KNF lining up of code with parentheses. Switch to KNF
formatting and/or rewrap the whole prototype in some cases.

Remove __P.

Add a missing open paren to a macro that's been broken (and apparently
unused) since rev 1.1 so it is at least correct.

Submitted by: Maxime Henrion <mux@qualys.com>

Declare or #define per-cpu globals in <machine/globals.h> in all cases.
The i386 UP case was messily different.

currentldt is now a "special" global-data variable, and as such, there
is no actual currentldt integer variable directly. Thus, don't claim that
there is.

Change #ifdef KERNEL to #ifdef _KERNEL in the public headers. "KERNEL"
is an application space macro and the applications are supposed to be free
to use it as they please (but cannot). This is consistant with the other
BSD's who made this change quite some time ago. More commits to come.

$Id$ -> $FreeBSD$

Mindbogglingly, many BIOS vendors expect to be able to load %ds with
0x40 and then access data stored in real-mode segment 0x40, even when
called in protected mode. Microsoft unfortunately coddle these individuals,
and so must we if we want to run their code.

This change works around GPFs in some APM and PnP BIOS implementations.

Obtained from: Linux

Major update to the kernel's BIOS-calling ability.

- Add support for calling 32-bit code in other segments
- Add support for calling 16-bit protected mode code

Update APM to use this facility.

Submitted by: jlemon

Changed the global `idt' from an array to a pointer so that npx.c
automatically hacks on the active copy of the IDT if f00f_hack()
has changed it. This also allows simplifications in setidt().
This fixes breakage of FP exception handling by rev.1.55 of
sys/kernel.h. FP exceptions were sent to npx.c's probe handlers
because npx.c "restored" the old handlers to the wrong copy of the
IDT. The SYSINIT for f00f_hack() was purposely run quite late to
avoid problems like this, but it is bogusly associated with the
SYSINIT for proc0 so it was moved with the latter.

Problem reported and fix tested by: Martin Cracauer <cracauer@cons.org>

Enable vmspace sharing on SMP. Major changes are,
- %fs register is added to trapframe and saved/restored upon kernel entry/exit.
- Per-cpu pages are no longer mapped at the same virtual address.
- Each cpu now has a separate gdt selector table. A new segment selector
is added to point to per-cpu pages, per-cpu global variables are now
accessed through this new selector (%fs). The selectors in gdt table are
rearranged for cache line optimization.
- fask_vfork is now on as default for both UP and SMP.
- Some aio code cleanup.

Reviewed by: Alan Cox <alc@cs.rice.edu>
John Dyson <dyson@iquest.net>
Julian Elischer <julian@whistel.com>
Bruce Evans <bde@zeta.org.au>
David Greenman <dg@root.com>

Sun Bug ID 1251858 (on http://sunsolve1.sun.com) discusses the way that
Sun implemented iBCS2 compatibility on Solaris >= 2.6: The emulator
runs in user-mode, patching the LDT so that client programs making
syscalls through the old iBCS2 call gate get handled by the emulator
process. Unemulated syscalls therefore need their own call-gate that
bypasses the emulator. Sun chose LDT entry 4 to implement this, which
is what we've been using as LUDATA_SEL, so we need to change LUDATA_SEL
if we want to run Solaris executables.

Discussed with: Mike Smith

Revert my previous commit about using CS_SECURE macro.
Requested by: Bruce.

Use CS_SECURE macro.
Reviewed by: John Dyson

Increased NIDT to 256 for case of SMP or APIC_IO.

Man the liferafts! Here comes the long awaited SMP -> -current merge!

There are various options documented in i386/conf/LINT, there is more to
come over the next few days.

The kernel should run pretty much "as before" without the options to
activate SMP mode.

There are a handful of known "loose ends" that need to be fixed, but
have been put off since the SMP kernel is in a moderately good condition
at the moment.

This commit is the result of the tinkering and testing over the last 14
months by many people. A special thanks to Steve Passe for implementing
the APIC code!

Back out part 1 of the MCFH that changed $Id$ to $FreeBSD$. We are not
ready for it yet.

Make the long-awaited change from $Id$ to $FreeBSD$

This will make a number of things easier in the future, as well as (finally!)
avoiding the Id-smashing problem which has plagued developers for so long.

Boy, I'm glad we're not using sup anymore. This update would have been
insane otherwise.

Apparently, BSDI have a new system call gate. I was experimenting
with this quite a while ago when somebody reported a BSD/OS 2.1 binary
that wouldn't run. I'm pretty sure they tried it and I'm pretty sure
they mentioned to me that the patch worked.

Fix a bunch of spelling errors in the comment fields of
a bunch of system include files.

Remove trailing whitespace.

First attempt to run linux binaries. This is only the changes needed to
the generic kernel. The actual emulator is a separate LKM. (not finished
yet, sorry).
Submitted by: sos@freebsd.org & sef@kithrup.com

Make gdt_segs[] public again for APM.

Make ldt[] public again and restore currentldt and _default_ldt for
USER_LDT.

Remove 1.5+K of bloat for unused idt entries.

Partly support BDE_DEBUGGER. Still broken by conflict with APM. Does
nothing if BDE_DEBUGGER is not defined.

Clean up prototypes and data declarations. Declare most of the segment
functions that are implemented in support.s. Make data private in
machdep.c if possible.

Parenthesize expressions in macros properly!

${Uniformize idempotency ifdef}.

Laptop Advanced Power Management support by HOSOKAWA Tatsumi.

Submitted by: HOSOKAWA Tatsumi

WINE/user LDT support from John Brezak, ported to FreeBSD by Jeffrey Hsu
<hsu@soda.berkeley.edu>.

Made all header files idempotent and moved incorrect common data from
headers into a related source file. Added cons.h as first step towards
moving i386/i386/cons.h to machine/cons.h where it belongs.

Removed all patch kit headers, sccsid and rcsid strings, put $Id$ in, some
minor cleanup. Added $Id$ to files that did not have any version info, etc

Initial import, 0.1 + pk 0.2.4-B1