Copy stable/10@r272459 to releng/10.1 as part of
the 10.1-RELEASE process.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Eliminate the PC_CURTHREAD symbol and load the current thread's
thread structure pointer atomically from r13 (the pcpu pointer)
for the current CPU/core.
Add a CTASSERT in machdep.c to make sure that pc_curthread is in
fact the first field in struct pcpu.

The only non-atomic operations left were those related to process-
space operations, such as casuword, subyte, suword16, fubyte,
fuword16, copyin, copyout and their variations.

The casuword function has been re-structured more complete than
the others. This way we have an example of a better bundling
without introducing a lot of risk when we get it wrong. The
other functions can be rebundled in separate commits and with
the appropriate testing.

Fix switching to physical mode as part of calling into EFI runtime
services or PAL procedures. The new implementation is based on
specific functions that are known to be called in certain scenarios
only. This in particular fixes the PAL call to obtain information
about translation registers. In general, the new implementation does
not bank on virtual addresses being direct-mapped and will work when
the kernel uses PBVM.

When new scenarios need to be supported, new functions are added if
the existing functions cannot be changed to handle the new scenario.
If a single generic implementation is possible, it will become clear
in due time.

While here, change bootinfo to a pointer type in anticipation of
future development.

Use VM_MAXUSER_ADDRESS rather than VM_MAX_ADDRESS when we talk about
the bounds of user space. Redefine VM_MAX_ADDRESS as ~0UL, even though
it's not used anywhere in the source tree.

Prefer I-units and M-units for nop instructions. This works around
McKinley flaws. It also avoids using the F-unit in the kernel for
no reason.

The flushrs instruction must be the first in an instruction
group. GNU as(1) already made sure of that, but it's better
to actually have the code right.

MFC after: 1 week

o Add keyword volatile for user mutex owner field.
o Fix type consistent problem by using type long for old
umtx and wait channel.
o Rename casuptr to casuword.

Implement casuword32, compare and set user integer, thank Marcel Moolenarr
who wrote the IA64 version of casuword32.

/* -> /*- for copyright notices, minor format tweaks as necessary

Further enhance the handling of misaligned loads and stores:
o implement double-extended and single precision loads and stores,
o implement double precision stores,
o replace the machdep.unaligned_print sysctl with debug.unaligned_print
and change the default value to 0,
o replace the machdep.unaligned_sigbus sysctl with debug.unaligned_test,
o Remmove the fillfd() function. The function is trvial enough for
inline assembly.

The debug.unaligned_test sysctl is used to test the emulation of
misaligned loads and stores. When PSR.ac is 0, the CPU will handle
misaligned memory accesses itselfi and we don't get an exception
for it. When PSR.ac is 1, the process needs to be signalled and we
should not emulate. The sysctl takes effect when PSR.ac is 1 and
tells us that we should emulate and not send a signal.

PR: 72268
MFC after: 1 week

s/ENTRY/ENTRY_NOPROFILE/g for particular functions that do not follow
the C calling convention or are otherwise not regular functions. This
allows us to boot a profiling kernel.

Make profiling actually work. The gcc compiler emits a call to the
_mcount() stub when profiling is enabled. Emit this code sequence
for assembly routines as welli (MCOUNT definition in <machine/asm.h>.
We do not pass the GOT entry however as the 4th argument, because it's
not used. The _mcount() stub calls __mcount(), which does the actual
work. Define _MCOUNT_DECL to define __mcount. We do not have an
implementation of mcount(), so we define MCOUNT as empty, but have a
weak alias to _mcount() in _mcount.S.
Note that the _mcount() stub in the kernel is slightly different from
the stub in userland. This is because we do not have to worry about
nested routines in the kernel.

Add spillfd(). This function loads a double-precision FP register
at the first address and spills it to the second address. This
allows unaligned_fixup() to update the context of the process in
a way that assures proper rounding.
Similar functions for single-and extended-precision are added when
needed.

Cleanup prototypes in cpu.h, including fswintrberr and any references
to it. Sort the remaining prototypes in cpu.h.

No functional change.

The .s files were repo-copied to .S files.

Approved by: marcel
Repocopied by: joe

Fix fu{byte|word*} and su{byte|word*}:
o If the address was not within user space we jumped to fusufault
where we would clear pcb_onfault and return 0. There are two
bugs here:
1. We never got to the point where we assigned the address of
pcb_onfault to r15, which means that we would clobber some
random memory location, including I/O space or ROM.
2. We're supposed to return -1 on error.
o Make sure we have proper memory ordering for setting pcb_onfault,
doing the memory access to user space and clearing pcb_onfault.
For the fu* family of functions this means that we need a mf
instruction, because we don't have acquire semantics on stores
and release semantics on loads (hence st;ld cannot be ordered
without intermediate mf).

While here, implement casuptr() so that we are a (small) step
closer to supporting libthr and deobfuscate the non-implementation
of {f|s}uswintr.

Approved by: re@ (blanket)

Revamp of the syscall path, exception and context handling. The
prime objectives are:
o Implement a syscall path based on the epc inststruction (see
sys/ia64/ia64/syscall.s).
o Revisit the places were we need to save and restore registers
and define those contexts in terms of the register sets (see
sys/ia64/include/_regset.h).

Secundairy objectives:
o Remove the requirement to use contigmalloc for kernel stacks.
o Better handling of the high FP registers for SMP systems.
o Switch to the new cpu_switch() and cpu_throw() semantics.
o Add a good unwinder to reconstruct contexts for the rare
cases we need to (see sys/contrib/ia64/libuwx)

Many files are affected by this change. Functionally it boils
down to:
o The EPC syscall doesn't preserve registers it does not need
to preserve and places the arguments differently on the stack.
This affects libc and truss.
o The address of the kernel page directory (kptdir) had to
be unstaticized for use by the nested TLB fault handler.
The name has been changed to ia64_kptdir to avoid conflicts.
The renaming affects libkvm.
o The trapframe only contains the special registers and the
scratch registers. For syscalls using the EPC syscall path
no scratch registers are saved. This affects all places where
the trapframe is accessed. Most notably the unaligned access
handler, the signal delivery code and the debugger.
o Context switching only partly saves the special registers
and the preserved registers. This affects cpu_switch() and
triggered the move to the new semantics, which additionally
affects cpu_throw().
o The high FP registers are either in the PCB or on some
CPU. context switching for them is done lazily. This affects
trap().
o The mcontext has room for all registers, but not all of them
have to be defined in all cases. This mostly affects signal
delivery code now. The *context syscalls are as of yet still
unimplemented.

Many details went into the removal of the requirement to use
contigmalloc for kernel stacks. The details are mostly CPU
specific and limited to exception_save() and exception_restore().
The few places where we create, destroy or switch stacks were
mostly simplified by not having to construct physical addresses
and additionally saving the virtual addresses for later use.

Besides more efficient context saving and restoring, which of
course yields a noticable speedup, this also fixes the dreaded
SMP bootup problem as a side-effect. The details of which are
still not fully understood.

This change includes all the necessary backward compatibility
code to have it handle older userland binaries that use the
break instruction for syscalls. Support for break-based syscalls
has been pessimized in favor of a clean implementation. Due to
the overall better performance of the kernel, this will still
be notived as an improvement if it's noticed at all.

Approved by: re@ (jhb)

Define ovbcopy() as a macro which expands to the equivalent bcopy() call,
to take care of the KAME IPv6 code which needs ovbcopy() because NetBSD's
bcopy() doesn't handle overlap like ours.

Remove all implementations of ovbcopy().

Previously, bzero was a function pointer on i386, to save a jmp to
bzero_vector. Get rid of this microoptimization as it only confuses
things, adds machine-dependent code to an MD header, and doesn't really
save all that much.

This commit does not add my pagezero() / pagecopy() code.

Update an 'XXX what is this?' type comment about suswintr and fuswintr.
These are 16 bit short values used only by the profiling code.

Deorbit suibyte(). It was only used for split address space systems
for supporting UIO_USERISPACE (ie: it wasn't used).

Use suword32/64 and fuword32/64 like elsewhere instead of inventing
suhword/fuhword.

Add suhword() and fuhword() for accessing 32-bit values ("half words") in
userland. All these functions should be renamed to be explicit about the
size of value being read or written.

Overhaul the per-CPU support a bit:

- The MI portions of struct globaldata have been consolidated into a MI
struct pcpu. The MD per-CPU data are specified via a macro defined in
machine/pcpu.h. A macro was chosen over a struct mdpcpu so that the
interface would be cleaner (PCPU_GET(my_md_field) vs.
PCPU_GET(md.md_my_md_field)).
- All references to globaldata are changed to pcpu instead. In a UP kernel,
this data was stored as global variables which is where the original name
came from. In an SMP world this data is per-CPU and ideally private to each
CPU outside of the context of debuggers. This also included combining
machine/globaldata.h and machine/globals.h into machine/pcpu.h.
- The pointer to the thread using the FPU on i386 was renamed from
npxthread to fpcurthread to be identical with other architectures.
- Make the show pcpu ddb command MI with a MD callout to display MD
fields.
- The globaldata_register() function was renamed to pcpu_init() and now
init's MI fields of a struct pcpu in addition to registering it with
the internal array and list.
- A pcpu_destroy() function was added to remove a struct pcpu from the
internal array and list.

Tested on: alpha, i386
Reviewed by: peter, jake

Various fixes to make stack traces using the unwind tables work properly.

* Preserve ar.rsc in ia64_change_mode.
* Convert sp to/from physical in ia64_change_mode.
* Add a shim for calling EFI procedures in virtual mode.

Fix a few comment typos from the last commit.

Add some code which can be used to change to/from physical mode when
calling various firmware functions.

KSE Milestone 2
Note ALL MODULES MUST BE RECOMPILED
make the kernel aware that there are smaller units of scheduling than the
process. (but only allow one thread per process at this time).
This is functionally equivalent to teh previousl -current except
that there is a thread associated with each process.

Sorry john! (your next MFC will be a doosie!)

Reviewed by: peter@freebsd.org, dillon@freebsd.org

X-MFC after: ha ha ha ha

Remove old setjmp/longjmp stubs.

* Fix exception handling so that it actually works. We can now handle
exceptions from both kernel and user mode.
* Fix context switching so that we can switch back to a proc which we
switched away from (we were saving the state in the wrong place).
* Implement lazy switching of the high-fp state. This needs to be looked
at again for SMP to cope with the case of a process migrating from one
processor to another while it has the high-fp state.
* Make setregs() work properly. I still think this should be called
cpu_exec() or something.
* Various other minor fixes.

With this lot, we can execve() /sbin/init and we get all the way up to its
first syscall. At that point, we stop because syscall handling is not done
yet.

Next round of fixes to the ia64 code. This includes simulated clock and
disk drivers along with a load of fixes to context switching, fork
handling and a load of other stuff I can't remember now. This takes us as
far as start_init() before it dies. I guess now I will have to finish off
the VM system and syscall handling :-).

Next round of ia64 work, including fixes to context switching,
implementing cpu_fork(), copy*str(), bcopy(), copy{in,out}(). With these
changes, my test kernel reaches the mountroot prompt.

This is the first snapshot of the FreeBSD/ia64 kernel. This kernel will
not work on any real hardware (or fully work on any simulator). Much more
needs to happen before this is actually functional but its nice to see
the FreeBSD copyright message appear in the ia64 simulator.