Copy stable/9 to releng/9.3 as part of the 9.3-RELEASE cycle.

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

Copy head to stable/9 as part of 9.0-RELEASE release cycle.

Approved by: re (implicit)

Resurrect amd64 support.
- Many drivers on amd64 are picking system uptime, interrupt time and ticks
via global data structure instead of calling functions for performance
reasons. For now just patch such address so driver will not trigger page
fault when trying to access such data. In future, additional callout may
be added to update data in periodic intervals.
- On amd64 we need to allocate "shadow space" on stack before calling any
function.

Submitted by: Paul B Mahol <onemda at gmail.com>

When setting up the new stack for a function in x86_64_wrap(), make
sure to make it 16-byte aligned, in keeping with amd64 calling
convention requirements.

Submitted by: Mikore Li at sun dot com

Make the Win64 -> ELF64 template a little smaller by using a string
copy op to shift arguments on the stack instead of transfering each
argument one by one through a register. Probably doesn't affect overall
operation, but makes the code a little less grotty and easier to update
later if I choose to make the wrapper handle more args. Also add
comments.

Remove redundant label.

Add support for Windows/x86-64 binaries to Project Evil.
Ville-Pertti Keinonen (will at exomi dot comohmygodnospampleasekthx)
deserves a big thanks for submitting initial patches to make it
work. I have mangled his contributions appropriately.

The main gotcha with Windows/x86-64 is that Microsoft uses a different
calling convention than everyone else. The standard ABI requires using
6 registers for argument passing, with other arguments on the stack.
Microsoft uses only 4 registers, and requires the caller to leave room
on the stack for the register arguments incase the callee needs to
spill them. Unlike x86, where Microsoft uses a mix of _cdecl, _stdcall
and _fastcall, all routines on Windows/x86-64 uses the same convention.
This unfortunately means that all the functions we export to the
driver require an intermediate translation wrapper. Similarly, we have
to wrap all calls back into the driver binary itself.

The original patches provided macros to wrap every single routine at
compile time, providing a secondary jump table with a customized
wrapper for each exported routine. I decided to use a different approach:
the call wrapper for each function is created from a template at
runtime, and the routine to jump to is patched into the wrapper as
it is created. The subr_pe module has been modified to patch in the
wrapped function instead of the original. (On x86, the wrapping
routine is a no-op.)

There are some minor API differences that had to be accounted for:

- KeAcquireSpinLock() is a real function on amd64, not a macro wrapper
around KfAcquireSpinLock()
- NdisFreeBuffer() is actually IoFreeMdl(). I had to change the whole
NDIS_BUFFER API a bit to accomodate this.

Bugs fixed along the way:
- IoAllocateMdl() always returned NULL
- kern_windrv.c:windrv_unload() wasn't releasing private driver object
extensions correctly (found thanks to memguard)

This has only been tested with the driver for the Broadcom 802.11g
chipset, which was the only Windows/x86-64 driver I could find.