With that change the Atheros 9xxx driver is actually usable and does not
panic anymore.
Submitted by: Paul B Mahol <onemda at gmail.com>
MFC after: 2 weeks
- 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>
According to the comment for MmIsAddressValid() there are issues on PAE
kernels using pmap_kextract().
Submitted by: Paul B Mahol <onemda at gmail.com>
and MmAllocateContiguousMemorySpecifyCache().
Those two functions take 64-bit variable(s) for their arguments. On i386
that takes additional 32-bit variable per argument. This is required so
that windrv_wrap() can correctly wrap function that miniport driver calls
with stdcall convention. Similar explanation is provided in subr_ndis.c for
other functions.
Submitted by: Paul B Mahol <onemda at gmail.com>
whatever the IRP flag is because some drivers (eg. RTL8187L NDIS driver)
call IoCompleteRequest() without setting flags. It will prevent waiting
a event forever at attach.
o implement URB_FUNCTION_ABORT_PIPE handling.
o remove unused code related with canceling the timer list for USB
drivers.
o whitespace cleanup and style(9)
Obtained from: hps's original patch
Now the NDISulator supports NDIS USB drivers that it've tested with
devices as follows:
- Anygate XM-142 (Conexant)
- Netgear WG111v2 (Realtek)
- U-Khan UW-2054u (Marvell)
- Shuttle XPC Accessory PN20 (Realtek)
- ipTIME G054U2 (Ralink)
- UNiCORN WL-54G (ZyDAS)
- ZyXEL G-200v2 (ZyDAS)
All of them succeeded to attach and worked though there are still some
problems that it's expected to be solved.
To use NDIS USB support, you should rebuild and install ndiscvt(8) and
if you encounter a problem to attach please set `hw.ndisusb.halt' to
0 then retry.
I expect no changes of the NDIS code for PCI, PCMCIA devices.
Obtained from: //depot/projects/ndisusb/...
for that argument. This will allow DDB to detect the broad category of
reason why the debugger has been entered, which it can use for the
purposes of deciding which DDB script to run.
Assign approximate why values to all current consumers of the
kdb_enter() interface.
January 1, 1601. The 1601 - 1970 period was in seconds rather than 100ns
units.
Remove duplication by having NdisGetCurrentSystemTime call ntoskrnl_time.
to kproc_xxx as they actually make whole processes.
Thos makes way for us to add REAL kthread_create() and friends
that actually make theads. it turns out that most of these
calls actually end up being moved back to the thread version
when it's added. but we need to make this cosmetic change first.
I'd LOVE to do this rename in 7.0 so that we can eventually MFC the
new kthread_xxx() calls.
be woken up by kthread_exit. This is racey and in some cases the kthread will
exit before ndis gets around to sleep so it will be stuck indefinitely. This
change reuses the kq_exit variable to indicate that the thread has gone and
will loop on tsleep with a timeout waiting for it. If the kthread has already
exited then it will not sleep at all.
Approved by: re (rwatson)
- Use thread_lock() rather than sched_lock for per-thread scheduling
sychronization.
- Use the per-process spinlock rather than the sched_lock for per-process
scheduling synchronization.
Tested by: kris, current@
Tested on: i386, amd64, ULE, 4BSD, libthr, libkse, PREEMPTION, etc.
Discussed with: kris, attilio, kmacy, jhb, julian, bde (small parts each)
for a Windows ISR is 'BOOLEAN isrfunc(KINTERRUPT *, void *)' meaning
the ISR get a pointer to the interrupt object and a context pointer,
and returns TRUE if the ISR determines the interrupt was really generated
by the associated device, or FALSE if not.
I had mistakenly used 'void isrfunc(void *)' instead. It happens the
only thing this affects is the internal ndis_intr() ISR in subr_ndis.c,
but it should be fixed just in case we ever need to register a real
Windows ISR vi IoConnectInterrupt().
For NDIS miniports that provide a MiniportISR() method, the 'is_our_intr'
value returned by the method serves as the return value from ndis_isr(),
and 'call_isr' is used to decide whether or not to schedule the interrupt
handler via DPC. For drivers that only supply MiniportEnableInterrupt()
and MiniportDisableInterrupt() methods, call_isr is always TRUE and
is_our_intr is always FALSE.
In the end, there should be no functional changes, except that now
ntoskrnl_intr() can terminate early once it finds the ISR that wants
to service the interrupt.
Intel's web site requires some minor tweaks to get it to work:
- The driver seems to have been released with full WMI tracing enabled,
and makes references to some WMI APIs, namely IoWMIRegistrationControl(),
WmiQueryTraceInformation() and WmiTraceMessage(). Only the first
one is ever called (during intialization). These have been implemented
as do-nothing stubs for now. Also added a definition for STATUS_NOT_FOUND
to ntoskrnl_var.h, which is used as a return code for one of the WMI
routines.
- The driver references KeRaiseIrqlToDpcLevel() and KeLowerIrql()
(the latter as a function, which is unusual because normally
KeLowerIrql() is a macro in the Windows DDK that calls KfLowewIrql()).
I'm not sure why these are being called since they're not really
part of WDM. Presumeably they're being used for backwards
compatibility with old versions of Windows. These have been
implemented in subr_hal.c. (Note that they're _stdcall routines
instead of _fastcall.)
- When querying the OID_802_11_BSSID_LIST OID to get a BSSID list,
you don't know ahead of time how many networks the NIC has found
during scanning, so you're allowed to pass 0 as the list length.
This should cause the driver to return an 'insufficient resources'
error and set the length to indicate how many bytes are actually
needed. However for some reason, the Intel driver does not honor
this convention: if you give it a length of 0, it returns some
other error and doesn't tell you how much space is really needed.
To get around this, if using a length of 0 yields anything besides
the expected error case, we arbitrarily assume a length of 64K.
This is similar to the hack that wpa_supplicant uses when doing
a BSSID list query.
for code to start out on one CPU when thunking into Windows
mode in ctxsw_utow(), and then be pre-empted and migrated to another
CPU before thunking back to UNIX mode in ctxsw_wtou(). This is
bad, because then we can end up looking at the wrong 'thread environment
block' when trying to come back to UNIX mode. To avoid this, we now
pin ourselves to the current CPU when thunking into Windows code.
Few other cleanups, since I'm here:
- Get rid of the ndis_isr(), ndis_enable_interrupt() and
ndis_disable_interrupt() wrappers from kern_ndis.c and just invoke
the miniport's methods directly in the interrupt handling routines
in subr_ndis.c. We may as well lose the function call overhead,
since we don't need to export these things outside of ndis.ko
now anyway.
- Remove call to ndis_enable_interrupt() from ndis_init() in if_ndis.c.
We don't need to do it there anyway (the miniport init routine handles
it, if needed).
- Fix the logic in NdisWriteErrorLogEntry() a little.
- Change some NDIS_STATUS_xxx codes in subr_ntoskrnl.c into STATUS_xxx
codes.
- Handle kthread_create() failure correctly in PsCreateSystemThread().
and ndis_halt_nic(). It's been disabled for some time anyway, and
it turns out there's a possible deadlock in NdisMInitializeTimer() when
acquiring the miniport block lock to modify the timer list: it's
possible for a driver to call NdisMInitializeTimer() when the miniport
block lock has already been acquired by an earlier piece of code. You
can't acquire the same spinlock twice, so this can deadlock.
Also, implement MmMapIoSpace() and MmUnmapIoSpace(), and make
NdisMMapIoSpace() and NdisMUnmapIoSpace() use them. There are some
drivers that want MmMapIoSpace() and MmUnmapIoSpace() so that they can
map arbitrary register spaces not directly associated with their
device resources. For example, there's an Atheros driver for
a miniPci card (0x168C:0x1014) on the IBM Thinkpad x40 that wants
to map some I/O spaces at 0xF00000 and 0xE00000 which are held by
the acpi0 device. I don't know what it wants these ranges for,
but if it can't map and access them, the MiniportInitialize() method
fails.
This avoids the need for sched_bind() in the default case so that you
can start up the NDIS subsystem at boot time when only CPU 0 is running.
There are potentially ways to fix it so that the DPC threads aren't
started until after the other CPUs are launched, but doing it correctly
is tricky. You need to defer the startup of the ntoskrnl subsystem
(ntoskrnl_libinit()), not just defer ndis_attach().
For now, I don't think it will make much difference having just the
single DPC thread (I started out with just one anyway). Note that this
turns the KeSetTargetProcessorDpc() routine into a no-op, since the
CPU number in struct kdpc is now ignored.
is KeRaiseIrql(newirql, &oldirql), not oldirql = KeRaiseIrql(newirql).
(The macro ultimately translates to KfRaiseIrql() which does use
the latter API, so this has no effect on generated code.)
Also, wait for thread termination the right way: kthread_exit()
will ultimately do a wakeup(td->td_proc). This is the event we
should wait on. Eliminate the previous synchronization machinery
for this since it was never guaranteed to work correctly.
processor, to insure DPC thread 0 runs on CPU0, DPC thread 1 runs on
CPU1, and so on.
Elevate the priority of the workitem threads, though don't use as
high a priority as the DPC threads.
- Change ndis_return() from a DPC to a workitem so that it doesn't
run at DISPATCH_LEVEL (with the dispatcher lock held).
- In if_ndis.c, submit packets to the stack via (*ifp->if_input)() in
a workitem instead of doing it directly in ndis_rxeof(), because
ndis_rxeof() runs in a DPC, and hence at DISPATCH_LEVEL. This
implies that the 'dispatch level' mutex for the current CPU is
being held, and we don't want to call if_input while holding
any locks.
- Reimplement IoConnectInterrupt()/IoDisconnectInterrupt(). The original
approach I used to track down the interrupt resource (by scanning
the device tree starting at the nexus) is prone to problems when
two devices share an interrupt. (E.g removing ndis1 might disable
interrupts for ndis0.) The new approach is to multiplex all the
NDIS interrupts through a common internal dispatcher (ntoskrnl_intr())
and allow IoConnectInterrupt()/IoDisconnectInterrupt() to add or
remove interrupts from the dispatch list.
- Implement KeAcquireInterruptSpinLock() and KeReleaseInterruptSpinLock().
- Change the DPC and workitem threads to use the KeXXXSpinLock
API instead of mtx_lock_spin()/mtx_unlock_spin().
- Simplify the NdisXXXPacket routines by creating an actual
packet pool structure and using the InterlockedSList routines
to manage the packet queue.
- Only honor the value returned by OID_GEN_MAXIMUM_SEND_PACKETS
for serialized drivers. For deserialized drivers, we now create
a packet array of 64 entries. (The Microsoft DDK documentation
says that for deserialized miniports, OID_GEN_MAXIMUM_SEND_PACKETS
is ignored, and the driver for the Marvell 8335 chip, which is
a deserialized miniport, returns 1 when queried.)
- Clean up timer handling in subr_ntoskrnl.
- Add the following conditional debugging code:
NTOSKRNL_DEBUG_TIMERS - add debugging and stats for timers
NDIS_DEBUG_PACKETS - add extra sanity checking for NdisXXXPacket API
NTOSKRNL_DEBUG_SPINLOCKS - add test for spinning too long
- In kern_ndis.c, always start the HAL first and shut it down last,
since Windows spinlocks depend on it. Ntoskrnl should similarly be
started second and shut down next to last.
First and most importantly, I threw out the thread priority-twiddling
implementation of KeRaiseIrql()/KeLowerIrq()/KeGetCurrentIrql() in
favor of a new scheme that uses sleep mutexes. The old scheme was
really very naughty and sought to provide the same behavior as
Windows spinlocks (i.e. blocking pre-emption) but in a way that
wouldn't raise the ire of WITNESS. The new scheme represents
'DISPATCH_LEVEL' as the acquisition of a per-cpu sleep mutex. If
a thread on cpu0 acquires the 'dispatcher mutex,' it will block
any other thread on the same processor that tries to acquire it,
in effect only allowing one thread on the processor to be at
'DISPATCH_LEVEL' at any given time. It can then do the 'atomic sit
and spin' routine on the spinlock variable itself. If a thread on
cpu1 wants to acquire the same spinlock, it acquires the 'dispatcher
mutex' for cpu1 and then it too does an atomic sit and spin to try
acquiring the spinlock.
Unlike real spinlocks, this does not disable pre-emption of all
threads on the CPU, but it does put any threads involved with
the NDISulator to sleep, which is just as good for our purposes.
This means I can now play nice with WITNESS, and I can safely do
things like call malloc() when I'm at 'DISPATCH_LEVEL,' which
you're allowed to do in Windows.
Next, I completely re-wrote most of the event/timer/mutex handling
and wait code. KeWaitForSingleObject() and KeWaitForMultipleObjects()
have been re-written to use condition variables instead of msleep().
This allows us to use the Windows convention whereby thread A can
tell thread B "wake up with a boosted priority." (With msleep(), you
instead have thread B saying "when I get woken up, I'll use this
priority here," and thread A can't tell it to do otherwise.) The
new KeWaitForMultipleObjects() has been better tested and better
duplicates the semantics of its Windows counterpart.
I also overhauled the IoQueueWorkItem() API and underlying code.
Like KeInsertQueueDpc(), IoQueueWorkItem() must insure that the
same work item isn't put on the queue twice. ExQueueWorkItem(),
which in my implementation is built on top of IoQueueWorkItem(),
was also modified to perform a similar test.
I renamed the doubly-linked list macros to give them the same names
as their Windows counterparts and fixed RemoveListTail() and
RemoveListHead() so they properly return the removed item.
I also corrected the list handling code in ntoskrnl_dpc_thread()
and ntoskrnl_workitem_thread(). I realized that the original logic
did not correctly handle the case where a DPC callout tries to
queue up another DPC. It works correctly now.
I implemented IoConnectInterrupt() and IoDisconnectInterrupt() and
modified NdisMRegisterInterrupt() and NdisMDisconnectInterrupt() to
use them. I also tried to duplicate the interrupt handling scheme
used in Windows. The interrupt handling is now internal to ndis.ko,
and the ndis_intr() function has been removed from if_ndis.c. (In
the USB case, interrupt handling isn't needed in if_ndis.c anyway.)
NdisMSleep() has been rewritten to use a KeWaitForSingleObject()
and a KeTimer, which is how it works in Windows. (This is mainly
to insure that the NDISulator uses the KeTimer API so I can spot
any problems with it that may arise.)
KeCancelTimer() has been changed so that it only cancels timers, and
does not attempt to cancel a DPC if the timer managed to fire and
queue one up before KeCancelTimer() was called. The Windows DDK
documentation seems to imply that KeCantelTimer() will also call
KeRemoveQueueDpc() if necessary, but it really doesn't.
The KeTimer implementation has been rewritten to use the callout API
directly instead of timeout()/untimeout(). I still cheat a little in
that I have to manage my own small callout timer wheel, but the timer
code works more smoothly now. I discovered a race condition using
timeout()/untimeout() with periodic timers where untimeout() fails
to actually cancel a timer. I don't quite understand where the race
is, using callout_init()/callout_reset()/callout_stop() directly
seems to fix it.
I also discovered and fixed a bug in winx32_wrap.S related to
translating _stdcall calls. There are a couple of routines
(i.e. the 64-bit arithmetic intrinsics in subr_ntoskrnl) that
return 64-bit quantities. On the x86 arch, 64-bit values are
returned in the %eax and %edx registers. However, it happens
that the ctxsw_utow() routine uses %edx as a scratch register,
and x86_stdcall_wrap() and x86_stdcall_call() were only preserving
%eax before branching to ctxsw_utow(). This means %edx was getting
clobbered in some cases. Curiously, the most noticeable effect of this
bug is that the driver for the TI AXC110 chipset would constantly drop
and reacquire its link for no apparent reason. Both %eax and %edx
are preserved on the stack now. The _fastcall and _regparm
wrappers already handled everything correctly.
I changed if_ndis to use IoAllocateWorkItem() and IoQueueWorkItem()
instead of the NdisScheduleWorkItem() API. This is to avoid possible
deadlocks with any drivers that use NdisScheduleWorkItem() themselves.
The unicode/ansi conversion handling code has been cleaned up. The
internal routines have been moved to subr_ntoskrnl and the
RtlXXX routines have been exported so that subr_ndis can call them.
This removes the incestuous relationship between the two modules
regarding this code and fixes the implementation so that it honors
the 'maxlen' fields correctly. (Previously it was possible for
NdisUnicodeStringToAnsiString() to possibly clobber memory it didn't
own, which was causing many mysterious crashes in the Marvell 8335
driver.)
The registry handling code (NdisOpen/Close/ReadConfiguration()) has
been fixed to allocate memory for all the parameters it hands out to
callers and delete whem when NdisCloseConfiguration() is called.
(Previously, it would secretly use a single static buffer.)
I also substantially updated if_ndis so that the source can now be
built on FreeBSD 7, 6 and 5 without any changes. On FreeBSD 5, only
WEP support is enabled. On FreeBSD 6 and 7, WPA-PSK support is enabled.
The original WPA code has been updated to fit in more cleanly with
the net80211 API, and to eleminate the use of magic numbers. The
ndis_80211_setstate() routine now sets a default authmode of OPEN
and initializes the RTS threshold and fragmentation threshold.
The WPA routines were changed so that the authentication mode is
always set first, followed by the cipher. Some drivers depend on
the operations being performed in this order.
I also added passthrough ioctls that allow application code to
directly call the MiniportSetInformation()/MiniportQueryInformation()
methods via ndis_set_info() and ndis_get_info(). The ndis_linksts()
routine also caches the last 4 events signalled by the driver via
NdisMIndicateStatus(), and they can be queried by an application via
a separate ioctl. This is done to allow wpa_supplicant to directly
program the various crypto and key management options in the driver,
allowing things like WPA2 support to work.
Whew.
as a part of the GENERIC kernel with INVARIANT* and WITNESS*
turned off.
(For non GENERIC kernel KTR and MUTEX_PROFILING should be also
off).
Submitted by: Eygene A. Ryabinkin <rea at rea dot mbslab dot kiae dot ru>
Approved by: re (scottl)
PR: 81767
works again.
This driver uses NdisScheduleWorkItem(), and we have to take special steps
to insure that its workitems don't collide with any of the other workitems
used by the NDISulator. In particular, if one of the driver's work jobs
blocks, it can prevent NdisMAllocateSharedMemoryAsync() from completing
when expected.
The original hack to fix this was to have NdisMAllocateSharedMemoryAsync()
defer its work to the DPC queue instead of the general task queue. To
fix it now, I decided to add some additional workitem threads. (There's
supposed to be a pool of worker threads in Windows anyway.) Currently,
there are 4. There should be at least 2. One is reserved for the legacy
ExQueueWorkItem() API, while the others are used in round-robin by the
IoQueueWorkItem() API. NdisMAllocateSharedMemoryAsync() uses the latter
API while NdisScheduleWorkItem() uses the former, so the deadlock is
avoided.
Fixed NdisMRegisterDevice()/NdisMDeregisterDevice() to work a little
more sensibly with the new driver_object/device_object framework. It
doesn't really register a working user-mode interface, but the existing
code was completely wrong for the new framework.
Fixed a couple of bugs dealing with the cancellation of events and
DPCs. When cancelling an event that's still on the timer queue (i.e.
hasn't expired yet), reset dh_inserted in its dispatch header to FALSE.
Previously, it was left set to TRUE, which would make a cancelled
timer appear to have not been cancelled. Also, when removing a DPC
from a queue, reset its list pointers, otherwise a cancelled DPC
might mistakenly be treated as still pending.
Lastly, fix the behavior of ntoskrnl_wakeup() when dealing with
objects that have nobody waiting on them: sync event objects get
their signalled state reset to FALSE, but notification objects
should still be set to TRUE.
routines (_alldiv(), _allmul(), _alludiv(), _aullmul(), etc...)
that use the _stdcall calling convention.
These routines all take two arguments, but the arguments are 64 bits wide.
On the i386 this means they each consume two 32-bit slots on the stack.
Consequently, when we specify the argument count in the IMPORT_SFUNC()
macro, we have to lie and claim there are 4 arguments instead of two.
This will cause the resulting i386 assembly wrapper to push the right
number of longwords onto the stack.
This fixes a crash I discovered with the RealTek 8180 driver, which
uses these routines a lot during initialization.
Remove unused fields from ndis_miniport_block.
Fix a bug in KeFlushQueuedDpcs() (we weren't calculating the kq pointer
correctly).
In if_ndis.c, clear the IFF_RUNNING flag before calling ndis_halt_nic().
Add some guards in kern_ndis.c to avoid letting anyone invoke ndis_get_info()
or ndis_set_info() if the NIC isn't fully initialized. Apparently, mdnsd
will sometimes try to invoke the ndis_ioctl() routine at exactly the
wrong moment (to futz with its multicast filters) when the interface
comes up, and can trigger a crash unless we guard against it.
- Remove the old task threads from kern_ndis.c and reimplement them in
subr_ntoskrnl.c, in order to more properly emulate the Windows DPC
API. Each CPU gets its own DPC queue/thread, and each queue can
have low, medium and high importance DPCs. New APIs implemented:
KeSetTargetProcessorDpc(), KeSetImportanceDpc() and KeFlushQueuedDpcs().
(This is the biggest change.)
- Fix a bug in NdisMInitializeTimer(): the k_dpc pointer in the
nmt_timer embedded in the ndis_miniport_timer struct must be set
to point to the DPC, also embedded in the struct. Failing to do
this breaks dequeueing of DPCs submitted via timers, and in turn
breaks cancelling timers.
- Fix a bug in KeCancelTimer(): if the timer is interted in the timer
queue (i.e. the timeout callback is still pending), we have to both
untimeout() the timer _and_ call KeRemoveQueueDpc() to nuke the DPC
that might be pending. Failing to do this breaks cancellation of
periodic timers, which always appear to be inserted in the timer queue.
- Make use of the nmt_nexttimer field in ndis_miniport_timer: keep a
queue of pending timers and cancel them all in ndis_halt_nic(), prior
to calling MiniportHalt(). Also call KeFlushQueuedDpcs() to make sure
any DPCs queued by the timers have expired.
- Modify NdisMAllocateSharedMemory() and NdisMFreeSharedMemory() to keep
track of both the virtual and physical addresses of the shared memory
buffers that get handed out. The AirGo MIMO driver appears to have a bug
in it: for one of the segments is allocates, it returns the wrong
virtual address. This would confuse NdisMFreeSharedMemory() and cause
a crash. Why it doesn't crash Windows too I have no idea (from reading
the documentation for NdisMFreeSharedMemory(), it appears to be a violation
of the API).
- Implement strstr(), strchr() and MmIsAddressValid().
- Implement IoAllocateWorkItem(), IoFreeWorkItem(), IoQueueWorkItem() and
ExQueueWorkItem(). (This is the second biggest change.)
- Make NdisScheduleWorkItem() call ExQueueWorkItem(). (Note that the
ExQueueWorkItem() API is deprecated by Microsoft, but NDIS still uses
it, since NdisScheduleWorkItem() is incompatible with the IoXXXWorkItem()
API.)
- Change if_ndis.c to use the NdisScheduleWorkItem() interface for scheduling
tasks.
With all these changes and fixes, the AirGo MIMO driver for the Belkin
F5D8010 Pre-N card now works. Special thanks to Paul Robinson
(paul dawt robinson at pwermedia dawt net) for the loan of a card
for testing.
here on in, if_ndis.ko will be pre-built as a module, and can be built
into a static kernel (though it's not part of GENERIC). Drivers are
created using the new ndisgen(8) script, which uses ndiscvt(8) under
the covers, along with a few other tools. The result is a driver module
that can be kldloaded into the kernel.
A driver with foo.inf and foo.sys files will be converted into
foo_sys.ko (and foo_sys.o, for those who want/need to make static
kernels). This module contains all of the necessary info from the
.INF file and the driver binary image, converted into an ELF module.
You can kldload this module (or add it to /boot/loader.conf) to have
it loaded automatically. Any required firmware files can be bundled
into the module as well (or converted/loaded separately).
Also, add a workaround for a problem in NdisMSleep(). During system
bootstrap (cold == 1), msleep() always returns 0 without actually
sleeping. The Intel 2200BG driver uses NdisMSleep() to wait for
the NIC's firmware to come to life, and fails to load if NdisMSleep()
doesn't actually delay. As a workaround, if msleep() (and hence
ndis_thsuspend()) returns 0, use a hard DELAY() to sleep instead).
This is not really the right thing to do, but we can't really do much
else. At the very least, this makes the Intel driver happy.
There are probably other drivers that fail in this way during bootstrap.
Unfortunately, the only workaround for those is to avoid pre-loading
them and kldload them once the system is running instead.
layer, but with a twist.
The twist has to do with the fact that Microsoft supports structured
exception handling in kernel mode. On the i386 arch, exception handling
is implemented by hanging an exception registration list off the
Thread Environment Block (TEB), and the TEB is accessed via the %fs
register. The problem is, we use %fs as a pointer to the pcpu stucture,
which means any driver that tries to write through %fs:0 will overwrite
the curthread pointer and make a serious mess of things.
To get around this, Project Evil now creates a special entry in
the GDT on each processor. When we call into Windows code, a context
switch routine will fix up %fs so it points to our new descriptor,
which in turn points to a fake TEB. When the Windows code returns,
or calls out to an external routine, we swap %fs back again. Currently,
Project Evil makes use of GDT slot 7, which is all 0s by default.
I fully expect someone to jump up and say I can't do that, but I
couldn't find any code that makes use of this entry anywhere. Sadly,
this was the only method I could come up with that worked on both
UP and SMP. (Modifying the LDT works on UP, but becomes incredibly
complicated on SMP.) If necessary, the context switching stuff can
be yanked out while preserving the convention calling wrappers.
(Fortunately, it looks like Microsoft uses some special epilog/prolog
code on amd64 to implement exception handling, so the same nastiness
won't be necessary on that arch.)
The advantages are:
- Any driver that uses %fs as though it were a TEB pointer won't
clobber pcpu.
- All the __stdcall/__fastcall/__regparm stuff that's specific to
gcc goes away.
Also, while I'm here, switch NdisGetSystemUpTime() back to using
nanouptime() again. It turns out nanouptime() is way more accurate
than just using ticks(). On slower machines, the Atheros drivers
I tested seem to take a long time to associate due to the loss
in accuracy.
- On amd64, InterlockedPushEntrySList() and InterlockedPopEntrySList()
are mapped to ExpInterlockedPushEntrySList and
ExpInterlockedPopEntrySList() via macros (which do the same thing).
Add IMPORT_FUNC_MAP()s for these.
- Implement ExQueryDepthSList().
