attempting to duplicate Windows spinlocks. Windows spinlocks differ
from FreeBSD spinlocks in the way they block preemption. FreeBSD
spinlocks use critical_enter(), which masks off _all_ interrupts.
This prevents any other threads from being scheduled, but it also
prevents ISRs from running. In Windows, preemption is achieved by
raising the processor IRQL to DISPATCH_LEVEL, which prevents other
threads from preempting you, but does _not_ prevent device ISRs
from running. (This is essentially what Solaris calls dispatcher
locks.) The Windows spinlock itself (kspin_lock) is just an integer
value which is atomically set when you acquire the lock and atomically
cleared when you release it.
FreeBSD doesn't have IRQ levels, so we have to cheat a little by
using thread priorities: normal thread priority is PASSIVE_LEVEL,
lowest interrupt thread priority is DISPATCH_LEVEL, highest thread
priority is DEVICE_LEVEL (PI_REALTIME) and critical_enter() is
HIGH_LEVEL. In practice, only PASSIVE_LEVEL and DISPATCH_LEVEL
matter to us. The immediate benefit of all this is that I no
longer have to rely on a mutex pool.
Now, I'm sure many people will be seized by the urge to criticize
me for doing an end run around our own spinlock implementation, but
it makes more sense to do it this way. Well, it does to me anyway.
Overview of the changes:
- Properly implement hal_lock(), hal_unlock(), hal_irql(),
hal_raise_irql() and hal_lower_irql() so that they more closely
resemble their Windows counterparts. The IRQL is determined by
thread priority.
- Make ntoskrnl_lock_dpc() and ntoskrnl_unlock_dpc() do what they do
in Windows, which is to atomically set/clear the lock value. These
routines are designed to be called from DISPATCH_LEVEL, and are
actually half of the work involved in acquiring/releasing spinlocks.
- Add FASTCALL1(), FASTCALL2() and FASTCALL3() macros/wrappers
that allow us to call a _fastcall function in spite of the fact
that our version of gcc doesn't support __attribute__((__fastcall__))
yet. The macros take 1, 2 or 3 arguments, respectively. We need
to call hal_lock(), hal_unlock() etc... ourselves, but can't really
invoke the function directly. I could have just made the underlying
functions native routines and put _fastcall wrappers around them for
the benefit of Windows binaries, but that would create needless bloat.
- Remove ndis_mtxpool and all references to it. We don't need it
anymore.
- Re-implement the NdisSpinLock routines so that they use hal_lock()
and friends like they do in Windows.
- Use the new spinlock methods for handling lookaside lists and
linked list updates in place of the mutex locks that were there
before.
- Remove mutex locking from ndis_isr() and ndis_intrhand() since they're
already called with ndis_intrmtx held in if_ndis.c.
- Put ndis_destroy_lock() code under explicit #ifdef notdef/#endif.
It turns out there are some drivers which stupidly free the memory
in which their spinlocks reside before calling ndis_destroy_lock()
on them (touch-after-free bug). The ADMtek wireless driver
is guilty of this faux pas. (Why this doesn't clobber Windows I
have no idea.)
- Make NdisDprAcquireSpinLock() and NdisDprReleaseSpinLock() into
real functions instead of aliasing them to NdisAcaquireSpinLock()
and NdisReleaseSpinLock(). The Dpr routines use
KeAcquireSpinLockAtDpcLevel() level and KeReleaseSpinLockFromDpcLevel(),
which acquires the lock without twiddling the IRQL.
- In ndis_linksts_done(), do _not_ call ndis_80211_getstate(). Some
drivers may call the status/status done callbacks as the result of
setting an OID: ndis_80211_getstate() gets OIDs, which means we
might cause the driver to recursively access some of its internal
structures unexpectedly. The ndis_ticktask() routine will call
ndis_80211_getstate() for us eventually anyway.
- Fix the channel setting code a little in ndis_80211_setstate(),
and initialize the channel to IEEE80211_CHAN_ANYC. (The Microsoft
spec says you're not supposed to twiddle the channel in BSS mode;
I may need to enforce this later.) This fixes the problems I was
having with the ADMtek adm8211 driver: we were setting the channel
to a non-standard default, which would cause it to fail to associate
in BSS mode.
- Use hal_raise_irql() to raise our IRQL to DISPATCH_LEVEL when
calling certain miniport routines, per the Microsoft documentation.
I think that's everything. Hopefully, other than fixing the ADMtek
driver, there should be no apparent change in behavior.
before calling BUS_GET_RESOURCE_LIST(). Previously, the list head would
only be initialized if BUS_GET_RESOURCE_LIST() succeeded; it needs to
be initialized unconditionally so that the list cleanup code won't
trip over potential stack garbage.
case we should wait for the resetdone handler to be called before
returning.
- When providing resources via ndis_query_resources(), uses the
computed rsclen when using bcopy() to copy out the resource data
rather than the caller-supplied buffer length.
- Avoid using ndis_reset_nic() in if_ndis.c unless we really need
to reset the NIC because of a problem.
- Allow interrupts to be fielded during ndis_attach(), at least
as far as allowing ndis_isr() and ndis_intrhand() to run.
- Use ndis_80211_rates_ex when probing for supported rates. Technically,
this isn't supposed to work since, although Microsoft added the extended
rate structure with the NDIS 5.1 update, the spec still says that
the OID_802_11_SUPPORTED_RATES OID uses ndis_80211_rates. In spite of
this, it appears some drivers use it anyway.
- When adding in our guessed rates, check to see if they already exist
so that we avoid any duplicates.
- Add a printf() to ndis_open_file() that alerts the user when a
driver attempts to open a file under /compat/ndis.
With these changes, I can get the driver for the SMC 2802W 54g PCI
card to load and run. This board uses a Prism54G chip. Note that in
order for this driver to work, you must place the supplied smc2802w.arm
firmware image under /compat/ndis. (The firmware is not resident on
the device.)
Note that this should also allow the 3Com 3CRWE154G72 card to work
as well; as far as I can tell, these cards also use a Prism54G chip.
1. This check if wrong, because it is true by default
(kern.ps_argsopen is 1 by default) (p_cansee() is not even checked).
2. Sysctl kern.ps_argsopen is going away.
resource_var.h.
In kern_ndis.c:ndis_convert_res(), fill in the cprd_flags and
cprd_sharedisp fields as best we can.
In if_ndis.c:ndis_setmulti(), don't bother updating the multicast
filter if our multicast address list is empty.
Add some missing updates to ndis_var.h and ntoskrnl_var.h that I
forgot to check in when I added the KeDpc stuff.
objects rather than synchronization objects. When a sync object is
signaled, only the first thread waiting on it is woken up, and then
it's automatically reset to the not-signaled state. When a
notification object is signaled, all threads waiting on it will
be woken up, and it remains in the signaled state until someone
resets it manually. We want the latter behavior for NDIS events.
- In kern_ndis.c:ndis_convert_res(), we have to create a temporary
copy of the list returned by BUS_GET_RESOURCE_LIST(). When the PCI
bus code probes resources for a given device, it enters them into
a singly linked list, head first. The result is that traversing
this list gives you the resources in reverse order. This means when
we create the Windows resource list, it will be in reverse order too.
Unfortunately, this can hose drivers for devices with multiple I/O
ranges of the same type, like, say, two memory mapped I/O regions (one
for registers, one to map the NVRAM/bootrom/whatever). Some drivers
test the range size to figure out which region is which, but others
just assume that the resources will be listed in ascending order from
lowest numbered BAR to highest. Reversing the order means such drivers
will choose the wrong resource as their I/O register range.
Since we can't traverse the resource SLIST backwards, we have to
make a temporary copy of the list in the right order and then build
the Windows resource list from that. I suppose we could just fix
the PCI bus code to use a TAILQ instead, but then I'd have to track
down all the consumers of the BUS_GET_RESOURCE_LIST() and fix them
too.
which pulls a job off a thread work queue (assuming it hasn't run yet).
This is needed for KeRemoveQueueDpc().
- In subr_ntoskrnl.c, implement KeInsertQueueDpc() and KeRemoveQueueDpc(),
to go with KeInitializeDpc() to round out the API. Also change the
KeTimer implementation to use this API instead of the private
timer callout scheduler. Functionality of the timer API remains
unchanged, but we get a couple new Windows kernel API routines and
more closely imitate the way thing works in Windows. (As of yet
I haven't encountered any drivers that use KeInsertQueueDpc() or
KeRemoveQueueDpc(), but it doesn't hurt to have them.)
when it associates with a net. Because FreeBSD's kstack size is only
2 pages by default, this blows the stack and causes a double fault.
To deal with this, we now create all our kthreads with 8 stack pages.
Also, we now run all timer callouts in the ndis swi thread (since
they would otherwise run in the clock ithread, whose stack is too
small). It happens that the alloca() in this case was occuring within
the interrupt handler, which was already running in the ndis swi
thread, but I want to deal with the callouts too just to be extra
safe.
NOTE: this will only work if you update vm_machdep.c with the change
I just committed. If you don't include this fix, setting the number
of stack pages with kthread_create() has essentially no effect.
are actually layered on top of the KeTimer API in subr_ntoskrnl.c, just
as it is in Windows. This reduces code duplication and more closely
imitates the way things are done in Windows.
- Modify ndis_encode_parm() to deal with the case where we have
a registry key expressed as a hex value ("0x1") which is being
read via NdisReadConfiguration() as an int. Previously, we tried
to decode things like "0x1" with strtol() using a base of 10, which
would always yield 0. This is what was causing problems with the
Intel 2200BG Centrino 802.11g driver: the .inf file that comes
with it has a key called RadioEnable with a value of 0x1. We
incorrectly decoded this value to '0' when it was queried, hence
the driver thought we wanted the radio turned off.
- In if_ndis.c, most drivers don't accept NDIS_80211_AUTHMODE_AUTO,
but NDIS_80211_AUTHMODE_SHARED may not be right in some cases,
so for now always use NDIS_80211_AUTHMODE_OPEN.
NOTE: There is still one problem with the Intel 2200BG driver: it
happens that the kernel stack in Windows is larger than the kernel
stack in FreeBSD. The 2200BG driver sometimes eats up more than 2
pages of stack space, which can lead to a double fault panic.
For the moment, I got things to work by adding the following to
my kernel config file:
options KSTACK_PAGES=8
I'm pretty sure 8 is too big; I just picked this value out of a hat
as a test, and it happened to work, so I left it. 4 pages might be
enough. Unfortunately, I don't think you can dynamically give a
thread a larger stack, so I'm not sure how to handle this short of
putting a note in the man page about it and dealing with the flood
of mail from people who never read man pages.
options, status pointer and rusage pointer as arguments. It is up to
the caller to copyout the status and rusage to userland if needed. This
lets us axe the 'compat' argument and hide all that functionality in
owait(), by the way. This also cleans up some locking in kern_wait()
since it no longer has to drop locks around copyout() since all the
copyout()'s are deferred.
- Convert owait(), wait4(), and the various ABI compat wait() syscalls to
use kern_wait() rather than wait1() or wait4(). This removes a bit
more stackgap usage.
Tested on: i386
Compiled on: i386, alpha, amd64
snprintf() and vsnprintf() in FreeBSD kernel land).
This is needed by the Intel Centrino 2200BG driver. Unfortunately, this
driver still doesn't work right with Project Evil even with this tweak,
but I'm unable to diagnose the problem since I don't have access to a
sample card.
for Windows are deserialized miniports. Such drivers maintain their own
queues and do their own locking. This particular driver is not deserialized
though, and we need special support to handle it correctly.
Typically, in the ndis_rxeof() handler, we pass all incoming packets
directly to (*ifp->if_input)(). This in turn may cause another thread
to run and preempt us, and the packet may actually be processed and
then released before we even exit the ndis_rxeof() routine. The
problem with this is that releasing a packet calls the ndis_return_packet()
function, which hands the packet and its buffers back to the driver.
Calling ndis_return_packet() before ndis_rxeof() returns will screw
up the driver's internal queues since, not being deserialized,
it does no locking.
To avoid this problem, if we detect a serialized driver (by checking
the attribute flags passed to NdisSetAttributesEx(), we use an alternate
ndis_rxeof() handler, ndis_rxeof_serial(), which puts the call to
(*ifp->if_input)() on the NDIS SWI work queue. This guarantees the
packet won't be processed until after ndis_rxeof_serial() returns.
Note that another approach is to always copy the packet data into
another mbuf and just let the driver retain ownership of the ndis_packet
structure (ndis_return_packet() never needs to be called in this
case). I'm not sure which method is faster.
that I added recently:
- When a periodic timer fires, it's automatically re-armed. We must
make sure to re-arm the timer _before_ invoking any caller-supplied
defered procedure call: the DPC may choose to call KeCancelTimer(),
and re-arming the timer after the DPC un-does the effect of the
cancel.
- Fix similar issue with periodic timers in subr_ndis.c.
- When calling KeSetTimer() or KeSetTimerEx(), if the timer is
already pending, untimeout() it first before timeout()ing
it again.
- The old Atheros driver for the 5211 seems to use KeSetTimerEx()
incorrectly, or at the very least in a very strange way that
doesn't quite follow the Microsoft documentation. In one case,
it calls KeSetTimerEx() with a duetime of 0 and a period of 5000.
The Microsoft documentation says that negative duetime values
are relative to the current time and positive values are absolute.
But it doesn't say what's supposed to happen with positive values
that less than the current time, i.e. absolute values that are
in the past.
Lacking any further information, I have decided that timers with
positive duetimes that are in the past should fire right away (or
in our case, after only 1 tick). This also takes care of the other
strange usage in the Atheros driver, where the duetime is
specified as 500000 and the period is 50. I think someone may
have meant to use -500000 and misinterpreted the documentation.
- Also modified KeWaitForSingleObject() and KeWaitForMultipleObjects()
to make the same duetime adjustment, since they have the same rules
regarding timeout values.
- Cosmetic: change name of 'timeout' variable in KeWaitForSingleObject()
and KeWaitForMultipleObjects() to 'duetime' to avoid senseless
(though harmless) overlap with timeout() function name.
With these fixes, I can get the 5211 card to associate properly with
my adhoc net using driver AR5211.SYS version 2.4.1.6.
if_ndis.c has been split into if_ndis_pci.c and if_ndis_pccard.c.
The ndiscvt(8) utility should be able to parse device info for PCMCIA
devices now. The ndis_alloc_amem() has moved from kern_ndis.c to
if_ndis_pccard.c so that kern_ndis.c no longer depends on pccard.
NOTE: this stuff is not guaranteed to work 100% correctly yet. So
far I have been able to load/init my PCMCIA Cisco Aironet 340 card,
but it crashes in the interrupt handler. The existing support for
PCI/cardbus devices should still work as before.
along with KeInitializeTimerEx(), KeSetTimer(), KeSetTimerEx(),
KeCancelTimer(), KeReadStateTimer() and KeInitializeDpc(). I don't
know for certain that these will make the Atheros driver happy since
I don't have the card/driver combo needed to test it, but these are
fairly independent so they shouldn't break anything else.
- Debugger() is present even in kernels without options DDB, so no
conditional compilation is necessary (pointed out by bde).
- Remove the extra km_acquirecnt member that I added to struct kmutant
and embed it within an unused portion of the structure instead, so that
we don't make the structure larger than it's defined to be in Windows.
I don't know what crack I was smoking when I decided it was ok to do
this, but it's worn off now.
routines to guard against problems caused by (possibly) buggy drivers.
The RealTek 8180 wireless driver calls NdisFreeBuffer() to release
some of its buffers _after_ it's already called NdisFreeBufferPool()
to destroy the pool to which the buffers belong. In our implementation,
this error causes NdisFreeBuffer() to touch stale heap memory.
If you are running a release kernel, and hence have INVARIANTS et al
turned off, it turns out nothing happens. But if you're using a
development kernel config with INVARIANTS on, the malloc()/free()
sanity checks will scribble over the pool memory with 0xdeadc0de
once it's released so that any attempts to touch it will cause a
trap, and indeed this is what happens. It happens that I run 5.2-RELEASE
on my laptop, so when I tested the rtl8180.sys driver, it worked fine
for me, but people trying to run it with development systems checked
out or cvsupped from -current would get a page fault on driver load.
I can't find any reason why the NDISulator would cause the RealTek
driver to do the NdisFreeBufferPool() prematurely, and the same driver
obviously works with Windows -- or at least, it doesn't cause a crash:
the Microsoft documentation for NdisFreeBufferPool() says that failing
to return all buffers to the pool before calling NdisFreeBufferPool()
causes a memory leak.
I've written to my contacts at RealTek asking them to check if this
is indeed a bug in their driver. In the meantime, these new sanity checks
will catch this problem and issue a warning rather than causing a trap.
The trick is to keep a count of outstanding buffers for each buffer pool,
and if the driver tries to call NdisFreeBufferPool() while there are still
buffers outstanding, we mark the pool for deletion and then defer
destroying it until after the last buffer has been reclaimed.
is set, since some drivers with debug info can be very chatty.
Also implement DbgBreakPoint(), which is the Windows equivalent of
Debugger(). Unfortunately, this forces subr_ntoskrnl.c to include
opt_ddb.h.
Remove the unused second argument from udev2dev().
Convert all remaining users of makedev() to use udev2dev(). The
semantic difference is that udev2dev() will only locate a pre-existing
dev_t, it will not line makedev() create a new one.
Apart from the tiny well controlled windown in D_PSEUDO drivers,
there should no longer be any "anonymous" dev_t's in the system
now, only dev_t's created with make_dev() and make_dev_alias()
- When adding new waiting threads to the waitlist for an object,
use INSERT_LIST_TAIL() instead of INSERT_LIST_HEAD() so that new
waiters go at the end of the list instead of the beginning. When we
wake up a synchronization object, only the first waiter is awakened,
and this needs to be the first thread that actually waited on the object.
- Correct missing semicolon in INSERT_LIST_TAIL() macro.
- Implement lookaside lists correctly. Note that the Am1771 driver
uses lookaside lists to manage shared memory (i.e. DMAable) buffers
by specifying its own alloc and free routines. The Microsoft documentation
says you should avoid doing this, but apparently this did not deter
the developers at AMD from doing it anyway.
With these changes (which are the result of two straight days of almost
non-stop debugging), I think I finally have the object/thread handling
semantics implemented correctly. The Am1771 driver no longer crashes
unexpectedly during association or bringing the interface up.
The Am1771 driver will sometimes do the following:
- Some thread-> NdisScheduleWorkItem(some work)
- Worker thread -> do some work, KeWaitForSingleObject(some event)
- Some other thread -> NdisScheduleWorkItem(some other work)
When the second call to NdisScheduleWorkItem() occurs, the NDIS worker
thread (in our case ndis taskqueue) is suspended in KeWaitForSingleObject()
and waiting for an event to be signaled. This is different from when
the worker thread is idle and waiting on NdisScheduleWorkItem() to
send it more jobs. However, the ndis_sched() function in kern_ndis.c
always calls kthread_resume() when queueing a new job. Normally this
would be ok, but here this causes KeWaitForSingleObject() to return
prematurely, which is not what we want.
To fix this, the NDIS threads created by kern_ndis.c maintain a state
variable to indicate whether they are running (scanning the job list
and executing jobs) or sleeping (blocked on kthread_suspend() in
ndis_runq()), and ndis_sched() will only call kthread_resume() if
the thread is in the sleeping state.
Note that we can't just check to see if the thread is on the run queue:
in both cases, the thread is sleeping, but it's sleeping for different
reasons.
This stops the Am1771 driver from emitting various "NDIS ERROR" messages
and fixes some cases where it crashes.
routines to do anything except return error if the miniport adapter context
is not set (meaning we either having init'ed the driver yet, or the
initialization failed).
Also, be sure to NULL out the adapter context along with the
miniport characteristics pointers if calling the MiniportInitialize()
method fails.
nodes, or if they did, they're now locked away on the Kurt Gdel
memorial home for the numerically confused:
Don't cast a kernel pointer (from makedev(9)) to an integer (maj+minor combo).
802.11b chipset work. This chip is present on the SMC2602W version 3
NIC, which is what was used for testing. This driver creates kernel
threads (12 of them!) for various purposes, and required the following
routines:
PsCreateSystemThread()
PsTerminateSystemThread()
KeInitializeEvent()
KeSetEvent()
KeResetEvent()
KeInitializeMutex()
KeReleaseMutex()
KeWaitForSingleObject()
KeWaitForMultipleObjects()
IoGetDeviceProperty()
and several more. Also, this driver abuses the fact that NDIS events
and timers are actually Windows events and timers, and uses NDIS events
with KeWaitForSingleObject(). The NDIS event routines have been rewritten
to interface with the ntoskrnl module. Many routines with incorrect
prototypes have been cleaned up.
Also, this driver puts jobs on the NDIS taskqueue (via NdisScheduleWorkItem())
which block on events, and this interferes with the operation of
NdisMAllocateSharedMemoryAsync(), which was also being put on the
NDIS taskqueue. To avoid the deadlock, NdisMAllocateSharedMemoryAsync()
is now performed in the NDIS SWI thread instead.
There's still room for some cleanups here, and I really should implement
KeInitializeTimer() and friends.
