dim [Thu, 26 Feb 2015 07:20:05 +0000 (07:20 +0000)]
Make libcxxrt's parsing of DWARF exception handling tables work on
architectures with strict alignment, by using memcpy() instead of
directly reading fields.
jchandra [Thu, 26 Feb 2015 01:53:24 +0000 (01:53 +0000)]
Fix up interrupt definitions for Broadcom XLP
Gather all the IRQ definitions to interrupt.h. Earlier these were in xlp.h
and pic.h. Update the definition of XLP_IRQ_IS_PICINTR to check for last
irq as well.
delphij [Wed, 25 Feb 2015 20:47:25 +0000 (20:47 +0000)]
Explicitly crypt_set_format("des") and bail out if we
can't. This would prevent problem when we changed the
default crypt(3) algorithm or removed it in the future.
kib [Wed, 25 Feb 2015 16:44:07 +0000 (16:44 +0000)]
For now, disable x2APIC mode when Xen is detected, even if CPU
declares support for it. Newer versions of Xen works fine with x2APIC
code, but e.g. Xen 4.2 delivers GPF on the LAPIC MSR write, despite
x2APIC mode being known to hypervisor.
Discussed with: royger
Sponsored by: The FreeBSD Foundation
kib [Wed, 25 Feb 2015 16:18:26 +0000 (16:18 +0000)]
Propagate errors from _thr_umutex_unlock2 through mutex_unlock_common.
Errors from _thr_umutex_unlock2 should "never happen" in normal
circumstances. If they do, however, return them to the application
so it can fail early and loudly. Hiding the errors will only delay
the inevitable failure, making it harder to find and diagnose.
Submitted by: Eric van Gyzen <eric_van_gyzen@dell.com>
Obtained from: Dell Inc.
PR: 198914
MFC after: 1 week
kib [Wed, 25 Feb 2015 16:17:16 +0000 (16:17 +0000)]
When failing to claim ownership of a umtx_pi, restore the umutex owner
to its previous, unowned state. This avoids compounding an existing
problem of inconsistent ownership.
Submitted by: Eric van Gyzen <eric_van_gyzen@dell.com>
Obtained from: Dell Inc.
PR: 198914
MFC after: 1 week
kib [Wed, 25 Feb 2015 16:12:56 +0000 (16:12 +0000)]
When unlocking a contested PI pthread mutex, if the queue of waiters
is empty, look up the umtx_pi and disown it if the current thread owns it.
This can happen if a signal or timeout removed the last waiter from
the queue, but there is still a thread in do_lock_pi() holding a reference
on the umtx_pi. The unlocking thread might not own the umtx_pi in this case,
but if it does, it must disown it to keep the ownership consistent between
the umtx_pi and the umutex.
Submitted by: Eric van Gyzen <eric_van_gyzen@dell.com>
with advice from: Elliott Rabe and Jim Muchow, also at Dell Inc.
Obtained from: Dell Inc.
PR: 198914
hselasky [Wed, 25 Feb 2015 13:58:43 +0000 (13:58 +0000)]
Fix a special case in ip_fragment() to produce a more sensible chain
of packets. When the data payload length excluding any headers, of an
outgoing IPv4 packet exceeds PAGE_SIZE bytes, a special case in
ip_fragment() can kick in to optimise the outgoing payload(s). The
code which was added in r98849 as part of zero copy socket support
assumes that the beginning of any MTU sized payload is aligned to
where a MBUF's "m_data" pointer points. This is not always the case
and can sometimes cause large IPv4 packets, as part of ping replies,
to be split more than needed.
Instead of iterating the MBUFs to figure out how much data is in the
current chain, use the value already in the "m_pkthdr.len" field of
the first MBUF in the chain.
cperciva [Wed, 25 Feb 2015 07:49:15 +0000 (07:49 +0000)]
Adjust wording slightly to emphasize that random(3) should not be used for
any applications which need unpredictable random numbers, not merely those
which are cryptographic in nature.
If you work for a lottery and you're using random(3) to select the winning
numbers, please let me know.
ken [Wed, 25 Feb 2015 04:30:23 +0000 (04:30 +0000)]
Fix several problems found by Coverity.
lib/libmt/mtlib.c:
In mt_start_element(), make sure we don't overflow the
cur_sb array. CID 1271325
usr.bin/mt/mt.c:
In main(), bzero the mt_com structure so that we aren't
using any uninitialized stack variables. CID 1271319
In mt_param(), only allow one -s and one -p argument. This
will prevent a memory leak caused by overwriting the
param_name and/or param_value variables. CID 1271320 and
CID 1271322
To make things simpler in mt_param(), make sure there
there is only one exit path for the function. Make sure
the arguments are explicitly freed.
gjb [Tue, 24 Feb 2015 22:27:02 +0000 (22:27 +0000)]
Add a CLOUDPACKAGE variable to contain a list of targets for
post-install packaging cloud provider images.
Add a 'gce-package.sh' script to generate the final output
image ready for upload to the GCE platform. Right now, this
is the only image that has a specific output format (GNU-tar),
and this implementation is expected to be temporary.
This is not directly connected to the other release targets.
MFC after: 1 week
X-MFC-with: r279249, r279250
Sponsored by: The FreeBSD Foundation
slm [Tue, 24 Feb 2015 22:07:42 +0000 (22:07 +0000)]
- Updated all files with 2015 Avago copyright, and updated LSI's copyright
dates.
- Changed all of the PCI device strings from LSI to Avago Technologies (LSI).
- Added a sysctl variable to control how StartStopUnit behavior works. User can
select to spin down disks based on if disk is SSD or HDD.
- Inquiry data is required to tell if a disk will support SSU at shutdown or
not. Due to the addition of mpssas_async, which gets Advanced Info but not
Inquiry data, the setting of supports_SSU was moved to the
mpssas_scsiio_complete function, which snoops for any Inquiry commands. And,
since disks are shutdown as a target and not a LUN, this process was
simplified by basing it on targets and not LUNs.
- Added a sysctl variable that sets the amount of time to retry after sending a
failed SATA ID command. This helps with some bad disks and large disks that
require a lot of time to spin up. Part of this change was to add a callout to
handle timeouts with the SATA ID command. The callout function is called
mpssas_ata_id_timeout(). (Fixes PR 191348)
- Changed the way resets work by allowing I/O to continue to devices that are
not currently under a reset condition. This uses devq's instead of simq's and
makes use of the MPSSAS_TARGET_INRESET flag. This change also adds a function
called mpssas_prepare_tm().
- Some changes were made to reduce code duplication when getting a SAS address
for a SATA disk.
nwhitehorn [Tue, 24 Feb 2015 21:37:20 +0000 (21:37 +0000)]
New pmap implementation for 64-bit PowerPC processors. The main focus of
this change is to improve concurrency:
- Drop global state stored in the shadow overflow page table (and all other
global state)
- Remove all global locks
- Use per-PTE lock bits to allow parallel page insertion
- Reconstruct state when requested for evicted PTEs instead of buffering
it during overflow
This drops total wall time for make buildworld on a 32-thread POWER8 system
by a factor of two and system time by a factor of three, providing performance
20% better than similarly clocked Core i7 Xeons per-core. Performance on
smaller SMP systems, where PMAP lock contention was not as much of an issue,
is nearly unchanged.
Tested on: POWER8, POWER5+, G5 UP, G5 SMP (64-bit and 32-bit kernels)
Merged from: user/nwhitehorn/ppc64-pmap-rework
Looked over by: jhibbits, andreast
MFC after: 3 months
Relnotes: yes
Sponsored by: FreeBSD Foundation
np [Tue, 24 Feb 2015 21:31:13 +0000 (21:31 +0000)]
cxgbe(4): allow tx hardware checksumming on the netmap interface.
It is disabled by default but users can set IFCAP_TXCSUM on the
netmap ifnet (ifconfig ncxl0 txcsum) to override netmap and force
the hardware to calculate and insert proper IP and L4 checksums in
outbound frames.
gjb [Tue, 24 Feb 2015 21:06:25 +0000 (21:06 +0000)]
Add 'cloudware-install' target to handle copying cloud
disk images to a directory within DESTDIR.
Add CLOUDINSTALL variable to automatically generate the
actual list of install targets. While here, rename the
cloud-specific names from 'vm-' to 'cw-' to avoid naming
collisions.
Add AZURE_DISK, GCE_DISK, and OPENSTACK_DISK output file
variables.
Add 'cloudware-install' to the 'install' target.
MFC after: 1 week
Sponsored by: The FreeBSD Foundation
emaste [Tue, 24 Feb 2015 19:27:51 +0000 (19:27 +0000)]
Unconditionally install debug directory hierarchy
This avoids various failure modes (e.g., when building and installing a
single binary with debug data on a system that otherwise does not have
it enabled).
It is also consistent with the way other directory hierarchies are
handled (e.g. share/man).
sjg [Tue, 24 Feb 2015 19:03:31 +0000 (19:03 +0000)]
If sys.mk were found via the magic path .../share/mk
replace it with the absolute path of .PARSEDIR, so that sub-makes
launched from objdirs (eg kernel) can still find the correct mk files.
This was due to instructions which do not support unaligned access,
whereas for __alignment(2) compiler replaced ldmia/stmia with some
logically equivalent memcpy operations.
In fact, the assumption that 'struct ip' is always 4-byte aligned
is definitely false, as we have no impact on data alignment of packet
stream received.
Another possible solution would be to explicitely perform memcpy()
on objects of 'struct ip' type, which, however, would suffer from
performance drop, and be merely a problem hiding.
Please, note that this has nothing to do with
ARM32_DISABLE_ALIGNMENT_FAULTS option, but is related strictly to
compiler behaviour.
Submitted by: Wojciech Macek <wma@semihalf.com>
Reviewed by: glebius, ian
Obtained from: Semihalf
ae [Tue, 24 Feb 2015 10:35:07 +0000 (10:35 +0000)]
Fix possible memory leak and several races in the IPsec policy management
code.
Resurrect the state field in the struct secpolicy, it has
IPSEC_SPSTATE_ALIVE value when security policy linked in the chain,
and IPSEC_SPSTATE_DEAD value in all other cases. This field protects
from trying to unlink one security policy several times from the different
threads.
Take additional reference in the key_flush_spd() to be sure that policy
won't be freed from the different thread while we are sending SPDEXPIRE message.
Add KEY_FREESP() call to the key_unlink() to release additional reference
that we take when use key_getsp*() functions.
hselasky [Tue, 24 Feb 2015 08:53:47 +0000 (08:53 +0000)]
Ensure that the XHCI driver will refresh the control endpoint settings
when re-enumerating a FULL speed device. Else the wrong max packet
setting might be used when trying to re-enumerate a FULL speed device.
luigi [Tue, 24 Feb 2015 06:20:50 +0000 (06:20 +0000)]
Add native netmap support to ixl.
Preliminary tests indicate 32 Mpps on tx, 24 Mpps on rx
with source and receiver on two different ports of the same 40G card.
Optimizations are likely possible.
The code follows closely the one for ixgbe so i do not
expect stability issues.
neel [Tue, 24 Feb 2015 05:35:15 +0000 (05:35 +0000)]
Always emulate MSR_PAT on Intel processors and don't rely on PAT save/restore
capability of VT-x. This lets bhyve run nested in older VMware versions that
don't support the PAT save/restore capability.
Note that the actual value programmed by the guest in MSR_PAT is irrelevant
because bhyve sets the 'Ignore PAT' bit in the nested PTE.
Reported by: marcel
Tested by: Leon Dang (ldang@nahannisys.com)
Sponsored by: Nahanni Systems
MFC after: 2 weeks
neel [Tue, 24 Feb 2015 02:04:16 +0000 (02:04 +0000)]
Add "-u" option to bhyve(8) to indicate that the RTC should maintain UTC time.
The default remains localtime for compatibility with the original device model
in bhyve(8). This is required for OpenBSD guests which assume that the RTC
keeps UTC time.
Reviewed by: grehan
Pointed out by: Jason Tubnor (jason@tubnor.net)
MFC after: 2 weeks
ken [Mon, 23 Feb 2015 21:59:30 +0000 (21:59 +0000)]
Significant upgrades to sa(4) and mt(1).
The primary focus of these changes is to modernize FreeBSD's
tape infrastructure so that we can take advantage of some of the
features of modern tape drives and allow support for LTFS.
Significant changes and new features include:
o sa(4) driver status and parameter information is now exported via an
XML structure. This will allow for changes and improvements later
on that will not break userland applications. The old MTIOCGET
status ioctl remains, so applications using the existing interface
will not break.
o 'mt status' now reports drive-reported tape position information
as well as the previously available calculated tape position
information. These numbers will be different at times, because
the drive-reported block numbers are relative to BOP (Beginning
of Partition), but the block numbers calculated previously via
sa(4) (and still provided) are relative to the last filemark.
Both numbers are now provided. 'mt status' now also shows the
drive INQUIRY information, serial number and any position flags
(BOP, EOT, etc.) provided with the tape position information.
'mt status -v' adds information on the maximum possible I/O size,
and the underlying values used to calculate it.
o The extra sa(4) /dev entries (/dev/saN.[0-3]) have been removed.
The extra devices were originally added as place holders for
density-specific device nodes. Some OSes (NetBSD, NetApp's OnTap
and Solaris) have had device nodes that, when you write to them,
will automatically select a given density for particular tape drives.
This is a convenient way of switching densities, but it was never
implemented in FreeBSD. Only the device nodes were there, and that
sometimes confused users.
For modern tape devices, the density is generally not selectable
(e.g. with LTO) or defaults to the highest availble density when
the tape is rewritten from BOT (e.g. TS11X0). So, for most users,
density selection won't be necessary. If they do need to select
the density, it is easy enough to use 'mt density' to change it.
o Protection information is now supported. This is either a
Reed-Solomon CRC or CRC32 that is included at the end of each block
read and written. On write, the tape drive verifies the CRC, and
on read, the tape drive provides a CRC for the userland application
to verify.
o New, extensible tape driver parameter get/set interface.
o Density reporting information. For drives that support it,
'mt getdensity' will show detailed information on what formats the
tape drive supports, and what formats the tape drive supports.
o Some mt(1) functionality moved into a new mt(3) library so that
external applications can reuse the code.
o The new mt(3) library includes helper routines to aid in parsing
the XML output of the sa(4) driver, and build a tree of driver
metadata.
o Support for the MTLOAD (load a tape in the drive) and MTWEOFI
(write filemark immediate) ioctls needed by IBM's LTFS
implementation.
o Improve device departure behavior for the sa(4) driver. The previous
implementation led to hangs when the device was open.
o This has been tested on the following types of drives:
IBM TS1150
IBM TS1140
IBM LTO-6
IBM LTO-5
HP LTO-2
Seagate DDS-4
Quantum DLT-4000
Exabyte 8505
Sony DDS-2
lib/libmt/Makefile,
lib/libmt/mt.3,
lib/libmt/mtlib.c,
lib/libmt/mtlib.h,
New mt(3) library that contains functions moved from mt(1) and
new functions needed to interact with the updated sa(4) driver.
This includes XML parser helper functions that application writers
can use when writing code to query tape parameters.
rescue/rescue/Makefile:
Add -lmt to CRUNCH_LIBS.
src/share/man/man4/mtio.4
Clarify this man page a bit, and since it contains what is
essentially the mtio.h header file, add new ioctls and structure
definitions from mtio.h.
src/share/man/man4/sa.4
Update BUGS and maintainer section.
sys/cam/scsi/scsi_all.c,
sys/cam/scsi/scsi_all.h:
Add SCSI SECURITY PROTOCOL IN/OUT CDB definitions and CDB building
functions.
sys/cam/scsi/scsi_sa.c
sys/cam/scsi/scsi_sa.h
Many tape driver changes, largely outlined above.
Increase the sa(4) driver read/write timeout from 4 to 32
minutes. This is based on the recommended values for IBM LTO
5/6 drives. This may also avoid timeouts for other tape
hardware that can take a long time to do retries and error
recovery. Longer term, a better way to handle this is to ask
the drive for recommended timeout values using the REPORT
SUPPORTED OPCODES command. Modern IBM and Oracle tape drives
at least support that command, and it would allow for more
accurate timeout values.
Add XML status generation. This is done with a series of
macros to eliminate as much duplicate code as possible. The
new XML-based status values are reported through the new
MTIOCEXTGET ioctl.
Add XML driver parameter reporting, using the new MTIOCPARAMGET
ioctl.
Add a new driver parameter setting interface, using the new
MTIOCPARAMSET and MTIOCSETLIST ioctls.
Add a new MTIOCRBLIM ioctl to get block limits information.
Add CCB/CDB building routines scsi_locate_16, scsi_locate_10,
and scsi_read_position_10().
scsi_locate_10 implements the LOCATE command, as does the
existing scsi_set_position() command. It just supports
additional arguments and features. If/when we figure out a
good way to provide backward compatibility for older
applications using the old function API, we can just revamp
scsi_set_position(). The same goes for
scsi_read_position_10() and the existing scsi_read_position()
function.
Revamp sasetpos() to take the new mtlocate structure as an
argument. It now will use either scsi_locate_10() or
scsi_locate_16(), depending upon the arguments the user
supplies. As before, once we change position we don't have a
clear idea of what the current logical position of the tape
drive is.
For tape drives that support long form position data, we
read the current position and store that for later reporting
after changing the position. This should help applications
like Bacula speed tape access under FreeBSD once they are
modified to support the new ioctls.
Add a new quirk, SA_QUIRK_NO_LONG_POS, that is set for all
drives that report SCSI-2 or older, as well as drives that
report an Illegal Request type error for READ POSITION with
the long format. So we should automatically detect drives
that don't support the long form and stop asking for it after
an initial try.
Add a partition number to the sa(4) softc.
Improve device departure handling. The previous implementation
led to hangs when the device was open.
If an application had the sa(4) driver open, and attempted to
close it after it went away, the cam_periph_release() call in
saclose() would cause the periph to get destroyed because that
was the last reference to it. Because destroy_dev() was
called from the sa(4) driver's cleanup routine (sacleanup()),
and would block waiting for the close to happen, a deadlock
would result.
So instead of calling destroy_dev() from the cleanup routine,
call destroy_dev_sched_cb() from saoninvalidate() and wait for
the callback.
Acquire a reference for devfs in saregister(), and release it
in the new sadevgonecb() routine when all devfs devices for
the particular sa(4) driver instance are gone.
Add a new function, sasetupdev(), to centralize setting
per-instance devfs device parameters instead of repeating the
code in saregister().
Add an open count to the softc, so we know how many
peripheral driver references are a result of open
sessions.
Add the D_TRACKCLOSE flag to the cdevsw flags so
that we get a 1:1 mapping of open to close calls
instead of a N:1 mapping.
This should be a no-op for everything except the
control device, since we don't allow more than one
open on non-control devices.
However, since we do allow multiple opens on the
control device, the combination of the open count
and the D_TRACKCLOSE flag should result in an
accurate peripheral driver reference count, and an
accurate open count.
The accurate open count allows us to release all
peripheral driver references that are the result
of open contexts once we get the callback from devfs.
sys/sys/mtio.h:
Add a number of new mt(4) ioctls and the requisite data
structures. None of the existing interfaces been removed
or changed.
This includes definitions for the following new ioctls:
MTIOCRBLIM /* get block limits */
MTIOCEXTLOCATE /* seek to position */
MTIOCEXTGET /* get tape status */
MTIOCPARAMGET /* get tape params */
MTIOCPARAMSET /* set tape params */
MTIOCSETLIST /* set N params */
usr.bin/mt/Makefile:
mt(1) now depends on libmt, libsbuf and libbsdxml.
usr.bin/mt/mt.1:
Document new mt(1) features and subcommands.
usr.bin/mt/mt.c:
Implement support for mt(1) subcommands that need to
use getopt(3) for their arguments.
Implement a new 'mt status' command to replace the old
'mt status' command. The old status command has been
renamed 'ostatus'.
The new status function uses the MTIOCEXTGET ioctl, and
therefore parses the XML data to determine drive status.
The -x argument to 'mt status' allows the user to dump out
the raw XML reported by the kernel.
The new status display is mostly the same as the old status
display, except that it doesn't print the redundant density
mode information, and it does print the current partition
number and position flags.
Add a new command, 'mt locate', that will supersede the
old 'mt setspos' and 'mt sethpos' commands. 'mt locate'
implements all of the functionality of the MTIOCEXTLOCATE
ioctl, and allows the user to change the logical position
of the tape drive in a number of ways. (Partition,
block number, file number, set mark number, end of data.)
The immediate bit and the explicit address bits are
implemented, but not documented in the man page.
Add a new 'mt weofi' command to use the new MTWEOFI ioctl.
This allows the user to ask the drive to write a filemark
without waiting around for the operation to complete.
Add a new 'mt getdensity' command that gets the XML-based
tape drive density report from the sa(4) driver and displays
it. This uses the SCSI REPORT DENSITY SUPPORT command
to get comprehensive information from the tape drive about
what formats it is able to read and write.
Add a new 'mt protect' command that allows getting and setting
tape drive protection information. The protection information
is a CRC tacked on to the end of every read/write from and to
the tape drive.
ian [Mon, 23 Feb 2015 20:09:05 +0000 (20:09 +0000)]
There is no reason to do i+dcache writeback and invalidate when changing
the translation table (this may be left over from armv5 days). It's
especially bad to do so using a cache operation that isn't coherent on
SMP systems.
glebius [Mon, 23 Feb 2015 18:57:09 +0000 (18:57 +0000)]
A lot of current code in network stack expects mbufs not having
m_nextpkt pointer, assuming that if there is one, then this is
a packet batch. Thus, mbufq_dequeue() needs to clear it on mbuf
that is being returned.
hselasky [Mon, 23 Feb 2015 17:01:38 +0000 (17:01 +0000)]
Add support for the DWC OTG v2 chipset found in the STM32F4 series of
processors. Make sure we pullup the data lines in device mode when we
power on the port.
ae [Mon, 23 Feb 2015 13:41:35 +0000 (13:41 +0000)]
In some cases soreceive_dgram() can return no data, but has control
message. This can happen when application is sending packets too big
for the path MTU and recvmsg() will return zero (indicating no data)
but there will be a cmsghdr with cmsg_type set to IPV6_PATHMTU.
Remove KASSERT() which does NULL pointer dereference in such case.
Also call m_freem() only when m isn't NULL.
nwhitehorn [Sun, 22 Feb 2015 21:40:27 +0000 (21:40 +0000)]
Kernel support for the Vector-Scalar eXtension (VSX) found on the POWER7
and POWER8. This instruction set unifies the 32 64-bit scalar floating
point registers with the 32 128-bit vector registers into a single bank
of 64 128-bit registers. Kernel support mostly amounts to saving and
restoring the wider version of the floating point registers and making
sure that both scalar FP and vector registers are enabled once a VSX
instruction is executed. get_mcontext() and friends currently cannot
see the high bits, which will require a little more work.
As the system compiler (GCC 4.2) does not support VSX, making use of this
from userland requires either newer GCC or clang.
nwhitehorn [Sun, 22 Feb 2015 20:52:29 +0000 (20:52 +0000)]
Add some opcodes for assembling forthcoming VSX (Vector-Scalar eXtension)
support in the kernel. Userspace programs are expected to rely on LLVM's
integrated assembler or newer binutils.
arybchik [Sun, 22 Feb 2015 19:24:08 +0000 (19:24 +0000)]
sfxge: add common code support for changing TX queue pace
To delay packets from a particular TX queue by a particular time, write a value
into the TX Pace table s.t. pace time <= TX Pace Clock Period * (2 ^ pace value)
- the TX pace clock is 1/13 of the system clock, so its period should be 104 or
52 ns depending on whether turbo mode is active.
EFX_TX_PACE_CLOCK_BASE added by me.
Submitted by: Mark Spender <mspender at solarflare.com>
Sponsored by: Solarflare Communications, Inc.
Approved by: gnn (mentor)
arybchik [Sun, 22 Feb 2015 18:54:16 +0000 (18:54 +0000)]
sfxge: do no allow EFSYS_MEM_ALLOC sleep
It solves locking problem when EFSYS_MEM_ALLOC is called in
the context holding a mutex (not allowed to sleep).
E.g. on interface bring up or multicast addresses addition.
Sponsored by: Solarflare Communications, Inc.
Approved by: gnn (mentor)
arybchik [Sun, 22 Feb 2015 18:50:59 +0000 (18:50 +0000)]
sfxge: pass correct address to free allocated memory in the case of load error
It is one more place missed in the previous fix.
Most likely is was just memory leak on the error handling path since
typically efsys_mem_t is filled in by zeros on allocation.
Sponsored by: Solarflare Communications, Inc.
Approved by: gnn (mentor)
dim [Sun, 22 Feb 2015 15:51:49 +0000 (15:51 +0000)]
Pull in r230058 from upstream llvm trunk (by Benjamin Kramer):
LoopRotate: When reconstructing loop simplify form don't split edges
from indirectbrs.
Yet another chapter in the endless story. While this looks like we
leave the loop in a non-canonical state this replicates the logic in
LoopSimplify so it doesn't diverge from the canonical form in any way.
http://llvm.org/PR21968
This fixes a "Cannot split critical edge from IndirectBrInst" assertion
failure when building the devel/radare2 port.