linux.git/Documentation/powerpc, branch v4.8

powerpc: signals: Discard transaction state from signal frames

2016-08-29T02:48:40+00:00

Userspace can begin and suspend a transaction within the signal
handler which means they might enter sys_rt_sigreturn() with the
processor in suspended state.

sys_rt_sigreturn() wants to restore process context (which may have
been in a transaction before signal delivery). To do this it must
restore TM SPRS. To achieve this, any transaction initiated within the
signal frame must be discarded in order to be able to restore TM SPRs
as TM SPRs can only be manipulated non-transactionally..
>From the PowerPC ISA:
  TM Bad Thing Exception [Category: Transactional Memory]
   An attempt is made to execute a mtspr targeting a TM register in
   other than Non-transactional state.

Not doing so results in a TM Bad Thing:
[12045.221359] Kernel BUG at c000000000050a40 [verbose debug info unavailable]
[12045.221470] Unexpected TM Bad Thing exception at c000000000050a40 (msr 0x201033)
[12045.221540] Oops: Unrecoverable exception, sig: 6 [#1]
[12045.221586] SMP NR_CPUS=2048 NUMA PowerNV
[12045.221634] Modules linked in: xt_CHECKSUM iptable_mangle ipt_MASQUERADE
 nf_nat_masquerade_ipv4 iptable_nat nf_nat_ipv4 nf_nat nf_conntrack_ipv4 nf_defrag_ipv4
 xt_conntrack nf_conntrack ipt_REJECT nf_reject_ipv4 xt_tcpudp bridge stp llc ebtable_filter
 ebtables ip6table_filter ip6_tables iptable_filter ip_tables x_tables kvm_hv kvm
 uio_pdrv_genirq ipmi_powernv uio powernv_rng ipmi_msghandler autofs4 ses enclosure
 scsi_transport_sas bnx2x ipr mdio libcrc32c
[12045.222167] CPU: 68 PID: 6178 Comm: sigreturnpanic Not tainted 4.7.0 #34
[12045.222224] task: c0000000fce38600 ti: c0000000fceb4000 task.ti: c0000000fceb4000
[12045.222293] NIP: c000000000050a40 LR: c0000000000163bc CTR: 0000000000000000
[12045.222361] REGS: c0000000fceb7ac0 TRAP: 0700   Not tainted (4.7.0)
[12045.222418] MSR: 9000000300201033  CR: 28444280  XER: 20000000
[12045.222625] CFAR: c0000000000163b8 SOFTE: 0 PACATMSCRATCH: 900000014280f033
GPR00: 01100000b8000001 c0000000fceb7d40 c00000000139c100 c0000000fce390d0
GPR04: 900000034280f033 0000000000000000 0000000000000000 0000000000000000
GPR08: 0000000000000000 b000000000001033 0000000000000001 0000000000000000
GPR12: 0000000000000000 c000000002926400 0000000000000000 0000000000000000
GPR16: 0000000000000000 0000000000000000 0000000000000000 0000000000000000
GPR20: 0000000000000000 0000000000000000 0000000000000000 0000000000000000
GPR24: 0000000000000000 00003ffff98cadd0 00003ffff98cb470 0000000000000000
GPR28: 900000034280f033 c0000000fceb7ea0 0000000000000001 c0000000fce390d0
[12045.223535] NIP [c000000000050a40] tm_restore_sprs+0xc/0x1c
[12045.223584] LR [c0000000000163bc] tm_recheckpoint+0x5c/0xa0
[12045.223630] Call Trace:
[12045.223655] [c0000000fceb7d80] [c000000000026e74] sys_rt_sigreturn+0x494/0x6c0
[12045.223738] [c0000000fceb7e30] [c0000000000092e0] system_call+0x38/0x108
[12045.223806] Instruction dump:
[12045.223841] 7c800164 4e800020 7c0022a6 f80304a8 7c0222a6 f80304b0 7c0122a6 f80304b8
[12045.223955] 4e800020 e80304a8 7c0023a6 e80304b0 <7c0223a6> e80304b8 7c0123a6 4e800020
[12045.224074] ---[ end trace cb8002ee240bae76 ]---

It isn't clear exactly if there is really a use case for userspace
returning with a suspended transaction, however, doing so doesn't (on
its own) constitute a bad frame. As such, this patch simply discards
the transactional state of the context calling the sigreturn and
continues.

Reported-by: Laurent Dufour 
Signed-off-by: Cyril Bur 
Tested-by: Laurent Dufour 
Reviewed-by: Laurent Dufour 
Acked-by: Simon Guo 
Signed-off-by: Benjamin Herrenschmidt

powerpc/eeh: rename EEH from "extended" to "enhanced" error handling

2016-04-11T10:30:42+00:00

IBM online documentation for EEH uses "extended error handling" and
"enhanced error handling" to refer to the same thing, in different
places.  The only place mentioning it as "enhanced error handling" in the
kernel is the MAINTAINERS file, and it's "extended" in some documentation.

IBM originally defined EEH as "enhanced error handling", so standardise
all mentions of EEH to use that term.

Signed-off-by: Russell Currey 
Acked-by: Gavin Shan 
Signed-off-by: Michael Ellerman

cxl: Support to flash a new image on the adapter from a guest

2016-03-09T12:39:56+00:00

The new flash.c file contains the logic to flash a new image on the
adapter, through a hcall. It is an iterative process, with chunks of
data of 1M at a time. There are also 2 phases: write and verify. The
flash operation itself is driven from a user-land tool.
Once flashing is successful, an rtas call is made to update the device
tree with the new properties values for the adapter and the AFU(s)

Add a new char device for the adapter, so that the flash tool can
access the card, even if there is no valid AFU on it.

Co-authored-by: Frederic Barrat 
Signed-off-by: Frederic Barrat 
Signed-off-by: Christophe Lombard 
Reviewed-by: Manoj Kumar 
Acked-by: Ian Munsie 
Signed-off-by: Michael Ellerman

Merge tag 'scsi-misc' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi

2015-09-02T19:22:54+00:00

Pull first round of SCSI updates from James Bottomley:
 "This includes one new driver: cxlflash plus the usual grab bag of
  updates for the major drivers: qla2xxx, ipr, storvsc, pm80xx, hptiop,
  plus a few assorted fixes.

  There's another tranch coming, but I want to incubate it another few
  days in the checkers, plus it includes a mpt2sas separated lifetime
  fix, which Avago won't get done testing until Friday"

* tag 'scsi-misc' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi: (85 commits)
  aic94xx: set an error code on failure
  storvsc: Set the error code correctly in failure conditions
  storvsc: Allow write_same when host is windows 10
  storvsc: use storage protocol version to determine storage capabilities
  storvsc: use correct defaults for values determined by protocol negotiation
  storvsc: Untangle the storage protocol negotiation from the vmbus protocol negotiation.
  storvsc: Use a single value to track protocol versions
  storvsc: Rather than look for sets of specific protocol versions, make decisions based on ranges.
  cxlflash: Remove unused variable from queuecommand
  cxlflash: shift wrapping bug in afu_link_reset()
  cxlflash: off by one bug in cxlflash_show_port_status()
  cxlflash: Virtual LUN support
  cxlflash: Superpipe support
  cxlflash: Base error recovery support
  qla2xxx: Update driver version to 8.07.00.26-k
  qla2xxx: Add pci device id 0x2261.
  qla2xxx: Fix missing device login retries.
  qla2xxx: do not clear slot in outstanding cmd array
  qla2xxx: Remove decrement of sp reference count in abort handler.
  qla2xxx: Add support to show MPI and PEP FW version for ISP27xx.
  ...

cxlflash: Virtual LUN support

2015-08-27T01:05:39+00:00

Add support for physical LUN segmentation (virtual LUNs) to device
driver supporting the IBM CXL Flash adapter. This patch allows user
space applications to virtually segment a physical LUN into N virtual
LUNs, taking advantage of the translation features provided by this
adapter.

Signed-off-by: Matthew R. Ochs 
Signed-off-by: Manoj N. Kumar 
Reviewed-by: Michael Neuling 
Reviewed-by: Wen Xiong 
Signed-off-by: James Bottomley

cxlflash: Superpipe support

2015-08-27T01:04:37+00:00

Add superpipe supporting infrastructure to device driver for the IBM CXL
Flash adapter. This patch allows userspace applications to take advantage
of the accelerated I/O features that this adapter provides and bypass the
traditional filesystem stack.

Signed-off-by: Matthew R. Ochs 
Signed-off-by: Manoj N. Kumar 
Reviewed-by: Michael Neuling 
Reviewed-by: Wen Xiong 
Reviewed-by: Brian King 
Signed-off-by: James Bottomley

Doc: powerpc: Fix typos in Documentation/powerpc

2015-07-10T20:00:51+00:00

This patch fix some spelling typo found in Documentation/powerpc.

Signed-off-by: Masanari Iida 
Acked-by: Ian Munsie 
Signed-off-by: Jonathan Corbet

powerpc/tm: Abort syscalls in active transactions

2015-06-19T07:10:28+00:00

This patch changes the syscall handler to doom (tabort) active
transactions when a syscall is made and return very early without
performing the syscall and keeping side effects to a minimum (no CPU
accounting or system call tracing is performed). Also included is a
new HWCAP2 bit, PPC_FEATURE2_HTM_NOSC, to indicate this
behaviour to userspace.

Currently, the system call instruction automatically suspends an
active transaction which causes side effects to persist when an active
transaction fails.

This does change the kernel's behaviour, but in a way that was
documented as unsupported.  It doesn't reduce functionality as
syscalls will still be performed after tsuspend; it just requires that
the transaction be explicitly suspended.  It also provides a
consistent interface and makes the behaviour of user code
substantially the same across powerpc and platforms that do not
support suspended transactions (e.g. x86 and s390).

Performance measurements using
http://ozlabs.org/~anton/junkcode/null_syscall.c indicate the cost of
a normal (non-aborted) system call increases by about 0.25%.

Signed-off-by: Sam Bobroff 
Signed-off-by: Michael Ellerman

powerpc/dscr: Add documentation for DSCR support

2015-06-07T09:29:27+00:00

This patch adds a new documentation file explaining the DSCR support on
powerpc platforms. This explains DSCR related data structure, code paths
and also available user interfaces. Any further functional changes to
the DSCR support in the kernel should definitely update the
documentation here.

Signed-off-by: Anshuman Khandual 
Signed-off-by: Michael Ellerman

cxl: Document external user of existing API

2015-06-03T03:27:16+00:00

Now that libcxl is public, let's document it.

Signed-off-by: Michael Neuling 
Acked-by: Ian Munsie 
Signed-off-by: Michael Ellerman