Merge branch 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/benh/powerpc

Pull powerpc updates from Benjamin Herrenschmidt:
 "So from the depth of frozen Minnesota, here's the powerpc pull request
  for 3.9.  It has a few interesting highlights, in addition to the
  usual bunch of bug fixes, minor updates, embedded device tree updates
  and new boards:

   - Hand tuned asm implementation of SHA1 (by Paulus & Michael
     Ellerman)

   - Support for Doorbell interrupts on Power8 (kind of fast
     thread-thread IPIs) by Ian Munsie

   - Long overdue cleanup of the way we handle relocation of our open
     firmware trampoline (prom_init.c) on 64-bit by Anton Blanchard

   - Support for saving/restoring & context switching the PPR (Processor
     Priority Register) on server processors that support it.  This
     allows the kernel to preserve thread priorities established by
     userspace.  By Haren Myneni.

   - DAWR (new watchpoint facility) support on Power8 by Michael Neuling

   - Ability to change the DSCR (Data Stream Control Register) which
     controls cache prefetching on a running process via ptrace by
     Alexey Kardashevskiy

   - Support for context switching the TAR register on Power8 (new
     branch target register meant to be used by some new specific
     userspace perf event interrupt facility which is yet to be enabled)
     by Ian Munsie.

   - Improve preservation of the CFAR register (which captures the
     origin of a branch) on various exception conditions by Paulus.

   - Move the Bestcomm DMA driver from arch powerpc to drivers/dma where
     it belongs by Philippe De Muyter

   - Support for Transactional Memory on Power8 by Michael Neuling
     (based on original work by Matt Evans).  For those curious about
     the feature, the patch contains a pretty good description."

(See commit db8ff907027b: "powerpc: Documentation for transactional
memory on powerpc" for the mentioned description added to the file
Documentation/powerpc/transactional_memory.txt)

* 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/benh/powerpc: (140 commits)
  powerpc/kexec: Disable hard IRQ before kexec
  powerpc/85xx: l2sram - Add compatible string for BSC9131 platform
  powerpc/85xx: bsc9131 - Correct typo in SDHC device node
  powerpc/e500/qemu-e500: enable coreint
  powerpc/mpic: allow coreint to be determined by MPIC version
  powerpc/fsl_pci: Store the pci ctlr device ptr in the pci ctlr struct
  powerpc/85xx: Board support for ppa8548
  powerpc/fsl: remove extraneous DIU platform functions
  arch/powerpc/platforms/85xx/p1022_ds.c: adjust duplicate test
  powerpc: Documentation for transactional memory on powerpc
  powerpc: Add transactional memory to pseries and ppc64 defconfigs
  powerpc: Add config option for transactional memory
  powerpc: Add transactional memory to POWER8 cpu features
  powerpc: Add new transactional memory state to the signal context
  powerpc: Hook in new transactional memory code
  powerpc: Routines for FP/VSX/VMX unavailable during a transaction
  powerpc: Add transactional memory unavaliable execption handler
  powerpc: Add reclaim and recheckpoint functions for context switching transactional memory processes
  powerpc: Add FP/VSX and VMX register load functions for transactional memory
  powerpc: Add helper functions for transactional memory context switching
  ...

2 files changed, 180 insertions, 5 deletions

diff --git a/Documentation/powerpc/cpu_features.txt b/Documentation/powerpc/cpu_features.txt
index ffa4183fdb8b..ae09df8722c8 100644
--- a/Documentation/powerpc/cpu_features.txt
+++ b/Documentation/powerpc/cpu_features.txt
@@ -11,10 +11,10 @@ split instruction and data caches, and if the CPU supports the DOZE and NAP
 sleep modes.
 
 Detection of the feature set is simple. A list of processors can be found in
-arch/ppc/kernel/cputable.c. The PVR register is masked and compared with each
-value in the list. If a match is found, the cpu_features of cur_cpu_spec is
-assigned to the feature bitmask for this processor and a __setup_cpu function
-is called.
+arch/powerpc/kernel/cputable.c. The PVR register is masked and compared with
+each value in the list. If a match is found, the cpu_features of cur_cpu_spec
+is assigned to the feature bitmask for this processor and a __setup_cpu
+function is called.
 
 C code may test 'cur_cpu_spec[smp_processor_id()]->cpu_features' for a
 particular feature bit. This is done in quite a few places, for example
@@ -51,6 +51,6 @@ should be used in the majority of cases.
 
 The END_FTR_SECTION macros are implemented by storing information about this
 code in the '__ftr_fixup' ELF section. When do_cpu_ftr_fixups
-(arch/ppc/kernel/misc.S) is invoked, it will iterate over the records in
+(arch/powerpc/kernel/misc.S) is invoked, it will iterate over the records in
 __ftr_fixup, and if the required feature is not present it will loop writing
 nop's from each BEGIN_FTR_SECTION to END_FTR_SECTION.
diff --git a/Documentation/powerpc/transactional_memory.txt b/Documentation/powerpc/transactional_memory.txt
new file mode 100644
index 000000000000..c907be41d60f
--- /dev/null
+++ b/Documentation/powerpc/transactional_memory.txt
@@ -0,0 +1,175 @@
+Transactional Memory support
+============================
+
+POWER kernel support for this feature is currently limited to supporting
+its use by user programs.  It is not currently used by the kernel itself.
+
+This file aims to sum up how it is supported by Linux and what behaviour you
+can expect from your user programs.
+
+
+Basic overview
+==============
+
+Hardware Transactional Memory is supported on POWER8 processors, and is a
+feature that enables a different form of atomic memory access.  Several new
+instructions are presented to delimit transactions; transactions are
+guaranteed to either complete atomically or roll back and undo any partial
+changes.
+
+A simple transaction looks like this:
+
+begin_move_money:
+  tbegin
+  beq   abort_handler
+
+  ld    r4, SAVINGS_ACCT(r3)
+  ld    r5, CURRENT_ACCT(r3)
+  subi  r5, r5, 1
+  addi  r4, r4, 1
+  std   r4, SAVINGS_ACCT(r3)
+  std   r5, CURRENT_ACCT(r3)
+
+  tend
+
+  b     continue
+
+abort_handler:
+  ... test for odd failures ...
+
+  /* Retry the transaction if it failed because it conflicted with
+   * someone else: */
+  b     begin_move_money
+
+
+The 'tbegin' instruction denotes the start point, and 'tend' the end point.
+Between these points the processor is in 'Transactional' state; any memory
+references will complete in one go if there are no conflicts with other
+transactional or non-transactional accesses within the system.  In this
+example, the transaction completes as though it were normal straight-line code
+IF no other processor has touched SAVINGS_ACCT(r3) or CURRENT_ACCT(r3); an
+atomic move of money from the current account to the savings account has been
+performed.  Even though the normal ld/std instructions are used (note no
+lwarx/stwcx), either *both* SAVINGS_ACCT(r3) and CURRENT_ACCT(r3) will be
+updated, or neither will be updated.
+
+If, in the meantime, there is a conflict with the locations accessed by the
+transaction, the transaction will be aborted by the CPU.  Register and memory
+state will roll back to that at the 'tbegin', and control will continue from
+'tbegin+4'.  The branch to abort_handler will be taken this second time; the
+abort handler can check the cause of the failure, and retry.
+
+Checkpointed registers include all GPRs, FPRs, VRs/VSRs, LR, CCR/CR, CTR, FPCSR
+and a few other status/flag regs; see the ISA for details.
+
+Causes of transaction aborts
+============================
+
+- Conflicts with cache lines used by other processors
+- Signals
+- Context switches
+- See the ISA for full documentation of everything that will abort transactions.
+
+
+Syscalls
+========
+
+Performing syscalls from within transaction is not recommended, and can lead
+to unpredictable results.
+
+Syscalls do not by design abort transactions, but beware: The kernel code will
+not be running in transactional state.  The effect of syscalls will always
+remain visible, but depending on the call they may abort your transaction as a
+side-effect, read soon-to-be-aborted transactional data that should not remain
+invisible, etc.  If you constantly retry a transaction that constantly aborts
+itself by calling a syscall, you'll have a livelock & make no progress.
+
+Simple syscalls (e.g. sigprocmask()) "could" be OK.  Even things like write()
+from, say, printf() should be OK as long as the kernel does not access any
+memory that was accessed transactionally.
+
+Consider any syscalls that happen to work as debug-only -- not recommended for
+production use.  Best to queue them up till after the transaction is over.
+
+
+Signals
+=======
+
+Delivery of signals (both sync and async) during transactions provides a second
+thread state (ucontext/mcontext) to represent the second transactional register
+state.  Signal delivery 'treclaim's to capture both register states, so signals
+abort transactions.  The usual ucontext_t passed to the signal handler
+represents the checkpointed/original register state; the signal appears to have
+arisen at 'tbegin+4'.
+
+If the sighandler ucontext has uc_link set, a second ucontext has been
+delivered.  For future compatibility the MSR.TS field should be checked to
+determine the transactional state -- if so, the second ucontext in uc->uc_link
+represents the active transactional registers at the point of the signal.
+
+For 64-bit processes, uc->uc_mcontext.regs->msr is a full 64-bit MSR and its TS
+field shows the transactional mode.
+
+For 32-bit processes, the mcontext's MSR register is only 32 bits; the top 32
+bits are stored in the MSR of the second ucontext, i.e. in
+uc->uc_link->uc_mcontext.regs->msr.  The top word contains the transactional
+state TS.
+
+However, basic signal handlers don't need to be aware of transactions
+and simply returning from the handler will deal with things correctly:
+
+Transaction-aware signal handlers can read the transactional register state
+from the second ucontext.  This will be necessary for crash handlers to
+determine, for example, the address of the instruction causing the SIGSEGV.
+
+Example signal handler:
+
+    void crash_handler(int sig, siginfo_t *si, void *uc)
+    {
+      ucontext_t *ucp = uc;
+      ucontext_t *transactional_ucp = ucp->uc_link;
+
+      if (ucp_link) {
+        u64 msr = ucp->uc_mcontext.regs->msr;
+        /* May have transactional ucontext! */
+#ifndef __powerpc64__
+        msr |= ((u64)transactional_ucp->uc_mcontext.regs->msr) << 32;
+#endif
+        if (MSR_TM_ACTIVE(msr)) {
+           /* Yes, we crashed during a transaction.  Oops. */
+   fprintf(stderr, "Transaction to be restarted at 0x%llx, but "
+                           "crashy instruction was at 0x%llx\n",
+                           ucp->uc_mcontext.regs->nip,
+                           transactional_ucp->uc_mcontext.regs->nip);
+        }
+      }
+
+      fix_the_problem(ucp->dar);
+    }
+
+
+Failure cause codes used by kernel
+==================================
+
+These are defined in <asm/reg.h>, and distinguish different reasons why the
+kernel aborted a transaction:
+
+ TM_CAUSE_RESCHED       Thread was rescheduled.
+ TM_CAUSE_FAC_UNAV      FP/VEC/VSX unavailable trap.
+ TM_CAUSE_SYSCALL       Currently unused; future syscalls that must abort
+                        transactions for consistency will use this.
+ TM_CAUSE_SIGNAL        Signal delivered.
+ TM_CAUSE_MISC          Currently unused.
+
+These can be checked by the user program's abort handler as TEXASR[0:7].
+
+
+GDB
+===
+
+GDB and ptrace are not currently TM-aware.  If one stops during a transaction,
+it looks like the transaction has just started (the checkpointed state is
+presented).  The transaction cannot then be continued and will take the failure
+handler route.  Furthermore, the transactional 2nd register state will be
+inaccessible.  GDB can currently be used on programs using TM, but not sensibly
+in parts within transactions.