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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 db8ff90: "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
  ...
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torvalds committed Feb 24, 2013
2 parents df24eef + 8520e44 commit 9d3cae2
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12 changes: 9 additions & 3 deletions Documentation/devicetree/bindings/crypto/fsl-sec4.txt
Expand Up @@ -54,8 +54,13 @@ PROPERTIES
- compatible
Usage: required
Value type: <string>
Definition: Must include "fsl,sec-v4.0". Also includes SEC
ERA versions (optional) with which the device is compatible.
Definition: Must include "fsl,sec-v4.0"

- fsl,sec-era
Usage: optional
Value type: <u32>
Definition: A standard property. Define the 'ERA' of the SEC
device.

- #address-cells
Usage: required
Expand Down Expand Up @@ -107,7 +112,8 @@ PROPERTIES

EXAMPLE
crypto@300000 {
compatible = "fsl,sec-v4.0", "fsl,sec-era-v2.0";
compatible = "fsl,sec-v4.0";
fsl,sec-era = <0x2>;
#address-cells = <1>;
#size-cells = <1>;
reg = <0x300000 0x10000>;
Expand Down
13 changes: 12 additions & 1 deletion Documentation/devicetree/bindings/powerpc/fsl/guts.txt
Expand Up @@ -17,9 +17,20 @@ Recommended properties:
contains a functioning "reset control register" (i.e. the board
is wired to reset upon setting the HRESET_REQ bit in this register).

Example:
- fsl,liodn-bits : Indicates the number of defined bits in the LIODN
registers, for those SOCs that have a PAMU device.

Examples:
global-utilities@e0000 { /* global utilities block */
compatible = "fsl,mpc8548-guts";
reg = <e0000 1000>;
fsl,has-rstcr;
};

guts: global-utilities@e0000 {
compatible = "fsl,qoriq-device-config-1.0";
reg = <0xe0000 0xe00>;
fsl,has-rstcr;
#sleep-cells = <1>;
fsl,liodn-bits = <12>;
};
140 changes: 140 additions & 0 deletions Documentation/devicetree/bindings/powerpc/fsl/pamu.txt
@@ -0,0 +1,140 @@
Freescale Peripheral Management Access Unit (PAMU) Device Tree Binding

DESCRIPTION

The PAMU is an I/O MMU that provides device-to-memory access control and
address translation capabilities.

Required properties:

- compatible : <string>
First entry is a version-specific string, such as
"fsl,pamu-v1.0". The second is "fsl,pamu".
- ranges : <prop-encoded-array>
A standard property. Utilized to describe the memory mapped
I/O space utilized by the controller. The size should
be set to the total size of the register space of all
physically present PAMU controllers. For example, for
PAMU v1.0, on an SOC that has five PAMU devices, the size
is 0x5000.
- interrupts : <prop-encoded-array>
Interrupt mappings. The first tuple is the normal PAMU
interrupt, used for reporting access violations. The second
is for PAMU hardware errors, such as PAMU operation errors
and ECC errors.
- #address-cells: <u32>
A standard property.
- #size-cells : <u32>
A standard property.

Optional properties:
- reg : <prop-encoded-array>
A standard property. It represents the CCSR registers of
all child PAMUs combined. Include it to provide support
for legacy drivers.
- interrupt-parent : <phandle>
Phandle to interrupt controller

Child nodes:

Each child node represents one PAMU controller. Each SOC device that is
connected to a specific PAMU device should have a "fsl,pamu-phandle" property
that links to the corresponding specific child PAMU controller.

- reg : <prop-encoded-array>
A standard property. Specifies the physical address and
length (relative to the parent 'ranges' property) of this
PAMU controller's configuration registers. The size should
be set to the size of this PAMU controllers's register space.
For PAMU v1.0, this size is 0x1000.
- fsl,primary-cache-geometry
: <prop-encoded-array>
Two cells that specify the geometry of the primary PAMU
cache. The first is the number of cache lines, and the
second is the number of "ways". For direct-mapped caches,
specify a value of 1.
- fsl,secondary-cache-geometry
: <prop-encoded-array>
Two cells that specify the geometry of the secondary PAMU
cache. The first is the number of cache lines, and the
second is the number of "ways". For direct-mapped caches,
specify a value of 1.

Device nodes:

Devices that have LIODNs need to specify links to the parent PAMU controller
(the actual PAMU controller that this device is connected to) and a pointer to
the LIODN register, if applicable.

- fsl,iommu-parent
: <phandle>
Phandle to the single, specific PAMU controller node to which
this device is connect. The PAMU topology is represented in
the device tree to assist code that dynamically determines the
best LIODN values to minimize PAMU cache thrashing.

- fsl,liodn-reg : <prop-encoded-array>
Two cells that specify the location of the LIODN register
for this device. Required for devices that have a single
LIODN. The first cell is a phandle to a node that contains
the registers where the LIODN is to be set. The second is
the offset from the first "reg" resource of the node where
the specific LIODN register is located.


Example:

iommu@20000 {
compatible = "fsl,pamu-v1.0", "fsl,pamu";
reg = <0x20000 0x5000>;
ranges = <0 0x20000 0x5000>;
#address-cells = <1>;
#size-cells = <1>;
interrupts = <
24 2 0 0
16 2 1 30>;

pamu0: pamu@0 {
reg = <0 0x1000>;
fsl,primary-cache-geometry = <32 1>;
fsl,secondary-cache-geometry = <128 2>;
};

pamu1: pamu@1000 {
reg = <0x1000 0x1000>;
fsl,primary-cache-geometry = <32 1>;
fsl,secondary-cache-geometry = <128 2>;
};

pamu2: pamu@2000 {
reg = <0x2000 0x1000>;
fsl,primary-cache-geometry = <32 1>;
fsl,secondary-cache-geometry = <128 2>;
};

pamu3: pamu@3000 {
reg = <0x3000 0x1000>;
fsl,primary-cache-geometry = <32 1>;
fsl,secondary-cache-geometry = <128 2>;
};

pamu4: pamu@4000 {
reg = <0x4000 0x1000>;
fsl,primary-cache-geometry = <32 1>;
fsl,secondary-cache-geometry = <128 2>;
};
};

guts: global-utilities@e0000 {
compatible = "fsl,qoriq-device-config-1.0";
reg = <0xe0000 0xe00>;
fsl,has-rstcr;
#sleep-cells = <1>;
fsl,liodn-bits = <12>;
};

/include/ "qoriq-dma-0.dtsi"
dma@100300 {
fsl,iommu-parent = <&pamu0>;
fsl,liodn-reg = <&guts 0x584>; /* DMA2LIODNR */
};
10 changes: 5 additions & 5 deletions Documentation/powerpc/cpu_features.txt
Expand Up @@ -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
Expand Down Expand Up @@ -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.
175 changes: 175 additions & 0 deletions 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.

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