diff options
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/devicetree/bindings/crypto/fsl-sec4.txt | 12 | ||||
| -rw-r--r-- | Documentation/devicetree/bindings/powerpc/fsl/guts.txt | 13 | ||||
| -rw-r--r-- | Documentation/devicetree/bindings/powerpc/fsl/pamu.txt | 140 | ||||
| -rw-r--r-- | Documentation/powerpc/cpu_features.txt | 10 | ||||
| -rw-r--r-- | Documentation/powerpc/transactional_memory.txt | 175 |
5 files changed, 341 insertions, 9 deletions
diff --git a/Documentation/devicetree/bindings/crypto/fsl-sec4.txt b/Documentation/devicetree/bindings/crypto/fsl-sec4.txt index fc9ce6f..6d21c02 100644 --- a/Documentation/devicetree/bindings/crypto/fsl-sec4.txt +++ b/Documentation/devicetree/bindings/crypto/fsl-sec4.txt @@ -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 @@ -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>; diff --git a/Documentation/devicetree/bindings/powerpc/fsl/guts.txt b/Documentation/devicetree/bindings/powerpc/fsl/guts.txt index 9e7a241..7f150b5 100644 --- a/Documentation/devicetree/bindings/powerpc/fsl/guts.txt +++ b/Documentation/devicetree/bindings/powerpc/fsl/guts.txt @@ -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>; + }; diff --git a/Documentation/devicetree/bindings/powerpc/fsl/pamu.txt b/Documentation/devicetree/bindings/powerpc/fsl/pamu.txt new file mode 100644 index 0000000..1f5e329 --- /dev/null +++ b/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 */ + }; diff --git a/Documentation/powerpc/cpu_features.txt b/Documentation/powerpc/cpu_features.txt index ffa4183..ae09df8 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 0000000..c907be4 --- /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. |
