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2017-11-03arm64/sve: Add documentationDave Martin
This patch adds basic documentation of the user/kernel interface provided by the for SVE. Signed-off-by: Dave Martin <Dave.Martin@arm.com> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Cc: Alan Hayward <alan.hayward@arm.com> Cc: Alex Bennée <alex.bennee@linaro.org> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Michael Kerrisk <mtk.manpages@gmail.com> Cc: Szabolcs Nagy <szabolcs.nagy@arm.com> Cc: linux-api@vger.kernel.org Signed-off-by: Will Deacon <will.deacon@arm.com>
2017-11-03arm64/sve: Detect SVE and activate runtime supportDave Martin
This patch enables detection of hardware SVE support via the cpufeatures framework, and reports its presence to the kernel and userspace via the new ARM64_SVE cpucap and HWCAP_SVE hwcap respectively. Userspace can also detect SVE using ID_AA64PFR0_EL1, using the cpufeatures MRS emulation. When running on hardware that supports SVE, this enables runtime kernel support for SVE, and allows user tasks to execute SVE instructions and make of the of the SVE-specific user/kernel interface extensions implemented by this series. Signed-off-by: Dave Martin <Dave.Martin@arm.com> Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com>
2017-11-03arm64/sve: KVM: Hide SVE from CPU features exposed to guestsDave Martin
KVM guests cannot currently use SVE, because SVE is always configured to trap to EL2. However, a guest that sees SVE reported as present in ID_AA64PFR0_EL1 may legitimately expect that SVE works and try to use it. Instead of working, the guest will receive an injected undef exception, which may cause the guest to oops or go into a spin. To avoid misleading the guest into believing that SVE will work, this patch masks out the SVE field from ID_AA64PFR0_EL1 when a guest attempts to read this register. No support is explicitly added for ID_AA64ZFR0_EL1 either, so that is still emulated as reading as zero, which is consistent with SVE not being implemented. This is a temporary measure, and will be removed in a later series when full KVM support for SVE is implemented. Signed-off-by: Dave Martin <Dave.Martin@arm.com> Reviewed-by: Alex Bennée <alex.bennee@linaro.org> Acked-by: Marc Zyngier <marc.zyngier@arm.com> Acked-by: Catalin Marinas <catalin.marinas@arm.com> Acked-by: Christoffer Dall <christoffer.dall@linaro.org> Signed-off-by: Will Deacon <will.deacon@arm.com>
2017-11-03arm64/sve: KVM: Treat guest SVE use as undefined instruction executionDave Martin
When trapping forbidden attempts by a guest to use SVE, we want the guest to see a trap consistent with SVE not being implemented. This patch injects an undefined instruction exception into the guest in response to such an exception. Signed-off-by: Dave Martin <Dave.Martin@arm.com> Reviewed-by: Alex Bennée <alex.bennee@linaro.org> Acked-by: Catalin Marinas <catalin.marinas@arm.com> Acked-by: Christoffer Dall <christoffer.dall@linaro.org> Signed-off-by: Will Deacon <will.deacon@arm.com>
2017-11-03arm64/sve: KVM: Prevent guests from using SVEDave Martin
Until KVM has full SVE support, guests must not be allowed to execute SVE instructions. This patch enables the necessary traps, and also ensures that the traps are disabled again on exit from the guest so that the host can still use SVE if it wants to. On guest exit, high bits of the SVE Zn registers may have been clobbered as a side-effect the execution of FPSIMD instructions in the guest. The existing KVM host FPSIMD restore code is not sufficient to restore these bits, so this patch explicitly marks the CPU as not containing cached vector state for any task, thus forcing a reload on the next return to userspace. This is an interim measure, in advance of adding full SVE awareness to KVM. This marking of cached vector state in the CPU as invalid is done using __this_cpu_write(fpsimd_last_state, NULL) in fpsimd.c. Due to the repeated use of this rather obscure operation, it makes sense to factor it out as a separate helper with a clearer name. This patch factors it out as fpsimd_flush_cpu_state(), and ports all callers to use it. As a side effect of this refactoring, a this_cpu_write() in fpsimd_cpu_pm_notifier() is changed to __this_cpu_write(). This should be fine, since cpu_pm_enter() is supposed to be called only with interrupts disabled. Signed-off-by: Dave Martin <Dave.Martin@arm.com> Reviewed-by: Alex Bennée <alex.bennee@linaro.org> Reviewed-by: Christoffer Dall <christoffer.dall@linaro.org> Acked-by: Catalin Marinas <catalin.marinas@arm.com> Acked-by: Marc Zyngier <marc.zyngier@arm.com> Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org> Signed-off-by: Will Deacon <will.deacon@arm.com>
2017-11-03arm64/sve: Add sysctl to set the default vector length for new processesDave Martin
Because of the effect of SVE on the size of the signal frame, the default vector length used for new processes involves a tradeoff between performance of SVE-enabled software on the one hand, and reliability of non-SVE-aware software on the other hand. For this reason, the best choice depends on the repertoire of userspace software in use and is thus best left up to distro maintainers, sysadmins and developers. If CONFIG_SYSCTL and CONFIG_PROC_SYSCTL are enabled, this patch exposes the default vector length in /proc/sys/abi/sve_default_vector_length, where boot scripts or the adventurous can poke it. In common with other arm64 ABI sysctls, this control is currently global: setting it requires CAP_SYS_ADMIN in the root user namespace, but the value set is effective for subsequent execs in all namespaces. The control only affects _new_ processes, however: changing it does not affect the vector length of any existing process. The intended usage model is that if userspace is known to be fully SVE-tolerant (or a developer is curious to find out) then this parameter can be cranked up during system startup. Signed-off-by: Dave Martin <Dave.Martin@arm.com> Reviewed-by: Alex Bennée <alex.bennee@linaro.org> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com>
2017-11-03arm64/sve: Add prctl controls for userspace vector length managementDave Martin
This patch adds two arm64-specific prctls, to permit userspace to control its vector length: * PR_SVE_SET_VL: set the thread's SVE vector length and vector length inheritance mode. * PR_SVE_GET_VL: get the same information. Although these prctls resemble instruction set features in the SVE architecture, they provide additional control: the vector length inheritance mode is Linux-specific and nothing to do with the architecture, and the architecture does not permit EL0 to set its own vector length directly. Both can be used in portable tools without requiring the use of SVE instructions. Signed-off-by: Dave Martin <Dave.Martin@arm.com> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Cc: Alex Bennée <alex.bennee@linaro.org> [will: Fixed up prctl constants to avoid clash with PDEATHSIG] Signed-off-by: Will Deacon <will.deacon@arm.com>
2017-11-03arm64/sve: ptrace and ELF coredump supportDave Martin
This patch defines and implements a new regset NT_ARM_SVE, which describes a thread's SVE register state. This allows a debugger to manipulate the SVE state, as well as being included in ELF coredumps for post-mortem debugging. Because the regset size and layout are dependent on the thread's current vector length, it is not possible to define a C struct to describe the regset contents as is done for existing regsets. Instead, and for the same reasons, NT_ARM_SVE is based on the freeform variable-layout approach used for the SVE signal frame. Additionally, to reduce debug overhead when debugging threads that might or might not have live SVE register state, NT_ARM_SVE may be presented in one of two different formats: the old struct user_fpsimd_state format is embedded for describing the state of a thread with no live SVE state, whereas a new variable-layout structure is embedded for describing live SVE state. This avoids a debugger needing to poll NT_PRFPREG in addition to NT_ARM_SVE, and allows existing userspace code to handle the non-SVE case without too much modification. For this to work, NT_ARM_SVE is defined with a fixed-format header of type struct user_sve_header, which the recipient can use to figure out the content, size and layout of the reset of the regset. Accessor macros are defined to allow the vector-length-dependent parts of the regset to be manipulated. Signed-off-by: Alan Hayward <alan.hayward@arm.com> Signed-off-by: Dave Martin <Dave.Martin@arm.com> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Cc: Alex Bennée <alex.bennee@linaro.org> Cc: Okamoto Takayuki <tokamoto@jp.fujitsu.com> Signed-off-by: Will Deacon <will.deacon@arm.com>
2017-11-03arm64/sve: Preserve SVE registers around EFI runtime service callsDave Martin
The EFI runtime services ABI allows EFI to make free use of the FPSIMD registers during EFI runtime service calls, subject to the callee-save requirements of the AArch64 procedure call standard. However, the SVE architecture allows upper bits of the SVE vector registers to be zeroed as a side-effect of FPSIMD V-register writes. This means that the SVE vector registers must be saved in their entirety in order to avoid data loss: non-SVE-aware EFI implementations cannot restore them correctly. The non-IRQ case is already handled gracefully by kernel_neon_begin(). For the IRQ case, this patch allocates a suitable per-CPU stash buffer for the full SVE register state and uses it to preserve the affected registers around EFI calls. It is currently unclear how the EFI runtime services ABI will be clarified with respect to SVE, so it safest to assume that the predicate registers and FFR must be saved and restored too. No attempt is made to restore the restore the vector length after a call, for now. It is deemed rather insane for EFI to change it, and contemporary EFI implementations certainly won't. Signed-off-by: Dave Martin <Dave.Martin@arm.com> Reviewed-by: Alex Bennée <alex.bennee@linaro.org> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org> Signed-off-by: Will Deacon <will.deacon@arm.com>
2017-11-03arm64/sve: Preserve SVE registers around kernel-mode NEON useDave Martin
Kernel-mode NEON will corrupt the SVE vector registers, due to the way they alias the FPSIMD vector registers in the hardware. This patch ensures that any live SVE register content for the task is saved by kernel_neon_begin(). The data will be restored in the usual way on return to userspace. Signed-off-by: Dave Martin <Dave.Martin@arm.com> Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Reviewed-by: Alex Bennée <alex.bennee@linaro.org> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com>
2017-11-03arm64/sve: Probe SVE capabilities and usable vector lengthsDave Martin
This patch uses the cpufeatures framework to determine common SVE capabilities and vector lengths, and configures the runtime SVE support code appropriately. ZCR_ELx is not really a feature register, but it is convenient to use it as a template for recording the maximum vector length supported by a CPU, using the LEN field. This field is similar to a feature field in that it is a contiguous bitfield for which we want to determine the minimum system-wide value. This patch adds ZCR as a pseudo-register in cpuinfo/cpufeatures, with appropriate custom code to populate it. Finding the minimum supported value of the LEN field is left to the cpufeatures framework in the usual way. The meaning of ID_AA64ZFR0_EL1 is not architecturally defined yet, so for now we just require it to be zero. Note that much of this code is dormant and SVE still won't be used yet, since system_supports_sve() remains hardwired to false. Signed-off-by: Dave Martin <Dave.Martin@arm.com> Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Cc: Alex Bennée <alex.bennee@linaro.org> Signed-off-by: Will Deacon <will.deacon@arm.com>
2017-11-03arm64: cpufeature: Move sys_caps_initialised declarationsDave Martin
update_cpu_features() currently cannot tell whether it is being called during early or late secondary boot. This doesn't desperately matter for anything it currently does. However, SVE will need to know here whether the set of available vector lengths is known or still to be determined when booting a CPU, so that it can be updated appropriately. This patch simply moves the sys_caps_initialised stuff to the top of the file so that it can be used more widely. There doesn't seem to be a more obvious place to put it. Signed-off-by: Dave Martin <Dave.Martin@arm.com> Reviewed-by: Alex Bennée <alex.bennee@linaro.org> Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com> Acked-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com>
2017-11-03arm64/sve: Backend logic for setting the vector lengthDave Martin
This patch implements the core logic for changing a task's vector length on request from userspace. This will be used by the ptrace and prctl frontends that are implemented in later patches. The SVE architecture permits, but does not require, implementations to support vector lengths that are not a power of two. To handle this, logic is added to check a requested vector length against a possibly sparse bitmap of available vector lengths at runtime, so that the best supported value can be chosen. Signed-off-by: Dave Martin <Dave.Martin@arm.com> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Cc: Alex Bennée <alex.bennee@linaro.org> Signed-off-by: Will Deacon <will.deacon@arm.com>
2017-11-03arm64/sve: Signal handling supportDave Martin
This patch implements support for saving and restoring the SVE registers around signals. A fixed-size header struct sve_context is always included in the signal frame encoding the thread's vector length at the time of signal delivery, optionally followed by a variable-layout structure encoding the SVE registers. Because of the need to preserve backwards compatibility, the FPSIMD view of the SVE registers is always dumped as a struct fpsimd_context in the usual way, in addition to any sve_context. The SVE vector registers are dumped in full, including bits 127:0 of each register which alias the corresponding FPSIMD vector registers in the hardware. To avoid any ambiguity about which alias to restore during sigreturn, the kernel always restores bits 127:0 of each SVE vector register from the fpsimd_context in the signal frame (which must be present): userspace needs to take this into account if it wants to modify the SVE vector register contents on return from a signal. FPSR and FPCR, which are used by both FPSIMD and SVE, are not included in sve_context because they are always present in fpsimd_context anyway. For signal delivery, a new helper fpsimd_signal_preserve_current_state() is added to update _both_ the FPSIMD and SVE views in the task struct, to make it easier to populate this information into the signal frame. Because of the redundancy between the two views of the state, only one is updated otherwise. Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Dave Martin <Dave.Martin@arm.com> Cc: Alex Bennée <alex.bennee@linaro.org> Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org> Cc: Will Deacon <will.deacon@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com>
2017-11-03arm64/sve: Support vector length resetting for new processesDave Martin
It's desirable to be able to reset the vector length to some sane default for new processes, since the new binary and its libraries may or may not be SVE-aware. This patch tracks the desired post-exec vector length (if any) in a new thread member sve_vl_onexec, and adds a new thread flag TIF_SVE_VL_INHERIT to control whether to inherit or reset the vector length. Currently these are inactive. Subsequent patches will provide the capability to configure them. Signed-off-by: Dave Martin <Dave.Martin@arm.com> Reviewed-by: Alex Bennée <alex.bennee@linaro.org> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com>
2017-11-03arm64/sve: Core task context handlingDave Martin
This patch adds the core support for switching and managing the SVE architectural state of user tasks. Calls to the existing FPSIMD low-level save/restore functions are factored out as new functions task_fpsimd_{save,load}(), since SVE now dynamically may or may not need to be handled at these points depending on the kernel configuration, hardware features discovered at boot, and the runtime state of the task. To make these decisions as fast as possible, const cpucaps are used where feasible, via the system_supports_sve() helper. The SVE registers are only tracked for threads that have explicitly used SVE, indicated by the new thread flag TIF_SVE. Otherwise, the FPSIMD view of the architectural state is stored in thread.fpsimd_state as usual. When in use, the SVE registers are not stored directly in thread_struct due to their potentially large and variable size. Because the task_struct slab allocator must be configured very early during kernel boot, it is also tricky to configure it correctly to match the maximum vector length provided by the hardware, since this depends on examining secondary CPUs as well as the primary. Instead, a pointer sve_state in thread_struct points to a dynamically allocated buffer containing the SVE register data, and code is added to allocate and free this buffer at appropriate times. TIF_SVE is set when taking an SVE access trap from userspace, if suitable hardware support has been detected. This enables SVE for the thread: a subsequent return to userspace will disable the trap accordingly. If such a trap is taken without sufficient system- wide hardware support, SIGILL is sent to the thread instead as if an undefined instruction had been executed: this may happen if userspace tries to use SVE in a system where not all CPUs support it for example. The kernel will clear TIF_SVE and disable SVE for the thread whenever an explicit syscall is made by userspace. For backwards compatibility reasons and conformance with the spirit of the base AArch64 procedure call standard, the subset of the SVE register state that aliases the FPSIMD registers is still preserved across a syscall even if this happens. The remainder of the SVE register state logically becomes zero at syscall entry, though the actual zeroing work is currently deferred until the thread next tries to use SVE, causing another trap to the kernel. This implementation is suboptimal: in the future, the fastpath case may be optimised to zero the registers in-place and leave SVE enabled for the task, where beneficial. TIF_SVE is also cleared in the following slowpath cases, which are taken as reasonable hints that the task may no longer use SVE: * exec * fork and clone Code is added to sync data between thread.fpsimd_state and thread.sve_state whenever enabling/disabling SVE, in a manner consistent with the SVE architectural programmer's model. Signed-off-by: Dave Martin <Dave.Martin@arm.com> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org> Cc: Alex Bennée <alex.bennee@linaro.org> [will: added #include to fix allnoconfig build] [will: use enable_daif in do_sve_acc] Signed-off-by: Will Deacon <will.deacon@arm.com>
2017-11-03arm64/sve: Low-level CPU setupDave Martin
To enable the kernel to use SVE, SVE traps from EL1 to EL2 must be disabled. To take maximum advantage of the hardware, the full available vector length also needs to be enabled for EL1 by programming ZCR_EL2.LEN. (The kernel will program ZCR_EL1.LEN as required, but this cannot override the limit set by ZCR_EL2.) This patch makes the appropriate changes to the EL2 early setup code. Signed-off-by: Dave Martin <Dave.Martin@arm.com> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Cc: Alex Bennée <alex.bennee@linaro.org> Signed-off-by: Will Deacon <will.deacon@arm.com>
2017-11-03arm64/sve: Signal frame and context structure definitionDave Martin
This patch defines the representation that will be used for the SVE register state in the signal frame, and implements support for saving and restoring the SVE registers around signals. The same layout will also be used for the in-kernel task state. Due to the variability of the SVE vector length, it is not possible to define a fixed C struct to describe all the registers. Instead, Macros are defined in sigcontext.h to facilitate access to the parts of the structure. Signed-off-by: Dave Martin <Dave.Martin@arm.com> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Cc: Alex Bennée <alex.bennee@linaro.org> Signed-off-by: Will Deacon <will.deacon@arm.com>
2017-11-03arm64/sve: Kconfig update and conditional compilation supportDave Martin
This patch adds CONFIG_ARM64_SVE to control building of SVE support into the kernel, and adds a stub predicate system_supports_sve() to control conditional compilation and runtime SVE support. system_supports_sve() just returns false for now: it will be replaced with a non-trivial implementation in a later patch, once SVE support is complete enough to be enabled safely. Signed-off-by: Dave Martin <Dave.Martin@arm.com> Reviewed-by: Alex Bennée <alex.bennee@linaro.org> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com>
2017-11-03arm64/sve: Low-level SVE architectural state manipulation functionsDave Martin
Manipulating the SVE architectural state, including the vector and predicate registers, first-fault register and the vector length, requires the use of dedicated instructions added by SVE. This patch adds suitable assembly functions for saving and restoring the SVE registers and querying the vector length. Setting of the vector length is done as part of register restore. Since people building kernels may not all get an SVE-enabled toolchain for a while, this patch uses macros that generate explicit opcodes in place of assembler mnemonics. Signed-off-by: Dave Martin <Dave.Martin@arm.com> Reviewed-by: Alex Bennée <alex.bennee@linaro.org> Acked-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com>
2017-11-03arm64/sve: System register and exception syndrome definitionsDave Martin
The SVE architecture adds some system registers, ID register fields and a dedicated ESR exception class. This patch adds the appropriate definitions that will be needed by the kernel. Signed-off-by: Dave Martin <Dave.Martin@arm.com> Reviewed-by: Alex Bennée <alex.bennee@linaro.org> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com>
2017-11-03arm64: fpsimd: Simplify uses of {set,clear}_ti_thread_flag()Dave Martin
The existing FPSIMD context switch code contains a couple of instances of {set,clear}_ti_thread(task_thread_info(task)). Since there are thread flag manipulators that operate directly on task_struct, this verbosity isn't strictly needed. For consistency, this patch simplifies the affected calls. This should have no impact on behaviour. Signed-off-by: Dave Martin <Dave.Martin@arm.com> Reviewed-by: Alex Bennée <alex.bennee@linaro.org> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Acked-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Signed-off-by: Will Deacon <will.deacon@arm.com>
2017-11-03arm64: Port deprecated instruction emulation to new sysctl interfaceDave Martin
Currently, armv8_deprected.c takes charge of the "abi" sysctl directory, which makes life difficult for other code that wants to register sysctls in the same directory. There is a "new" [1] sysctl registration interface that removes the need to define ctl_tables for parent directories explicitly, which is ideal here. This patch ports register_insn_emulation_sysctl() over to the register_sysctl() interface and removes the redundant ctl_table for "abi". Signed-off-by: Dave Martin <Dave.Martin@arm.com> Reviewed-by: Alex Bennée <alex.bennee@linaro.org> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> [1] fea478d4101a (sysctl: Add register_sysctl for normal sysctl users) The commit message notes an intent to port users of the pre-existing interfaces over to register_sysctl(), though the number of users of the new interface currently appears negligible. Signed-off-by: Will Deacon <will.deacon@arm.com>
2017-11-03arm64: efi: Add missing Kconfig dependency on KERNEL_MODE_NEONDave Martin
The EFI runtime services ABI permits calls to EFI to clobber certain FPSIMD/NEON registers, as per the AArch64 procedure call standard. Saving/restoring the clobbered registers around such calls needs KERNEL_MODE_NEON, but the dependency is missing from Kconfig. This patch adds the missing dependency. This will aid bisection of the patches implementing support for the ARM Scalable Vector Extension (SVE). Signed-off-by: Dave Martin <Dave.Martin@arm.com> Reviewed-by: Alex Bennée <alex.bennee@linaro.org> Acked-by: Catalin Marinas <catalin.marinas@arm.com> Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org> Signed-off-by: Will Deacon <will.deacon@arm.com>
2017-11-03arm64: KVM: Hide unsupported AArch64 CPU features from guestsDave Martin
Currently, a guest kernel sees the true CPU feature registers (ID_*_EL1) when it reads them using MRS instructions. This means that the guest may observe features that are present in the hardware but the host doesn't understand or doesn't provide support for. A guest may legimitately try to use such a feature as per the architecture, but use of the feature may trap instead of working normally, triggering undef injection into the guest. This is not a problem for the host, but the guest may go wrong when running on newer hardware than the host knows about. This patch hides from guest VMs any AArch64-specific CPU features that the host doesn't support, by exposing to the guest the sanitised versions of the registers computed by the cpufeatures framework, instead of the true hardware registers. To achieve this, HCR_EL2.TID3 is now set for AArch64 guests, and emulation code is added to KVM to report the sanitised versions of the affected registers in response to MRS and register reads from userspace. The affected registers are removed from invariant_sys_regs[] (since the invariant_sys_regs handling is no longer quite correct for them) and added to sys_reg_desgs[], with appropriate access(), get_user() and set_user() methods. No runtime vcpu storage is allocated for the registers: instead, they are read on demand from the cpufeatures framework. This may need modification in the future if there is a need for userspace to customise the features visible to the guest. Attempts by userspace to write the registers are handled similarly to the current invariant_sys_regs handling: writes are permitted, but only if they don't attempt to change the value. This is sufficient to support VM snapshot/restore from userspace. Because of the additional registers, restoring a VM on an older kernel may not work unless userspace knows how to handle the extra VM registers exposed to the KVM user ABI by this patch. Under the principle of least damage, this patch makes no attempt to handle any of the other registers currently in invariant_sys_regs[], or to emulate registers for AArch32: however, these could be handled in a similar way in future, as necessary. Signed-off-by: Dave Martin <Dave.Martin@arm.com> Reviewed-by: Marc Zyngier <marc.zyngier@arm.com> Acked-by: Catalin Marinas <catalin.marinas@arm.com> Acked-by: Christoffer Dall <christoffer.dall@linaro.org> Signed-off-by: Will Deacon <will.deacon@arm.com>
2017-11-03arm64: signal: Verify extra data is user-readable in sys_rt_sigreturnDave Martin
Currently sys_rt_sigreturn() verifies that the base sigframe is readable, but no similar check is performed on the extra data to which an extra_context record points. This matters because the extra data will be read with the unprotected user accessors. However, this is not a problem at present because the extra data base address is required to be exactly at the end of the base sigframe. So, there would need to be a non-user-readable kernel address within about 59K (SIGFRAME_MAXSZ - sizeof(struct rt_sigframe)) of some address for which access_ok(VERIFY_READ) returns true, in order for sigreturn to be able to read kernel memory that should be inaccessible to the user task. This is currently impossible due to the untranslatable address hole between the TTBR0 and TTBR1 address ranges. Disappearance of the hole between the TTBR0 and TTBR1 mapping ranges would require the VA size for TTBR0 and TTBR1 to grow to at least 55 bits, and either the disabling of tagged pointers for userspace or enabling of tagged pointers for kernel space; none of which is currently envisaged. Even so, it is wrong to use the unprotected user accessors without an accompanying access_ok() check. To avoid the potential for future surprises, this patch does an explicit access_ok() check on the extra data space when parsing an extra_context record. Fixes: 33f082614c34 ("arm64: signal: Allow expansion of the signal frame") Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Dave Martin <Dave.Martin@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com>
2017-11-03arm64: fpsimd: Correctly annotate exception helpers called from asmDave Martin
A couple of FPSIMD exception handling functions that are called from entry.S are currently not annotated as such. This is not a big deal since asmlinkage does nothing on arm/arm64, but fixing the annotations is more consistent and may help avoid future surprises. This patch adds appropriate asmlinkage annotations for do_fpsimd_acc() and do_fpsimd_exc(). Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Dave Martin <Dave.Martin@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com>
2017-11-03regset: Add support for dynamically sized regsetsDave Martin
Currently the regset API doesn't allow for the possibility that regsets (or at least, the amount of meaningful data in a regset) may change in size. In particular, this results in useless padding being added to coredumps if a regset's current size is smaller than its theoretical maximum size. This patch adds a get_size() function to struct user_regset. Individual regset implementations can implement this function to return the current size of the regset data. A regset_size() function is added to provide callers with an abstract interface for determining the size of a regset without needing to know whether the regset is dynamically sized or not. The only affected user of this interface is the ELF coredump code: This patch ports ELF coredump to dump regsets with their actual size in the coredump. This has no effect except for new regsets that are dynamically sized and provide a get_size() implementation. Signed-off-by: Dave Martin <Dave.Martin@arm.com> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Dmitry Safonov <dsafonov@virtuozzo.com> Cc: H. J. Lu <hjl.tools@gmail.com> Signed-off-by: Will Deacon <will.deacon@arm.com>
2017-11-03arm-ccn: perf: Prevent module unload while PMU is in useSuzuki K Poulose
When the PMU driver is built as a module, the perf expects the pmu->module to be valid, so that the driver is prevented from being unloaded while it is in use. Fix the CCN pmu driver to fill in this field. Fixes: a33b0daab73a0 ("bus: ARM CCN PMU driver") Cc: Pawel Moll <pawel.moll@arm.com> Cc: Will Deacon <will.deacon@arm.com> Acked-by: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com>
2017-11-03perf: arm_spe: Prevent module unload while the PMU is in useSuzuki K Poulose
When the PMU driver is built as a module, the perf expects the pmu->module to be valid, so that the driver is prevented from being unloaded while it is in use. Fix the SPE pmu driver to fill in this field. Cc: Will Deacon <will.deacon@arm.com> Acked-by: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com>
2017-11-03scsi: scsi_error: DID_SOFT_ERROR comment clean upPetros Koutoupis
Updated comment. We are keeping track of maximum number of retries per command via retries/allowed in struct scsi_cmnd. Corrected comment positioning. [mkp: applied by hand] Signed-off-by: Petros Koutoupis <petros@petroskoutoupis.com> Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
2017-11-03staging: fsl-dpaa2/eth: Extra headroom in RX buffersBogdan Purcareata
The needed headroom that we ask the stack to reserve for us in TX skbs is larger than the headroom available in RX frames, which leads to skb reallocations in forwarding scenarios involving two DPNI interfaces. Configure the hardware to reserve some extra space in the RX frame headroom to avoid this situation. The value is chosen based on the Tx frame data offset, the Rx buffer alignment value and the netdevice required headroom. The network stack will take care to reserve space for HH_DATA_MOD when building the skb, so there's no need to account for it in the netdevice needed headroom. Signed-off-by: Bogdan Purcareata <bogdan.purcareata@nxp.com> Signed-off-by: Ioana Radulescu <ruxandra.radulescu@nxp.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-11-03staging: fsl-dpaa2/eth: Change RX buffer alignmentBogdan Purcareata
The WRIOP hardware block v1.0.0 (found on LS2080A board) requires data in RX buffers to be aligned to 256B, but newer revisions (e.g. on LS2088A, LS1088A) only require 64B alignment. Check WRIOP version and decide at runtime which alignment requirement to configure for ingress buffers. Signed-off-by: Bogdan Purcareata <bogdan.purcareata@nxp.com> Signed-off-by: Ioana Radulescu <ruxandra.radulescu@nxp.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-11-03staging: fsl-dpaa2/eth: Don't account SWA in tx_data_offsetBogdan Purcareata
When configuring the Tx buffer layout, the software annotation size is mentioned, and MC accounts for it when configuring the frame tx_data_offset. No need to handle it in the driver as well. This results in 64B less memory allocated per frame. Signed-off-by: Bogdan Purcareata <bogdan.purcareata@nxp.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-11-03staging: fsl-dpaa2/eth: Split functionIoana Radulescu
Since setup_dpni() became a bit too long, move the buffer layout configuration to a separate function. Signed-off-by: Ioana Radulescu <ruxandra.radulescu@nxp.com> Signed-off-by: Bogdan Purcareata <bogdan.purcareata@nxp.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-11-03staging: fsl-dpaa2/eth: Label cleanupIoana Radulescu
Clean up goto labels in a couple of functions, by removing/renaming redundant ones. Signed-off-by: Ioana Radulescu <ruxandra.radulescu@nxp.com> Signed-off-by: Bogdan Purcareata <bogdan.purcareata@nxp.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-11-03staging: unisys: don't care about debugfs errorsgregkh@linuxfoundation.org
A caller should never care about a debugfs error return value, and it should never abort its normal operation if something "odd" goes on. Fix up the unisys init code to not care if the root debugfs directory for the subsystem is created or not, as no place it is used will matter. Cc: David Kershner <david.kershner@unisys.com> Cc: Tim Sell <Timothy.Sell@unisys.com> Cc: Sameer Wadgaonkar <sameer.wadgaonkar@unisys.com> Cc: David Binder <david.binder@unisys.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-11-03mm, swap: fix race between swap count continuation operationsHuang Ying
One page may store a set of entries of the sis->swap_map (swap_info_struct->swap_map) in multiple swap clusters. If some of the entries has sis->swap_map[offset] > SWAP_MAP_MAX, multiple pages will be used to store the set of entries of the sis->swap_map. And the pages are linked with page->lru. This is called swap count continuation. To access the pages which store the set of entries of the sis->swap_map simultaneously, previously, sis->lock is used. But to improve the scalability of __swap_duplicate(), swap cluster lock may be used in swap_count_continued() now. This may race with add_swap_count_continuation() which operates on a nearby swap cluster, in which the sis->swap_map entries are stored in the same page. The race can cause wrong swap count in practice, thus cause unfreeable swap entries or software lockup, etc. To fix the race, a new spin lock called cont_lock is added to struct swap_info_struct to protect the swap count continuation page list. This is a lock at the swap device level, so the scalability isn't very well. But it is still much better than the original sis->lock, because it is only acquired/released when swap count continuation is used. Which is considered rare in practice. If it turns out that the scalability becomes an issue for some workloads, we can split the lock into some more fine grained locks. Link: http://lkml.kernel.org/r/20171017081320.28133-1-ying.huang@intel.com Fixes: 235b62176712 ("mm/swap: add cluster lock") Signed-off-by: "Huang, Ying" <ying.huang@intel.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Shaohua Li <shli@kernel.org> Cc: Tim Chen <tim.c.chen@intel.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Aaron Lu <aaron.lu@intel.com> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Andi Kleen <ak@linux.intel.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Hugh Dickins <hughd@google.com> Cc: <stable@vger.kernel.org> [4.11+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-11-03mm/huge_memory.c: deposit page table when copying a PMD migration entryZi Yan
We need to deposit pre-allocated PTE page table when a PMD migration entry is copied in copy_huge_pmd(). Otherwise, we will leak the pre-allocated page and cause a NULL pointer dereference later in zap_huge_pmd(). The missing counters during PMD migration entry copy process are added as well. The bug report is here: https://lkml.org/lkml/2017/10/29/214 Link: http://lkml.kernel.org/r/20171030144636.4836-1-zi.yan@sent.com Fixes: 84c3fc4e9c563 ("mm: thp: check pmd migration entry in common path") Signed-off-by: Zi Yan <zi.yan@cs.rutgers.edu> Reported-by: Fengguang Wu <fengguang.wu@intel.com> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-11-03initramfs: fix initramfs rebuilds w/ compression after disablingFlorian Fainelli
This is a follow-up to commit 57ddfdaa9a72 ("initramfs: fix disabling of initramfs (and its compression)"). This particular commit fixed the use case where we build the kernel with an initramfs with no compression, and then we build the kernel with no initramfs. Now this still left us with the same case as described here: http://lkml.kernel.org/r/20170521033337.6197-1-f.fainelli@gmail.com not working with initramfs compression. This can be seen by the following steps/timestamps: https://www.spinics.net/lists/kernel/msg2598153.html .initramfs_data.cpio.gz.cmd is correct: cmd_usr/initramfs_data.cpio.gz := /bin/bash ./scripts/gen_initramfs_list.sh -o usr/initramfs_data.cpio.gz -u 1000 -g 1000 /home/fainelli/work/uclinux-rootfs/romfs /home/fainelli/work/uclinux-rootfs/misc/initramfs.dev and was generated the first time we did generate the gzip initramfs, so the command has not changed, nor its arguments, so we just don't call it, no initramfs cpio is re-generated as a consequence. The fix for this problem is just to properly keep track of the .initramfs_cpio_data.d file by suffixing it with the compression extension. This takes care of properly tracking dependencies such that the initramfs get (re)generated any time files are added/deleted etc. Link: http://lkml.kernel.org/r/20170930033936.6722-1-f.fainelli@gmail.com Fixes: db2aa7fd15e8 ("initramfs: allow again choice of the embedded initramfs compression algorithm") Fixes: 9e3596b0c653 ("kbuild: initramfs cleanup, set target from Kconfig") Signed-off-by: Florian Fainelli <f.fainelli@gmail.com> Cc: "Francisco Blas Izquierdo Riera (klondike)" <klondike@xiscosoft.net> Cc: Nicholas Piggin <npiggin@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-11-03fs/hugetlbfs/inode.c: fix hwpoison reserve accountingMike Kravetz
Calling madvise(MADV_HWPOISON) on a hugetlbfs page will result in bad (negative) reserved huge page counts. This may not happen immediately, but may happen later when the underlying file is removed or filesystem unmounted. For example: AnonHugePages: 0 kB ShmemHugePages: 0 kB HugePages_Total: 1 HugePages_Free: 0 HugePages_Rsvd: 18446744073709551615 HugePages_Surp: 0 Hugepagesize: 2048 kB In routine hugetlbfs_error_remove_page(), hugetlb_fix_reserve_counts is called after remove_huge_page. hugetlb_fix_reserve_counts is designed to only be called/used only if a failure is returned from hugetlb_unreserve_pages. Therefore, call hugetlb_unreserve_pages as required and only call hugetlb_fix_reserve_counts in the unlikely event that hugetlb_unreserve_pages returns an error. Link: http://lkml.kernel.org/r/20171019230007.17043-2-mike.kravetz@oracle.com Fixes: 78bb920344b8 ("mm: hwpoison: dissolve in-use hugepage in unrecoverable memory error") Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Acked-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com> Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-11-03ocfs2: fstrim: Fix start offset of first cluster group during fstrimAshish Samant
The first cluster group descriptor is not stored at the start of the group but at an offset from the start. We need to take this into account while doing fstrim on the first cluster group. Otherwise we will wrongly start fstrim a few blocks after the desired start block and the range can cross over into the next cluster group and zero out the group descriptor there. This can cause filesytem corruption that cannot be fixed by fsck. Link: http://lkml.kernel.org/r/1507835579-7308-1-git-send-email-ashish.samant@oracle.com Signed-off-by: Ashish Samant <ashish.samant@oracle.com> Reviewed-by: Junxiao Bi <junxiao.bi@oracle.com> Reviewed-by: Joseph Qi <jiangqi903@gmail.com> Cc: Mark Fasheh <mfasheh@versity.com> Cc: Joel Becker <jlbec@evilplan.org> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-11-03mm, /proc/pid/pagemap: fix soft dirty marking for PMD migration entryHuang Ying
When the pagetable is walked in the implementation of /proc/<pid>/pagemap, pmd_soft_dirty() is used for both the PMD huge page map and the PMD migration entries. That is wrong, pmd_swp_soft_dirty() should be used for the PMD migration entries instead because the different page table entry flag is used. As a result, /proc/pid/pagemap may report incorrect soft dirty information for PMD migration entries. Link: http://lkml.kernel.org/r/20171017081818.31795-1-ying.huang@intel.com Fixes: 84c3fc4e9c56 ("mm: thp: check pmd migration entry in common path") Signed-off-by: "Huang, Ying" <ying.huang@intel.com> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Acked-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Michal Hocko <mhocko@suse.com> Cc: David Rientjes <rientjes@google.com> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Hugh Dickins <hughd@google.com> Cc: "Jérôme Glisse" <jglisse@redhat.com> Cc: Daniel Colascione <dancol@google.com> Cc: Zi Yan <zi.yan@cs.rutgers.edu> Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-11-03userfaultfd: hugetlbfs: prevent UFFDIO_COPY to fill beyond the end of i_sizeAndrea Arcangeli
This oops: kernel BUG at fs/hugetlbfs/inode.c:484! RIP: remove_inode_hugepages+0x3d0/0x410 Call Trace: hugetlbfs_setattr+0xd9/0x130 notify_change+0x292/0x410 do_truncate+0x65/0xa0 do_sys_ftruncate.constprop.3+0x11a/0x180 SyS_ftruncate+0xe/0x10 tracesys+0xd9/0xde was caused by the lack of i_size check in hugetlb_mcopy_atomic_pte. mmap() can still succeed beyond the end of the i_size after vmtruncate zapped vmas in those ranges, but the faults must not succeed, and that includes UFFDIO_COPY. We could differentiate the retval to userland to represent a SIGBUS like a page fault would do (vs SIGSEGV), but it doesn't seem very useful and we'd need to pick a random retval as there's no meaningful syscall retval that would differentiate from SIGSEGV and SIGBUS, there's just -EFAULT. Link: http://lkml.kernel.org/r/20171016223914.2421-2-aarcange@redhat.com Signed-off-by: Andrea Arcangeli <aarcange@redhat.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: "Dr. David Alan Gilbert" <dgilbert@redhat.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-11-03crypto: atmel-aes - Reset the controller before each useRomain Izard
When using the rfc4543(gcm(aes))) mode, the registers of the hardware engine are not empty after use. If the engine is not reset before its next use, the following results will be invalid. Always reset the hardware engine. Signed-off-by: Romain Izard <romain.izard.pro@gmail.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2017-11-03crypto: atmel-aes - properly set IV after {en,de}cryptRomain Izard
Certain cipher modes like CTS expect the IV (req->info) of ablkcipher_request (or equivalently req->iv of skcipher_request) to contain the last ciphertext block when the {en,de}crypt operation is done. Fix this issue for the Atmel AES hardware engine. The tcrypt test case for cts(cbc(aes)) is now correctly passed. In the case of in-place decryption, copy the ciphertext in an intermediate buffer before decryption. Signed-off-by: Romain Izard <romain.izard.pro@gmail.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2017-11-03hwrng: core - Reset user selected rng by writing "" to rng_currentPrasannaKumar Muralidharan
User is able to select a chosen rng by writing its name to rng_current but there is no way to reset it without unbinding the rng. Let user write "" to rng_current and delesect the chosen rng. Signed-off-by: PrasannaKumar Muralidharan <prasannatsmkumar@gmail.com> reviewed-by: Harald Freudenberger <freude@linux.vnet.ibm.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2017-11-03crypto: s5p-sss - Add HASH support for ExynosKamil Konieczny
Add support for MD5, SHA1, SHA256 hash algorithms for Exynos HW. It uses the crypto framework asynchronous hash api. It is based on omap-sham.c driver. S5P has some HW differencies and is not implemented. Modifications in s5p-sss: - Add hash supporting structures and functions. - Modify irq handler to handle both aes and hash signals. - Resize resource end in probe if EXYNOS_HASH is enabled in Kconfig. - Add new copyright line and new author. - Tested on Odroid-U3 with Exynos 4412 CPU, kernel 4.13-rc6 with crypto run-time self test testmgr and with tcrypt module with: modprobe tcrypt sec=1 mode=N where N=402, 403, 404 (MD5, SHA1, SHA256). Modifications in drivers/crypto/Kconfig: - Add new CRYPTO_DEV_EXYNOS_HASH, depend on !EXYNOS_RNG and CRYPTO_DEV_S5P - Select sw algorithms MD5, SHA1 and SHA256 in EXYNOS_HASH as they are needed for fallback. Acked-by: Vladimir Zapolskiy <vz@mleia.com> Reviewed-by: Krzysztof Kozlowski <krzk@kernel.org> Signed-off-by: Kamil Konieczny <k.konieczny@partner.samsung.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2017-11-03crypto: s5p-sss - Change spaces to tabsKamil Konieczny
Change #define lines to use tabs consistently. Acked-by: Vladimir Zapolskiy <vz@mleia.com> Reviewed-by: Krzysztof Kozlowski <krzk@kernel.org> Signed-off-by: Kamil Konieczny <k.konieczny@partner.samsung.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2017-11-03crypto: drivers - Convert timers to use timer_setup()Kees Cook
In preparation for unconditionally passing the struct timer_list pointer to all timer callbacks, switch to using the new timer_setup() and from_timer() to pass the timer pointer explicitly. Cc: Herbert Xu <herbert@gondor.apana.org.au> Cc: Jesper Nilsson <jesper.nilsson@axis.com> Cc: Lars Persson <lars.persson@axis.com> Cc: Niklas Cassel <niklas.cassel@axis.com> Cc: "David S. Miller" <davem@davemloft.net> Cc: Jamie Iles <jamie@jamieiles.com> Cc: linux-arm-kernel@axis.com Cc: linux-crypto@vger.kernel.org Cc: linux-arm-kernel@lists.infradead.org Signed-off-by: Kees Cook <keescook@chromium.org> Acked-by: Jamie Iles <jamie@jamieiles.com> Acked-by: Lars Persson <lars.persson@axis.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>