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203f2b95 |
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06-Mar-2024 |
Mark Brown <broonie@kernel.org> |
arm64/fpsimd: Support FEAT_FPMR FEAT_FPMR defines a new EL0 accessible register FPMR use to configure the FP8 related features added to the architecture at the same time. Detect support for this register and context switch it for EL0 when present. Due to the sharing of responsibility for saving floating point state between the host kernel and KVM FP8 support is not yet implemented in KVM and a stub similar to that used for SVCR is provided for FPMR in order to avoid bisection issues. To make it easier to share host state with the hypervisor we store FPMR as a hardened usercopy field in uw (along with some padding). Signed-off-by: Mark Brown <broonie@kernel.org> Link: https://lore.kernel.org/r/20240306-arm64-2023-dpisa-v5-3-c568edc8ed7f@kernel.org Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
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#
1984c805 |
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08-Jan-2024 |
Leonardo Bras <leobras@redhat.com> |
arm64: remove unnecessary ifdefs around is_compat_task() Currently some parts of the codebase will test for CONFIG_COMPAT before testing is_compat_task(). is_compat_task() is a inlined function only present on CONFIG_COMPAT. On the other hand, for !CONFIG_COMPAT, we have in linux/compat.h: #define is_compat_task() (0) Since we have this define available in every usage of is_compat_task() for !CONFIG_COMPAT, it's unnecessary to keep the ifdefs, since the compiler is smart enough to optimize-out those snippets on CONFIG_COMPAT=n This requires some regset code as well as a few other defines to be made available on !CONFIG_COMPAT, so some symbols can get resolved before getting optimized-out. Signed-off-by: Leonardo Bras <leobras@redhat.com> Reviewed-by: Arnd Bergmann <arnd@arndb.de> Link: https://lore.kernel.org/r/20240109034651.478462-2-leobras@redhat.com Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
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#
95338648 |
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13-Feb-2024 |
Mark Brown <broonie@kernel.org> |
arm64/sme: Restore SME registers on exit from suspend The fields in SMCR_EL1 and SMPRI_EL1 reset to an architecturally UNKNOWN value. Since we do not otherwise manage the traps configured in this register at runtime we need to reconfigure them after a suspend in case nothing else was kind enough to preserve them for us. The vector length will be restored as part of restoring the SME state for the next SME using task. Fixes: a1f4ccd25cc2 ("arm64/sme: Provide Kconfig for SME") Reported-by: Jackson Cooper-Driver <Jackson.Cooper-Driver@arm.com> Signed-off-by: Mark Brown <broonie@kernel.org> Link: https://lore.kernel.org/r/20240213-arm64-sme-resume-v3-1-17e05e493471@kernel.org Signed-off-by: Will Deacon <will@kernel.org>
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#
28139262 |
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13-Feb-2024 |
Mark Brown <broonie@kernel.org> |
arm64/sve: Lower the maximum allocation for the SVE ptrace regset Doug Anderson observed that ChromeOS crashes are being reported which include failing allocations of order 7 during core dumps due to ptrace allocating storage for regsets: chrome: page allocation failure: order:7, mode:0x40dc0(GFP_KERNEL|__GFP_COMP|__GFP_ZERO), nodemask=(null),cpuset=urgent,mems_allowed=0 ... regset_get_alloc+0x1c/0x28 elf_core_dump+0x3d8/0xd8c do_coredump+0xeb8/0x1378 with further investigation showing that this is: [ 66.957385] DOUG: Allocating 279584 bytes which is the maximum size of the SVE regset. As Doug observes it is not entirely surprising that such a large allocation of contiguous memory might fail on a long running system. The SVE regset is currently sized to hold SVE registers with a VQ of SVE_VQ_MAX which is 512, substantially more than the architectural maximum of 16 which we might see even in a system emulating the limits of the architecture. Since we don't expose the size we tell the regset core externally let's define ARCH_SVE_VQ_MAX with the actual architectural maximum and use that for the regset, we'll still overallocate most of the time but much less so which will be helpful even if the core is fixed to not require contiguous allocations. Specify ARCH_SVE_VQ_MAX in terms of the maximum value that can be written into ZCR_ELx.LEN (where this is set in the hardware). For consistency update the maximum SME vector length to be specified in the same style while we are at it. We could also teach the ptrace core about runtime discoverable regset sizes but that would be a more invasive change and this is being observed in practical systems. Reported-by: Doug Anderson <dianders@chromium.org> Signed-off-by: Mark Brown <broonie@kernel.org> Tested-by: Douglas Anderson <dianders@chromium.org> Link: https://lore.kernel.org/r/20240213-arm64-sve-ptrace-regset-size-v2-1-c7600ca74b9b@kernel.org Signed-off-by: Will Deacon <will@kernel.org>
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#
34f66c4c |
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16-Oct-2023 |
Mark Rutland <mark.rutland@arm.com> |
arm64: Use a positive cpucap for FP/SIMD Currently we have a negative cpucap which describes the *absence* of FP/SIMD rather than *presence* of FP/SIMD. This largely works, but is somewhat awkward relative to other cpucaps that describe the presence of a feature, and it would be nicer to have a cpucap which describes the presence of FP/SIMD: * This will allow the cpucap to be treated as a standard ARM64_CPUCAP_SYSTEM_FEATURE, which can be detected with the standard has_cpuid_feature() function and ARM64_CPUID_FIELDS() description. * This ensures that the cpucap will only transition from not-present to present, reducing the risk of unintentional and/or unsafe usage of FP/SIMD before cpucaps are finalized. * This will allow using arm64_cpu_capabilities::cpu_enable() to enable the use of FP/SIMD later, with FP/SIMD being disabled at boot time otherwise. This will ensure that any unintentional and/or unsafe usage of FP/SIMD prior to this is trapped, and will ensure that FP/SIMD is never unintentionally enabled for userspace in mismatched big.LITTLE systems. This patch replaces the negative ARM64_HAS_NO_FPSIMD cpucap with a positive ARM64_HAS_FPSIMD cpucap, making changes as described above. Note that as FP/SIMD will now be trapped when not supported system-wide, do_fpsimd_acc() must handle these traps in the same way as for SVE and SME. The commentary in fpsimd_restore_current_state() is updated to describe the new scheme. No users of system_supports_fpsimd() need to know that FP/SIMD is available prior to alternatives being patched, so this is updated to use alternative_has_cap_likely() to check for the ARM64_HAS_FPSIMD cpucap, without generating code to test the system_cpucaps bitmap. Signed-off-by: Mark Rutland <mark.rutland@arm.com> Reviewed-by: Mark Brown <broonie@kernel.org> Cc: Suzuki K Poulose <suzuki.poulose@arm.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
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#
14567ba4 |
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16-Oct-2023 |
Mark Rutland <mark.rutland@arm.com> |
arm64: Rename SVE/SME cpu_enable functions The arm64_cpu_capabilities::cpu_enable() callbacks for SVE, SME, SME2, and FA64 are named with an unusual "${feature}_kernel_enable" pattern rather than the much more common "cpu_enable_${feature}". Now that we only use these as cpu_enable() callbacks, it would be nice to have them match the usual scheme. This patch renames the cpu_enable() callbacks to match this scheme. At the same time, the comment above cpu_enable_sve() is removed for consistency with the other cpu_enable() callbacks. There should be no functional change as a result of this patch. Signed-off-by: Mark Rutland <mark.rutland@arm.com> Reviewed-by: Mark Brown <broonie@kernel.org> Cc: Suzuki K Poulose <suzuki.poulose@arm.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
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#
bc9bbb78 |
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16-Oct-2023 |
Mark Rutland <mark.rutland@arm.com> |
arm64: Explicitly save/restore CPACR when probing SVE and SME When a CPUs onlined we first probe for supported features and propetites, and then we subsequently enable features that have been detected. This is a little problematic for SVE and SME, as some properties (e.g. vector lengths) cannot be probed while they are disabled. Due to this, the code probing for SVE properties has to enable SVE for EL1 prior to proving, and the code probing for SME properties has to enable SME for EL1 prior to probing. We never disable SVE or SME for EL1 after probing. It would be a little nicer to transiently enable SVE and SME during probing, leaving them both disabled unless explicitly enabled, as this would make it much easier to catch unintentional usage (e.g. when they are not present system-wide). This patch reworks the SVE and SME feature probing code to only transiently enable support at EL1, disabling after probing is complete. Signed-off-by: Mark Rutland <mark.rutland@arm.com> Cc: Suzuki K Poulose <suzuki.poulose@arm.com> Cc: Will Deacon <will@kernel.org> Reviewed-by: Mark Brown <broonie@kernel.org> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
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#
abef0695 |
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13-Sep-2023 |
Mark Brown <broonie@kernel.org> |
arm64/sve: Remove ZCR pseudo register from cpufeature code For reasons that are not currently apparent during cpufeature enumeration we maintain a pseudo register for ZCR which records the maximum supported vector length using the value that would be written to ZCR_EL1.LEN to configure it. This is not exposed to userspace and is not sufficient for detecting unsupportable configurations, we need the more detailed checks in vec_update_vq_map() for that since we can't cope with missing vector lengths on late CPUs and KVM requires an exactly matching set of supported vector lengths as EL1 can enumerate VLs directly with the hardware. Remove the code, replacing the usage in sve_setup() with a query of the vq_map. Signed-off-by: Mark Brown <broonie@kernel.org> Link: https://lore.kernel.org/r/20230913-arm64-vec-len-cpufeature-v1-1-cc69b0600a8a@kernel.org Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
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#
5d0a8d2f |
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09-Aug-2023 |
Mark Brown <broonie@kernel.org> |
arm64/ptrace: Ensure that SME is set up for target when writing SSVE state When we use NT_ARM_SSVE to either enable streaming mode or change the vector length for a process we do not currently do anything to ensure that there is storage allocated for the SME specific register state. If the task had not previously used SME or we changed the vector length then the task will not have had TIF_SME set or backing storage for ZA/ZT allocated, resulting in inconsistent register sizes when saving state and spurious traps which flush the newly set register state. We should set TIF_SME to disable traps and ensure that storage is allocated for ZA and ZT if it is not already allocated. This requires modifying sme_alloc() to make the flush of any existing register state optional so we don't disturb existing state for ZA and ZT. Fixes: e12310a0d30f ("arm64/sme: Implement ptrace support for streaming mode SVE registers") Reported-by: David Spickett <David.Spickett@arm.com> Signed-off-by: Mark Brown <broonie@kernel.org> Cc: <stable@vger.kernel.org> # 5.19.x Link: https://lore.kernel.org/r/20230810-arm64-fix-ptrace-race-v1-1-a5361fad2bd6@kernel.org Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
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#
ee072cf7 |
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16-Jan-2023 |
Mark Brown <broonie@kernel.org> |
arm64/sme: Implement signal handling for ZT Add a new signal context type for ZT which is present in the signal frame when ZA is enabled and ZT is supported by the system. In order to account for the possible addition of further ZT registers in the future we make the number of registers variable in the ABI, though currently the only possible number is 1. We could just use a bare list head for the context since the number of registers can be inferred from the size of the context but for usability and future extensibility we define a header with the number of registers and some reserved fields in it. Signed-off-by: Mark Brown <broonie@kernel.org> Link: https://lore.kernel.org/r/20221208-arm64-sme2-v4-11-f2fa0aef982f@kernel.org Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
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#
95fcec71 |
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16-Jan-2023 |
Mark Brown <broonie@kernel.org> |
arm64/sme: Implement context switching for ZT0 When the system supports SME2 the ZT0 register must be context switched as part of the floating point state. This register is stored immediately after ZA in memory and is only accessible when PSTATE.ZA is set so we handle it in the same functions we use to save and restore ZA. Signed-off-by: Mark Brown <broonie@kernel.org> Link: https://lore.kernel.org/r/20221208-arm64-sme2-v4-10-f2fa0aef982f@kernel.org Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
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#
d6138b4a |
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16-Jan-2023 |
Mark Brown <broonie@kernel.org> |
arm64/sme: Provide storage for ZT0 When the system supports SME2 there is an additional register ZT0 which we must store when the task is using SME. Since ZT0 is accessible only when PSTATE.ZA is set just like ZA we allocate storage for it along with ZA, increasing the allocation size for the memory region where we store ZA and storing the data for ZT after that for ZA. Signed-off-by: Mark Brown <broonie@kernel.org> Link: https://lore.kernel.org/r/20221208-arm64-sme2-v4-9-f2fa0aef982f@kernel.org Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
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#
d4913eee |
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16-Jan-2023 |
Mark Brown <broonie@kernel.org> |
arm64/sme: Add basic enumeration for SME2 Add basic feature detection for SME2, detecting that the feature is present and disabling traps for ZT0. Signed-off-by: Mark Brown <broonie@kernel.org> Link: https://lore.kernel.org/r/20221208-arm64-sme2-v4-8-f2fa0aef982f@kernel.org Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
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#
ce514000 |
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16-Jan-2023 |
Mark Brown <broonie@kernel.org> |
arm64/sme: Rename za_state to sme_state In preparation for adding support for storage for ZT0 to the thread_struct rename za_state to sme_state. Since ZT0 is accessible when PSTATE.ZA is set just like ZA itself we will extend the allocation done for ZA to cover it, avoiding the need to further expand task_struct for non-SME tasks. No functional changes. Signed-off-by: Mark Brown <broonie@kernel.org> Link: https://lore.kernel.org/r/20221208-arm64-sme2-v4-1-f2fa0aef982f@kernel.org Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
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#
1192b93b |
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15-Nov-2022 |
Mark Brown <broonie@kernel.org> |
arm64/fp: Use a struct to pass data to fpsimd_bind_state_to_cpu() For reasons that are unclear to this reader fpsimd_bind_state_to_cpu() populates the struct fpsimd_last_state_struct that it uses to store the active floating point state for KVM guests by passing an argument for each member of the structure. As the richness of the architecture increases this is resulting in a function with a rather large number of arguments which isn't ideal. Simplify the interface by using the struct directly as the single argument for the function, renaming it as we lift the definition into the header. This could be built on further to reduce the work we do adding storage for new FP state in various places but for now it just simplifies this one interface. Signed-off-by: Mark Brown <broonie@kernel.org> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Reviewed-by: Marc Zyngier <maz@kernel.org> Link: https://lore.kernel.org/r/20221115094640.112848-9-broonie@kernel.org Signed-off-by: Will Deacon <will@kernel.org>
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#
deeb8f9a |
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15-Nov-2022 |
Mark Brown <broonie@kernel.org> |
arm64/fpsimd: Have KVM explicitly say which FP registers to save In order to avoid needlessly saving and restoring the guest registers KVM relies on the host FPSMID code to save the guest registers when we context switch away from the guest. This is done by binding the KVM guest state to the CPU on top of the task state that was originally there, then carefully managing the TIF_SVE flag for the task to cause the host to save the full SVE state when needed regardless of the needs of the host task. This works well enough but isn't terribly direct about what is going on and makes it much more complicated to try to optimise what we're doing with the SVE register state. Let's instead have KVM pass in the register state it wants saving when it binds to the CPU. We introduce a new FP_STATE_CURRENT for use during normal task binding to indicate that we should base our decisions on the current task. This should not be used when actually saving. Ideally we might want to use a separate enum for the type to save but this enum and the enum values would then need to be named which has problems with clarity and ambiguity. In order to ease any future debugging that might be required this patch does not actually update any of the decision making about what to save, it merely starts tracking the new information and warns if the requested state is not what we would otherwise have decided to save. Signed-off-by: Mark Brown <broonie@kernel.org> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Reviewed-by: Marc Zyngier <maz@kernel.org> Link: https://lore.kernel.org/r/20221115094640.112848-4-broonie@kernel.org Signed-off-by: Will Deacon <will@kernel.org>
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#
baa85152 |
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15-Nov-2022 |
Mark Brown <broonie@kernel.org> |
arm64/fpsimd: Track the saved FPSIMD state type separately to TIF_SVE When we save the state for the floating point registers this can be done in the form visible through either the FPSIMD V registers or the SVE Z and P registers. At present we track which format is currently used based on TIF_SVE and the SME streaming mode state but particularly in the SVE case this limits our options for optimising things, especially around syscalls. Introduce a new enum which we place together with saved floating point state in both thread_struct and the KVM guest state which explicitly states which format is active and keep it up to date when we change it. At present we do not use this state except to verify that it has the expected value when loading the state, future patches will introduce functional changes. Signed-off-by: Mark Brown <broonie@kernel.org> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Reviewed-by: Marc Zyngier <maz@kernel.org> Link: https://lore.kernel.org/r/20221115094640.112848-3-broonie@kernel.org Signed-off-by: Will Deacon <will@kernel.org>
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#
93ae6b01 |
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15-Nov-2022 |
Mark Brown <broonie@kernel.org> |
KVM: arm64: Discard any SVE state when entering KVM guests Since 8383741ab2e773a99 (KVM: arm64: Get rid of host SVE tracking/saving) KVM has not tracked the host SVE state, relying on the fact that we currently disable SVE whenever we perform a syscall. This may not be true in future since performance optimisation may result in us keeping SVE enabled in order to avoid needing to take access traps to reenable it. Handle this by clearing TIF_SVE and converting the stored task state to FPSIMD format when preparing to run the guest. This is done with a new call fpsimd_kvm_prepare() to keep the direct state manipulation functions internal to fpsimd.c. Signed-off-by: Mark Brown <broonie@kernel.org> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Reviewed-by: Marc Zyngier <maz@kernel.org> Link: https://lore.kernel.org/r/20221115094640.112848-2-broonie@kernel.org Signed-off-by: Will Deacon <will@kernel.org>
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#
826a4fdd |
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17-Aug-2022 |
Mark Brown <broonie@kernel.org> |
arm64/sme: Don't flush SVE register state when allocating SME storage Currently when taking a SME access trap we allocate storage for the SVE register state in order to be able to handle storage of streaming mode SVE. Due to the original usage in a purely SVE context the SVE register state allocation this also flushes the register state for SVE if storage was already allocated but in the SME context this is not desirable. For a SME access trap to be taken the task must not be in streaming mode so either there already is SVE register state present for regular SVE mode which would be corrupted or the task does not have TIF_SVE and the flush is redundant. Fix this by adding a flag to sve_alloc() indicating if we are in a SVE context and need to flush the state. Freshly allocated storage is always zeroed either way. Fixes: 8bd7f91c03d8 ("arm64/sme: Implement traps and syscall handling for SME") Signed-off-by: Mark Brown <broonie@kernel.org> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Link: https://lore.kernel.org/r/20220817182324.638214-4-broonie@kernel.org Signed-off-by: Will Deacon <will@kernel.org>
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#
ec0067a6 |
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10-May-2022 |
Mark Brown <broonie@kernel.org> |
arm64/sme: Remove _EL0 from name of SVCR - FIXME sysreg.h The defines for SVCR call it SVCR_EL0 however the architecture calls the register SVCR with no _EL0 suffix. In preparation for generating the sysreg definitions rename to match the architecture, no functional change. Signed-off-by: Mark Brown <broonie@kernel.org> Link: https://lore.kernel.org/r/20220510161208.631259-6-broonie@kernel.org Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
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#
e65fc01b |
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10-May-2022 |
Mark Brown <broonie@kernel.org> |
arm64/sme: Standardise bitfield names for SVCR The bitfield definitions for SVCR have a SYS_ added to the names of the constant which will be a problem for automatic generation. Remove the prefixes, no functional change. Signed-off-by: Mark Brown <broonie@kernel.org> Link: https://lore.kernel.org/r/20220510161208.631259-5-broonie@kernel.org Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
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#
d158a060 |
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05-May-2022 |
Mark Brown <broonie@kernel.org> |
arm64/sme: More sensibly define the size for the ZA register set Since the vector length configuration mechanism is identical between SVE and SME we share large elements of the code including the definition for the maximum vector length. Unfortunately when we were defining the ABI for SVE we included not only the actual maximum vector length of 2048 bits but also the value possible if all the bits reserved in the architecture for expansion of the LEN field were used, 16384 bits. This starts creating problems if we try to allocate anything for the ZA matrix based on the maximum possible vector length, as we do for the regset used with ptrace during the process of generating a core dump. While the maximum potential size for ZA with the current architecture is a reasonably managable 64K with the higher reserved limit ZA would be 64M which leads to entirely reasonable complaints from the memory management code when we try to allocate a buffer of that size. Avoid these issues by defining the actual maximum vector length for the architecture and using it for the SME regsets. Also use the full ZA_PT_SIZE() with the header rather than just the actual register payload when specifying the size, fixing support for the largest vector lengths now that we have this new, lower define. With the SVE maximum this did not cause problems due to the extra headroom we had. While we're at it add a comment clarifying why even though ZA is a single register we tell the regset code that it is a multi-register regset. Reported-by: Qian Cai <quic_qiancai@quicinc.com> Signed-off-by: Mark Brown <broonie@kernel.org> Tested-by: Naresh Kamboju <naresh.kamboju@linaro.org> Link: https://lore.kernel.org/r/20220505221517.1642014-1-broonie@kernel.org Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
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#
e12310a0 |
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18-Apr-2022 |
Mark Brown <broonie@kernel.org> |
arm64/sme: Implement ptrace support for streaming mode SVE registers The streaming mode SVE registers are represented using the same data structures as for SVE but since the vector lengths supported and in use may not be the same as SVE we represent them with a new type NT_ARM_SSVE. Unfortunately we only have a single 16 bit reserved field available in the header so there is no space to fit the current and maximum vector length for both standard and streaming SVE mode without redefining the structure in a way the creates a complicatd and fragile ABI. Since FFR is not present in streaming mode it is read and written as zero. Setting NT_ARM_SSVE registers will put the task into streaming mode, similarly setting NT_ARM_SVE registers will exit it. Reads that do not correspond to the current mode of the task will return the header with no register data. For compatibility reasons on write setting no flag for the register type will be interpreted as setting SVE registers, though users can provide no register data as an alternative mechanism for doing so. Signed-off-by: Mark Brown <broonie@kernel.org> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Link: https://lore.kernel.org/r/20220419112247.711548-21-broonie@kernel.org Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
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#
8bd7f91c |
|
18-Apr-2022 |
Mark Brown <broonie@kernel.org> |
arm64/sme: Implement traps and syscall handling for SME By default all SME operations in userspace will trap. When this happens we allocate storage space for the SME register state, set up the SVE registers and disable traps. We do not need to initialize ZA since the architecture guarantees that it will be zeroed when enabled and when we trap ZA is disabled. On syscall we exit streaming mode if we were previously in it and ensure that all but the lower 128 bits of the registers are zeroed while preserving the state of ZA. This follows the aarch64 PCS for SME, ZA state is preserved over a function call and streaming mode is exited. Since the traps for SME do not distinguish between streaming mode SVE and ZA usage if ZA is in use rather than reenabling traps we instead zero the parts of the SVE registers not shared with FPSIMD and leave SME enabled, this simplifies handling SME traps. If ZA is not in use then we reenable SME traps and fall through to normal handling of SVE. Signed-off-by: Mark Brown <broonie@kernel.org> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Link: https://lore.kernel.org/r/20220419112247.711548-17-broonie@kernel.org Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
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#
0033cd93 |
|
18-Apr-2022 |
Mark Brown <broonie@kernel.org> |
arm64/sme: Implement ZA context switching Allocate space for storing ZA on first access to SME and use that to save and restore ZA state when context switching. We do this by using the vector form of the LDR and STR ZA instructions, these do not require streaming mode and have implementation recommendations that they avoid contention issues in shared SMCU implementations. Since ZA is architecturally guaranteed to be zeroed when enabled we do not need to explicitly zero ZA, either we will be restoring from a saved copy or trapping on first use of SME so we know that ZA must be disabled. Signed-off-by: Mark Brown <broonie@kernel.org> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Link: https://lore.kernel.org/r/20220419112247.711548-16-broonie@kernel.org Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
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#
af7167d6 |
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18-Apr-2022 |
Mark Brown <broonie@kernel.org> |
arm64/sme: Implement streaming SVE context switching When in streaming mode we need to save and restore the streaming mode SVE register state rather than the regular SVE register state. This uses the streaming mode vector length and omits FFR but is otherwise identical, if TIF_SVE is enabled when we are in streaming mode then streaming mode takes precedence. This does not handle use of streaming SVE state with KVM, ptrace or signals. This will be updated in further patches. Signed-off-by: Mark Brown <broonie@kernel.org> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Link: https://lore.kernel.org/r/20220419112247.711548-15-broonie@kernel.org Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
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b40c559b |
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18-Apr-2022 |
Mark Brown <broonie@kernel.org> |
arm64/sme: Implement SVCR context switching In SME the use of both streaming SVE mode and ZA are tracked through PSTATE.SM and PSTATE.ZA, visible through the system register SVCR. In order to context switch the floating point state for SME we need to context switch the contents of this register as part of context switching the floating point state. Since changing the vector length exits streaming SVE mode and disables ZA we also make sure we update SVCR appropriately when setting vector length, and similarly ensure that new threads have streaming SVE mode and ZA disabled. Signed-off-by: Mark Brown <broonie@kernel.org> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Link: https://lore.kernel.org/r/20220419112247.711548-14-broonie@kernel.org Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
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9e4ab6c8 |
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18-Apr-2022 |
Mark Brown <broonie@kernel.org> |
arm64/sme: Implement vector length configuration prctl()s As for SVE provide a prctl() interface which allows processes to configure their SME vector length. Signed-off-by: Mark Brown <broonie@kernel.org> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Link: https://lore.kernel.org/r/20220419112247.711548-12-broonie@kernel.org Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
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b42990d3 |
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18-Apr-2022 |
Mark Brown <broonie@kernel.org> |
arm64/sme: Identify supported SME vector lengths at boot The vector lengths used for SME are controlled through a similar set of registers to those for SVE and enumerated using a similar algorithm with some slight differences due to the fact that unlike SVE there are no restrictions on which combinations of vector lengths can be supported nor any mandatory vector lengths which must be implemented. Add a new vector type and implement support for enumerating it. One slightly awkward feature is that we need to read the current vector length using a different instruction (or enter streaming mode which would have the same issue and be higher cost). Rather than add an ops structure we add special cases directly in the otherwise generic vec_probe_vqs() function, this is a bit inelegant but it's the only place where this is an issue. Signed-off-by: Mark Brown <broonie@kernel.org> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Link: https://lore.kernel.org/r/20220419112247.711548-10-broonie@kernel.org Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
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5e64b862 |
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18-Apr-2022 |
Mark Brown <broonie@kernel.org> |
arm64/sme: Basic enumeration support This patch introduces basic cpufeature support for discovering the presence of the Scalable Matrix Extension. Signed-off-by: Mark Brown <broonie@kernel.org> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Link: https://lore.kernel.org/r/20220419112247.711548-9-broonie@kernel.org Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
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ca8a4ebc |
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18-Apr-2022 |
Mark Brown <broonie@kernel.org> |
arm64/sme: Manually encode SME instructions As with SVE rather than impose ambitious toolchain requirements for SME we manually encode the few instructions which we require in order to perform the work the kernel needs to do. The instructions used to save and restore context are provided as assembler macros while those for entering and leaving streaming mode are done in asm volatile blocks since they are expected to be used from C. We could do the SMSTART and SMSTOP operations with read/modify/write cycles on SVCR but using the aliases provided for individual field accesses should be slightly faster. These instructions are aliases for MSR but since our minimum toolchain requirements are old enough to mean that we can't use the sX_X_cX_cX_X form and they always use xzr rather than taking a value like write_sysreg_s() wants we just use .inst. Signed-off-by: Mark Brown <broonie@kernel.org> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Link: https://lore.kernel.org/r/20220419112247.711548-7-broonie@kernel.org Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
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30c43e73 |
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10-Dec-2021 |
Mark Brown <broonie@kernel.org> |
arm64/sve: Generalise vector length configuration prctl() for SME In preparation for adding SME support update the bulk of the implementation for the vector length configuration prctl() calls to be independent of vector type. Signed-off-by: Mark Brown <broonie@kernel.org> Link: https://lore.kernel.org/r/20211210184133.320748-3-broonie@kernel.org Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
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49ed9204 |
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22-Oct-2021 |
Mark Brown <broonie@kernel.org> |
arm64/sve: Add stub for sve_max_virtualisable_vl() Fixes build problems for configurations with KVM enabled but SVE disabled. Reported-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Mark Brown <broonie@kernel.org> Link: https://lore.kernel.org/r/20211022141635.2360415-2-broonie@kernel.org Signed-off-by: Will Deacon <will@kernel.org>
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ddc806b5 |
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19-Oct-2021 |
Mark Brown <broonie@kernel.org> |
arm64/sve: Explicitly load vector length when restoring SVE state Currently when restoring the SVE state we supply the SVE vector length as an argument to sve_load_state() and the underlying macros. This becomes inconvenient with the addition of SME since we may need to restore any combination of SVE and SME vector lengths, and we already separately restore the vector length in the KVM code. We don't need to know the vector length during the actual register load since the SME load instructions can index into the data array for us. Refactor the interface so we explicitly set the vector length separately to restoring the SVE registers in preparation for adding SME support, no functional change should be involved. Signed-off-by: Mark Brown <broonie@kernel.org> Link: https://lore.kernel.org/r/20211019172247.3045838-9-broonie@kernel.org Signed-off-by: Will Deacon <will@kernel.org>
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b5bc00ff |
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19-Oct-2021 |
Mark Brown <broonie@kernel.org> |
arm64/sve: Put system wide vector length information into structs With the introduction of SME we will have a second vector length in the system, enumerated and configured in a very similar fashion to the existing SVE vector length. While there are a few differences in how things are handled this is a relatively small portion of the overall code so in order to avoid code duplication we factor out We create two structs, one vl_info for the static hardware properties and one vl_config for the runtime configuration, with an array instantiated for each and update all the users to reference these. Some accessor functions are provided where helpful for readability, and the write to set the vector length is put into a function since the system register being updated needs to be chosen at compile time. This is a mostly mechanical replacement, further work will be required to actually make things generic, ensuring that we handle those places where there are differences properly. Signed-off-by: Mark Brown <broonie@kernel.org> Link: https://lore.kernel.org/r/20211019172247.3045838-8-broonie@kernel.org Signed-off-by: Will Deacon <will@kernel.org>
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0423eedc |
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19-Oct-2021 |
Mark Brown <broonie@kernel.org> |
arm64/sve: Use accessor functions for vector lengths in thread_struct In a system with SME there are parallel vector length controls for SVE and SME vectors which function in much the same way so it is desirable to share the code for handling them as much as possible. In order to prepare for doing this add a layer of accessor functions for the various VL related operations on tasks. Since almost all current interactions are actually via task->thread rather than directly with the thread_info the accessors use that. Accessors are provided for both generic and SVE specific usage, the generic accessors should be used for cases where register state is being manipulated since the registers are shared between streaming and regular SVE so we know that when SME support is implemented we will always have to be in the appropriate mode already and hence can generalise now. Since we are using task_struct and we don't want to cause widespread inclusion of sched.h the acessors are all out of line, it is hoped that none of the uses are in a sufficiently critical path for this to be an issue. Those that are most likely to present an issue are in the same translation unit so hopefully the compiler may be able to inline anyway. This is purely adding the layer of abstraction, additional work will be needed to support tasks using SME. Signed-off-by: Mark Brown <broonie@kernel.org> Link: https://lore.kernel.org/r/20211019172247.3045838-7-broonie@kernel.org Signed-off-by: Will Deacon <will@kernel.org>
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9f584866 |
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19-Oct-2021 |
Mark Brown <broonie@kernel.org> |
arm64/sve: Make access to FFR optional SME introduces streaming SVE mode in which FFR is not present and the instructions for accessing it UNDEF. In preparation for handling this update the low level SVE state access functions to take a flag specifying if FFR should be handled. When saving the register state we store a zero for FFR to guard against uninitialized data being read. No behaviour change should be introduced by this patch. Signed-off-by: Mark Brown <broonie@kernel.org> Link: https://lore.kernel.org/r/20211019172247.3045838-5-broonie@kernel.org Signed-off-by: Will Deacon <will@kernel.org>
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12cc2352 |
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19-Oct-2021 |
Mark Brown <broonie@kernel.org> |
arm64/sve: Make sve_state_size() static There are no users outside fpsimd.c so make sve_state_size() static. KVM open codes an equivalent. Signed-off-by: Mark Brown <broonie@kernel.org> Link: https://lore.kernel.org/r/20211019172247.3045838-4-broonie@kernel.org Signed-off-by: Will Deacon <will@kernel.org>
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b53223e0 |
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19-Oct-2021 |
Mark Brown <broonie@kernel.org> |
arm64/sve: Remove sve_load_from_fpsimd_state() Following optimisations of the SVE register handling we no longer load the SVE state from a saved copy of the FPSIMD registers, we convert directly in registers or from one saved state to another. Remove the function so we don't need to update it during further refactoring. Signed-off-by: Mark Brown <broonie@kernel.org> Link: https://lore.kernel.org/r/20211019172247.3045838-3-broonie@kernel.org Signed-off-by: Will Deacon <will@kernel.org>
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b24b5205 |
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30-Jul-2021 |
Mark Brown <broonie@kernel.org> |
arm64/sve: Make fpsimd_bind_task_to_cpu() static This function is not referenced outside fpsimd.c so can be static, making it that little bit easier to follow what is called from where. Signed-off-by: Mark Brown <broonie@kernel.org> Link: https://lore.kernel.org/r/20210730165846.18558-1-broonie@kernel.org Reviewed-by: Dave Martin <Dave.Martin@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
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ad4711f9 |
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12-May-2021 |
Mark Brown <broonie@kernel.org> |
arm64/sve: Skip flushing Z registers with 128 bit vectors When the SVE vector length is 128 bits then there are no bits in the Z registers which are not shared with the V registers so we can skip them when zeroing state not shared with FPSIMD, this results in a minor performance improvement. Signed-off-by: Mark Brown <broonie@kernel.org> Reviewed-by: Dave Martin <Dave.Martin@arm.com> Acked-by: Catalin Marinas <catalin.marinas@arm.com> Link: https://lore.kernel.org/r/20210512151131.27877-4-broonie@kernel.org Signed-off-by: Will Deacon <will@kernel.org>
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a9f8696d |
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31-Mar-2021 |
Xiaofei Tan <tanxiaofei@huawei.com> |
arm64: sve: Provide sve_cond_update_zcr_vq fallback when !ARM64_SVE Compilation fails when KVM is selected and ARM64_SVE isn't. The root cause is that sve_cond_update_zcr_vq is not defined when ARM64_SVE is not selected. Fix it by adding an empty definition when CONFIG_ARM64_SVE=n. Signed-off-by: Xiaofei Tan <tanxiaofei@huawei.com> [maz: simplified commit message, fleshed out dummy #define] Signed-off-by: Marc Zyngier <maz@kernel.org> Link: https://lore.kernel.org/r/1617183879-48748-1-git-send-email-tanxiaofei@huawei.com
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71ce1ae5 |
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18-Mar-2021 |
Marc Zyngier <maz@kernel.org> |
arm64: sve: Provide a conditional update accessor for ZCR_ELx A common pattern is to conditionally update ZCR_ELx in order to avoid the "self-synchronizing" effect that writing to this register has. Let's provide an accessor that does exactly this. Acked-by: Will Deacon <will@kernel.org> Signed-off-by: Marc Zyngier <maz@kernel.org>
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cccb78ce |
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12-Mar-2021 |
Mark Brown <broonie@kernel.org> |
arm64/sve: Rework SVE access trap to convert state in registers When we enable SVE usage in userspace after taking a SVE access trap we need to ensure that the portions of the register state that are not shared with the FPSIMD registers are zeroed. Currently we do this by forcing the FPSIMD registers to be saved to the task struct and converting them there. This is wasteful in the common case where the task state is loaded into the registers and we will immediately return to userspace since we can initialise the SVE state directly in registers instead of accessing multiple copies of the register state in memory. Instead in that common case do the conversion in the registers and update the task metadata so that we can return to userspace without spilling the register state to memory unless there is some other reason to do so. Signed-off-by: Mark Brown <broonie@kernel.org> Link: https://lore.kernel.org/r/20210312190313.24598-1-broonie@kernel.org Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
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9c4b4c70 |
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28-Aug-2020 |
Julien Grall <julien.grall@arm.com> |
arm64/sve: Implement a helper to load SVE registers from FPSIMD state In a follow-up patch, we may save the FPSIMD rather than the full SVE state when the state has to be zeroed on return to userspace (e.g during a syscall). Introduce an helper to load SVE vectors from FPSIMD state and zero the rest of SVE registers. Signed-off-by: Julien Grall <julien.grall@arm.com> Signed-off-by: Mark Brown <broonie@kernel.org> Reviewed-by: Dave Martin <Dave.Martin@arm.com> Link: https://lore.kernel.org/r/20200828181155.17745-7-broonie@kernel.org Signed-off-by: Will Deacon <will@kernel.org>
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1e530f13 |
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28-Aug-2020 |
Julien Grall <julien.grall@arm.com> |
arm64/sve: Implement a helper to flush SVE registers Introduce a new helper that will zero all SVE registers but the first 128-bits of each vector. This will be used by subsequent patches to avoid costly store/maipulate/reload sequences in places like do_sve_acc(). Signed-off-by: Julien Grall <julien.grall@arm.com> Signed-off-by: Mark Brown <broonie@kernel.org> Reviewed-by: Dave Martin <Dave.Martin@arm.com> Link: https://lore.kernel.org/r/20200828181155.17745-6-broonie@kernel.org Signed-off-by: Will Deacon <will@kernel.org>
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b907b80d |
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08-Jul-2019 |
Mark Rutland <mark.rutland@arm.com> |
arm64: remove pointless __KERNEL__ guards For a number of years, UAPI headers have been split from kernel-internal headers. The latter are never exposed to userspace, and always built with __KERNEL__ defined. Most headers under arch/arm64 don't have __KERNEL__ guards, but there are a few stragglers lying around. To make things more consistent, and to set a good example going forward, let's remove these redundant __KERNEL__ guards. In a couple of cases, a trailing #endif lacked a comment describing its corresponding #if or #ifdef, so these are fixes up at the same time. Guards in auto-generated crypto code are left as-is, as these guards are generated by scripting imported from the upstream openssl project scripts. Guards in UAPI headers are left as-is, as these can be included by userspace or the kernel. There should be no functional change as a result of this patch. Signed-off-by: Mark Rutland <mark.rutland@arm.com> Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Will Deacon <will.deacon@arm.com> Signed-off-by: Will Deacon <will@kernel.org>
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caab277b |
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02-Jun-2019 |
Thomas Gleixner <tglx@linutronix.de> |
treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 234 Based on 1 normalized pattern(s): this program is free software you can redistribute it and or modify it under the terms of the gnu general public license version 2 as published by the free software foundation this program is distributed in the hope that it will be useful but without any warranty without even the implied warranty of merchantability or fitness for a particular purpose see the gnu general public license for more details you should have received a copy of the gnu general public license along with this program if not see http www gnu org licenses extracted by the scancode license scanner the SPDX license identifier GPL-2.0-only has been chosen to replace the boilerplate/reference in 503 file(s). Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Alexios Zavras <alexios.zavras@intel.com> Reviewed-by: Allison Randal <allison@lohutok.net> Reviewed-by: Enrico Weigelt <info@metux.net> Cc: linux-spdx@vger.kernel.org Link: https://lkml.kernel.org/r/20190602204653.811534538@linutronix.de Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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54b8c7cb |
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21-May-2019 |
Julien Grall <julien.grall@arm.com> |
arm64/fpsimd: Introduce fpsimd_save_and_flush_cpu_state() and use it The only external user of fpsimd_save() and fpsimd_flush_cpu_state() is the KVM FPSIMD code. A following patch will introduce a mechanism to acquire owernship of the FPSIMD/SVE context for performing context management operations. Rather than having to export the new helpers to get/put the context, we can just introduce a new function to combine fpsimd_save() and fpsimd_flush_cpu_state(). This has also the advantage to remove any external call of fpsimd_save() and fpsimd_flush_cpu_state(), so they can be turned static. Lastly, the new function can also be used in the PM notifier. Reviewed-by: Dave Martin <Dave.Martin@arm.com> Acked-by: Marc Zyngier <marc.zyngier@arm.com> Signed-off-by: Julien Grall <julien.grall@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
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6fa9b41f |
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21-May-2019 |
Julien Grall <julien.grall@arm.com> |
arm64/fpsimd: Remove the prototype for sve_flush_cpu_state() The function sve_flush_cpu_state() has been removed in commit 21cdd7fd76e3 ("KVM: arm64: Remove eager host SVE state saving"). So remove the associated prototype in asm/fpsimd.h. Reviewed-by: Dave Martin <Dave.Martin@arm.com> Acked-by: Marc Zyngier <marc.zyngier@arm.com> Signed-off-by: Julien Grall <julien.grall@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
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624835ab |
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11-Apr-2019 |
Dave Martin <Dave.Martin@arm.com> |
arm64/sve: Clarify vq map semantics Currently the meanings of sve_vq_map and the ancillary helpers __bit_to_vq() and __vq_to_bit() are not clearly explained. This patch makes the explanatory comment clearer, and removes the duplicate comment from fpsimd.h. The WARN_ON() currently present in __bit_to_vq() confuses the intended use of this helper. Since these are low-level helpers not intended for general-purpose use anyway, it is better not to make guesses about how these functions will be used: rather, this patch removes the WARN_ON() and relies on callers to use the helpers sensibly. Suggested-by: Andrew Jones <drjones@redhat.com> Signed-off-by: Dave Martin <Dave.Martin@arm.com> Reviewed-by: Andrew Jones <drjones@redhat.com> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
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ead9e430 |
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28-Sep-2018 |
Dave Martin <Dave.Martin@arm.com> |
arm64/sve: In-kernel vector length availability query interface KVM will need to interrogate the set of SVE vector lengths available on the system. This patch exposes the relevant bits to the kernel, along with a sve_vq_available() helper to check whether a particular vector length is supported. __vq_to_bit() and __bit_to_vq() are not intended for use outside these functions: now that these are exposed outside fpsimd.c, they are prefixed with __ in order to provide an extra hint that they are not intended for general-purpose use. Signed-off-by: Dave Martin <Dave.Martin@arm.com> Reviewed-by: Alex Bennée <alex.bennee@linaro.org> Tested-by: zhang.lei <zhang.lei@jp.fujitsu.com> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
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04950674 |
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28-Sep-2018 |
Dave Martin <Dave.Martin@arm.com> |
arm64/sve: Enable SVE state tracking for non-task contexts The current FPSIMD/SVE context handling support for non-task (i.e., KVM vcpu) contexts does not take SVE into account. This means that only task contexts can safely use SVE at present. In preparation for enabling KVM guests to use SVE, it is necessary to keep track of SVE state for non-task contexts too. This patch adds the necessary support, removing assumptions from the context switch code about the location of the SVE context storage. When binding a vcpu context, its vector length is arbitrarily specified as SVE_VL_MIN for now. In any case, because TIF_SVE is presently cleared at vcpu context bind time, the specified vector length will not be used for anything yet. In later patches TIF_SVE will be set here as appropriate, and the appropriate maximum vector length for the vcpu will be passed when binding. Signed-off-by: Dave Martin <Dave.Martin@arm.com> Reviewed-by: Alex Bennée <alex.bennee@linaro.org> Reviewed-by: Julien Grall <julien.grall@arm.com> Tested-by: zhang.lei <zhang.lei@jp.fujitsu.com> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
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d06b76be |
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28-Sep-2018 |
Dave Martin <Dave.Martin@arm.com> |
arm64/sve: Check SVE virtualisability Due to the way the effective SVE vector length is controlled and trapped at different exception levels, certain mismatches in the sets of vector lengths supported by different physical CPUs in the system may prevent straightforward virtualisation of SVE at parity with the host. This patch analyses the extent to which SVE can be virtualised safely without interfering with migration of vcpus between physical CPUs, and rejects late secondary CPUs that would erode the situation further. It is left up to KVM to decide what to do with this information. Signed-off-by: Dave Martin <Dave.Martin@arm.com> Reviewed-by: Julien Thierry <julien.thierry@arm.com> Tested-by: zhang.lei <zhang.lei@jp.fujitsu.com> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
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f9209e26 |
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11-Jul-2018 |
Mark Rutland <mark.rutland@arm.com> |
arm64: move sve_user_{enable,disable} to <asm/fpsimd.h> In subsequent patches, we'll want to make use of sve_user_enable() and sve_user_disable() outside of kernel/fpsimd.c. Let's move these to <asm/fpsimd.h> where we can make use of them. To avoid ifdeffery in sequences like: if (system_supports_sve() && some_condition) sve_user_disable(); ... empty stubs are provided when support for SVE is not enabled. Note that system_supports_sve() contains as IS_ENABLED(CONFIG_ARM64_SVE), so the sve_user_disable() call should be optimized away entirely when CONFIG_ARM64_SVE is not selected. To ensure that this is the case, the stub definitions contain a BUILD_BUG(), as we do for other stubs for which calls should always be optimized away when the relevant config option is not selected. At the same time, the include list of <asm/fpsimd.h> is sorted while adding <asm/sysreg.h>. Signed-off-by: Mark Rutland <mark.rutland@arm.com> Acked-by: Catalin Marinas <catalin.marinas@arm.com> Reviewed-by: Dave Martin <dave.martin@arm.com> Cc: Will Deacon <will.deacon@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com>
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#
9a6e5948 |
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12-Apr-2018 |
Dave Martin <Dave.Martin@arm.com> |
arm64/sve: Move sve_pffr() to fpsimd.h and make inline In order to make sve_save_state()/sve_load_state() more easily reusable and to get rid of a potential branch on context switch critical paths, this patch makes sve_pffr() inline and moves it to fpsimd.h. <asm/processor.h> must be included in fpsimd.h in order to make this work, and this creates an #include cycle that is tricky to avoid without modifying core code, due to the way the PR_SVE_*() prctl helpers are included in the core prctl implementation. Instead of breaking the cycle, this patch defers inclusion of <asm/fpsimd.h> in <asm/processor.h> until the point where it is actually needed: i.e., immediately before the prctl definitions. No functional change. 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: Marc Zyngier <marc.zyngier@arm.com> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
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#
31dc52b3 |
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12-Apr-2018 |
Dave Martin <Dave.Martin@arm.com> |
arm64/sve: Move read_zcr_features() out of cpufeature.h Having read_zcr_features() inline in cpufeature.h results in that header requiring #includes which make it hard to include <asm/fpsimd.h> elsewhere without triggering header inclusion cycles. This is not a hot-path function and arguably should not be in cpufeature.h in the first place, so this patch moves it to fpsimd.c, compiled conditionally if CONFIG_ARM64_SVE=y. This allows some SVE-related #includes to be dropped from cpufeature.h, which will ease future maintenance. A couple of missing #includes of <asm/fpsimd.h> are exposed by this change under arch/arm64/. This patch adds the missing #includes as necessary. No functional change. 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: Marc Zyngier <marc.zyngier@arm.com> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
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#
e6b673b7 |
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06-Apr-2018 |
Dave Martin <Dave.Martin@arm.com> |
KVM: arm64: Optimise FPSIMD handling to reduce guest/host thrashing This patch refactors KVM to align the host and guest FPSIMD save/restore logic with each other for arm64. This reduces the number of redundant save/restore operations that must occur, and reduces the common-case IRQ blackout time during guest exit storms by saving the host state lazily and optimising away the need to restore the host state before returning to the run loop. Four hooks are defined in order to enable this: * kvm_arch_vcpu_run_map_fp(): Called on PID change to map necessary bits of current to Hyp. * kvm_arch_vcpu_load_fp(): Set up FP/SIMD for entering the KVM run loop (parse as "vcpu_load fp"). * kvm_arch_vcpu_ctxsync_fp(): Get FP/SIMD into a safe state for re-enabling interrupts after a guest exit back to the run loop. For arm64 specifically, this involves updating the host kernel's FPSIMD context tracking metadata so that kernel-mode NEON use will cause the vcpu's FPSIMD state to be saved back correctly into the vcpu struct. This must be done before re-enabling interrupts because kernel-mode NEON may be used by softirqs. * kvm_arch_vcpu_put_fp(): Save guest FP/SIMD state back to memory and dissociate from the CPU ("vcpu_put fp"). Also, the arm64 FPSIMD context switch code is updated to enable it to save back FPSIMD state for a vcpu, not just current. A few helpers drive this: * fpsimd_bind_state_to_cpu(struct user_fpsimd_state *fp): mark this CPU as having context fp (which may belong to a vcpu) currently loaded in its registers. This is the non-task equivalent of the static function fpsimd_bind_to_cpu() in fpsimd.c. * task_fpsimd_save(): exported to allow KVM to save the guest's FPSIMD state back to memory on exit from the run loop. * fpsimd_flush_state(): invalidate any context's FPSIMD state that is currently loaded. Used to disassociate the vcpu from the CPU regs on run loop exit. These changes allow the run loop to enable interrupts (and thus softirqs that may use kernel-mode NEON) without having to save the guest's FPSIMD state eagerly. Some new vcpu_arch fields are added to make all this work. Because host FPSIMD state can now be saved back directly into current's thread_struct as appropriate, host_cpu_context is no longer used for preserving the FPSIMD state. However, it is still needed for preserving other things such as the host's system registers. To avoid ABI churn, the redundant storage space in host_cpu_context is not removed for now. arch/arm is not addressed by this patch and continues to use its current save/restore logic. It could provide implementations of the helpers later if desired. Signed-off-by: Dave Martin <Dave.Martin@arm.com> Reviewed-by: Marc Zyngier <marc.zyngier@arm.com> Reviewed-by: Christoffer Dall <christoffer.dall@arm.com> Reviewed-by: Alex Bennée <alex.bennee@linaro.org> Acked-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
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20b85472 |
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28-Mar-2018 |
Dave Martin <Dave.Martin@arm.com> |
arm64: fpsimd: Split cpu field out from struct fpsimd_state In preparation for using a common representation of the FPSIMD state for tasks and KVM vcpus, this patch separates out the "cpu" field that is used to track the cpu on which the state was most recently loaded. This will allow common code to operate on task and vcpu contexts without requiring the cpu field to be stored at the same offset from the FPSIMD register data in both cases. This should avoid the need for messing with the definition of those parts of struct vcpu_arch that are exposed in the KVM user ABI. The resulting change is also convenient for grouping and defining the set of thread_struct fields that are supposed to be accessible to copy_{to,from}_user(), which includes user_fpsimd_state but should exclude the cpu field. This patch does not amend the usercopy whitelist to match: that will be addressed in a subsequent patch. Signed-off-by: Dave Martin <Dave.Martin@arm.com> [will: inline fpsimd_flush_state for now] Signed-off-by: Will Deacon <will.deacon@arm.com>
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b4f9b390 |
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13-Feb-2018 |
Will Deacon <will@kernel.org> |
arm64: fpsimd: include <linux/init.h> in fpsimd.h fpsimd.h uses the __init annotation, so pull in linux/init.h Acked-by: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com>
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c0cda3b8 |
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26-Mar-2018 |
Dave Martin <dave.martin@arm.com> |
arm64: capabilities: Update prototype for enable call back We issue the enable() call back for all CPU hwcaps capabilities available on the system, on all the CPUs. So far we have ignored the argument passed to the call back, which had a prototype to accept a "void *" for use with on_each_cpu() and later with stop_machine(). However, with commit 0a0d111d40fd1 ("arm64: cpufeature: Pass capability structure to ->enable callback"), there are some users of the argument who wants the matching capability struct pointer where there are multiple matching criteria for a single capability. Clean up the declaration of the call back to make it clear. 1) Renamed to cpu_enable(), to imply taking necessary actions on the called CPU for the entry. 2) Pass const pointer to the capability, to allow the call back to check the entry. (e.,g to check if any action is needed on the CPU) 3) We don't care about the result of the call back, turning this to a void. Cc: Will Deacon <will.deacon@arm.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Andre Przywara <andre.przywara@arm.com> Cc: James Morse <james.morse@arm.com> Acked-by: Robin Murphy <robin.murphy@arm.com> Reviewed-by: Julien Thierry <julien.thierry@arm.com> Signed-off-by: Dave Martin <dave.martin@arm.com> [suzuki: convert more users, rename call back and drop results] Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com>
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0abdeff5 |
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15-Dec-2017 |
Dave Martin <Dave.Martin@arm.com> |
arm64: fpsimd: Fix state leakage when migrating after sigreturn When refactoring the sigreturn code to handle SVE, I changed the sigreturn implementation to store the new FPSIMD state from the user sigframe into task_struct before reloading the state into the CPU regs. This makes it easier to convert the data for SVE when needed. However, it turns out that the fpsimd_state structure passed into fpsimd_update_current_state is not fully initialised, so assigning the structure as a whole corrupts current->thread.fpsimd_state.cpu with uninitialised data. This means that if the garbage data written to .cpu happens to be a valid cpu number, and the task is subsequently migrated to the cpu identified by the that number, and then tries to enter userspace, the CPU FPSIMD regs will be assumed to be correct for the task and not reloaded as they should be. This can result in returning to userspace with the FPSIMD registers containing data that is stale or that belongs to another task or to the kernel. Knowingly handing around a kernel structure that is incompletely initialised with user data is a potential source of mistakes, especially across source file boundaries. To help avoid a repeat of this issue, this patch adapts the relevant internal API to hand around the user-accessible subset only: struct user_fpsimd_state. To avoid future surprises, this patch also converts all uses of struct fpsimd_state that really only access the user subset, to use struct user_fpsimd_state. A few missing consts are added to function prototypes for good measure. Thanks to Will for spotting the cause of the bug here. Reported-by: Geert Uytterhoeven <geert@linux-m68k.org> Signed-off-by: Dave Martin <Dave.Martin@arm.com> Cc: Will Deacon <will.deacon@arm.com> Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
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17eed27b |
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31-Oct-2017 |
Dave Martin <Dave.Martin@arm.com> |
arm64/sve: KVM: Prevent guests from using SVE 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>
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2d2123bc |
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31-Oct-2017 |
Dave Martin <Dave.Martin@arm.com> |
arm64/sve: Add prctl controls for userspace vector length management 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>
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43d4da2c4 |
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31-Oct-2017 |
Dave Martin <Dave.Martin@arm.com> |
arm64/sve: ptrace and ELF coredump support 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>
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2e0f2478 |
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31-Oct-2017 |
Dave Martin <Dave.Martin@arm.com> |
arm64/sve: Probe SVE capabilities and usable vector lengths 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>
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7582e220 |
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31-Oct-2017 |
Dave Martin <Dave.Martin@arm.com> |
arm64/sve: Backend logic for setting the vector length 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>
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8cd969d2 |
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31-Oct-2017 |
Dave Martin <Dave.Martin@arm.com> |
arm64/sve: Signal handling support 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>
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#
bc0ee476 |
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31-Oct-2017 |
Dave Martin <Dave.Martin@arm.com> |
arm64/sve: Core task context handling 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>
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1fc5dce7 |
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31-Oct-2017 |
Dave Martin <Dave.Martin@arm.com> |
arm64/sve: Low-level SVE architectural state manipulation functions 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>
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cb84d11e |
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03-Aug-2017 |
Dave Martin <Dave.Martin@arm.com> |
arm64: neon: Remove support for nested or hardirq kernel-mode NEON Support for kernel-mode NEON to be nested and/or used in hardirq context adds significant complexity, and the benefits may be marginal. In practice, kernel-mode NEON is not used in hardirq context, and is rarely used in softirq context (by certain mac80211 drivers). This patch implements an arm64 may_use_simd() function to allow clients to check whether kernel-mode NEON is usable in the current context, and simplifies kernel_neon_{begin,end}() to handle only saving of the task FPSIMD state (if any). Without nesting, there is no other state to save. The partial fpsimd save/restore functions become redundant as a result of these changes, so they are removed too. The save/restore model is changed to operate directly on task_struct without additional percpu storage. This simplifies the code and saves a bit of memory, but means that softirqs must now be disabled when manipulating the task fpsimd state from task context: correspondingly, preempt_{en,dis}sable() calls are upgraded to local_bh_{en,dis}able() as appropriate. fpsimd_thread_switch() already runs with hardirqs disabled and so is already protected from softirqs. These changes should make it easier to support kernel-mode NEON in the presence of the Scalable Vector extension in the future. Signed-off-by: Dave Martin <Dave.Martin@arm.com> Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
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4328825d |
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03-Aug-2017 |
Dave Martin <Dave.Martin@arm.com> |
arm64: neon: Allow EFI runtime services to use FPSIMD in irq context In order to be able to cope with kernel-mode NEON being unavailable in hardirq/nmi context and non-nestable, we need special handling for EFI runtime service calls that may be made during an interrupt that interrupted a kernel_neon_begin()..._end() block. This will occur if the kernel tries to write diagnostic data to EFI persistent storage during a panic triggered by an NMI for example. EFI runtime services specify an ABI that clobbers the FPSIMD state, rather than being able to use it optionally as an accelerator. This means that EFI is really a special case and can be handled specially. To enable EFI calls from interrupts, this patch creates dedicated __efi_fpsimd_{begin,end}() helpers solely for this purpose, which save/restore to a separate percpu buffer if called in a context where kernel_neon_begin() is not usable. Signed-off-by: Dave Martin <Dave.Martin@arm.com> Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
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190f1ca8 |
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24-Feb-2014 |
Ard Biesheuvel <ardb@kernel.org> |
arm64: add support for kernel mode NEON in interrupt context This patch modifies kernel_neon_begin() and kernel_neon_end(), so they may be called from any context. To address the case where only a couple of registers are needed, kernel_neon_begin_partial(u32) is introduced which takes as a parameter the number of bottom 'n' NEON q-registers required. To mark the end of such a partial section, the regular kernel_neon_end() should be used. Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
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005f78cd |
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08-May-2014 |
Ard Biesheuvel <ardb@kernel.org> |
arm64: defer reloading a task's FPSIMD state to userland resume If a task gets scheduled out and back in again and nothing has touched its FPSIMD state in the mean time, there is really no reason to reload it from memory. Similarly, repeated calls to kernel_neon_begin() and kernel_neon_end() will preserve and restore the FPSIMD state every time. This patch defers the FPSIMD state restore to the last possible moment, i.e., right before the task returns to userland. If a task does not return to userland at all (for any reason), the existing FPSIMD state is preserved and may be reused by the owning task if it gets scheduled in again on the same CPU. This patch adds two more functions to abstract away from straight FPSIMD register file saves and restores: - fpsimd_restore_current_state -> ensure current's FPSIMD state is loaded - fpsimd_flush_task_state -> invalidate live copies of a task's FPSIMD state Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
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c51f9269 |
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24-Feb-2014 |
Ard Biesheuvel <ardb@kernel.org> |
arm64: add abstractions for FPSIMD state manipulation There are two tacit assumptions in the FPSIMD handling code that will no longer hold after the next patch that optimizes away some FPSIMD state restores: . the FPSIMD registers of this CPU contain the userland FPSIMD state of task 'current'; . when switching to a task, its FPSIMD state will always be restored from memory. This patch adds the following functions to abstract away from straight FPSIMD register file saves and restores: - fpsimd_preserve_current_state -> ensure current's FPSIMD state is saved - fpsimd_update_current_state -> replace current's FPSIMD state Where necessary, the signal handling and fork code are updated to use the above wrappers instead of poking into the FPSIMD registers directly. Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
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6ba1bc82 |
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06-Nov-2012 |
Will Deacon <will@kernel.org> |
arm64: elf: fix core dumping definitions for GP and FP registers struct user_fp does not exist for arm64, so use struct user_fpsimd_state instead for the ELF core dumping definitions. Furthermore, since we use regset-based core dumping, we do not need definitions for dump_task_regs and dump_fpu. Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
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53631b54 |
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05-Mar-2012 |
Catalin Marinas <catalin.marinas@arm.com> |
arm64: Floating point and SIMD This patch adds support for FP/ASIMD register bank saving and restoring during context switch and FP exception handling to generate SIGFPE. There are 32 128-bit registers and the context switching is currently done non-lazily. Benchmarks on real hardware are required before implementing lazy FP state saving/restoring. Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> Acked-by: Tony Lindgren <tony@atomide.com> Acked-by: Arnd Bergmann <arnd@arndb.de> Acked-by: Nicolas Pitre <nico@linaro.org> Acked-by: Olof Johansson <olof@lixom.net> Acked-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
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