When we need a buffer for SVE register state we call sve_alloc() to make
sure that one is there. In order to avoid repeated allocations and frees
we keep the buffer around unless we change vector length and just memset()
it to ensure a clean register state. The function that deals with this
takes the task to operate on as an argument, however in the case where we
do a memset() we initialise using the SVE state size for the current task
rather than the task passed as an argument.
This is only an issue in the case where we are setting the register state
for a task via ptrace and the task being configured has a different vector
length to the task tracing it. In the case where the buffer is larger in
the traced process we will leak old state from the traced process to
itself, in the case where the buffer is smaller in the traced process we
will overflow the buffer and corrupt memory.
Fixes: bc0ee4760364 ("arm64/sve: Core task context handling")
Cc: <stable@vger.kernel.org> # 4.15.x
Signed-off-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20210909165356.10675-1-broonie@kernel.org
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Currently we "handle" failure to allocate the SVE register storage by doing a BUG_ON() and hoping for the best. This is obviously not great and the memory allocation failure will already be loud enough without the BUG_ON(). As the comment says it is a corner case but let's try to do a bit better, remove the BUG_ON() and add code to handle the failure in the callers. For the ptrace and signal code we can return -ENOMEM gracefully however we have no real error reporting path available to us for the SVE access trap so instead generate a SIGKILL if the allocation fails there. This at least means that we won't try to soldier on and end up trying to access the nonexistant state and while it's obviously not ideal for userspace SIGKILL doesn't allow any handling so minimises the ABI impact, making it easier to improve the interface later if we come up with a better idea. Signed-off-by: Mark Brown <broonie@kernel.org> Link: https://lore.kernel.org/r/20210824153417.18371-1-broonie@kernel.org Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
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>
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>
* for-next/misc: : Miscellaneous patches arm64/sve: Add compile time checks for SVE hooks in generic functions arm64/kernel/probes: Use BUG_ON instead of if condition followed by BUG. arm64/sve: Remove redundant system_supports_sve() tests arm64: mte: Remove unused mte_assign_mem_tag_range() arm64: Add __init section marker to some functions arm64/sve: Rework SVE access trap to convert state in registers docs: arm64: Fix a grammar error arm64: smp: Add missing prototype for some smp.c functions arm64: setup: name `tcr` register arm64: setup: name `mair` register arm64: stacktrace: Move start_backtrace() out of the header arm64: barrier: Remove spec_bar() macro arm64: entry: remove test_irqs_unmasked macro ARM64: enable GENERIC_FIND_FIRST_BIT arm64: defconfig: Use DEBUG_INFO_REDUCED * for-next/kselftest: : Various kselftests for arm64 kselftest: arm64: Add BTI tests kselftest/arm64: mte: Report filename on failing temp file creation kselftest/arm64: mte: Fix clang warning kselftest/arm64: mte: Makefile: Fix clang compilation kselftest/arm64: mte: Output warning about failing compiler kselftest/arm64: mte: Use cross-compiler if specified kselftest/arm64: mte: Fix MTE feature detection kselftest/arm64: mte: common: Fix write() warnings kselftest/arm64: mte: user_mem: Fix write() warning kselftest/arm64: mte: ksm_options: Fix fscanf warning kselftest/arm64: mte: Fix pthread linking kselftest/arm64: mte: Fix compilation with native compiler * for-next/xntable: : Add hierarchical XN permissions for all page tables arm64: mm: use XN table mapping attributes for user/kernel mappings arm64: mm: use XN table mapping attributes for the linear region arm64: mm: add missing P4D definitions and use them consistently * for-next/vdso: : Minor improvements to the compat vdso and sigpage arm64: compat: Poison the compat sigpage arm64: vdso: Avoid ISB after reading from cntvct_el0 arm64: compat: Allow signal page to be remapped arm64: vdso: Remove redundant calls to flush_dcache_page() arm64: vdso: Use GFP_KERNEL for allocating compat vdso and signal pages * for-next/fiq: : Support arm64 FIQ controller registration arm64: irq: allow FIQs to be handled arm64: Always keep DAIF.[IF] in sync arm64: entry: factor irq triage logic into macros arm64: irq: rework root IRQ handler registration arm64: don't use GENERIC_IRQ_MULTI_HANDLER genirq: Allow architectures to override set_handle_irq() fallback * for-next/epan: : Support for Enhanced PAN (execute-only permissions) arm64: Support execute-only permissions with Enhanced PAN * for-next/kasan-vmalloc: : Support CONFIG_KASAN_VMALLOC on arm64 arm64: Kconfig: select KASAN_VMALLOC if KANSAN_GENERIC is enabled arm64: kaslr: support randomized module area with KASAN_VMALLOC arm64: Kconfig: support CONFIG_KASAN_VMALLOC arm64: kasan: abstract _text and _end to KERNEL_START/END arm64: kasan: don't populate vmalloc area for CONFIG_KASAN_VMALLOC * for-next/fgt-boot-init: : Booting clarifications and fine grained traps setup arm64: Require that system registers at all visible ELs be initialized arm64: Disable fine grained traps on boot arm64: Document requirements for fine grained traps at boot * for-next/vhe-only: : Dealing with VHE-only CPUs (a.k.a. M1) arm64: Get rid of CONFIG_ARM64_VHE arm64: Cope with CPUs stuck in VHE mode arm64: cpufeature: Allow early filtering of feature override * arm64/for-next/perf: arm64: perf: Remove redundant initialization in perf_event.c perf/arm_pmu_platform: Clean up with dev_printk perf/arm_pmu_platform: Fix error handling perf/arm_pmu_platform: Use dev_err_probe() for IRQ errors docs: perf: Address some html build warnings docs: perf: Add new description on HiSilicon uncore PMU v2 drivers/perf: hisi: Add support for HiSilicon PA PMU driver drivers/perf: hisi: Add support for HiSilicon SLLC PMU driver drivers/perf: hisi: Update DDRC PMU for programmable counter drivers/perf: hisi: Add new functions for HHA PMU drivers/perf: hisi: Add new functions for L3C PMU drivers/perf: hisi: Add PMU version for uncore PMU drivers. drivers/perf: hisi: Refactor code for more uncore PMUs drivers/perf: hisi: Remove unnecessary check of counter index drivers/perf: Simplify the SMMUv3 PMU event attributes drivers/perf: convert sysfs sprintf family to sysfs_emit drivers/perf: convert sysfs scnprintf family to sysfs_emit_at() and sysfs_emit() drivers/perf: convert sysfs snprintf family to sysfs_emit * for-next/neon-softirqs-disabled: : Run kernel mode SIMD with softirqs disabled arm64: fpsimd: run kernel mode NEON with softirqs disabled arm64: assembler: introduce wxN aliases for wN registers arm64: assembler: remove conditional NEON yield macros
The FPSIMD code was relying on IS_ENABLED() checks in system_suppors_sve()
to cause the compiler to delete references to SVE functions in some places,
add explicit IS_ENABLED() checks back.
Fixes: ef9c5d09797d ("arm64/sve: Remove redundant system_supports_sve() tests")
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20210415121742.36628-1-broonie@kernel.org
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Currently there are a number of places in the SVE code where we check both system_supports_sve() and TIF_SVE. This is a bit redundant given that we should never get into a situation where we have set TIF_SVE without having SVE support and it is not clear that silently ignoring a mistakenly set TIF_SVE flag is the most sensible error handling approach. For now let's just drop the system_supports_sve() checks since this will at least reduce overhead a little. Signed-off-by: Mark Brown <broonie@kernel.org> Link: https://lore.kernel.org/r/20210412172320.3315-1-broonie@kernel.org Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Kernel mode NEON can be used in task or softirq context, but only in a non-nesting manner, i.e., softirq context is only permitted if the interrupt was not taken at a point where the kernel was using the NEON in task context. This means all users of kernel mode NEON have to be aware of this limitation, and either need to provide scalar fallbacks that may be much slower (up to 20x for AES instructions) and potentially less safe, or use an asynchronous interface that defers processing to a later time when the NEON is guaranteed to be available. Given that grabbing and releasing the NEON is cheap, we can relax this restriction, by increasing the granularity of kernel mode NEON code, and always disabling softirq processing while the NEON is being used in task context. Signed-off-by: Ard Biesheuvel <ardb@kernel.org> Acked-by: Will Deacon <will@kernel.org> Link: https://lore.kernel.org/r/20210302090118.30666-4-ardb@kernel.org Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
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>
It doesn't make sense to issue prctl(PR_PAC_RESET_KEYS) on a
compat task because the 32-bit instruction set does not offer PAuth
instructions. For consistency with other 64-bit only prctls such as
{SET,GET}_TAGGED_ADDR_CTRL, reject the prctl on compat tasks.
Although this is a userspace-visible change, maybe it isn't too late
to make this change given that the hardware isn't available yet and
it's very unlikely that anyone has 32-bit software that actually
depends on this succeeding.
Signed-off-by: Peter Collingbourne <pcc@google.com>
Link: https://linux-review.googlesource.com/id/Ie885a1ff84ab498cc9f62d6451e9f2cfd4b1d06a
Link: https://lore.kernel.org/r/20201014052430.11630-1-pcc@google.com
[will: Do the same for the SVE prctl()s]
Signed-off-by: Will Deacon <will@kernel.org>