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2853d5fafb
- Atomic operations (lock prefixed instructions) which span two cache
lines have to acquire the global bus lock. This is at least 1k cycles
slower than an atomic operation within a cache line and disrupts
performance on other cores. Aside of performance disruption this is
a unpriviledged form of DoS.
Some newer CPUs have the capability to raise an #AC trap when such an
operation is attempted. The detection is by default enabled in warning
mode which will warn once when a user space application is caught. A
command line option allows to disable the detection or to select fatal
mode which will terminate offending applications with SIGBUS.
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Merge tag 'x86-splitlock-2020-03-30' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 splitlock updates from Thomas Gleixner:
"Support for 'split lock' detection:
Atomic operations (lock prefixed instructions) which span two cache
lines have to acquire the global bus lock. This is at least 1k cycles
slower than an atomic operation within a cache line and disrupts
performance on other cores. Aside of performance disruption this is a
unpriviledged form of DoS.
Some newer CPUs have the capability to raise an #AC trap when such an
operation is attempted. The detection is by default enabled in warning
mode which will warn once when a user space application is caught. A
command line option allows to disable the detection or to select fatal
mode which will terminate offending applications with SIGBUS"
* tag 'x86-splitlock-2020-03-30' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/split_lock: Avoid runtime reads of the TEST_CTRL MSR
x86/split_lock: Rework the initialization flow of split lock detection
x86/split_lock: Enable split lock detection by kernel
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| accounting | ||
| admin-guide | ||
| arm | ||
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| x86 | ||
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| .gitignore | ||
| asm-annotations.rst | ||
| atomic_bitops.txt | ||
| atomic_t.txt | ||
| bus-virt-phys-mapping.txt | ||
| Changes | ||
| CodingStyle | ||
| conf.py | ||
| COPYING-logo | ||
| crc32.txt | ||
| debugging-via-ohci1394.txt | ||
| digsig.txt | ||
| DMA-API-HOWTO.txt | ||
| DMA-API.txt | ||
| DMA-attributes.txt | ||
| DMA-ISA-LPC.txt | ||
| docutils.conf | ||
| dontdiff | ||
| futex-requeue-pi.txt | ||
| hwspinlock.txt | ||
| index.rst | ||
| IPMI.txt | ||
| IRQ-affinity.txt | ||
| IRQ-domain.txt | ||
| IRQ.txt | ||
| irqflags-tracing.txt | ||
| Kconfig | ||
| kprobes.txt | ||
| kref.txt | ||
| logo.gif | ||
| lzo.txt | ||
| mailbox.txt | ||
| Makefile | ||
| memory-barriers.txt | ||
| nommu-mmap.txt | ||
| percpu-rw-semaphore.txt | ||
| pi-futex.txt | ||
| preempt-locking.txt | ||
| rbtree.txt | ||
| remoteproc.txt | ||
| robust-futex-ABI.txt | ||
| robust-futexes.txt | ||
| rpmsg.txt | ||
| speculation.txt | ||
| static-keys.txt | ||
| SubmittingPatches | ||
| tee.txt | ||
| this_cpu_ops.txt | ||
| unaligned-memory-access.txt | ||
| xz.txt | ||
