[BOLT] Add support for Linux kernel static keys jump table #86090
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maksfb
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ayermolo and
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Mar 21, 2024
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dcci
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Mar 23, 2024
Runtime code modification used by static keys is the most ubiquitous self-modifying feature of the Linux kernel. The idea is to to eliminate the condition check and associated conditional jump on a hot path if that condition (based on a boolean value of a static key) does not change often. Whenever they condition changes, the kernel runtime modifies all code paths associated with that key flipping the code between nop and (unconditional) jump.
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Runtime code modification used by static keys is the most ubiquitous
self-modifying feature of the Linux kernel. The idea is to to eliminate
the condition check and associated conditional jump on a hot path if
that condition (based on a boolean value of a static key) does not
change often. Whenever they condition changes, the kernel runtime
modifies all code paths associated with that key flipping the code
between nop and (unconditional) jump.