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Fix divide-by-zero panic when ALSR is enabled and superpages disabled
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Authored by jah on Mon, Feb 15, 3:08 AM.

Details

Summary

When locating the anonymous memory region for a vm_map with ASLR
enabled, we try to keep the slid base address aligned on a superpage
boundary to minimize pagetable fragmentation and maximize the potential
usage of superpage mappings. We can't (portably) do this if superpages
have been disabled by loader tunable and pagesizes[1] is 0, and it
would be less beneficial in that case anyway.

PR: 253511
Reported by: johannes@jo-t.de
MFC after: 1 week

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R10 FreeBSD src repository
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