From: Michal Suchánek
Sent: 09 May 2019 14:38
...
quoted
The problem is the combination of some new code called via printk(),
check_pointer() which calls probe_kernel_read(). That then calls
allow_user_access() (PPC_KUAP) and that uses mmu_has_feature() too early
(before we've patched features).
There is early_mmu_has_feature for this case. mmu_has_feature does not
work before patching so parts of kernel that can run before patching
must use the early_ variant which actually runs code reading the
feature bitmap to determine the answer.
Does the early_ variant get patched so the it is reasonably
efficient after the 'patching' is done?
Or should there be a third version which gets patched across?
David
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