Messages in this thread | | | From | David Laight <> | Subject | RE: [PATCH] vsprintf: Do not break early boot with probing addresses | Date | Thu, 9 May 2019 13:46:59 +0000 |
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From: Michal Suchánek > Sent: 09 May 2019 14:38 ... > > 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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