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| H A D | code-patching.c | diff 8b4bb0ad00cb347f62e76a636ce08eb179c843fc Mon Aug 15 13:48:40 CEST 2022 Christophe Leroy <christophe.leroy@csgroup.eu> powerpc/code-patching: Speed up page mapping/unmapping
Since commit 591b4b268435 ("powerpc/code-patching: Pre-map patch area")
the patch area is premapped so intermediate page tables are already
allocated.
Use __set_pte_at() directly instead of the heavy map_kernel_page(),
at for unmapping just do a pte_clear() followed by a flush.
__set_pte_at() can be used directly without the filters in
set_pte_at() because we are mapping a normal page non executable.
Make sure gcc knows text_poke_area is page aligned in order to
optimise the flush.
This change reduces by 66% the time needed to activate ftrace on
an 8xx (588000 tb ticks instead of 1744000).
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
[mpe: Add ptesync needed on radix to avoid spurious fault]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20220815114840.1468656-1-mpe@ellerman.id.au
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