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8b4bb0ad00
Since commit 591b4b2684 ("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
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.