On Fri, 14 May 2021 00:07:59 +1000, Michael Ellerman wrote:
> The entry flush mitigation can be enabled/disabled at runtime. When this
> happens it results in the kernel patching its own instructions to
> enable/disable the mitigation sequence.
>
> With strict kernel RWX enabled instruction patching happens via a
> secondary mapping of the kernel text, so that we don't have to make the
> primary mapping writable. With the hash MMU this leads to a hash fault,
> which causes us to execute the exception entry which contains the entry
> flush mitigation.
>
> [...]
Applied to powerpc/fixes.
[1/2] powerpc/64s: Fix entry flush patching w/strict RWX & hash
https://git.kernel.org/powerpc/c/49b39ec248af863781a13aa6d81c5f69a2928094
[2/2] powerpc/64s: Fix stf mitigation patching w/strict RWX & hash
https://git.kernel.org/powerpc/c/5b48ba2fbd77bc68feebd336ffad5ff166782bde
cheers
