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1401bef703
Because only the idmap sets a non-standard T0SZ, __cpu_set_tcr_t0sz() can check for platforms that need to do this using __cpu_uses_extended_idmap() before doing its work. The idmap is only built with enough levels, (and T0SZ bits) to map its single page. To allow hibernate, and then kexec to idmap their single page copy routines, __cpu_set_tcr_t0sz() needs to consider additional users, who may need a different number of levels/T0SZ-bits to the idmap. (i.e. VA_BITS may be enough for the idmap, but not hibernate/kexec) Always read TCR_EL1, and check whether any work needs doing for this request. __cpu_uses_extended_idmap() remains as it is used by KVM, whose idmap is also part of the kernel image. This mostly affects the cpuidle path, where we now get an extra system register read . CC: Lorenzo Pieralisi <Lorenzo.Pieralisi@arm.com> CC: Sudeep Holla <sudeep.holla@arm.com> Signed-off-by: James Morse <james.morse@arm.com> Signed-off-by: Pavel Tatashin <pasha.tatashin@soleen.com> Link: https://lore.kernel.org/r/20210125191923.1060122-8-pasha.tatashin@soleen.com Signed-off-by: Will Deacon <will@kernel.org>
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.