arm64: ptdump: Deal with translation levels folded at runtime

Currently, the ptdump code deals with folded PMD or PUD levels at build
time, by omitting those levels when invoking note_page. IOW, note_page()
is never invoked with level == 1 if P4Ds are folded in the build
configuration.

With the introduction of LPA2 support, we will defer some of these
folding decisions to runtime, so let's take care of this by overriding
the 'level' argument when this condition triggers.

Substituting the PUD or PMD strings for "PGD" when the level in question
is folded at build time is no longer necessary, and so the conditional
expressions can be simplified. This also makes the indirection of the
'name' field unnecessary, so change that into a char[] array, and make
the whole thing __ro_after_init.

Note that the mm_p?d_folded() functions currently ignore their mm
pointer arguments, but let's wire them up correctly anyway.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20240214122845.2033971-83-ardb+git@google.com


Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>