powerpc/mm/radix: Implement STRICT_RWX/mark_rodata_ro() for Radix

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The Radix linear mapping code (create_physical_mapping()) tries to use
the largest page size it can at each step. Currently the only reason
it steps down to a smaller page size is if the start addr is
unaligned (never happens in practice), or the end of memory is not
aligned to a huge page boundary.

To support STRICT_RWX we need to break the mapping at __init_begin,
so that the text and rodata prior to that can be marked R_X and the
regular pages after can be marked RW.

Having done that we can now implement mark_rodata_ro() for Radix,
knowing that we won't need to split any mappings.

Signed-off-by: Balbir Singh <bsingharora@gmail.com>
[mpe: Split down to PAGE_SIZE, not 2MB, rewrite change log]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

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This commit is contained in:

Balbir Singh 2017-06-29 03:04:09 +10:00 • committed by Michael Ellerman

parent cd65d69713

commit 7614ff3272

2 changed files with 69 additions and 2 deletions

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67

arch/powerpc/mm/pgtable-radix.c

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4

arch/powerpc/mm/pgtable_64.c

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