arm64: reduce ID map to a single page
Commit ea8c2e11 ("arm64: Extend the idmap to the whole kernel image") changed the early page table code so that the entire kernel Image is covered by the identity map. This allows functions that need to enable or disable the MMU to reside anywhere in the kernel Image. However, this change has the unfortunate side effect that the Image cannot cross a physical 512 MB alignment boundary anymore, since the early page table code cannot deal with the Image crossing a /virtual/ 512 MB alignment boundary. So instead, reduce the ID map to a single page, that is populated by the contents of the .idmap.text section. Only three functions reside there at the moment: __enable_mmu(), cpu_resume_mmu() and cpu_reset(). If new code is introduced that needs to manipulate the MMU state, it should be added to this section as well. Reviewed-by: NMark Rutland <mark.rutland@arm.com> Tested-by: NMark Rutland <mark.rutland@arm.com> Signed-off-by: NArd Biesheuvel <ard.biesheuvel@linaro.org> Signed-off-by: NCatalin Marinas <catalin.marinas@arm.com>
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