[PATCH v6 2/3] arm64: vmlinux.ld: Add mmuoff data sections and move mmuoff text into idmap

[Catalin Marinas]

On Wed, Aug 24, 2016 at 06:27:29PM +0100, James Morse wrote:
> Resume from hibernate needs to clean any text executed by the kernel with
> the MMU off to the PoC. Collect these functions together into the
> .idmap.text section as all this code is tightly coupled and also needs
> the same cleaning after resume.
> 
> Data is more complicated, secondary_holding_pen_release is written with
> the MMU on, clean and invalidated, then read with the MMU off. In contrast
> __boot_cpu_mode is written with the MMU off, the corresponding cache line
> is invalidated, so when we read it with the MMU on we don't get stale data.
> These cache maintenance operations conflict with each other if the values
> are within a Cache Writeback Granule (CWG) of each other.
> Collect the data into two sections .mmuoff.data.read and .mmuoff.data.write,
> the linker script ensures mmuoff.data.write section is aligned to the
> architectural maximum CWG of 2KB.
> 
> Signed-off-by: James Morse <james.morse at arm.com>
> Cc: Ard Biesheuvel <ard.biesheuvel at linaro.org>
> Cc: Mark Rutland <mark.rutland at arm.com>

Reviewed-by: Catalin Marinas <catalin.marinas at arm.com>