Re: [PATCH 3/3] arm64: mm: ensure patched kernel text is fetched from PoU

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On Tue, Feb 02, 2016 at 12:06:47PM +0800, Hanjun Guo wrote:
> From: Will Deacon <will.deacon@xxxxxxx>
> 
> The arm64 booting document requires that the bootloader has cleaned the
> kernel image to the PoC. However, when a CPU re-enters the kernel due to
> either a CPU hotplug "on" event or resuming from a low-power state (e.g.
> cpuidle), the kernel text may in-fact be dirty at the PoU due to things
> like alternative patching or even module loading.
> 
> Thanks to I-cache speculation with the MMU off, stale instructions could
> be fetched prior to enabling the MMU, potentially leading to crashes
> when executing regions of code that have been modified at runtime.
> 
> This patch addresses the issue by ensuring that the local I-cache is
> invalidated immediately after a CPU has enabled its MMU but before
> jumping out of the identity mapping. Any stale instructions fetched from
> the PoC will then be discarded and refetched correctly from the PoU.
> Patching kernel text executed prior to the MMU being enabled is
> prohibited, so the early entry code will always be clean.
> 
> Reviewed-by: Mark Rutland <mark.rutland@xxxxxxx>
> Tested-by: Mark Rutland <mark.rutland@xxxxxxx>
> Signed-off-by: Will Deacon <will.deacon@xxxxxxx>
> Signed-off-by: Hanjun Guo <hanjun.guo@xxxxxxxxxx>
> ---
>  arch/arm64/kernel/head.S  | 8 ++++++++
>  arch/arm64/kernel/sleep.S | 8 ++++++++
>  arch/arm64/mm/proc.S      | 1 -
>  3 files changed, 16 insertions(+), 1 deletion(-)

You forgot to say what the upstream git commit id is for this :(
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