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

[Hanjun Guo <guohanjun@huawei.com>]

On 2016/2/15 5:00, Greg KH wrote:
> On Tue, Feb 02, 2016 at 12:06:47PM +0800, Hanjun Guo wrote:
>> From: Will Deacon <will.deacon@arm.com>
>>
>> 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@arm.com>
>> Tested-by: Mark Rutland <mark.rutland@arm.com>
>> Signed-off-by: Will Deacon <will.deacon@arm.com>
>> Signed-off-by: Hanjun Guo <hanjun.guo@linaro.org>
>> ---
>>  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 :(
>

Sorry, it's 8ec41987436d566f7c4559c6871738b869f7ef07.

Thanks
Hanjun