Re: [PATCH 1/2] arm64: kernel: Add SMC Session ID to results

Lorenzo Pieralisi
2016-08-23T10:39:22Z

On Mon, Aug 22, 2016 at 05:38:31PM -0700, Stephen Boyd wrote:

[...]

> This all comes about because the firmware generates a session id
> for the SMC call and jams it in x6. The assembly on the
> non-secure side is written with a tight loop around the smc
> instruction so that when the return value indicates
> "interrupted", x6 is kept intact and the non-secure OS can jump
> back to the secure OS without register reloading. Perhaps
> referring to x6 as result value is not correct because it's
> really a session id that's irrelevant once the smc call
> completes.

Sorry I missed this bit. The session id is _generated_ by secure
firmware (probably only when the value passed in x6 == 0 (?))
and actually returned to the caller so that subsequent (interrupted)
calls can re-issue the same value, is that correct ?

If that's the case the value in x6 is a result value from an SMCCC
perspective and your current FW is not SMCCC compliant.

Lorenzo