[U-Boot] [PATCH v4 06/10] ARM: HYP/non-sec: allow relocation to secure RAM

[Marc Zyngier]

On Fri, May 02 2014 at 10:03:37 pm BST, Jon Loeliger <loeliger at gmail.com> wrote:
> Mark,
>
> In your nonsec_init code, you suggest this change:
>
> +       mrc     p15, 0, r0, c1, c1, 2
>         movw    r1, #0x3fff
> -       movt    r1, #0x0006
> -       mcr     p15, 0, r1, c1, c1, 2           @ NSACR = all copros to non-sec
> +       movt    r1, #0x0004
> +       orr     r0, r0, r1
> +       mcr     p15, 0, r0, c1, c1, 2           @ NSACR = all copros to non-sec
>
> Leaving:
>
>        mrc     p15, 0, r0, c1, c1, 2
>        movw    r1, #0x3fff
>        movt    r1, #0x0004
>        orr     r0, r0, r1
>        mcr     p15, 0, r0, c1, c1, 2           @ NSACR = all copros to non-sec
>
> That sets all the co-processor bits, but the man page suggests that only

Just to be clear: which document are you referring to?

> copros with bits 10 and 11 should be modified.  It also seems that if the

The ARM ARM says that NSACR[13:0] is either RAZ/WI or writable from
secure for unimplemented coprocessors. So I believe the above is
safe. If you wanted to be really picky, you'd start by reading CPACR,
write either 1 or 3 to all the CPn fields, read it back again, see what
sticks, and populate NSACR accordingly. Did I hear someone saying
"Boring"? ;-)

> PLE is enabled, we should mark it NS-enabled at bit 16 also:.  Perhaps:
>
>     mrc    p15, 0, r0, c1, c1, 2
>     movw    r1, #0x0c00
>     movt    r1, #0x0005
>     orr    r0, r0, r1
>     mcr    p15, 0, r0, c1, c1, 2        @ NSACR = all copros to non-sec

We're getting into IMPDEF territory pretty quickly here. PLE only exists
on A9, and is optionnal there (and probably doesn't exist on all
versions, if memory serves well...).

This could be implemented as a per-platform optional feature,
though. What do you think?

	M.
-- 
Without deviation from the norm, progress is not possible.