On Fri, May 02 2014 at 10:03:37 pm BST, Jon Loeliger loeliger@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, #0x0006mcr p15, 0, r1, c1, c1, 2 @ NSACR = all copros to non-sec
movt r1, #0x0004orr r0, r0, r1mcr p15, 0, r0, c1, c1, 2 @ NSACR = all copros to non-secLeaving:
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-secThat 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.