This is an attempt at cleaning up a bit the way we handle execute
permission on powerpc. _PAGE_HWEXEC is gone, _PAGE_EXEC is now only
defined by CPUs that can do something with it, and the myriad of
#ifdef's in the I$/D$ coherency code is reduced to 2 cases that
hopefully should cover everything.
The logic on BookE is a little bit different than what it was though
not by much. Since now, _PAGE_EXEC will be set by the generic code
for executable pages, we need to filter out if they are unclean and
recover it. However, I don't expect the code to be more bloated than
it already was in that area due to that change.
I could boast that this brings proper enforcing of per-page execute
permissions to all BookE and 40x but in fact, we've had that now for
some time as a side effect of my previous rework in that area (and
I didn't even know it :-) We would only enable execute permission if
the page was cache clean and we would only cache clean it if we took
and exec fault. Since we now enforce that the later only work if
VM_EXEC is part of the VMA flags, we de-fact already enforce per-page
execute permissions... Unless I missed something
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
If the size of DRAM is not an exact power of two, we may not have
covered DRAM in its entirety with large 16 and 4 MiB pages. If that
is the case, we can get non-recoverable page faults when doing the
final PTE mappings for the non-large page PTEs.
Consequently, we restrict the top end of DRAM currently allocable
by updating '__initial_memory_limit_addr' so that calls to the LMB to
allocate PTEs for "tail" coverage with normal-sized pages (or other
reasons) do not attempt to allocate outside the allowed range.
Signed-off-by: Grant Erickson <gerickson@nuovations.com>
Signed-off-by: Josh Boyer <jwboyer@linux.vnet.ibm.com>
A number of users of PPC_MEMSTART (40x, ppc_mmu_32) can just always
use 0 as we don't support booting these kernels at non-zero physical
addresses since their exception vectors must be at 0 (or 0xfffx_xxxx).
For the sub-arches that support relocatable interrupt vectors
(book-e), it's reasonable to have memory start at a non-zero physical
address. For those cases use the variable memstart_addr instead of
the #define PPC_MEMSTART since the only uses of PPC_MEMSTART are for
initialization and in the future we can set memstart_addr at runtime
to have a relocatable kernel.
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
mmu_mapin_ram() loops over total_lowmem to setup page tables. However, if
total_lowmem is less that 16M, the subtraction rolls over and results in
a number just under 4G (because total_lowmem is an unsigned value).
This patch rejigs the loop from countup to countdown to eliminate the
bug.
Special thanks to Magnus Hjorth who wrote the original patch to fix this
bug. This patch improves on his by making the loop code simpler (which
also eliminates the possibility of another rollover at the high end)
and also applies the change to arch/powerpc.
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
Signed-off-by: Josh Boyer <jwboyer@linux.vnet.ibm.com>
Add MMU definitions for 40x platforms. Also fixes two warnings in 40x_mmu.c.
Signed-off-by: Josh Boyer <jwboyer@linux.vnet.ibm.com>
Acked-by: David Gibson <david@gibson.dropbear.id.au>
4xx is a bit of a misnomer for certain things, as they really apply to PowerPC
40x only. Rename some of the files to clean this up.
Signed-off-by: Josh Boyer <jwboyer@linux.vnet.ibm.com>
Acked-by: David Gibson <david@gibson.dropbear.id.au>
Benjamin Herrenschmidt