e500 supports many page sizes among which the following size are
implemented in the kernel at the time being: 4M, 16M, 64M, 256M, 1G.
On e500, TLB miss for hugepages is exclusively handled by SW even on e6500
which has HW assistance for 4k pages, so there are no constraints like on
the 8xx.
On e500/32, all are at PGD/PMD level and can be handled as cont-PMD.
On e500/64, smaller ones are on PMD while bigger ones are on PUD. Again,
they can easily be handled as cont-PMD and cont-PUD instead of hugepd.
On e500/32, use the pagesize bits in PTE to know if it is a PMD or a leaf
entry. This works because the pagesize bits are in the last 12 bits and
page tables are 4k aligned.
On e500/64, use highest bit which is always 1 on PxD (Because PxD contains
virtual address of a kernel memory) and always 0 on PTEs because not all
bits of RPN are used/possible.
Link: https://lkml.kernel.org/r/dd085987816ed2a0c70adb7e34966cb833fc03e1.1719928057.git.christophe.leroy@csgroup.eu
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Peter Xu <peterx@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
e500 MMU has 6 page protection bits:
- R, W, X for supervisor
- R, W, X for user
It means that it can support X without R.
To do that, _PAGE_READ flag is needed.
With 32 bits PTE there is no bit available for it in PTE. On the
other hand the only real use of _PAGE_USER is to implement PAGE_NONE
by clearing _PAGE_USER. As _PAGE_NONE can also be implemented by
clearing _PAGE_READ, remove _PAGE_USER and add _PAGE_READ. Move
_PAGE_PRESENT into bit 30 so that _PAGE_READ can match SR bit.
With 64 bits PTE _PAGE_USER is already the combination of SR and UR
so all we need to do is to rename it _PAGE_READ.
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/0849ab6bf7ae2af23f94b0457fa40d0ea3983fe4.1695659959.git.christophe.leroy@csgroup.eu
objtool throws the following warning:
arch/powerpc/kernel/head_85xx.o: warning: objtool: .head.text+0x1a6c:
unannotated intra-function call
Fix the warning by annotating KernelSPE symbol with SYM_FUNC_START_LOCAL
and SYM_FUNC_END macros.
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Sathvika Vasireddy <sv@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20230128124138.1066176-1-sv@linux.ibm.com
