[PATCH v9 0/4] mm: Enable conversion of powerpc to default topdown mmap layout

[Christophe Leroy]

Rebased on top of Linux 5.18-rc1

This is the mm part of the series that converts powerpc to default
topdown mmap layout, for merge into v5.18

powerpc requires its own arch_get_unmapped_area() only when
slices are needed, which is only for book3s/64. First part of
the series moves slices into book3s/64 specific directories
and cleans up other subarchitectures.

The actual convertion of powerpc to default topdown mmap layout will
then be resent in a follow-up series for application on v5.19

First patch modifies the core mm to allow powerpc to still provide its
own arch_randomize_brk()

Second patch modifies core mm to give len and flags to
arch_get_mmap_end() as powerpc needs it. 

Third patch modifies core mm to allow powerpc to use generic versions
of get_unmapped_area functions for Radix while still providing its own
implementation for Hash, the selection between Radix and Hash being
done at runtime.

Fourth patch is a complement/fix of f6795053dac8 ("mm: mmap: Allow for
"high" userspace addresses") for hugetlb. It adds support for "high"
userspace addresses that are optionally supported on the system and
have to be requested via a hint mechanism ("high" addr parameter to mmap).

Previous version of the series is available at
https://patchwork.ozlabs.org/project/linuxppc-dev/list/?state=*&series=289718

Signed-off-by: Christophe Leroy <christophe.leroy@xxxxxxxxxx>

Changes in v9:
- Sending mm patches and powerpc patches separately with the objective
of mm patches going into kernel v5.18 and powerpc patches folling up
into kernel v5.19

Changes in v8:
- Moved patch "sizes.h: Add SZ_1T macro" up from which is already in linux-next but not in Linus tree yet.
- Rebased on today's powerpc/next

Changes in v7:
- Taken into account comments from Catalin (patches 3 and 4)

Changes in v6:
- New patch (patch 4) to take arch_get_mmap_base() and arch_get_mmap_end() into account in generic hugetlb_get_unmapped_area()
- Get back arch_randomize_brk() simplification as it relies on default topdown mmap layout.
- Fixed precedence between || and && in powerpc's arch_get_mmap_end() (patch 9)

Changes in v5:
- Added patch 3
- Added arch_get_mmap_base() and arch_get_mmap_end() to patch 7 to better match original powerpc behaviour
- Switched patched 10 and 11 and performed full randomisation in patch 10 just before switching to default implementation, as suggested by Nic.

Changes in v4:
- Move arch_randomize_brk() simplification out of this series
- Add a change to core mm to enable using generic implementation
while providing arch specific one at the same time.
- Reworked radix get_unmapped_area to use generic implementation
- Rebase on top of Nic's series v6

Changes in v3:
- Fixed missing <linux/elf-randomize.h> in last patch
- Added a patch to move SZ_1T out of drivers/pci/controller/pci-xgene.c

Changes in v2:
- Moved patch 4 before patch 2
- Make generic arch_randomize_brk() __weak
- Added patch 9

Christophe Leroy (4):
  mm: Allow arch specific arch_randomize_brk() with
    CONFIG_ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT
  mm, hugetlbfs: Allow an arch to always use generic versions of
    get_unmapped_area functions
  mm: Add len and flags parameters to arch_get_mmap_end()
  mm, hugetlbfs: Allow for "high" userspace addresses

 arch/arm64/include/asm/processor.h |  4 +--
 fs/hugetlbfs/inode.c               | 26 ++++++++++++------
 include/linux/hugetlb.h            |  5 ++++
 include/linux/sched/mm.h           | 17 ++++++++++++
 mm/mmap.c                          | 43 ++++++++++++++++++------------
 mm/util.c                          |  2 +-
 6 files changed, 69 insertions(+), 28 deletions(-)

-- 
2.35.1