[PATCH v2 0/5] Provide generic top-down mmap layout functions

[Alexandre Ghiti <alex@ghiti.fr>]

This series introduces generic functions to make top-down mmap layout
easily accessible to architectures, in particular riscv which was
the initial goal of this series.
The generic implementation was taken from arm64 and used successively
by arm, mips and finally riscv.

Note that in addition the series fixes 2 issues:
- stack randomization was taken into account even if not necessary.
- [1] fixed an issue with mmap base which did not take into account
  randomization but did not report it to arm and mips, so by moving
  arm64 into a generic library, this problem is now fixed for both
  architectures.

This work is an effort to factorize architecture functions to avoid
code duplication and oversights as in [1].

[1]: https://www.mail-archive.com/linux-kernel@vger.kernel.org/msg1429066.html

Changes in v2 as suggested by Christoph Hellwig:
  - Preparatory patch that moves randomize_stack_top
  - Fix duplicate config in riscv
  - Align #if defined on next line => this gives rise to a checkpatch
    warning. I found this pattern all around the tree, in the same proportion
    as the previous pattern which was less pretty:
    git grep -C 1 -n -P "^#if defined.+\|\|.*\\\\$" 

Alexandre Ghiti (5):
  mm, fs: Move randomize_stack_top from fs to mm
  arm64, mm: Move generic mmap layout functions to mm
  arm: Use generic mmap top-down layout
  mips: Use generic mmap top-down layout
  riscv: Make mmap allocation top-down by default

 arch/Kconfig                       |  8 +++
 arch/arm/Kconfig                   |  1 +
 arch/arm/include/asm/processor.h   |  2 -
 arch/arm/mm/mmap.c                 | 52 ----------------
 arch/arm64/Kconfig                 |  1 +
 arch/arm64/include/asm/processor.h |  2 -
 arch/arm64/mm/mmap.c               | 72 ----------------------
 arch/mips/Kconfig                  |  1 +
 arch/mips/include/asm/processor.h  |  5 --
 arch/mips/mm/mmap.c                | 57 -----------------
 arch/riscv/Kconfig                 | 11 ++++
 fs/binfmt_elf.c                    | 20 ------
 include/linux/mm.h                 |  2 +
 kernel/sysctl.c                    |  6 +-
 mm/util.c                          | 99 +++++++++++++++++++++++++++++-
 15 files changed, 126 insertions(+), 213 deletions(-)

-- 
2.20.1