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@xxxxxxxxxxxxxxx/msg1429066.html Changes in v3: - Split into small patches to ease review as suggested by Christoph Hellwig and Kees Cook - Move help text of new config as a comment, as suggested by Christoph - Make new config depend on MMU, as suggested by Christoph 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 (11): mm, fs: Move randomize_stack_top from fs to mm arm64: Make use of is_compat_task instead of hardcoding this test arm64: Consider stack randomization for mmap base only when necessary arm64, mm: Move generic mmap layout functions to mm arm: Properly account for stack randomization and stack guard gap arm: Use STACK_TOP when computing mmap base address arm: Use generic mmap top-down layout mips: Properly account for stack randomization and stack guard gap mips: Use STACK_TOP when computing mmap base address 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 | 96 +++++++++++++++++++++++++++++- 15 files changed, 123 insertions(+), 213 deletions(-) -- 2.20.1
