[PATCH v6 0/4] RISC-V: mm: Make SV48 the default address space

[Charlie Jenkins]

Make sv48 the default address space for mmap as some applications
currently depend on this assumption. Users can now select a
desired address space using a non-zero hint address to mmap. Previously,
requesting the default address space from mmap by passing zero as the hint
address would result in using the largest address space possible. Some
applications depend on empty bits in the virtual address space, like Go and
Java, so this patch provides more flexibility for application developers.

-Charlie

---
v6:
- Rebase onto the correct base

v5:
- Minor wording change in documentation
- Change some parenthesis in arch_get_mmap_ macros
- Added case for addr==0 in arch_get_mmap_ because without this, programs would
  crash if RLIMIT_STACK was modified before executing the program. This was
  tested using the libhugetlbfs tests. 

v4:
- Split testcases/document patch into test cases, in-code documentation, and
  formal documentation patches
- Modified the mmap_base macro to be more legible and better represent memory
  layout
- Fixed documentation to better reflect the implmentation
- Renamed DEFAULT_VA_BITS to MMAP_VA_BITS
- Added additional test case for rlimit changes
---

Charlie Jenkins (4):
  RISC-V: mm: Restrict address space for sv39,sv48,sv57
  RISC-V: mm: Add tests for RISC-V mm
  RISC-V: mm: Update pgtable comment documentation
  RISC-V: mm: Document mmap changes

 Documentation/riscv/vm-layout.rst             |  22 +++
 arch/riscv/include/asm/elf.h                  |   2 +-
 arch/riscv/include/asm/pgtable.h              |  20 ++-
 arch/riscv/include/asm/processor.h            |  46 +++++-
 tools/testing/selftests/riscv/Makefile        |   2 +-
 tools/testing/selftests/riscv/mm/.gitignore   |   1 +
 tools/testing/selftests/riscv/mm/Makefile     |  21 +++
 .../selftests/riscv/mm/testcases/mmap.c       | 133 ++++++++++++++++++
 8 files changed, 234 insertions(+), 13 deletions(-)
 create mode 100644 tools/testing/selftests/riscv/mm/.gitignore
 create mode 100644 tools/testing/selftests/riscv/mm/Makefile
 create mode 100644 tools/testing/selftests/riscv/mm/testcases/mmap.c

-- 
2.41.0