[PATCH v3 0/9] Support strict kernel memory permissions for security

[Zong Li <zong.li@sifive.com>]

The main purpose of this patch series is changing the kernel mapping permission
, make sure that code is not writeable, data is not executable, and read-only
data is neither writable nor executable.

This patch series also supports the relevant implementations such as
ARCH_HAS_SET_MEMORY, ARCH_HAS_SET_DIRECT_MAP,
ARCH_SUPPORTS_DEBUG_PAGEALLOC and DEBUG_WX.

Changes in v3:
 - Fix build error on nommu configuration. We already support nommu on
   RISC-V, so we should consider nommu case and test not only rv32/64,
   but also nommu.

Changes in v2:
 - Use _data to specify the start of data section with write permission.
 - Change ftrace patch text implementaion.
 - Separate DEBUG_WX patch to another patchset.

Zong Li (9):
  riscv: add ARCH_HAS_SET_MEMORY support
  riscv: add ARCH_HAS_SET_DIRECT_MAP support
  riscv: add ARCH_SUPPORTS_DEBUG_PAGEALLOC support
  riscv: move exception table immediately after RO_DATA
  riscv: add alignment for text, rodata and data sections
  riscv: add STRICT_KERNEL_RWX support
  riscv: add macro to get instruction length
  riscv: introduce interfaces to patch kernel code
  riscv: patch code by fixmap mapping

 arch/riscv/Kconfig                  |   6 +
 arch/riscv/include/asm/bug.h        |   8 ++
 arch/riscv/include/asm/fixmap.h     |   2 +
 arch/riscv/include/asm/patch.h      |  12 ++
 arch/riscv/include/asm/set_memory.h |  48 +++++++
 arch/riscv/kernel/Makefile          |   4 +-
 arch/riscv/kernel/ftrace.c          |  13 +-
 arch/riscv/kernel/patch.c           | 120 ++++++++++++++++++
 arch/riscv/kernel/traps.c           |   3 +-
 arch/riscv/kernel/vmlinux.lds.S     |  11 +-
 arch/riscv/mm/Makefile              |   2 +-
 arch/riscv/mm/init.c                |  44 +++++++
 arch/riscv/mm/pageattr.c            | 187 ++++++++++++++++++++++++++++
 13 files changed, 445 insertions(+), 15 deletions(-)
 create mode 100644 arch/riscv/include/asm/patch.h
 create mode 100644 arch/riscv/include/asm/set_memory.h
 create mode 100644 arch/riscv/kernel/patch.c
 create mode 100644 arch/riscv/mm/pageattr.c

-- 
2.25.1