Improve the performance of icache flushing by creating a new prctl flag
PR_RISCV_SET_ICACHE_FLUSH_CTX. The interface is left generic to allow
for future expansions such as with the proposed J extension [1].

Documentation is also provided to explain the use case.

[1] https://github.com/riscv/riscv-j-extension

Signed-off-by: Charlie Jenkins <charlie@rivosinc.com>
---
Charlie Jenkins (2):
      riscv: Include riscv_set_icache_flush_ctx prctl
      documentation: Document PR_RISCV_SET_ICACHE_FLUSH_CTX prctl

 Documentation/arch/riscv/cmodx.rst | 98 ++++++++++++++++++++++++++++++++++++++
 Documentation/arch/riscv/index.rst |  1 +
 arch/riscv/include/asm/mmu.h       |  2 +
 arch/riscv/include/asm/processor.h |  6 +++
 arch/riscv/mm/cacheflush.c         | 37 ++++++++++++++
 arch/riscv/mm/context.c            |  8 ++--
 include/uapi/linux/prctl.h         |  3 ++
 kernel/sys.c                       |  6 +++
 8 files changed, 158 insertions(+), 3 deletions(-)
---
base-commit: b85ea95d086471afb4ad062012a4d73cd328fa86
change-id: 20231117-fencei-f9f60d784fa0
-- 
- Charlie