[v4,0/2] riscv: Create and document PR_RISCV_SET_ICACHE_FLUSH_CTX prctl

Message

Charlie Jenkins Jan. 8, 2024, 6:21 a.m. UTC

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 <[e-mail]>
---
Changes in v4:
- Add OFF flag to disallow fence.i in userspace (Atish)
- Fix documentation issues (Atish)
- Link to v3: https://lore.kernel.org/r/[e-mail]

Changes in v3:
- Check if value force_icache_flush set on thread, rather than in mm
  twice (Clément)
- Link to v2: https://lore.kernel.org/r/[e-mail]

Changes in v2:
- Fix kernel-doc comment (Conor)
- Link to v1: https://lore.kernel.org/r/[e-mail]

---
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 | 88 ++++++++++++++++++++++++++++++++++++++
 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         | 56 ++++++++++++++++++++++++
 arch/riscv/mm/context.c            |  8 ++--
 include/uapi/linux/prctl.h         |  4 ++
 kernel/sys.c                       |  6 +++
 8 files changed, 168 insertions(+), 3 deletions(-)
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base-commit: b85ea95d086471afb4ad062012a4d73cd328fa86
change-id: 20231117-fencei-f9f60d784fa0