[PATCH v6 0/2] riscv: Create and document PR_RISCV_SET_ICACHE_FLUSH_CTX prctl

From: Charlie Jenkins
Date: Tue Jan 09 2024 - 13:43:50 EST


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@xxxxxxxxxxxx>
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Changes in v6:
- Fixup documentation formatting
- Link to v5: https://lore.kernel.org/r/20240108-fencei-v5-0-aa1e51d7222f@xxxxxxxxxxxx

Changes in v5:
- Minor documentation changes (Randy)
- Link to v4: https://lore.kernel.org/r/20240107-fencei-v4-0-d4cf2fb905d3@xxxxxxxxxxxx

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/20231213-fencei-v3-0-b75158238eb7@xxxxxxxxxxxx

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/20231130-fencei-v2-0-2cb623ab1b1f@xxxxxxxxxxxx

Changes in v2:
- Fix kernel-doc comment (Conor)
- Link to v1: https://lore.kernel.org/r/20231122-fencei-v1-0-bec0811cb212@xxxxxxxxxxxx

---
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 | 58 +++++++++++++++++++++++++
arch/riscv/mm/context.c | 8 ++--
include/uapi/linux/prctl.h | 4 ++
kernel/sys.c | 6 +++
8 files changed, 170 insertions(+), 3 deletions(-)
---
base-commit: b85ea95d086471afb4ad062012a4d73cd328fa86
change-id: 20231117-fencei-f9f60d784fa0
--
- Charlie