| From: |
| Cyril Bur <cyrilbur-AT-tenstorrent.com> |
| To: |
| palmer-AT-dabbelt.com, aou-AT-eecs.berkeley.edu, paul.walmsley-AT-sifive.com, charlie-AT-rivosinc.com, jrtc27-AT-jrtc27.com, ben.dooks-AT-codethink.co.uk |
| Subject: |
| [PATCH v3 0/4] riscv: uaccess: optimizations |
| Date: |
| Fri, 21 Feb 2025 00:09:20 +0000 |
| Message-ID: |
| <20250221000924.734006-1-cyrilbur@tenstorrent.com> |
| Cc: |
| linux-riscv-AT-lists.infradead.org, linux-kernel-AT-vger.kernel.org, jszhang-AT-kernel.org |
| Archive-link: |
| Article |
This series tries to optimize riscv uaccess by allowing the use of
user_access_begin() and user_access_end() which permits grouping user accesses
and avoiding the CSR write penalty for each access.
The error path can also be optimised using asm goto which patches 3 and 4
achieve. This will speed up jumping to labels by avoiding the need of an
intermediary error type variable within the uaccess macros
I did read the discussion this series generated. It isn't clear to me
which direction to take the patches, if any.
V2:
I've taken on this series as there isn't any response from Jisheng. No
significant changes other than build fixes.
- Fixes build breakage in patch 3 to do with not having used 'goto' keyword.
- Fixes build breakage in patch 4 on 32bit not having delcared __ptr in the
macro.
V3:
Significant commit message rewrites.
- Corrected the justification for patch 2
- Better explained/justified patches 3 and 4
Minor code changes for legibility and more comments.
Jisheng Zhang (4):
riscv: implement user_access_begin() and families
riscv: uaccess: use input constraints for ptr of __put_user()
riscv: uaccess: use 'asm goto' for put_user()
riscv: uaccess: use 'asm_goto_output' for get_user()
arch/riscv/include/asm/uaccess.h | 205 +++++++++++++++++++++++--------
1 file changed, 152 insertions(+), 53 deletions(-)
--
2.34.1
