Messages in this thread | | | Date | Sun, 10 Sep 2023 04:50:29 -0400 | From | Guo Ren <> | Subject | Re: [RFC PATCH v5 0/5] Rework & improve riscv cmpxchg.h and atomic.h |
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On Thu, Aug 10, 2023 at 01:03:42AM -0300, Leonardo Bras wrote: > While studying riscv's cmpxchg.h file, I got really interested in > understanding how RISCV asm implemented the different versions of > {cmp,}xchg. > > When I understood the pattern, it made sense for me to remove the > duplications and create macros to make it easier to understand what exactly > changes between the versions: Instruction sufixes & barriers. > > Also, did the same kind of work on atomic.c. > > After that, I noted both cmpxchg and xchg only accept variables of > size 4 and 8, compared to x86 and arm64 which do 1,2,4,8. > > Now that deduplication is done, it is quite direct to implement them > for variable sizes 1 and 2, so I did it. Then Guo Ren already presented > me some possible users :) > > I did compare the generated asm on a test.c that contained usage for every > changed function, and could not detect any change on patches 1 + 2 + 3 > compared with upstream. > > Pathes 4 & 5 were compiled-tested, merged with guoren/qspinlock_v11 and > booted just fine with qemu -machine virt -append "qspinlock". > > (tree: https://gitlab.com/LeoBras/linux/-/commits/guo_qspinlock_v11) Tested-by: Guo Ren <guoren@kernel.org>
Sorry for late reply, because we are stress testing CNA qspinlock on sg2042 128 cores hardware platform. This series has passed our test for several weeks. For more detail, ref: https://lore.kernel.org/linux-riscv/20230910082911.3378782-1-guoren@kernel.org/
> > Thanks! > Leo > > Changes since squashed cmpxchg RFCv4: > - Added (__typeof__(*(p))) before returning from {cmp,}xchg, as done > in current upstream, (possibly) fixing the bug from kernel test robot > https://lore.kernel.org/all/20230809021311.1390578-2-leobras@redhat.com/ > > Changes since squashed cmpxchg RFCv3: > - Fixed bug on cmpxchg macro for var size 1 & 2: now working > - Macros for var size 1 & 2's lr.w and sc.w now are guaranteed to receive > input of a 32-bit aligned address > - Renamed internal macros from _mask to _masked for patches 4 & 5 > - __rc variable on macros for var size 1 & 2 changed from register to ulong > https://lore.kernel.org/all/20230804084900.1135660-2-leobras@redhat.com/ > > Changes since squashed cmpxchg RFCv2: > - Removed rc parameter from the new macro: it can be internal to the macro > - 2 new patches: cmpxchg size 1 and 2, xchg size 1 and 2 > https://lore.kernel.org/all/20230803051401.710236-2-leobras@redhat.com/ > > Changes since squashed cmpxchg RFCv1: > - Unified with atomic.c patchset > - Rebased on top of torvalds/master (thanks Andrea Parri!) > - Removed helper macros that were not being used elsewhere in the kernel. > https://lore.kernel.org/all/20230419062505.257231-1-leobras@redhat.com/ > https://lore.kernel.org/all/20230406082018.70367-1-leobras@redhat.com/ > > Changes since (cmpxchg) RFCv3: > - Squashed the 6 original patches in 2: one for cmpxchg and one for xchg > https://lore.kernel.org/all/20230404163741.2762165-1-leobras@redhat.com/ > > Changes since (cmpxchg) RFCv2: > - Fixed macros that depend on having a local variable with a magic name > - Previous cast to (long) is now only applied on 4-bytes cmpxchg > https://lore.kernel.org/all/20230321074249.2221674-1-leobras@redhat.com/ > > Changes since (cmpxchg) RFCv1: > - Fixed patch 4/6 suffix from 'w.aqrl' to '.w.aqrl', to avoid build error > https://lore.kernel.org/all/20230318080059.1109286-1-leobras@redhat.com/ > > Leonardo Bras (5): > riscv/cmpxchg: Deduplicate xchg() asm functions > riscv/cmpxchg: Deduplicate cmpxchg() asm and macros > riscv/atomic.h : Deduplicate arch_atomic.* > riscv/cmpxchg: Implement cmpxchg for variables of size 1 and 2 > riscv/cmpxchg: Implement xchg for variables of size 1 and 2 > > arch/riscv/include/asm/atomic.h | 164 ++++++------- > arch/riscv/include/asm/cmpxchg.h | 404 ++++++++++--------------------- > 2 files changed, 200 insertions(+), 368 deletions(-) > > > base-commit: cacc6e22932f373a91d7be55a9b992dc77f4c59b > -- > 2.41.0 > > > _______________________________________________ > linux-riscv mailing list > linux-riscv@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/linux-riscv >
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