Messages in this thread | | | Date | Fri, 26 Aug 2022 14:44:48 +0800 | Subject | Re: [PATCH -next v2 2/2] riscv: extable: add new extable type EX_TYPE_KACCESS_ERR_ZERO support | From | Tong Tiangen <> |
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在 2022/8/25 19:06, Andrew Jones 写道: > On Mon, Aug 15, 2022 at 03:20:25AM +0000, Tong Tiangen wrote: >> Currently, The extable type EX_TYPE_UACCESS_ERR_ZERO is used by >> __get/put_kernel_nofault(), but those helpers are not uaccess type, so we >> add a new extable type EX_TYPE_KACCESS_ERR_ZERO which can be used by >> __get/put_kernel_no_fault(). >> >> Only refactor code without any functional changes. > > This isn't quite true. __get/put_kernel_nofault now sets a different > extable type (as the commit message says). But, nothing special seems > to be done with that, so there's effectively no functional change. Can > you please elaborate on the motivation for this change? Where will the > KACCESS type need to be distinguished from the UACCESS type?
The introduction of EX_TYPE_KACCESS_ERR_ZERO does not change any function, but makes a correct distinction in the actual type, indicating that there are indeed some kaccess entries in extable. I think this optimization is more clear and reasonable.
A few weeks ago, I did something similar on arm64[1]. I think this optimization can also be used on riscv.
We can do some features that are used on uaccss but not applicable on kaccess in the future[2].
[1] https://lore.kernel.org/lkml/20220621072638.1273594-2-tongtiangen@huawei.com/ [2]https://lore.kernel.org/lkml/20220812070557.1028499-4-tongtiangen@huawei.com/
Thanks, Tong.
> > Thanks, > drew > .
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