On Thu, Jun 27, 2024 at 10:34:39AM +0200, Alice Ryhl wrote:
On Tue, Jun 25, 2024 at 6:18 PM Boqun Feng [off-list ref] wrote:
quoted
Hi Alice,
On Fri, Jun 21, 2024 at 10:35:26AM +0000, Alice Ryhl wrote:
quoted
Add just enough support for static key so that we can use it from
tracepoints. Tracepoints rely on `static_key_false` even though it is
deprecated, so we add the same functionality to Rust.
It is not possible to use the existing C implementation of
arch_static_branch because it passes the argument `key` to inline
assembly as an 'i' parameter, so any attempt to add a C helper for this
function will fail to compile because the value of `key` must be known
at compile-time.
Signed-off-by: Alice Ryhl <aliceryhl@google.com>
[Add linux-arch, and related arch maintainers Cced]
Since inline asms are touched here, please consider copying linux-arch
and arch maintainers next time ;-)
Will do.
quoted
For x86_64 and arm64 bits:
Acked-by: Boqun Feng <redacted>
One thing though, we should split the arch-specific impls into different
files, for example: rust/kernel/arch/arm64.rs or rust/arch/arm64.rs.
That'll be easier for arch maintainers to watch the Rust changes related
to a particular architecture.
Is that how you would prefer to name these files? You don't want
static_key somewhere in the filename?
I could have been more explicit. My preference is (for example ARM64)
* we have a rust/kernel/arch.rs, where we do:
#[cfg(CONFIG_ARM64)]
mod arm64::*;
#[cfg(CONFIG_ARM64)]
pub use arm64::*;
* we have a rust/kernel/arch/arm64.rs:
pub(crate) mod jump_label;
* we have a rust/kernel/arch/arm64/jump_label.rs, where we put
ARM64 arch_static_branch() there. (or static_key.rs and
arch_static_key_false()).
Then linux-arch can watch:
rust/kernel/arch.rs
rust/kernel/arch/
And ARM64 maintainers can watch:
rust/kernel/arch/arm64.rs
rust/kernel/arch/arm64
This is similar to how <asm/*.h> are organized today.
Does this make sense?
Regards,
Boqun
quoted
Another thought is that, could you implement an arch_static_branch!()
(instead of _static_key_false!()) and use it for static_key_false!()
similar to what we have in C? The benefit is that at least for myself
it'll be easier to compare the implementation between C and Rust.
I can try to include that.
Alice