Re: [PATCH v8 0/5] Tracepoints and static branch in Rust

[Steven Rostedt]

Hi Alice,

Can you rebase this series on v6.12-rc1?

Thanks,

-- Steve


On Thu, 22 Aug 2024 12:04:12 +0000
Alice Ryhl <aliceryhl@xxxxxxxxxx> wrote:

> An important part of a production ready Linux kernel driver is
> tracepoints. So to write production ready Linux kernel drivers in Rust,
> we must be able to call tracepoints from Rust code. This patch series
> adds support for calling tracepoints declared in C from Rust.
> 
> This series includes a patch that adds a user of tracepoits to the
> rust_print sample. Please see that sample for details on what is needed
> to use this feature in Rust code.
> 
> This is intended for use in the Rust Binder driver, which was originally
> sent as an RFC [1]. The RFC did not include tracepoint support, but you
> can see how it will be used in Rust Binder at [2]. The author has
> verified that the tracepoint support works on Android devices.
> 
> This implementation implements support for static keys in Rust so that
> the actual static branch happens in the Rust object file. However, the
> __DO_TRACE body remains in C code. See v1 for an implementation where
> __DO_TRACE is also implemented in Rust.
> 
> When compiling for x86, this patchset has a dependency on [3] as we need
> objtool to convert jmp instructions to nop instructions. This patchset
> is based on top of the series containing [3].
> 
> There is also a conflict with splitting up the C helpers [4]. I've
> included an alternate version of the first patch that shows how to
> resolve the conflict. When using the alternate version of the first
> patch, this series applies cleanly on top of rust-next.
> 
> Both [3] and [4] are already in rust-next.
> 
> Link: https://lore.kernel.org/rust-for-linux/20231101-rust-binder-v1-0-08ba9197f637@xxxxxxxxxx/ [1]
> Link: https://r.android.com/3119993 [2]
> Link: https://lore.kernel.org/all/20240725183325.122827-7-ojeda@xxxxxxxxxx/ [3]
> Link: https://lore.kernel.org/all/20240815103016.2771842-1-nmi@xxxxxxxxxxxx/ [4]
> Signed-off-by: Alice Ryhl <aliceryhl@xxxxxxxxxx>
> ---
> Changes in v8:
> - Use OBJTREE instead of SRCTREE for temporary asm file.
> - Adjust comments on `asm!` wrapper to be less confusing.
> - Include resolution of conflict with helpers splitting.
> - Link to v7: https://lore.kernel.org/r/20240816-tracepoint-v7-0-d609b916b819@xxxxxxxxxx
> 
> Changes in v7:
> - Fix spurious file included in first patch.
> - Fix issue with riscv asm.
> - Fix tags on fourth patch to match fifth patch.
> - Add Reviewed-by/Acked-by tags where appropriate.
> - Link to v6: https://lore.kernel.org/r/20240808-tracepoint-v6-0-a23f800f1189@xxxxxxxxxx
> 
> Changes in v6:
> - Add support for !CONFIG_JUMP_LABEL.
> - Add tracepoint to rust_print sample.
> - Deduplicate inline asm.
> - Require unsafe inside `declare_trace!`.
> - Fix bug on x86 due to use of intel syntax.
> - Link to v5: https://lore.kernel.org/r/20240802-tracepoint-v5-0-faa164494dcb@xxxxxxxxxx
> 
> Changes in v5:
> - Update first patch regarding inline asm duplication.
> - Add __rust_do_trace helper to support conditions.
> - Rename DEFINE_RUST_DO_TRACE_REAL to __DEFINE_RUST_DO_TRACE.
> - Get rid of glob-import in tracepoint macro.
> - Address safety requirements on tracepoints in docs.
> - Link to v4: https://lore.kernel.org/rust-for-linux/20240628-tracepoint-v4-0-353d523a9c15@xxxxxxxxxx
> 
> Changes in v4:
> - Move arch-specific code into rust/kernel/arch.
> - Restore DEFINE_RUST_DO_TRACE at end of define_trace.h
> - Link to v3: https://lore.kernel.org/r/20240621-tracepoint-v3-0-9e44eeea2b85@xxxxxxxxxx
> 
> Changes in v3:
> - Support for Rust static_key on loongarch64 and riscv64.
> - Avoid failing compilation on architectures that are missing Rust
>   static_key support when the archtectures does not actually use it.
> - Link to v2: https://lore.kernel.org/r/20240610-tracepoint-v2-0-faebad81b355@xxxxxxxxxx
> 
> Changes in v2:
> - Call into C code for __DO_TRACE.
> - Drop static_call patch, as it is no longer needed.
> - Link to v1: https://lore.kernel.org/r/20240606-tracepoint-v1-0-6551627bf51b@xxxxxxxxxx
> 
> ---
> Alice Ryhl (5):
>       rust: add generic static_key_false
>       rust: add tracepoint support
>       rust: samples: add tracepoint to Rust sample
>       jump_label: adjust inline asm to be consistent
>       rust: add arch_static_branch
> 
>  MAINTAINERS                             |  1 +
>  arch/arm/include/asm/jump_label.h       | 14 +++--
>  arch/arm64/include/asm/jump_label.h     | 20 +++++---
>  arch/loongarch/include/asm/jump_label.h | 16 +++---
>  arch/riscv/include/asm/jump_label.h     | 50 ++++++++++--------
>  arch/x86/include/asm/jump_label.h       | 38 ++++++--------
>  include/linux/tracepoint.h              | 22 +++++++-
>  include/trace/define_trace.h            | 12 +++++
>  include/trace/events/rust_sample.h      | 31 +++++++++++
>  rust/Makefile                           |  5 +-
>  rust/bindings/bindings_helper.h         |  3 ++
>  rust/helpers.c                          |  9 ++++
>  rust/kernel/.gitignore                  |  3 ++
>  rust/kernel/arch_static_branch_asm.rs.S |  7 +++
>  rust/kernel/jump_label.rs               | 91 +++++++++++++++++++++++++++++++++
>  rust/kernel/lib.rs                      | 37 ++++++++++++++
>  rust/kernel/tracepoint.rs               | 49 ++++++++++++++++++
>  samples/rust/Makefile                   |  3 +-
>  samples/rust/rust_print.rs              | 18 +++++++
>  samples/rust/rust_print_events.c        |  8 +++
>  scripts/Makefile.build                  |  9 +++-
>  21 files changed, 379 insertions(+), 67 deletions(-)
> ---
> base-commit: 88359b25b950670432ef1da4352eb6cc62e0fa9f
> change-id: 20240606-tracepoint-31e15b90e471
> 
> Best regards,