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It initializes this struct by querying the gpu and then writes >> the struct into userspace memory faithfully byte-by-byte. >> >> Currently, the struct drm_panthor_gpu_info does not have any implicit >> padding, but if implicit padding were added in the future Rust does not >> guarantee that it would be initialized. Then when Tyr writes the struct >> back to userspace it could expose uninitialized kernel memory. >> >> Tyr implements the unsafe trait AsBytes for GpuInfo whereby the develope= r >> guarantees that struct drm_panthor_gpu_info does not include implicit >> padding, pointers, or interior mutability. This allows Tyr to safely cop= y >> the struct into userspace memory. However, relying on the unsafe trait >> AsBytes is fragile because if the Panthor UAPI changes, the SAFETY >> guarantees may no longer be accurate. >> >> Instead, use the derive macro `zerocopy_derive::most_traits` for struct >> drm_panthor_gpu_info. This macro will attempt to implement the zerocopy >> traits for struct drm_panthor_gpu_info. If the Panthor UAPI changes so >> that the traits IntoBytes or Immutable can no longer be implemented, Tyr >> will no longer compile. >> >> Signed-off-by: Deborah Brouwer > > So this looks good to me > > Reviewed-by: Alice Ryhl > > but needs Miguel's ok since it modifies the Makefile. And I imagine he > may ask the commit to be split into two. FWIW I do think this should be two commits, one making Make changes and app= ly to both uapi and bindings, and the second adding the Tyr-specific parts. Best, Gary