Hello, this series is a follow-up to the RFC sent in [1], which aimed to make sure that functions consuming struct by value on stack were not encoded in BTF. This new series comes with a less "aggressive" strategy, and only skips function encoding if: - the function consumes a struct by value - the struct is passed on the stack - it is detected as packed (see class__infer_packed_attributes) The detection is not done anymore in parameter__new, as it may be done too early to have all the relevant info to properly infer the attributes; it is now done in btf_encoder__encode_cu. The series also comes with a simple test, but as the kernel don't have such case exposed, this new test comes with a small out-of-tree module. The logic is kept simple and the test is by default skipped (it needs to be provided with a path to some kernel sources), as I am not sure how it should integrate with the current CI effort done by Alan. [1] https://lore.kernel.org/dwarves/20250618-btf_skip_structs_on_stack-v1-1-e70be639cc53@xxxxxxxxxxx/ Signed-off-by: Alexis Lothoré (eBPF Foundation) <alexis.lothore@xxxxxxxxxxx> --- Changes in v2: - infer structs attributes - skip function encoded if some consumed struct (passed on stack) is marked as packed - add some tests in btf_functions.sh - drop RFC prefix - Link to v1: https://lore.kernel.org/r/20250618-btf_skip_structs_on_stack-v1-1-e70be639cc53@xxxxxxxxxxx --- Alexis Lothoré (eBPF Foundation) (3): btf_encoder: skip functions consuming packed structs passed by value on stack tests: add some tests validating skipped functions due to uncertain arg location gitignore: ignore all the test kmod build-related files .gitignore | 3 ++ btf_encoder.c | 50 ++++++++++++++++++++++++- dwarves.h | 1 + tests/btf_functions.sh | 99 ++++++++++++++++++++++++++++++++++++++++++++++++++ tests/kmod/Makefile | 1 + tests/kmod/kmod.c | 69 +++++++++++++++++++++++++++++++++++ 6 files changed, 221 insertions(+), 2 deletions(-) --- base-commit: 042d73962d35fdd1466e056f1ea14590b1cdbb9b change-id: 20250617-btf_skip_structs_on_stack-006adf457d50 Best regards, -- Alexis Lothoré, Bootlin Embedded Linux and Kernel engineering https://bootlin.com
