I'm sending v6 as RFC hoping to get feedback on the macro implementation used in this version. I hope to receive feedback so that I can use the time while the merge window is closed to address any remaining comments. This series improves the packing library with a new API for packing or unpacking a large number of fields at once with minimal code footprint. The API is then used to replace bespoke packing logic in the ice driver, preparing it to handle unpacking in the future. Finally, the ice driver has a few other cleanups related to the packing logic. The pack_fields and unpack_fields functions have the following improvements over the existing pack() and unpack() API: 1. Packing or unpacking a large number of fields takes significantly less code. This significantly reduces the .text size for an increase in the .data size which is much smaller. 2. The unpacked data can be stored in sizes smaller than u64 variables. This reduces the storage requirement both for runtime data structures, and for the rodata defining the fields. This scales with the number of fields used. 3. Most of the error checking is done at compile time, rather than runtime, via CHECK_PACKED_FIELD macros. The actual packing and unpacking code still uses the u64 size variables. However, these are converted to the appropriate field sizes when storing or reading the data from the buffer. This version returns to the C pre-processor macro checks, rather than use of external tools. To limit the amount of generated code and ease the driver burden, we now enforce ordering (same as with v5), where the fields must be in ascending or descending order. This reduces the overlap checks from O(N^2) to O(N), and reduces the amount of generated code from 20K lines to 3K lines. I also refactored to place the generator script in scripts/gen_packed_field_checks.c, and no longer automatically generate at compile time. This avoids needing to mess too much with the top level build system, at the expense of saving the macros in git. I think the reduction to 3K lines is a bit more within reason vs the 20K lines from v2. This version returns to the 5-argument format of pack_fields and unpack_fields, but now enforces that the passed pbuflen is a compile-time constant via __builtin_constant_p(). This ensures we can still perform the size checks, but keeps the API flexible rather than forcing users to always wrap their buffer in a struct typedef. I think this is acceptable, and enforcing a compile-time known size is a reasonable constraint. Signed-off-by: Jacob Keller <jacob.e.keller@xxxxxxxxx> --- Changes in v6: - Revert to macro checks similar to v2. - Add a __builtin_choose_expr() based macro to automatically select the appropriate size macro. - Keep the pbuflen check separate from the main loop check, similar to v5. - Link to v5: https://lore.kernel.org/r/20241111-packing-pack-fields-and-ice-implementation-v5-0-80c07349e6b7@xxxxxxxxx Changes in v5: - Fix printf format specifier for the sym->st_size - Link to v4: https://lore.kernel.org/r/20241108-packing-pack-fields-and-ice-implementation-v4-0-81a9f42c30e5@xxxxxxxxx Changes in v4: - Move the buffer size checks to (un)pack_fields() macros. - Enforce use of a sized type of the packed buffer, removing the now unnecessary pbuflen argument of (un)pack_fields(). - Drop exporting the buffer size to modpost. - Simplify modpost implementation to directly check each symbol in the handle_packed_field_symbol() function. This removes the need for a hash, and is ultimately much simpler now that modpost doesn't need the size of the target buffer. - Fix the width check to correctly calculate the width and compare it properly. - Refactor modpost messages to consistently report the module name first, the symbol name second, and the field number 3rd. - Correctly implement overlap checks in the modpost, rather than only checking field ordering. - Link to v3: https://lore.kernel.org/r/20241107-packing-pack-fields-and-ice-implementation-v3-0-27c566ac2436@xxxxxxxxx Changes in v3: - Replace macro-based C pre-processor checks with checks implemented in modpost. - Move structure definitions into <linux/packing_types.h> to enable reuse within modpost. - Add DECLARE_PACKED_FIELDS_S and DECLARE_PACKED_FIELDS_M to enable automatically generating the buffer size constants and the section attributes. - Add additional unit tests for the pack_fields and unpack_fields APIs. - Update documentation with an explanation of the new API as well as some example code. - Link to v2: https://lore.kernel.org/r/20241025-packing-pack-fields-and-ice-implementation-v2-0-734776c88e40@xxxxxxxxx Changes in v2: - Add my missing sign-off to the first patch - Update the descriptions for a few patches - Only generate CHECK_PACKED_FIELDS_N when another module selects it - Add a new patch introducing wrapper structures for the packed Tx and Rx queue context, suggested by Vladimir. - Drop the now unnecessary macros in ice, thanks to the new types - Link to v1: https://lore.kernel.org/r/20241011-packing-pack-fields-and-ice-implementation-v1-0-d9b1f7500740@xxxxxxxxx --- Jacob Keller (6): ice: remove int_q_state from ice_tlan_ctx ice: use structures to keep track of queue context size ice: use <linux/packing.h> for Tx and Rx queue context data ice: reduce size of queue context fields ice: move prefetch enable to ice_setup_rx_ctx ice: cleanup Rx queue context programming functions Vladimir Oltean (3): lib: packing: create __pack() and __unpack() variants without error checking lib: packing: demote truncation error in pack() to a warning in __pack() lib: packing: add pack_fields() and unpack_fields() Makefile | 4 + drivers/net/ethernet/intel/ice/ice_adminq_cmd.h | 11 +- drivers/net/ethernet/intel/ice/ice_common.h | 5 +- drivers/net/ethernet/intel/ice/ice_lan_tx_rx.h | 49 +- include/linux/packing.h | 37 + include/linux/packing_types.h | 2831 +++++++++++++++++++++++ drivers/net/dsa/sja1105/sja1105_static_config.c | 8 +- drivers/net/ethernet/intel/ice/ice_base.c | 6 +- drivers/net/ethernet/intel/ice/ice_common.c | 293 +-- lib/packing.c | 285 ++- lib/packing_test.c | 61 + scripts/gen_packed_field_checks.c | 38 + Documentation/core-api/packing.rst | 58 + MAINTAINERS | 2 + drivers/net/ethernet/intel/Kconfig | 1 + scripts/Makefile | 2 +- 16 files changed, 3336 insertions(+), 355 deletions(-) --- base-commit: d7ef9eeef0723cc47601923c508ecbebd864f0c0 change-id: 20241004-packing-pack-fields-and-ice-implementation-b17c7ce8e373 Best regards, -- Jacob Keller <jacob.e.keller@xxxxxxxxx>