This series adds generic 64-bit bitops kfuncs and JIT inlining support on x86_64 and arm64.
The new kfuncs are: * bpf_clz64(): Count leading zeros. * bpf_ctz64(): Count trailing zeros. * bpf_ffs64(): Find first set bit, 1-based index, returns 0 when input is 0. * bpf_fls64(): Find last set bit, 1-based index. * bpf_bitrev64(): Reverse bits. * bpf_popcnt64(): Population count. * bpf_rol64(): Rotate left. * bpf_ror64(): Rotate right. Defined zero-input behavior: * bpf_clz64(0) = 64 * bpf_ctz64(0) = 64 * bpf_ffs64(0) = 0 * bpf_fls64(0) = 0 bpf_ffs64() was previously discussed in "bpf: Add generic kfunc bpf_ffs64()" [1]. The main concern in that discussion was ABI overhead: a regular kfunc call follows the BPF calling convention and can introduce extra spill/fill compared to dedicated instructions. This series keeps the user-facing API as kfuncs while avoiding that overhead on hot paths. When the JIT/backend and CPU support it, calls are inlined into native instructions; otherwise they fall back to regular function calls. Links: [1] https://lore.kernel.org/bpf/[email protected]/ Changes: v1 -> v2: * Drop RFC. * Add __cpu_feature annotation for CPU-feature-gated tests. * Add JIT disassembly tests for 64-bit bitops kfuncs * Address comments from Alexei: * Drop KF_MUST_INLINE. * Drop internal BPF_ALU64 opcode BPF_BITOPS. * Mark all of the kfuncs as fastcall and do push/pop in JIT when necessary. * v1: https://lore.kernel.org/bpf/[email protected]/ Leon Hwang (6): bpf: Introduce 64-bit bitops kfuncs bpf, x86: Add 64-bit bitops kfuncs support for x86_64 bpf, arm64: Add 64-bit bitops kfuncs support selftests/bpf: Add tests for 64-bit bitops kfuncs selftests/bpf: Add __cpu_feature annotation for CPU-feature-gated tests selftests/bpf: Add JIT disassembly tests for 64-bit bitops kfuncs arch/arm64/net/bpf_jit_comp.c | 123 ++++++++++++ arch/x86/net/bpf_jit_comp.c | 141 +++++++++++++ include/linux/filter.h | 10 + kernel/bpf/core.c | 6 + kernel/bpf/helpers.c | 50 +++++ kernel/bpf/verifier.c | 53 ++++- .../testing/selftests/bpf/bpf_experimental.h | 9 + .../testing/selftests/bpf/prog_tests/bitops.c | 188 ++++++++++++++++++ tools/testing/selftests/bpf/progs/bitops.c | 68 +++++++ .../testing/selftests/bpf/progs/bitops_jit.c | 153 ++++++++++++++ tools/testing/selftests/bpf/progs/bpf_misc.h | 7 + tools/testing/selftests/bpf/test_loader.c | 150 ++++++++++++++ 12 files changed, 957 insertions(+), 1 deletion(-) create mode 100644 tools/testing/selftests/bpf/prog_tests/bitops.c create mode 100644 tools/testing/selftests/bpf/progs/bitops.c create mode 100644 tools/testing/selftests/bpf/progs/bitops_jit.c -- 2.52.0
