On Wed, Mar 4, 2020 at 7:21 AM Daniel Borkmann <daniel@xxxxxxxxxxxxx> wrote: > > On 3/3/20 1:32 AM, Andrii Nakryiko wrote: > > Convert BPF-related UAPI constants, currently defined as #define macro, into > > anonymous enums. This has no difference in terms of usage of such constants in > > C code (they are still could be used in all the compile-time contexts that > > `#define`s can), but they are recorded as part of DWARF type info, and > > subsequently get recorded as part of kernel's BTF type info. This allows those > > constants to be emitted as part of vmlinux.h auto-generated header file and be > > used from BPF programs. Which is especially convenient for all kinds of BPF > > helper flags and makes CO-RE BPF programs nicer to write. > > > > libbpf's btf_dump logic currently assumes enum values are signed 32-bit > > values, but that doesn't match a typical case, so switch it to emit unsigned > > values. Once BTF encoding of BTF_KIND_ENUM is extended to capture signedness > > properly, this will be made more flexible. > > > > As an immediate validation of the approach, runqslower's copy of > > BPF_F_CURRENT_CPU #define is dropped in favor of its enum variant from > > vmlinux.h. > > > > v2->v3: > > - convert only constants usable from BPF programs (BPF helper flags, map > > create flags, etc) (Alexei); > > > > v1->v2: > > - fix up btf_dump test to use max 32-bit unsigned value instead of negative one. > > > > > > Andrii Nakryiko (3): > > bpf: switch BPF UAPI #define constants used from BPF program side to > > enums > > libbpf: assume unsigned values for BTF_KIND_ENUM > > tools/runqslower: drop copy/pasted BPF_F_CURRENT_CPU definiton > > > > include/uapi/linux/bpf.h | 175 ++++++++++------- > > tools/bpf/runqslower/runqslower.bpf.c | 3 - > > tools/include/uapi/linux/bpf.h | 177 +++++++++++------- > > tools/lib/bpf/btf_dump.c | 8 +- > > .../bpf/progs/btf_dump_test_case_syntax.c | 2 +- > > 5 files changed, 224 insertions(+), 141 deletions(-) > > > > Applied, thanks! Great, thanks! This is a huge usability boost for BPF programs relying on vmlinux.h!
