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082108fd69
Resolve forward declarations that don't take part in type graphs comparisons if declaration name is unambiguous. Example: CU #1: struct foo; // standalone forward declaration struct foo *some_global; CU #2: struct foo { int x; }; struct foo *another_global; The `struct foo` from CU #1 is not a part of any definition that is compared against another definition while `btf_dedup_struct_types` processes structural types. The the BTF after `btf_dedup_struct_types` the BTF looks as follows: [1] STRUCT 'foo' size=4 vlen=1 ... [2] INT 'int' size=4 ... [3] PTR '(anon)' type_id=1 [4] FWD 'foo' fwd_kind=struct [5] PTR '(anon)' type_id=4 This commit adds a new pass `btf_dedup_resolve_fwds`, that maps such forward declarations to structs or unions with identical name in case if the name is not ambiguous. The pass is positioned before `btf_dedup_ref_types` so that types [3] and [5] could be merged as a same type after [1] and [4] are merged. The final result for the example above looks as follows: [1] STRUCT 'foo' size=4 vlen=1 'x' type_id=2 bits_offset=0 [2] INT 'int' size=4 bits_offset=0 nr_bits=32 encoding=SIGNED [3] PTR '(anon)' type_id=1 For defconfig kernel with BTF enabled this removes 63 forward declarations. Examples of removed declarations: `pt_regs`, `in6_addr`. The running time of `btf__dedup` function is increased by about 3%. Signed-off-by: Eduard Zingerman <eddyz87@gmail.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Reviewed-by: Alan Maguire <alan.maguire@oracle.com> Acked-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/bpf/20221109142611.879983-3-eddyz87@gmail.com |
History
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| .. | ||
| .gitignore | ||
| bpf.c | ||
| bpf.h | ||
| bpf_core_read.h | ||
| bpf_endian.h | ||
| bpf_gen_internal.h | ||
| bpf_helpers.h | ||
| bpf_prog_linfo.c | ||
| bpf_tracing.h | ||
| btf.c | ||
| btf.h | ||
| btf_dump.c | ||
| Build | ||
| gen_loader.c | ||
| hashmap.c | ||
| hashmap.h | ||
| libbpf.c | ||
| libbpf.h | ||
| libbpf.map | ||
| libbpf.pc.template | ||
| libbpf_common.h | ||
| libbpf_errno.c | ||
| libbpf_internal.h | ||
| libbpf_legacy.h | ||
| libbpf_probes.c | ||
| libbpf_version.h | ||
| linker.c | ||
| Makefile | ||
| netlink.c | ||
| nlattr.c | ||
| nlattr.h | ||
| relo_core.c | ||
| relo_core.h | ||
| ringbuf.c | ||
| skel_internal.h | ||
| str_error.c | ||
| str_error.h | ||
| strset.c | ||
| strset.h | ||
| usdt.bpf.h | ||
| usdt.c | ||