Lennart Poettering
7736a71fd2
Make sure that the sym_xyz function pointers have the types that the functions we'll assign them have. And of course, this found a number of incompatibilities right-away, in particular in the bpf hookup. (Doing this will trigger deprecation warnings from libbpf. I simply turned them off locally now, since we are well aware of what we are doing in that regard.) There's one return type fix (bool → int), that actually matters I think, as it might have created an incompatibility on some archs.
55 lines
2.5 KiB
C
55 lines
2.5 KiB
C
/* SPDX-License-Identifier: LGPL-2.1-or-later */
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#pragma once
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/* libbpf has been moving quickly.
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* They added new symbols in the 0.x versions and shortly after removed
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* deprecated symbols in 1.0.
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* We only need bpf_map_create and libbpf_probe_bpf_prog_type so we work
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* around the incompatibility here by:
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* - declaring both symbols, and looking for either depending on the libbpf
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* so version we found
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* - having helpers that automatically use the appropriate version behind the
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* new API for easy cleanup later
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*
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* The advantage of doing this instead of only looking for the symbols declared at
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* compile time is that we can then load either the old or the new symbols at runtime
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* regardless of the version we were compiled with */
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/* declare the struct for libbpf <= 0.6.0 -- it causes no harm on newer versions */
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struct bpf_map_create_opts;
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/* new symbols available from 0.7.0.
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* We need the symbols here:
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* - after bpf_map_create_opts struct has been defined for older libbpf
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* - before the compat static inline helpers that use them.
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* When removing this file move these back to bpf-dlopen.h */
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extern int (*sym_bpf_map_create)(enum bpf_map_type, const char *, __u32, __u32, __u32, const struct bpf_map_create_opts *);
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extern int (*sym_libbpf_probe_bpf_prog_type)(enum bpf_prog_type, const void *);
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/* compat symbols removed in libbpf 1.0 */
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extern int (*sym_bpf_create_map)(enum bpf_map_type, int key_size, int value_size, int max_entries, __u32 map_flags);
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extern bool (*sym_bpf_probe_prog_type)(enum bpf_prog_type, __u32);
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/* helpers to use the available variant behind new API */
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static inline int compat_bpf_map_create(enum bpf_map_type map_type,
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const char *map_name,
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__u32 key_size,
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__u32 value_size,
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__u32 max_entries,
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const struct bpf_map_create_opts *opts) {
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if (sym_bpf_map_create)
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return sym_bpf_map_create(map_type, map_name, key_size,
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value_size, max_entries, opts);
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return sym_bpf_create_map(map_type, key_size, value_size, max_entries,
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0 /* opts->map_flags, but opts is always NULL for us so skip build dependency on the type */);
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}
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static inline int compat_libbpf_probe_bpf_prog_type(enum bpf_prog_type prog_type, const void *opts) {
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if (sym_libbpf_probe_bpf_prog_type)
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return sym_libbpf_probe_bpf_prog_type(prog_type, opts);
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return sym_bpf_probe_prog_type(prog_type, 0);
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}
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