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libbpf: fix sym_is_subprog() logic for weak global subprogs

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sym_is_subprog() is incorrectly rejecting relocations against *weak*
global subprogs. Fix that by realizing that STB_WEAK is also a global
function.

While it seems like verifier doesn't support taking an address of
non-static subprog right now, it's still best to fix support for it on
libbpf side, otherwise users will get a very confusing error during BPF
skeleton generation or static linking due to misinterpreted relocation:

  libbpf: prog 'handle_tp': bad map relo against 'foo' in section '.text'
  Error: failed to open BPF object file: Relocation failed

It's clearly not a map relocation, but is treated and reported as such
without this fix.

Fixes: 53eddb5e04 ("libbpf: Support subprog address relocation")
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20241009011554.880168-1-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Andrii Nakryiko 2024-10-08 18:15:54 -07:00 committed by Alexei Starovoitov
parent 965fdf95a3
commit 4073213488
1 changed files with 1 additions and 1 deletions
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2
tools/lib/bpf/libbpf.c
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@ -4013,7 +4013,7 @@ static bool sym_is_subprog(const Elf64_Sym *sym, int text_shndx)
return true;
/* global function */
return bind == STB_GLOBAL && type == STT_FUNC;
return (bind == STB_GLOBAL || bind == STB_WEAK) && type == STT_FUNC;
}
static int find_extern_btf_id(const struct btf *btf, const char *ext_name)