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tc, bpf: give some more hints wrt false relos 

Provide some more hints to the user/developer when relos have been found
that don't point to ld64 imm instruction. Ran couple of times into relos
generated by clang [1], where the compiler tried to uninline inlined
functions with eBPF and emitted BPF_JMP | BPF_CALL opcodes. If this seems
the case, give a hint that the user should do a work-around to use
always_inline annotation.

  [1] https://llvm.org/bugs/show_bug.cgi?id=26243#c3

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
This commit is contained in:
Daniel Borkmann 2016-02-07 02:11:52 +01:00 committed by Stephen Hemminger
parent f31645d138
commit a576c6b977
1 changed files with 9 additions and 1 deletions
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10
tc/tc_bpf.c
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@ -1385,8 +1385,16 @@ static int bpf_apply_relo_data(struct bpf_elf_ctx *ctx,
ioff = relo.r_offset / sizeof(struct bpf_insn);
if (ioff >= num_insns ||
insns[ioff].code != (BPF_LD | BPF_IMM | BPF_DW))
insns[ioff].code != (BPF_LD | BPF_IMM | BPF_DW)) {
fprintf(stderr, "ELF contains relo data for non ld64 "
"instruction at offset %u! Compiler bug?!\n",
ioff);
if (ioff < num_insns &&
insns[ioff].code == (BPF_JMP | BPF_CALL))
fprintf(stderr, " - Try to annotate functions "
"with always_inline attribute!\n");
return -EINVAL;
}
if (gelf_getsym(ctx->sym_tab, GELF_R_SYM(relo.r_info), &sym) != &sym)
return -EIO;