From: Andrii Nakryiko <andriin@fb.com>
Date: Tue, 23 Jul 2019 14:11:33 -0700
Subject: libbpf: provide more helpful message on uninitialized global var
Patch-mainline: v5.4-rc1
Git-commit: f2a3e4e95f408314938d37fa3146a9f7b304ce74
References: bsc#1154353
When BPF program defines uninitialized global variable, it's put into
a special COMMON section. Libbpf will reject such programs, but will
provide very unhelpful message with garbage-looking section index.
This patch detects special section cases and gives more explicit error
message.
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Acked-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
tools/lib/bpf/libbpf.c | 13 ++++++++++---
1 file changed, 10 insertions(+), 3 deletions(-)
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -1769,15 +1769,22 @@ bpf_program__collect_reloc(struct bpf_pr
(long long) sym.st_value, sym.st_name, name);
shdr_idx = sym.st_shndx;
+ insn_idx = rel.r_offset / sizeof(struct bpf_insn);
+ pr_debug("relocation: insn_idx=%u, shdr_idx=%u\n",
+ insn_idx, shdr_idx);
+
+ if (shdr_idx >= SHN_LORESERVE) {
+ pr_warning("relocation: not yet supported relo for non-static global \'%s\' variable in special section (0x%x) found in insns[%d].code 0x%x\n",
+ name, shdr_idx, insn_idx,
+ insns[insn_idx].code);
+ return -LIBBPF_ERRNO__RELOC;
+ }
if (!bpf_object__relo_in_known_section(obj, shdr_idx)) {
pr_warning("Program '%s' contains unrecognized relo data pointing to section %u\n",
prog->section_name, shdr_idx);
return -LIBBPF_ERRNO__RELOC;
}
- insn_idx = rel.r_offset / sizeof(struct bpf_insn);
- pr_debug("relocation: insn_idx=%u\n", insn_idx);
-
if (insns[insn_idx].code == (BPF_JMP | BPF_CALL)) {
if (insns[insn_idx].src_reg != BPF_PSEUDO_CALL) {
pr_warning("incorrect bpf_call opcode\n");