@@ -141,6 +141,7 @@ struct bpf_program {
RELO_LD64,
RELO_CALL,
RELO_DATA,
+ RELO_ZERO,
} type;
int insn_idx;
union {
@@ -222,6 +223,7 @@ struct bpf_object {
int maps_shndx;
int text_shndx;
int data_shndx;
+ int bss_shndx;
} efile;
/*
* All loaded bpf_object is linked in a list, which is
@@ -901,6 +903,8 @@ static int bpf_object__elf_collect(struct bpf_object *obj, int flags)
obj->efile.reloc[n].shdr = sh;
obj->efile.reloc[n].data = data;
}
+ } else if (sh.sh_type == SHT_NOBITS && strcmp(name, ".bss") == 0) {
+ obj->efile.bss_shndx = idx;
} else {
pr_debug("skip section(%d) %s\n", idx, name);
}
@@ -971,6 +975,7 @@ bpf_program__collect_reloc(struct bpf_program *prog, GElf_Shdr *shdr,
int text_shndx = obj->efile.text_shndx;
int maps_shndx = obj->efile.maps_shndx;
int data_shndx = obj->efile.data_shndx;
+ int bss_shndx = obj->efile.bss_shndx;
struct bpf_map *maps = obj->maps;
size_t nr_maps = obj->nr_maps;
int i, nrels;
@@ -1010,7 +1015,7 @@ bpf_program__collect_reloc(struct bpf_program *prog, GElf_Shdr *shdr,
(long long) sym.st_value, sym.st_name);
if (sym.st_shndx != maps_shndx && sym.st_shndx != text_shndx &&
- sym.st_shndx != data_shndx) {
+ sym.st_shndx != data_shndx && sym.st_shndx != bss_shndx) {
pr_warning("Program '%s' contains unrecognized relo data pointing to section %u\n",
prog->section_name, sym.st_shndx);
return -LIBBPF_ERRNO__RELOC;
@@ -1070,6 +1075,9 @@ bpf_program__collect_reloc(struct bpf_program *prog, GElf_Shdr *shdr,
prog->reloc_desc[i].type = RELO_DATA;
prog->reloc_desc[i].insn_idx = insn_idx;
prog->reloc_desc[i].data = *static_data;
+ } else if (sym.st_shndx == bss_shndx) {
+ prog->reloc_desc[i].type = RELO_ZERO;
+ prog->reloc_desc[i].insn_idx = insn_idx;
}
}
return 0;
@@ -1429,6 +1437,10 @@ bpf_program__relocate(struct bpf_program *prog, struct bpf_object *obj)
insn_idx = prog->reloc_desc[i].insn_idx;
insns[insn_idx].imm = prog->reloc_desc[i].data;
+ } else if (prog->reloc_desc[i].type == RELO_ZERO) {
+ int insn_idx = prog->reloc_desc[i].insn_idx;
+
+ prog->insns[insn_idx].imm = 0;
}
}
The BSS section in an ELF generated by LLVM represents constants for uninitialized variables or variables that are configured with a zero value. Support initializing zeroed static data by parsing the relocations with references to the .bss section and zeroing them. Signed-off-by: Joe Stringer <joe@wand.net.nz> --- tools/lib/bpf/libbpf.c | 14 +++++++++++++- 1 file changed, 13 insertions(+), 1 deletion(-)