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libbpf: Record extern sym relocation first

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This patch records the extern sym relocs first before recording
subprog relocs.  The later patch will have relocs for extern
kernel function call which is also using BPF_JMP | BPF_CALL.
It will be easier to handle the extern symbols first in
the later patch.

is_call_insn() helper is added.  The existing is_ldimm64() helper
is renamed to is_ldimm64_insn() for consistency.

Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210325015227.1548623-1-kafai@fb.com
This commit is contained in:
Martin KaFai Lau 2021-03-24 18:52:27 -07:00 committed by Alexei Starovoitov
parent 0c091e5c2d
commit aa0b8d43e9
1 changed files with 34 additions and 29 deletions
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63
tools/lib/bpf/libbpf.c
View file

@ -573,14 +573,19 @@ static bool insn_is_subprog_call(const struct bpf_insn *insn)
insn->off == 0;
}
static bool is_ldimm64(struct bpf_insn *insn)
static bool is_ldimm64_insn(struct bpf_insn *insn)
{
return insn->code == (BPF_LD | BPF_IMM | BPF_DW);
}
static bool is_call_insn(const struct bpf_insn *insn)
{
return insn->code == (BPF_JMP | BPF_CALL);
}
static bool insn_is_pseudo_func(struct bpf_insn *insn)
{
return is_ldimm64(insn) && insn->src_reg == BPF_PSEUDO_FUNC;
return is_ldimm64_insn(insn) && insn->src_reg == BPF_PSEUDO_FUNC;
}
static int
@ -3408,31 +3413,7 @@ static int bpf_program__record_reloc(struct bpf_program *prog,
reloc_desc->processed = false;
/* sub-program call relocation */
if (insn->code == (BPF_JMP | BPF_CALL)) {
if (insn->src_reg != BPF_PSEUDO_CALL) {
pr_warn("prog '%s': incorrect bpf_call opcode\n", prog->name);
return -LIBBPF_ERRNO__RELOC;
}
/* text_shndx can be 0, if no default "main" program exists */
if (!shdr_idx || shdr_idx != obj->efile.text_shndx) {
sym_sec_name = elf_sec_name(obj, elf_sec_by_idx(obj, shdr_idx));
pr_warn("prog '%s': bad call relo against '%s' in section '%s'\n",
prog->name, sym_name, sym_sec_name);
return -LIBBPF_ERRNO__RELOC;
}
if (sym->st_value % BPF_INSN_SZ) {
pr_warn("prog '%s': bad call relo against '%s' at offset %zu\n",
prog->name, sym_name, (size_t)sym->st_value);
return -LIBBPF_ERRNO__RELOC;
}
reloc_desc->type = RELO_CALL;
reloc_desc->insn_idx = insn_idx;
reloc_desc->sym_off = sym->st_value;
return 0;
}
if (!is_ldimm64(insn)) {
if (!is_call_insn(insn) && !is_ldimm64_insn(insn)) {
pr_warn("prog '%s': invalid relo against '%s' for insns[%d].code 0x%x\n",
prog->name, sym_name, insn_idx, insn->code);
return -LIBBPF_ERRNO__RELOC;
@ -3461,6 +3442,30 @@ static int bpf_program__record_reloc(struct bpf_program *prog,
return 0;
}
/* sub-program call relocation */
if (is_call_insn(insn)) {
if (insn->src_reg != BPF_PSEUDO_CALL) {
pr_warn("prog '%s': incorrect bpf_call opcode\n", prog->name);
return -LIBBPF_ERRNO__RELOC;
}
/* text_shndx can be 0, if no default "main" program exists */
if (!shdr_idx || shdr_idx != obj->efile.text_shndx) {
sym_sec_name = elf_sec_name(obj, elf_sec_by_idx(obj, shdr_idx));
pr_warn("prog '%s': bad call relo against '%s' in section '%s'\n",
prog->name, sym_name, sym_sec_name);
return -LIBBPF_ERRNO__RELOC;
}
if (sym->st_value % BPF_INSN_SZ) {
pr_warn("prog '%s': bad call relo against '%s' at offset %zu\n",
prog->name, sym_name, (size_t)sym->st_value);
return -LIBBPF_ERRNO__RELOC;
}
reloc_desc->type = RELO_CALL;
reloc_desc->insn_idx = insn_idx;
reloc_desc->sym_off = sym->st_value;
return 0;
}
if (!shdr_idx || shdr_idx >= SHN_LORESERVE) {
pr_warn("prog '%s': invalid relo against '%s' in special section 0x%x; forgot to initialize global var?..\n",
prog->name, sym_name, shdr_idx);
@ -5700,7 +5705,7 @@ static int bpf_core_patch_insn(struct bpf_program *prog,
/* poison second part of ldimm64 to avoid confusing error from
* verifier about "unknown opcode 00"
*/
if (is_ldimm64(insn))
if (is_ldimm64_insn(insn))
bpf_core_poison_insn(prog, relo_idx, insn_idx + 1, insn + 1);
bpf_core_poison_insn(prog, relo_idx, insn_idx, insn);
return 0;
@ -5776,7 +5781,7 @@ static int bpf_core_patch_insn(struct bpf_program *prog,
case BPF_LD: {
__u64 imm;
if (!is_ldimm64(insn) ||
if (!is_ldimm64_insn(insn) ||
insn[0].src_reg != 0 || insn[0].off != 0 ||
insn_idx + 1 >= prog->insns_cnt ||
insn[1].code != 0 || insn[1].dst_reg != 0 ||