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libbpf: Split bpf_core_apply_relo() into bpf_program independent helper.
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bpf_core_apply_relo() doesn't need to know bpf_program internals
and hashmap details.

Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210721000822.40958-3-alexei.starovoitov@gmail.com
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Alexei Starovoitov authored and Andrii Nakryiko committed Jul 26, 2021
1 parent 6e43b28 commit 3ee4f53
Showing 1 changed file with 71 additions and 46 deletions.
117 changes: 71 additions & 46 deletions tools/lib/bpf/libbpf.c
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Original file line number Diff line number Diff line change
Expand Up @@ -5972,26 +5972,13 @@ static int insn_bytes_to_bpf_size(__u32 sz)
* 5. *(T *)(rX + <off>) = rY, where T is one of {u8, u16, u32, u64};
* 6. *(T *)(rX + <off>) = <imm>, where T is one of {u8, u16, u32, u64}.
*/
static int bpf_core_patch_insn(struct bpf_program *prog,
const struct bpf_core_relo *relo,
int relo_idx,
const struct bpf_core_relo_res *res)
static int bpf_core_patch_insn(const char *prog_name, struct bpf_insn *insn,
int insn_idx, const struct bpf_core_relo *relo,
int relo_idx, const struct bpf_core_relo_res *res)
{
const char *prog_name = prog->name;
__u32 orig_val, new_val;
struct bpf_insn *insn;
int insn_idx;
__u8 class;

if (relo->insn_off % BPF_INSN_SZ)
return -EINVAL;
insn_idx = relo->insn_off / BPF_INSN_SZ;
/* adjust insn_idx from section frame of reference to the local
* program's frame of reference; (sub-)program code is not yet
* relocated, so it's enough to just subtract in-section offset
*/
insn_idx = insn_idx - prog->sec_insn_off;
insn = &prog->insns[insn_idx];
class = BPF_CLASS(insn->code);

if (res->poison) {
Expand Down Expand Up @@ -6077,7 +6064,6 @@ static int bpf_core_patch_insn(struct bpf_program *prog,

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 ||
insn[1].src_reg != 0 || insn[1].off != 0) {
pr_warn("prog '%s': relo #%d: insn #%d (LDIMM64) has unexpected form\n",
Expand Down Expand Up @@ -6227,19 +6213,17 @@ static void *u32_as_hash_key(__u32 x)
* between multiple relocations for the same type ID and is updated as some
* of the candidates are pruned due to structural incompatibility.
*/
static int bpf_core_apply_relo(struct bpf_program *prog,
const struct bpf_core_relo *relo,
int relo_idx,
const struct btf *local_btf,
struct hashmap *cand_cache)
static int bpf_core_apply_relo_insn(const char *prog_name, struct bpf_insn *insn,
int insn_idx,
const struct bpf_core_relo *relo,
int relo_idx,
const struct btf *local_btf,
struct core_cand_list *cands)
{
struct bpf_core_spec local_spec, cand_spec, targ_spec = {};
const void *type_key = u32_as_hash_key(relo->type_id);
struct bpf_core_relo_res cand_res, targ_res;
const struct btf_type *local_type;
const char *local_name;
struct core_cand_list *cands = NULL;
const char *prog_name = prog->name;
__u32 local_id;
const char *spec_str;
int i, j, err;
Expand All @@ -6257,12 +6241,6 @@ static int bpf_core_apply_relo(struct bpf_program *prog,
if (str_is_empty(spec_str))
return -EINVAL;

if (prog->obj->gen_loader) {
pr_warn("// TODO core_relo: prog %td insn[%d] %s %s kind %d\n",
prog - prog->obj->programs, relo->insn_off / 8,
local_name, spec_str, relo->kind);
return -ENOTSUP;
}
err = bpf_core_parse_spec(local_btf, local_id, spec_str, relo->kind, &local_spec);
if (err) {
pr_warn("prog '%s': relo #%d: parsing [%d] %s %s + %s failed: %d\n",
Expand Down Expand Up @@ -6293,20 +6271,6 @@ static int bpf_core_apply_relo(struct bpf_program *prog,
return -EOPNOTSUPP;
}

if (!hashmap__find(cand_cache, type_key, (void **)&cands)) {
cands = bpf_core_find_cands(prog->obj, local_btf, local_id);
if (IS_ERR(cands)) {
pr_warn("prog '%s': relo #%d: target candidate search failed for [%d] %s %s: %ld\n",
prog_name, relo_idx, local_id, btf_kind_str(local_type),
local_name, PTR_ERR(cands));
return PTR_ERR(cands);
}
err = hashmap__set(cand_cache, type_key, cands, NULL, NULL);
if (err) {
bpf_core_free_cands(cands);
return err;
}
}

for (i = 0, j = 0; i < cands->len; i++) {
err = bpf_core_spec_match(&local_spec, cands->cands[i].btf,
Expand Down Expand Up @@ -6391,7 +6355,7 @@ static int bpf_core_apply_relo(struct bpf_program *prog,

patch_insn:
/* bpf_core_patch_insn() should know how to handle missing targ_spec */
err = bpf_core_patch_insn(prog, relo, relo_idx, &targ_res);
err = bpf_core_patch_insn(prog_name, insn, insn_idx, relo, relo_idx, &targ_res);
if (err) {
pr_warn("prog '%s': relo #%d: failed to patch insn #%zu: %d\n",
prog_name, relo_idx, relo->insn_off / BPF_INSN_SZ, err);
Expand All @@ -6401,6 +6365,67 @@ static int bpf_core_apply_relo(struct bpf_program *prog,
return 0;
}

static int bpf_core_apply_relo(struct bpf_program *prog,
const struct bpf_core_relo *relo,
int relo_idx,
const struct btf *local_btf,
struct hashmap *cand_cache)
{
const void *type_key = u32_as_hash_key(relo->type_id);
struct core_cand_list *cands = NULL;
const char *prog_name = prog->name;
const struct btf_type *local_type;
const char *local_name;
__u32 local_id = relo->type_id;
struct bpf_insn *insn;
int insn_idx, err;

if (relo->insn_off % BPF_INSN_SZ)
return -EINVAL;
insn_idx = relo->insn_off / BPF_INSN_SZ;
/* adjust insn_idx from section frame of reference to the local
* program's frame of reference; (sub-)program code is not yet
* relocated, so it's enough to just subtract in-section offset
*/
insn_idx = insn_idx - prog->sec_insn_off;
if (insn_idx > prog->insns_cnt)
return -EINVAL;
insn = &prog->insns[insn_idx];

local_type = btf__type_by_id(local_btf, local_id);
if (!local_type)
return -EINVAL;

local_name = btf__name_by_offset(local_btf, local_type->name_off);
if (!local_name)
return -EINVAL;

if (prog->obj->gen_loader) {
pr_warn("// TODO core_relo: prog %td insn[%d] %s kind %d\n",
prog - prog->obj->programs, relo->insn_off / 8,
local_name, relo->kind);
return -ENOTSUP;
}

if (relo->kind != BPF_TYPE_ID_LOCAL &&
!hashmap__find(cand_cache, type_key, (void **)&cands)) {
cands = bpf_core_find_cands(prog->obj, local_btf, local_id);
if (IS_ERR(cands)) {
pr_warn("prog '%s': relo #%d: target candidate search failed for [%d] %s %s: %ld\n",
prog_name, relo_idx, local_id, btf_kind_str(local_type),
local_name, PTR_ERR(cands));
return PTR_ERR(cands);
}
err = hashmap__set(cand_cache, type_key, cands, NULL, NULL);
if (err) {
bpf_core_free_cands(cands);
return err;
}
}

return bpf_core_apply_relo_insn(prog_name, insn, insn_idx, relo, relo_idx, local_btf, cands);
}

static int
bpf_object__relocate_core(struct bpf_object *obj, const char *targ_btf_path)
{
Expand Down

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