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authorAlexei Starovoitov <ast@kernel.org>2021-12-03 10:28:36 -0800
committerAndrii Nakryiko <andrii@kernel.org>2021-12-03 13:21:59 -0800
commit78c1f8d0634cc35da613d844eda7c849fc50f643 (patch)
tree107e51571324b5bc0cbf35095e5359d1f83115fe /tools/lib
parent0bf40542c05ef62997738cd45eea553415adb045 (diff)
downloadlinux-78c1f8d0634cc35da613d844eda7c849fc50f643.tar.bz2
libbpf: Reduce bpf_core_apply_relo_insn() stack usage.
Reduce bpf_core_apply_relo_insn() stack usage and bump BPF_CORE_SPEC_MAX_LEN limit back to 64. Fixes: 29db4bea1d10 ("bpf: Prepare relo_core.c for kernel duty.") Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/bpf/20211203182836.16646-1-alexei.starovoitov@gmail.com
Diffstat (limited to 'tools/lib')
-rw-r--r--tools/lib/bpf/libbpf.c4
-rw-r--r--tools/lib/bpf/relo_core.c62
-rw-r--r--tools/lib/bpf/relo_core.h30
3 files changed, 51 insertions, 45 deletions
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index de260c94e418..6db0b5e8540e 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -5515,6 +5515,7 @@ static int bpf_core_apply_relo(struct bpf_program *prog,
const struct btf *local_btf,
struct hashmap *cand_cache)
{
+ struct bpf_core_spec specs_scratch[3] = {};
const void *type_key = u32_as_hash_key(relo->type_id);
struct bpf_core_cand_list *cands = NULL;
const char *prog_name = prog->name;
@@ -5569,7 +5570,8 @@ static int bpf_core_apply_relo(struct bpf_program *prog,
}
}
- return bpf_core_apply_relo_insn(prog_name, insn, insn_idx, relo, relo_idx, local_btf, cands);
+ return bpf_core_apply_relo_insn(prog_name, insn, insn_idx, relo,
+ relo_idx, local_btf, cands, specs_scratch);
}
static int
diff --git a/tools/lib/bpf/relo_core.c b/tools/lib/bpf/relo_core.c
index d194fb9306ed..32464f0ab4b1 100644
--- a/tools/lib/bpf/relo_core.c
+++ b/tools/lib/bpf/relo_core.c
@@ -68,33 +68,6 @@ enum libbpf_print_level {
#include "libbpf_internal.h"
#endif
-#define BPF_CORE_SPEC_MAX_LEN 32
-
-/* represents BPF CO-RE field or array element accessor */
-struct bpf_core_accessor {
- __u32 type_id; /* struct/union type or array element type */
- __u32 idx; /* field index or array index */
- const char *name; /* field name or NULL for array accessor */
-};
-
-struct bpf_core_spec {
- const struct btf *btf;
- /* high-level spec: named fields and array indices only */
- struct bpf_core_accessor spec[BPF_CORE_SPEC_MAX_LEN];
- /* original unresolved (no skip_mods_or_typedefs) root type ID */
- __u32 root_type_id;
- /* CO-RE relocation kind */
- enum bpf_core_relo_kind relo_kind;
- /* high-level spec length */
- int len;
- /* raw, low-level spec: 1-to-1 with accessor spec string */
- int raw_spec[BPF_CORE_SPEC_MAX_LEN];
- /* raw spec length */
- int raw_len;
- /* field bit offset represented by spec */
- __u32 bit_offset;
-};
-
static bool is_flex_arr(const struct btf *btf,
const struct bpf_core_accessor *acc,
const struct btf_array *arr)
@@ -1200,9 +1173,12 @@ int bpf_core_apply_relo_insn(const char *prog_name, struct bpf_insn *insn,
const struct bpf_core_relo *relo,
int relo_idx,
const struct btf *local_btf,
- struct bpf_core_cand_list *cands)
+ struct bpf_core_cand_list *cands,
+ struct bpf_core_spec *specs_scratch)
{
- struct bpf_core_spec local_spec, cand_spec, targ_spec = {};
+ struct bpf_core_spec *local_spec = &specs_scratch[0];
+ struct bpf_core_spec *cand_spec = &specs_scratch[1];
+ struct bpf_core_spec *targ_spec = &specs_scratch[2];
struct bpf_core_relo_res cand_res, targ_res;
const struct btf_type *local_type;
const char *local_name;
@@ -1221,7 +1197,7 @@ int bpf_core_apply_relo_insn(const char *prog_name, struct bpf_insn *insn,
return -EINVAL;
err = bpf_core_parse_spec(prog_name, local_btf, local_id, spec_str,
- relo->kind, &local_spec);
+ relo->kind, local_spec);
if (err) {
pr_warn("prog '%s': relo #%d: parsing [%d] %s %s + %s failed: %d\n",
prog_name, relo_idx, local_id, btf_kind_str(local_type),
@@ -1232,15 +1208,15 @@ int bpf_core_apply_relo_insn(const char *prog_name, struct bpf_insn *insn,
pr_debug("prog '%s': relo #%d: kind <%s> (%d), spec is ", prog_name,
relo_idx, core_relo_kind_str(relo->kind), relo->kind);
- bpf_core_dump_spec(prog_name, LIBBPF_DEBUG, &local_spec);
+ bpf_core_dump_spec(prog_name, LIBBPF_DEBUG, local_spec);
libbpf_print(LIBBPF_DEBUG, "\n");
/* TYPE_ID_LOCAL relo is special and doesn't need candidate search */
if (relo->kind == BPF_CORE_TYPE_ID_LOCAL) {
targ_res.validate = true;
targ_res.poison = false;
- targ_res.orig_val = local_spec.root_type_id;
- targ_res.new_val = local_spec.root_type_id;
+ targ_res.orig_val = local_spec->root_type_id;
+ targ_res.new_val = local_spec->root_type_id;
goto patch_insn;
}
@@ -1253,38 +1229,38 @@ int bpf_core_apply_relo_insn(const char *prog_name, struct bpf_insn *insn,
for (i = 0, j = 0; i < cands->len; i++) {
- err = bpf_core_spec_match(&local_spec, cands->cands[i].btf,
- cands->cands[i].id, &cand_spec);
+ err = bpf_core_spec_match(local_spec, cands->cands[i].btf,
+ cands->cands[i].id, cand_spec);
if (err < 0) {
pr_warn("prog '%s': relo #%d: error matching candidate #%d ",
prog_name, relo_idx, i);
- bpf_core_dump_spec(prog_name, LIBBPF_WARN, &cand_spec);
+ bpf_core_dump_spec(prog_name, LIBBPF_WARN, cand_spec);
libbpf_print(LIBBPF_WARN, ": %d\n", err);
return err;
}
pr_debug("prog '%s': relo #%d: %s candidate #%d ", prog_name,
relo_idx, err == 0 ? "non-matching" : "matching", i);
- bpf_core_dump_spec(prog_name, LIBBPF_DEBUG, &cand_spec);
+ bpf_core_dump_spec(prog_name, LIBBPF_DEBUG, cand_spec);
libbpf_print(LIBBPF_DEBUG, "\n");
if (err == 0)
continue;
- err = bpf_core_calc_relo(prog_name, relo, relo_idx, &local_spec, &cand_spec, &cand_res);
+ err = bpf_core_calc_relo(prog_name, relo, relo_idx, local_spec, cand_spec, &cand_res);
if (err)
return err;
if (j == 0) {
targ_res = cand_res;
- targ_spec = cand_spec;
- } else if (cand_spec.bit_offset != targ_spec.bit_offset) {
+ *targ_spec = *cand_spec;
+ } else if (cand_spec->bit_offset != targ_spec->bit_offset) {
/* if there are many field relo candidates, they
* should all resolve to the same bit offset
*/
pr_warn("prog '%s': relo #%d: field offset ambiguity: %u != %u\n",
- prog_name, relo_idx, cand_spec.bit_offset,
- targ_spec.bit_offset);
+ prog_name, relo_idx, cand_spec->bit_offset,
+ targ_spec->bit_offset);
return -EINVAL;
} else if (cand_res.poison != targ_res.poison || cand_res.new_val != targ_res.new_val) {
/* all candidates should result in the same relocation
@@ -1328,7 +1304,7 @@ int bpf_core_apply_relo_insn(const char *prog_name, struct bpf_insn *insn,
prog_name, relo_idx);
/* calculate single target relo result explicitly */
- err = bpf_core_calc_relo(prog_name, relo, relo_idx, &local_spec, NULL, &targ_res);
+ err = bpf_core_calc_relo(prog_name, relo, relo_idx, local_spec, NULL, &targ_res);
if (err)
return err;
}
diff --git a/tools/lib/bpf/relo_core.h b/tools/lib/bpf/relo_core.h
index 4f864b8e33b7..17799819ad7c 100644
--- a/tools/lib/bpf/relo_core.h
+++ b/tools/lib/bpf/relo_core.h
@@ -17,11 +17,39 @@ struct bpf_core_cand_list {
int len;
};
+#define BPF_CORE_SPEC_MAX_LEN 64
+
+/* represents BPF CO-RE field or array element accessor */
+struct bpf_core_accessor {
+ __u32 type_id; /* struct/union type or array element type */
+ __u32 idx; /* field index or array index */
+ const char *name; /* field name or NULL for array accessor */
+};
+
+struct bpf_core_spec {
+ const struct btf *btf;
+ /* high-level spec: named fields and array indices only */
+ struct bpf_core_accessor spec[BPF_CORE_SPEC_MAX_LEN];
+ /* original unresolved (no skip_mods_or_typedefs) root type ID */
+ __u32 root_type_id;
+ /* CO-RE relocation kind */
+ enum bpf_core_relo_kind relo_kind;
+ /* high-level spec length */
+ int len;
+ /* raw, low-level spec: 1-to-1 with accessor spec string */
+ int raw_spec[BPF_CORE_SPEC_MAX_LEN];
+ /* raw spec length */
+ int raw_len;
+ /* field bit offset represented by spec */
+ __u32 bit_offset;
+};
+
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 bpf_core_cand_list *cands);
+ struct bpf_core_cand_list *cands,
+ struct bpf_core_spec *specs_scratch);
int bpf_core_types_are_compat(const struct btf *local_btf, __u32 local_id,
const struct btf *targ_btf, __u32 targ_id);