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libbpf: BTF relocation followup fixing naming, loop logic

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Use less verbose names in BTF relocation code and fix off-by-one error
and typo in btf_relocate.c.  Simplify loop over matching distilled
types, moving from assigning a _next value in loop body to moving
match check conditions into the guard.

Suggested-by: Andrii Nakryiko <andrii.nakryiko@gmail.com>
Signed-off-by: Alan Maguire <alan.maguire@oracle.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/bpf/20240620091733.1967885-2-alan.maguire@oracle.com
This commit is contained in:
Alan Maguire 2024-06-20 10:17:28 +01:00 • committed by Andrii Nakryiko
parent cd387ce548
commit d1cf840854
1 changed files with 31 additions and 41 deletions
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72
tools/lib/bpf/btf_relocate.c
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@ -160,7 +160,7 @@ static int btf_mark_embedded_composite_type_ids(struct btf_relocate *r, __u32 i)
*/ */
static int btf_relocate_map_distilled_base(struct btf_relocate *r) static int btf_relocate_map_distilled_base(struct btf_relocate *r)
{ {
struct btf_name_info *dist_base_info_sorted, *dist_base_info_sorted_end; struct btf_name_info *info, *info_end;
struct btf_type *base_t, *dist_t; struct btf_type *base_t, *dist_t;
__u8 *base_name_cnt = NULL; __u8 *base_name_cnt = NULL;
int err = 0; int err = 0;
@ -169,26 +169,24 @@ static int btf_relocate_map_distilled_base(struct btf_relocate *r)
/* generate a sort index array of name/type ids sorted by name for /* generate a sort index array of name/type ids sorted by name for
* distilled base BTF to speed name-based lookups. * distilled base BTF to speed name-based lookups.
*/ */
dist_base_info_sorted = calloc(r->nr_dist_base_types, sizeof(*dist_base_info_sorted)); info = calloc(r->nr_dist_base_types, sizeof(*info));
if (!dist_base_info_sorted) { if (!info) {
err = -ENOMEM; err = -ENOMEM;
goto done; goto done;
} }
dist_base_info_sorted_end = dist_base_info_sorted + r->nr_dist_base_types; info_end = info + r->nr_dist_base_types;
for (id = 0; id < r->nr_dist_base_types; id++) { for (id = 0; id < r->nr_dist_base_types; id++) {
dist_t = btf_type_by_id(r->dist_base_btf, id); dist_t = btf_type_by_id(r->dist_base_btf, id);
dist_base_info_sorted[id].name = btf__name_by_offset(r->dist_base_btf, info[id].name = btf__name_by_offset(r->dist_base_btf, dist_t->name_off);
dist_t->name_off); info[id].id = id;
dist_base_info_sorted[id].id = id; info[id].size = dist_t->size;
dist_base_info_sorted[id].size = dist_t->size; info[id].needs_size = true;
dist_base_info_sorted[id].needs_size = true;
} }
qsort(dist_base_info_sorted, r->nr_dist_base_types, sizeof(*dist_base_info_sorted), qsort(info, r->nr_dist_base_types, sizeof(*info), cmp_btf_name_size);
cmp_btf_name_size);
/* Mark distilled base struct/union members of split BTF structs/unions /* Mark distilled base struct/union members of split BTF structs/unions
* in id_map with BTF_IS_EMBEDDED; this signals that these types * in id_map with BTF_IS_EMBEDDED; this signals that these types
* need to match both name and size, otherwise embeddding the base * need to match both name and size, otherwise embedding the base
* struct/union in the split type is invalid. * struct/union in the split type is invalid.
*/ */
for (id = r->nr_dist_base_types; id < r->nr_split_types; id++) { for (id = r->nr_dist_base_types; id < r->nr_split_types; id++) {
@ -216,8 +214,7 @@ static int btf_relocate_map_distilled_base(struct btf_relocate *r)
/* Now search base BTF for matching distilled base BTF types. */ /* Now search base BTF for matching distilled base BTF types. */
for (id = 1; id < r->nr_base_types; id++) { for (id = 1; id < r->nr_base_types; id++) {
struct btf_name_info *dist_name_info, *dist_name_info_next = NULL; struct btf_name_info *dist_info, base_info = {};
struct btf_name_info base_name_info = {};
int dist_kind, base_kind; int dist_kind, base_kind;
base_t = btf_type_by_id(r->base_btf, id); base_t = btf_type_by_id(r->base_btf, id);
@ -225,16 +222,16 @@ static int btf_relocate_map_distilled_base(struct btf_relocate *r)
if (!base_t->name_off) if (!base_t->name_off)
continue; continue;
base_kind = btf_kind(base_t); base_kind = btf_kind(base_t);
base_name_info.id = id; base_info.id = id;
base_name_info.name = btf__name_by_offset(r->base_btf, base_t->name_off); base_info.name = btf__name_by_offset(r->base_btf, base_t->name_off);
switch (base_kind) { switch (base_kind) {
case BTF_KIND_INT: case BTF_KIND_INT:
case BTF_KIND_FLOAT: case BTF_KIND_FLOAT:
case BTF_KIND_ENUM: case BTF_KIND_ENUM:
case BTF_KIND_ENUM64: case BTF_KIND_ENUM64:
/* These types should match both name and size */ /* These types should match both name and size */
base_name_info.needs_size = true; base_info.needs_size = true;
base_name_info.size = base_t->size; base_info.size = base_t->size;
break; break;
case BTF_KIND_FWD: case BTF_KIND_FWD:
/* No size considerations for fwds. */ /* No size considerations for fwds. */
@ -248,31 +245,24 @@ static int btf_relocate_map_distilled_base(struct btf_relocate *r)
* unless corresponding _base_ types to match them are * unless corresponding _base_ types to match them are
* missing. * missing.
*/ */
base_name_info.needs_size = base_name_cnt[base_t->name_off] > 1; base_info.needs_size = base_name_cnt[base_t->name_off] > 1;
base_name_info.size = base_t->size; base_info.size = base_t->size;
break; break;
default: default:
continue; continue;
} }
/* iterate over all matching distilled base types */ /* iterate over all matching distilled base types */
for (dist_name_info = search_btf_name_size(&base_name_info, dist_base_info_sorted, for (dist_info = search_btf_name_size(&base_info, info, r->nr_dist_base_types);
r->nr_dist_base_types); dist_info != NULL && dist_info < info_end &&
dist_name_info != NULL; dist_name_info = dist_name_info_next) { cmp_btf_name_size(&base_info, dist_info) == 0;
/* Are there more distilled matches to process after dist_info++) {
* this one? if (!dist_info->id || dist_info->id >= r->nr_dist_base_types) {
*/
dist_name_info_next = dist_name_info + 1;
if (dist_name_info_next >= dist_base_info_sorted_end ||
cmp_btf_name_size(&base_name_info, dist_name_info_next))
dist_name_info_next = NULL;
if (!dist_name_info->id || dist_name_info->id > r->nr_dist_base_types) {
pr_warn("base BTF id [%d] maps to invalid distilled base BTF id [%d]\n", pr_warn("base BTF id [%d] maps to invalid distilled base BTF id [%d]\n",
id, dist_name_info->id); id, dist_info->id);
err = -EINVAL; err = -EINVAL;
goto done; goto done;
} }
dist_t = btf_type_by_id(r->dist_base_btf, dist_name_info->id); dist_t = btf_type_by_id(r->dist_base_btf, dist_info->id);
dist_kind = btf_kind(dist_t); dist_kind = btf_kind(dist_t);
/* Validate that the found distilled type is compatible. /* Validate that the found distilled type is compatible.
@ -319,15 +309,15 @@ static int btf_relocate_map_distilled_base(struct btf_relocate *r)
/* size verification is required for embedded /* size verification is required for embedded
* struct/unions. * struct/unions.
*/ */
if (r->id_map[dist_name_info->id] == BTF_IS_EMBEDDED && if (r->id_map[dist_info->id] == BTF_IS_EMBEDDED &&
base_t->size != dist_t->size) base_t->size != dist_t->size)
continue; continue;
break; break;
default: default:
continue; continue;
} }
if (r->id_map[dist_name_info->id] && if (r->id_map[dist_info->id] &&
r->id_map[dist_name_info->id] != BTF_IS_EMBEDDED) { r->id_map[dist_info->id] != BTF_IS_EMBEDDED) {
/* we already have a match; this tells us that /* we already have a match; this tells us that
* multiple base types of the same name * multiple base types of the same name
* have the same size, since for cases where * have the same size, since for cases where
@ -337,13 +327,13 @@ static int btf_relocate_map_distilled_base(struct btf_relocate *r)
* to in base BTF, so error out. * to in base BTF, so error out.
*/ */
pr_warn("distilled base BTF type '%s' [%u], size %u has multiple candidates of the same size (ids [%u, %u]) in base BTF\n", pr_warn("distilled base BTF type '%s' [%u], size %u has multiple candidates of the same size (ids [%u, %u]) in base BTF\n",
base_name_info.name, dist_name_info->id, base_info.name, dist_info->id,
base_t->size, id, r->id_map[dist_name_info->id]); base_t->size, id, r->id_map[dist_info->id]);
err = -EINVAL; err = -EINVAL;
goto done; goto done;
} }
/* map id and name */ /* map id and name */
r->id_map[dist_name_info->id] = id; r->id_map[dist_info->id] = id;
r->str_map[dist_t->name_off] = base_t->name_off; r->str_map[dist_t->name_off] = base_t->name_off;
} }
} }
@ -362,7 +352,7 @@ static int btf_relocate_map_distilled_base(struct btf_relocate *r)
} }
done: done:
free(base_name_cnt); free(base_name_cnt);
free(dist_base_info_sorted); free(info);
return err; return err;
} }