From 6ebaa3fb88bbe4c33a0e01ce27007e1dd4fd133c Mon Sep 17 00:00:00 2001 From: Eduard Zingerman Date: Wed, 6 Mar 2024 12:45:26 +0200 Subject: libbpf: Rewrite btf datasec names starting from '?' Optional struct_ops maps are defined using question mark at the start of the section name, e.g.: SEC("?.struct_ops") struct test_ops optional_map = { ... }; This commit teaches libbpf to detect if kernel allows '?' prefix in datasec names, and if it doesn't then to rewrite such names by replacing '?' with '_', e.g.: DATASEC ?.struct_ops -> DATASEC _.struct_ops Signed-off-by: Eduard Zingerman Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20240306104529.6453-13-eddyz87@gmail.com --- tools/lib/bpf/libbpf.c | 19 +++++++++++++++++-- 1 file changed, 17 insertions(+), 2 deletions(-) (limited to 'tools/lib/bpf/libbpf.c') diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index ec0f508b853d..672fca94ff53 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c @@ -2869,6 +2869,11 @@ static bool section_have_execinstr(struct bpf_object *obj, int idx) return sh->sh_flags & SHF_EXECINSTR; } +static bool starts_with_qmark(const char *s) +{ + return s && s[0] == '?'; +} + static bool btf_needs_sanitization(struct bpf_object *obj) { bool has_func_global = kernel_supports(obj, FEAT_BTF_GLOBAL_FUNC); @@ -2878,9 +2883,10 @@ static bool btf_needs_sanitization(struct bpf_object *obj) bool has_decl_tag = kernel_supports(obj, FEAT_BTF_DECL_TAG); bool has_type_tag = kernel_supports(obj, FEAT_BTF_TYPE_TAG); bool has_enum64 = kernel_supports(obj, FEAT_BTF_ENUM64); + bool has_qmark_datasec = kernel_supports(obj, FEAT_BTF_QMARK_DATASEC); return !has_func || !has_datasec || !has_func_global || !has_float || - !has_decl_tag || !has_type_tag || !has_enum64; + !has_decl_tag || !has_type_tag || !has_enum64 || !has_qmark_datasec; } static int bpf_object__sanitize_btf(struct bpf_object *obj, struct btf *btf) @@ -2892,6 +2898,7 @@ static int bpf_object__sanitize_btf(struct bpf_object *obj, struct btf *btf) bool has_decl_tag = kernel_supports(obj, FEAT_BTF_DECL_TAG); bool has_type_tag = kernel_supports(obj, FEAT_BTF_TYPE_TAG); bool has_enum64 = kernel_supports(obj, FEAT_BTF_ENUM64); + bool has_qmark_datasec = kernel_supports(obj, FEAT_BTF_QMARK_DATASEC); int enum64_placeholder_id = 0; struct btf_type *t; int i, j, vlen; @@ -2918,7 +2925,7 @@ static int bpf_object__sanitize_btf(struct bpf_object *obj, struct btf *btf) name = (char *)btf__name_by_offset(btf, t->name_off); while (*name) { - if (*name == '.') + if (*name == '.' || *name == '?') *name = '_'; name++; } @@ -2933,6 +2940,14 @@ static int bpf_object__sanitize_btf(struct bpf_object *obj, struct btf *btf) vt = (void *)btf__type_by_id(btf, v->type); m->name_off = vt->name_off; } + } else if (!has_qmark_datasec && btf_is_datasec(t) && + starts_with_qmark(btf__name_by_offset(btf, t->name_off))) { + /* replace '?' prefix with '_' for DATASEC names */ + char *name; + + name = (char *)btf__name_by_offset(btf, t->name_off); + if (name[0] == '?') + name[0] = '_'; } else if (!has_func && btf_is_func_proto(t)) { /* replace FUNC_PROTO with ENUM */ vlen = btf_vlen(t); -- cgit v1.2.3