From 92b57121ca79b286bef4f304e887272f3f2d86bb Mon Sep 17 00:00:00 2001 From: Okash Khawaja Date: Fri, 13 Jul 2018 21:57:02 -0700 Subject: [PATCH] bpf: btf: export btf types and name by offset from lib This patch introduces btf__resolve_type() function and exports two existing functions from libbpf. btf__resolve_type follows modifier types like const and typedef until it hits a type which actually takes up memory, and then returns it. This function follows similar pattern to btf__resolve_size but instead of computing size, it just returns the type. These functions will be used in the followig patch which parses information inside array of `struct btf_type *`. btf_name_by_offset is used for printing variable names. Signed-off-by: Okash Khawaja Acked-by: Martin KaFai Lau Acked-by: Song Liu Reviewed-by: Jakub Kicinski Signed-off-by: Daniel Borkmann --- tools/lib/bpf/btf.c | 65 +++++++++++++++++++++++++++++++-------------- tools/lib/bpf/btf.h | 3 +++ 2 files changed, 48 insertions(+), 20 deletions(-) diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c index 8c54a4b6f187..03161be094b4 100644 --- a/tools/lib/bpf/btf.c +++ b/tools/lib/bpf/btf.c @@ -17,6 +17,11 @@ #define BTF_MAX_NR_TYPES 65535 +#define IS_MODIFIER(k) (((k) == BTF_KIND_TYPEDEF) || \ + ((k) == BTF_KIND_VOLATILE) || \ + ((k) == BTF_KIND_CONST) || \ + ((k) == BTF_KIND_RESTRICT)) + static struct btf_type btf_void; struct btf { @@ -33,14 +38,6 @@ struct btf { int fd; }; -static const char *btf_name_by_offset(const struct btf *btf, uint32_t offset) -{ - if (offset < btf->hdr->str_len) - return &btf->strings[offset]; - else - return NULL; -} - static int btf_add_type(struct btf *btf, struct btf_type *t) { if (btf->types_size - btf->nr_types < 2) { @@ -190,15 +187,6 @@ static int btf_parse_type_sec(struct btf *btf, btf_print_fn_t err_log) return 0; } -static const struct btf_type *btf_type_by_id(const struct btf *btf, - uint32_t type_id) -{ - if (type_id > btf->nr_types) - return NULL; - - return btf->types[type_id]; -} - static bool btf_type_is_void(const struct btf_type *t) { return t == &btf_void || BTF_INFO_KIND(t->info) == BTF_KIND_FWD; @@ -234,7 +222,7 @@ int64_t btf__resolve_size(const struct btf *btf, uint32_t type_id) int64_t size = -1; int i; - t = btf_type_by_id(btf, type_id); + t = btf__type_by_id(btf, type_id); for (i = 0; i < MAX_RESOLVE_DEPTH && !btf_type_is_void_or_null(t); i++) { size = btf_type_size(t); @@ -259,7 +247,7 @@ int64_t btf__resolve_size(const struct btf *btf, uint32_t type_id) return -EINVAL; } - t = btf_type_by_id(btf, type_id); + t = btf__type_by_id(btf, type_id); } if (size < 0) @@ -271,6 +259,26 @@ int64_t btf__resolve_size(const struct btf *btf, uint32_t type_id) return nelems * size; } +int btf__resolve_type(const struct btf *btf, __u32 type_id) +{ + const struct btf_type *t; + int depth = 0; + + t = btf__type_by_id(btf, type_id); + while (depth < MAX_RESOLVE_DEPTH && + !btf_type_is_void_or_null(t) && + IS_MODIFIER(BTF_INFO_KIND(t->info))) { + type_id = t->type; + t = btf__type_by_id(btf, type_id); + depth++; + } + + if (depth == MAX_RESOLVE_DEPTH || btf_type_is_void_or_null(t)) + return -EINVAL; + + return type_id; +} + int32_t btf__find_by_name(const struct btf *btf, const char *type_name) { uint32_t i; @@ -280,7 +288,7 @@ int32_t btf__find_by_name(const struct btf *btf, const char *type_name) for (i = 1; i <= btf->nr_types; i++) { const struct btf_type *t = btf->types[i]; - const char *name = btf_name_by_offset(btf, t->name_off); + const char *name = btf__name_by_offset(btf, t->name_off); if (name && !strcmp(type_name, name)) return i; @@ -371,3 +379,20 @@ int btf__fd(const struct btf *btf) { return btf->fd; } + +const char *btf__name_by_offset(const struct btf *btf, __u32 offset) +{ + if (offset < btf->hdr->str_len) + return &btf->strings[offset]; + else + return NULL; +} + +const struct btf_type *btf__type_by_id(const struct btf *btf, + __u32 type_id) +{ + if (type_id > btf->nr_types) + return NULL; + + return btf->types[type_id]; +} diff --git a/tools/lib/bpf/btf.h b/tools/lib/bpf/btf.h index 74bb344035bb..24f361d99a5e 100644 --- a/tools/lib/bpf/btf.h +++ b/tools/lib/bpf/btf.h @@ -17,6 +17,9 @@ void btf__free(struct btf *btf); struct btf *btf__new(uint8_t *data, uint32_t size, btf_print_fn_t err_log); int32_t btf__find_by_name(const struct btf *btf, const char *type_name); int64_t btf__resolve_size(const struct btf *btf, uint32_t type_id); +int btf__resolve_type(const struct btf *btf, __u32 type_id); int btf__fd(const struct btf *btf); +const char *btf__name_by_offset(const struct btf *btf, __u32 offset); +const struct btf_type *btf__type_by_id(const struct btf *btf, __u32 type_id); #endif -- GitLab