Re: [PATCH 06/10] libbpf: Add libbpf_kallsyms_parse function

Andrii Nakryiko
2022-03-04T23:11:39Z

On Tue, Feb 22, 2022 at 9:07 AM Jiri Olsa <jolsa@kernel.org> wrote:
>
> Move the kallsyms parsing in internal libbpf_kallsyms_parse
> function, so it can be used from other places.
>
> It will be used in following changes.
>
> Signed-off-by: Jiri Olsa <jolsa@kernel.org>
> ---

LGTM

Acked-by: Andrii Nakryiko <andrii@kernel.org>

> tools/lib/bpf/libbpf.c | 62 ++++++++++++++++++++-------------
> tools/lib/bpf/libbpf_internal.h | 5 +++
> 2 files changed, 43 insertions(+), 24 deletions(-)
>
> diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
> index ad43b6ce825e..fb530b004a0d 100644
> --- a/tools/lib/bpf/libbpf.c
> +++ b/tools/lib/bpf/libbpf.c
> @@ -7172,12 +7172,10 @@ static int bpf_object__sanitize_maps(struct bpf_object *obj)
> return 0;
> }
>
> -static int bpf_object__read_kallsyms_file(struct bpf_object *obj)
> +int libbpf_kallsyms_parse(kallsyms_cb_t cb, void *ctx)
> {
> char sym_type, sym_name[500];
> unsigned long long sym_addr;
> - const struct btf_type *t;
> - struct extern_desc *ext;
> int ret, err = 0;
> FILE *f;
>
> @@ -7196,35 +7194,51 @@ static int bpf_object__read_kallsyms_file(struct bpf_object *obj)
> if (ret != 3) {
> pr_warn("failed to read kallsyms entry: %d\n", ret);
> err = -EINVAL;
> - goto out;
> + break;
> }
>
> - ext = find_extern_by_name(obj, sym_name);
> - if (!ext || ext->type != EXT_KSYM)
> - continue;
> -
> - t = btf__type_by_id(obj->btf, ext->btf_id);
> - if (!btf_is_var(t))
> - continue;
> -
> - if (ext->is_set && ext->ksym.addr != sym_addr) {
> - pr_warn("extern (ksym) '%s' resolution is ambiguous: 0x%llx or 0x%llx\n",
> - sym_name, ext->ksym.addr, sym_addr);
> - err = -EINVAL;
> - goto out;
> - }
> - if (!ext->is_set) {
> - ext->is_set = true;
> - ext->ksym.addr = sym_addr;
> - pr_debug("extern (ksym) %s=0x%llx\n", sym_name, sym_addr);
> - }
> + err = cb(sym_addr, sym_type, sym_name, ctx);
> + if (err)
> + break;
> }
>
> -out:
> fclose(f);
> return err;
> }
>
> +static int kallsyms_cb(unsigned long long sym_addr, char sym_type,
> + const char *sym_name, void *ctx)
> +{
> + struct bpf_object *obj = ctx;
> + const struct btf_type *t;
> + struct extern_desc *ext;
> +
> + ext = find_extern_by_name(obj, sym_name);
> + if (!ext || ext->type != EXT_KSYM)
> + return 0;
> +
> + t = btf__type_by_id(obj->btf, ext->btf_id);
> + if (!btf_is_var(t))
> + return 0;
> +
> + if (ext->is_set && ext->ksym.addr != sym_addr) {
> + pr_warn("extern (ksym) '%s' resolution is ambiguous: 0x%llx or 0x%llx\n",
> + sym_name, ext->ksym.addr, sym_addr);
> + return -EINVAL;
> + }
> + if (!ext->is_set) {
> + ext->is_set = true;
> + ext->ksym.addr = sym_addr;
> + pr_debug("extern (ksym) %s=0x%llx\n", sym_name, sym_addr);
> + }
> + return 0;
> +}
> +
> +static int bpf_object__read_kallsyms_file(struct bpf_object *obj)
> +{
> + return libbpf_kallsyms_parse(kallsyms_cb, obj);
> +}
> +
> static int find_ksym_btf_id(struct bpf_object *obj, const char *ksym_name,
> __u16 kind, struct btf **res_btf,
> struct module_btf **res_mod_btf)
> diff --git a/tools/lib/bpf/libbpf_internal.h b/tools/lib/bpf/libbpf_internal.h
> index 4fda8bdf0a0d..b6247dc7f8eb 100644
> --- a/tools/lib/bpf/libbpf_internal.h
> +++ b/tools/lib/bpf/libbpf_internal.h
> @@ -449,6 +449,11 @@ __s32 btf__find_by_name_kind_own(const struct btf *btf, const char *type_name,
>
> extern enum libbpf_strict_mode libbpf_mode;
>
> +typedef int (*kallsyms_cb_t)(unsigned long long sym_addr, char sym_type,
> + const char *sym_name, void *ctx);
> +
> +int libbpf_kallsyms_parse(kallsyms_cb_t cb, void *arg);
> +
> /* handle direct returned errors */
> static inline int libbpf_err(int ret)
> {
> --
> 2.35.1
>