[bpf-next,v5,1/6] libbpf: expose resolve_func_ptr() through libbpf_internal.h.

Commit Message

Kui-Feng Lee Feb. 27, 2024, 1:04 a.m. UTC

bpftool is going to reuse this helper function to support shadow types of
struct_ops maps.

Signed-off-by: Kui-Feng Lee <[e-mail]>
---
 tools/lib/bpf/libbpf.c          | 2 +-
 tools/lib/bpf/libbpf_internal.h | 2 ++
 2 files changed, 3 insertions(+), 1 deletion(-)

Comments

Quentin Monnet Feb. 28, 2024, 2:38 p.m. UTC | #1

2024-02-27 01:04 UTC+0000 ~ Kui-Feng Lee <[e-mail]>
> bpftool is going to reuse this helper function to support shadow types of
> struct_ops maps.
> 
> Signed-off-by: Kui-Feng Lee <[e-mail]>

Acked-by: Quentin Monnet <[e-mail]>

Andrii Nakryiko Feb. 28, 2024, 5:45 p.m. UTC | #2

On Mon, Feb 26, 2024 at 5:04 PM Kui-Feng Lee <[e-mail]> wrote:
>
> bpftool is going to reuse this helper function to support shadow types of
> struct_ops maps.
>
> Signed-off-by: Kui-Feng Lee <[e-mail]>
> ---
>  tools/lib/bpf/libbpf.c          | 2 +-
>  tools/lib/bpf/libbpf_internal.h | 2 ++
>  2 files changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
> index 01f407591a92..ef8fd20f33ca 100644
> --- a/tools/lib/bpf/libbpf.c
> +++ b/tools/lib/bpf/libbpf.c
> @@ -2145,7 +2145,7 @@ skip_mods_and_typedefs(const struct btf *btf, __u32 id, __u32 *res_id)
>         return t;
>  }
>
> -static const struct btf_type *
> +const struct btf_type *
>  resolve_func_ptr(const struct btf *btf, __u32 id, __u32 *res_id)
>  {
>         const struct btf_type *t;
> diff --git a/tools/lib/bpf/libbpf_internal.h b/tools/lib/bpf/libbpf_internal.h
> index ad936ac5e639..17e6d381da6a 100644
> --- a/tools/lib/bpf/libbpf_internal.h
> +++ b/tools/lib/bpf/libbpf_internal.h
> @@ -234,6 +234,8 @@ struct btf_type;
>  struct btf_type *btf_type_by_id(const struct btf *btf, __u32 type_id);
>  const char *btf_kind_str(const struct btf_type *t);
>  const struct btf_type *skip_mods_and_typedefs(const struct btf *btf, __u32 id, __u32 *res_id);
> +/* This function is exposed to bpftool */
> +const struct btf_type *resolve_func_ptr(const struct btf *btf, __u32 id, __u32 *res_id);

it's trivial helper, there is no need for bpftool to reuse it, let's
just implement a local helper for bpftool. We should have done the
same with skip_mods_and_typedefs() in gen.c, but oh well, we can fix
that later.

Generally speaking, I'd like to minimize amount of internal functions
exposed from libbpf to bpftool. It's justified if the logic is
non-trivial, but resolve_func_ptr() is not such case.

>
>  static inline enum btf_func_linkage btf_func_linkage(const struct btf_type *t)
>  {
> --
> 2.34.1
>

Kui-Feng Lee Feb. 28, 2024, 6:27 p.m. UTC | #3

On 2/28/24 09:45, Andrii Nakryiko wrote:
> On Mon, Feb 26, 2024 at 5:04 PM Kui-Feng Lee <[e-mail]> wrote:
>>
>> bpftool is going to reuse this helper function to support shadow types of
>> struct_ops maps.
>>
>> Signed-off-by: Kui-Feng Lee <[e-mail]>
>> ---
>>   tools/lib/bpf/libbpf.c          | 2 +-
>>   tools/lib/bpf/libbpf_internal.h | 2 ++
>>   2 files changed, 3 insertions(+), 1 deletion(-)
>>
>> diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
>> index 01f407591a92..ef8fd20f33ca 100644
>> --- a/tools/lib/bpf/libbpf.c
>> +++ b/tools/lib/bpf/libbpf.c
>> @@ -2145,7 +2145,7 @@ skip_mods_and_typedefs(const struct btf *btf, __u32 id, __u32 *res_id)
>>          return t;
>>   }
>>
>> -static const struct btf_type *
>> +const struct btf_type *
>>   resolve_func_ptr(const struct btf *btf, __u32 id, __u32 *res_id)
>>   {
>>          const struct btf_type *t;
>> diff --git a/tools/lib/bpf/libbpf_internal.h b/tools/lib/bpf/libbpf_internal.h
>> index ad936ac5e639..17e6d381da6a 100644
>> --- a/tools/lib/bpf/libbpf_internal.h
>> +++ b/tools/lib/bpf/libbpf_internal.h
>> @@ -234,6 +234,8 @@ struct btf_type;
>>   struct btf_type *btf_type_by_id(const struct btf *btf, __u32 type_id);
>>   const char *btf_kind_str(const struct btf_type *t);
>>   const struct btf_type *skip_mods_and_typedefs(const struct btf *btf, __u32 id, __u32 *res_id);
>> +/* This function is exposed to bpftool */
>> +const struct btf_type *resolve_func_ptr(const struct btf *btf, __u32 id, __u32 *res_id);
> 
> it's trivial helper, there is no need for bpftool to reuse it, let's
> just implement a local helper for bpftool. We should have done the
> same with skip_mods_and_typedefs() in gen.c, but oh well, we can fix
> that later.
> 
> Generally speaking, I'd like to minimize amount of internal functions
> exposed from libbpf to bpftool. It's justified if the logic is
> non-trivial, but resolve_func_ptr() is not such case.

Ok! I will add an implementation in gen.c

> 
>>
>>   static inline enum btf_func_linkage btf_func_linkage(const struct btf_type *t)
>>   {
>> --
>> 2.34.1
>>

Patch

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 01f407591a92..ef8fd20f33ca 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -2145,7 +2145,7 @@  skip_mods_and_typedefs(const struct btf *btf, __u32 id, __u32 *res_id)
 	return t;
 }
 
-static const struct btf_type *
+const struct btf_type *
 resolve_func_ptr(const struct btf *btf, __u32 id, __u32 *res_id)
 {
 	const struct btf_type *t;
diff --git a/tools/lib/bpf/libbpf_internal.h b/tools/lib/bpf/libbpf_internal.h
index ad936ac5e639..17e6d381da6a 100644
--- a/tools/lib/bpf/libbpf_internal.h
+++ b/tools/lib/bpf/libbpf_internal.h
@@ -234,6 +234,8 @@  struct btf_type;
 struct btf_type *btf_type_by_id(const struct btf *btf, __u32 type_id);
 const char *btf_kind_str(const struct btf_type *t);
 const struct btf_type *skip_mods_and_typedefs(const struct btf *btf, __u32 id, __u32 *res_id);
+/* This function is exposed to bpftool */
+const struct btf_type *resolve_func_ptr(const struct btf *btf, __u32 id, __u32 *res_id);
 
 static inline enum btf_func_linkage btf_func_linkage(const struct btf_type *t)
 {