diff mbox series

[v4,bpf-next,5/5] tools/bpftool: add support for in-kernel and named BTF in `btf show`

Message ID 20201110011932.3201430-6-andrii@kernel.org (mailing list archive)
State Accepted
Delegated to: BPF
Headers show
Series Integrate kernel module BTF support | expand

Checks

Context Check Description
netdev/cover_letter success Link
netdev/fixes_present success Link
netdev/patch_count success Link
netdev/tree_selection success Clearly marked for bpf-next
netdev/subject_prefix success Link
netdev/source_inline success Was 0 now: 0
netdev/verify_signedoff success Link
netdev/module_param success Was 0 now: 0
netdev/build_32bit fail Errors and warnings before: 4 this patch: 4
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/verify_fixes success Link
netdev/checkpatch fail Link
netdev/build_allmodconfig_warn success Errors and warnings before: 0 this patch: 0
netdev/header_inline success Link
netdev/stable success Stable not CCed

Commit Message

Andrii Nakryiko Nov. 10, 2020, 1:19 a.m. UTC
Display vmlinux BTF name and kernel module names when listing available BTFs
on the system.

In human-readable output mode, module BTFs are reported with "name
[module-name]", while vmlinux BTF will be reported as "name [vmlinux]".
Square brackets are added by bpftool and follow kernel convention when
displaying modules in human-readable text outputs.

[vmuser@archvm bpf]$ sudo ../../../bpf/bpftool/bpftool btf s
1: name [vmlinux]  size 4082281B
6: size 2365B  prog_ids 8,6  map_ids 3
7: name [button]  size 46895B
8: name [pcspkr]  size 42328B
9: name [serio_raw]  size 39375B
10: name [floppy]  size 57185B
11: name [i2c_core]  size 76186B
12: name [crc32c_intel]  size 16036B
13: name [i2c_piix4]  size 50497B
14: name [irqbypass]  size 14124B
15: name [kvm]  size 197985B
16: name [kvm_intel]  size 123564B
17: name [cryptd]  size 42466B
18: name [crypto_simd]  size 17187B
19: name [glue_helper]  size 39205B
20: name [aesni_intel]  size 41034B
25: size 36150B
        pids bpftool(2519)

In JSON mode, two fields (boolean "kernel" and string "name") are reported for
each BTF object. vmlinux BTF is reported with name "vmlinux" (kernel itself
returns and empty name for vmlinux BTF).

[vmuser@archvm bpf]$ sudo ../../../bpf/bpftool/bpftool btf s -jp
[{
        "id": 1,
        "size": 4082281,
        "prog_ids": [],
        "map_ids": [],
        "kernel": true,
        "name": "vmlinux"
    },{
        "id": 6,
        "size": 2365,
        "prog_ids": [8,6
        ],
        "map_ids": [3
        ],
        "kernel": false
    },{
        "id": 7,
        "size": 46895,
        "prog_ids": [],
        "map_ids": [],
        "kernel": true,
        "name": "button"
    },{

...

Tested-by: Alan Maguire <alan.maguire@oracle.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
---
 tools/bpf/bpftool/btf.c | 28 +++++++++++++++++++++++++++-
 1 file changed, 27 insertions(+), 1 deletion(-)

Comments

Song Liu Nov. 11, 2020, 1:15 a.m. UTC | #1
> On Nov 9, 2020, at 5:19 PM, Andrii Nakryiko <andrii@kernel.org> wrote:

[...]

> ...
> 
> Tested-by: Alan Maguire <alan.maguire@oracle.com>
> Signed-off-by: Andrii Nakryiko <andrii@kernel.org>

Acked-by: Song Liu <songliubraving@fb.com>

With one nit:

> ---
> tools/bpf/bpftool/btf.c | 28 +++++++++++++++++++++++++++-
> 1 file changed, 27 insertions(+), 1 deletion(-)
> 
> diff --git a/tools/bpf/bpftool/btf.c b/tools/bpf/bpftool/btf.c
> index c96b56e8e3a4..ed5e97157241 100644
> --- a/tools/bpf/bpftool/btf.c
> +++ b/tools/bpf/bpftool/btf.c
> @@ -742,9 +742,14 @@ show_btf_plain(struct bpf_btf_info *info, int fd,
> 	       struct btf_attach_table *btf_map_table)
> {
> 	struct btf_attach_point *obj;
> +	const char *name = u64_to_ptr(info->name);
> 	int n;
> 
> 	printf("%u: ", info->id);
> +	if (info->kernel_btf)
> +		printf("name [%s]  ", name);
> +	else if (name && name[0])
> +		printf("name %s  ", name);

Maybe explicitly say "name <anonymous>" for btf without a name? I think 
it will benefit plain output.  

> 	printf("size %uB", info->btf_size);
> 
> 	n = 0;

[...]
Andrii Nakryiko Nov. 11, 2020, 4:19 a.m. UTC | #2
On Tue, Nov 10, 2020 at 5:15 PM Song Liu <songliubraving@fb.com> wrote:
>
>
>
> > On Nov 9, 2020, at 5:19 PM, Andrii Nakryiko <andrii@kernel.org> wrote:
>
> [...]
>
> > ...
> >
> > Tested-by: Alan Maguire <alan.maguire@oracle.com>
> > Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
>
> Acked-by: Song Liu <songliubraving@fb.com>
>
> With one nit:
>
> > ---
> > tools/bpf/bpftool/btf.c | 28 +++++++++++++++++++++++++++-
> > 1 file changed, 27 insertions(+), 1 deletion(-)
> >
> > diff --git a/tools/bpf/bpftool/btf.c b/tools/bpf/bpftool/btf.c
> > index c96b56e8e3a4..ed5e97157241 100644
> > --- a/tools/bpf/bpftool/btf.c
> > +++ b/tools/bpf/bpftool/btf.c
> > @@ -742,9 +742,14 @@ show_btf_plain(struct bpf_btf_info *info, int fd,
> >              struct btf_attach_table *btf_map_table)
> > {
> >       struct btf_attach_point *obj;
> > +     const char *name = u64_to_ptr(info->name);
> >       int n;
> >
> >       printf("%u: ", info->id);
> > +     if (info->kernel_btf)
> > +             printf("name [%s]  ", name);
> > +     else if (name && name[0])
> > +             printf("name %s  ", name);
>
> Maybe explicitly say "name <anonymous>" for btf without a name? I think
> it will benefit plain output.

This patch set is already landed. But I can do a follow-up patch to add this.

>
> >       printf("size %uB", info->btf_size);
> >
> >       n = 0;
>
> [...]
Song Liu Nov. 11, 2020, 7:44 a.m. UTC | #3
> On Nov 10, 2020, at 8:19 PM, Andrii Nakryiko <andrii.nakryiko@gmail.com> wrote:
> 
> On Tue, Nov 10, 2020 at 5:15 PM Song Liu <songliubraving@fb.com> wrote:
>> 
>> 
>> 
>>> On Nov 9, 2020, at 5:19 PM, Andrii Nakryiko <andrii@kernel.org> wrote:
>> 
>> [...]
>> 
>>> ...
>>> 
>>> Tested-by: Alan Maguire <alan.maguire@oracle.com>
>>> Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
>> 
>> Acked-by: Song Liu <songliubraving@fb.com>
>> 
>> With one nit:
>> 
>>> ---
>>> tools/bpf/bpftool/btf.c | 28 +++++++++++++++++++++++++++-
>>> 1 file changed, 27 insertions(+), 1 deletion(-)
>>> 
>>> diff --git a/tools/bpf/bpftool/btf.c b/tools/bpf/bpftool/btf.c
>>> index c96b56e8e3a4..ed5e97157241 100644
>>> --- a/tools/bpf/bpftool/btf.c
>>> +++ b/tools/bpf/bpftool/btf.c
>>> @@ -742,9 +742,14 @@ show_btf_plain(struct bpf_btf_info *info, int fd,
>>>             struct btf_attach_table *btf_map_table)
>>> {
>>>      struct btf_attach_point *obj;
>>> +     const char *name = u64_to_ptr(info->name);
>>>      int n;
>>> 
>>>      printf("%u: ", info->id);
>>> +     if (info->kernel_btf)
>>> +             printf("name [%s]  ", name);
>>> +     else if (name && name[0])
>>> +             printf("name %s  ", name);
>> 
>> Maybe explicitly say "name <anonymous>" for btf without a name? I think
>> it will benefit plain output.
> 
> This patch set is already landed. But I can do a follow-up patch to add this.

I realized this was applied soon after sending this. Yeah, a follow-up 
patch would be great. 

Thanks,
Song
diff mbox series

Patch

diff --git a/tools/bpf/bpftool/btf.c b/tools/bpf/bpftool/btf.c
index c96b56e8e3a4..ed5e97157241 100644
--- a/tools/bpf/bpftool/btf.c
+++ b/tools/bpf/bpftool/btf.c
@@ -742,9 +742,14 @@  show_btf_plain(struct bpf_btf_info *info, int fd,
 	       struct btf_attach_table *btf_map_table)
 {
 	struct btf_attach_point *obj;
+	const char *name = u64_to_ptr(info->name);
 	int n;
 
 	printf("%u: ", info->id);
+	if (info->kernel_btf)
+		printf("name [%s]  ", name);
+	else if (name && name[0])
+		printf("name %s  ", name);
 	printf("size %uB", info->btf_size);
 
 	n = 0;
@@ -771,6 +776,7 @@  show_btf_json(struct bpf_btf_info *info, int fd,
 	      struct btf_attach_table *btf_map_table)
 {
 	struct btf_attach_point *obj;
+	const char *name = u64_to_ptr(info->name);
 
 	jsonw_start_object(json_wtr);	/* btf object */
 	jsonw_uint_field(json_wtr, "id", info->id);
@@ -796,6 +802,11 @@  show_btf_json(struct bpf_btf_info *info, int fd,
 
 	emit_obj_refs_json(&refs_table, info->id, json_wtr); /* pids */
 
+	jsonw_bool_field(json_wtr, "kernel", info->kernel_btf);
+
+	if (name && name[0])
+		jsonw_string_field(json_wtr, "name", name);
+
 	jsonw_end_object(json_wtr);	/* btf object */
 }
 
@@ -803,15 +814,30 @@  static int
 show_btf(int fd, struct btf_attach_table *btf_prog_table,
 	 struct btf_attach_table *btf_map_table)
 {
-	struct bpf_btf_info info = {};
+	struct bpf_btf_info info;
 	__u32 len = sizeof(info);
+	char name[64];
 	int err;
 
+	memset(&info, 0, sizeof(info));
 	err = bpf_obj_get_info_by_fd(fd, &info, &len);
 	if (err) {
 		p_err("can't get BTF object info: %s", strerror(errno));
 		return -1;
 	}
+	/* if kernel support emitting BTF object name, pass name pointer */
+	if (info.name_len) {
+		memset(&info, 0, sizeof(info));
+		info.name_len = sizeof(name);
+		info.name = ptr_to_u64(name);
+		len = sizeof(info);
+
+		err = bpf_obj_get_info_by_fd(fd, &info, &len);
+		if (err) {
+			p_err("can't get BTF object info: %s", strerror(errno));
+			return -1;
+		}
+	}
 
 	if (json_output)
 		show_btf_json(&info, fd, btf_prog_table, btf_map_table);