Commit 51746f94 authored by Alexei Starovoitov's avatar Alexei Starovoitov
Browse files

Merge branch 'btf_get_next_id' 



Quentin Monnet says:

====================
This set adds a new command BPF_BTF_GET_NEXT_ID to the bpf() system call,
adds the relevant API function in libbpf, and uses it in bpftool to list
all BTF objects loaded on the system (and to dump the ids of maps and
programs associated with them, if any).

The main motivation of listing BTF objects is introspection and debugging
purposes. By getting BPF program and map information, it should already be
possible to list all BTF objects associated to at least one map or one
program. But there may be unattached BTF objects, held by a file descriptor
from a user space process only, and we may want to list them too.

As a side note, it also turned useful for examining the BTF objects
attached to offloaded programs, which would not show in program information
because the BTF id is not copied when retrieving such info. A fix is in
progress on that side.

v2:
- Rebase patch with new libbpf function on top of Andrii's changes
  regarding libbpf versioning.
====================

Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parents 09845436 4d374ba0

include/linux/bpf.h

+3 −0
Original line number Diff line number Diff line
@@ -24,6 +24,9 @@ struct seq_file; 
struct btf;

struct btf_type;



extern struct idr btf_idr;

extern spinlock_t btf_idr_lock;



/* map is generic key/value storage optionally accesible by eBPF programs */

struct bpf_map_ops {

	/* funcs callable from userspace (via syscall) */

include/uapi/linux/bpf.h

+1 −0
Original line number Diff line number Diff line
@@ -106,6 +106,7 @@ enum bpf_cmd { 
	BPF_TASK_FD_QUERY,

	BPF_MAP_LOOKUP_AND_DELETE_ELEM,

	BPF_MAP_FREEZE,

	BPF_BTF_GET_NEXT_ID,

};



enum bpf_map_type {

kernel/bpf/btf.c

+2 −2
Original line number Diff line number Diff line
@@ -195,8 +195,8 @@ 
	     i < btf_type_vlen(struct_type);					\

	     i++, member++)



static DEFINE_IDR(btf_idr);

static DEFINE_SPINLOCK(btf_idr_lock);

DEFINE_IDR(btf_idr);

DEFINE_SPINLOCK(btf_idr_lock);



struct btf {

	void *data;

kernel/bpf/syscall.c

+4 −0
Original line number Diff line number Diff line
@@ -2884,6 +2884,10 @@ SYSCALL_DEFINE3(bpf, int, cmd, union bpf_attr __user *, uattr, unsigned int, siz 
		err = bpf_obj_get_next_id(&attr, uattr,

					  &map_idr, &map_idr_lock);

		break;

	case BPF_BTF_GET_NEXT_ID:

		err = bpf_obj_get_next_id(&attr, uattr,

					  &btf_idr, &btf_idr_lock);

		break;

	case BPF_PROG_GET_FD_BY_ID:

		err = bpf_prog_get_fd_by_id(&attr);

		break;

tools/bpf/bpftool/Documentation/bpftool-btf.rst

+7 −0
Original line number Diff line number Diff line
@@ -19,6 +19,7 @@ SYNOPSIS 
BTF COMMANDS

=============



|	**bpftool** **btf** { **show** | **list** } [**id** *BTF_ID*]

|	**bpftool** **btf dump** *BTF_SRC* [**format** *FORMAT*]

|	**bpftool** **btf help**

|
@@ -29,6 +30,12 @@ BTF COMMANDS 


DESCRIPTION

===========

	**bpftool btf { show | list }** [**id** *BTF_ID*]

		  Show information about loaded BTF objects. If a BTF ID is

		  specified, show information only about given BTF object,

		  otherwise list all BTF objects currently loaded on the

		  system.



	**bpftool btf dump** *BTF_SRC*

		  Dump BTF entries from a given *BTF_SRC*.

CRA Git | Maintained and supported by SUSTech CRA and CCSE