From: Quentin Monnet <quentin.monnet@netronome.com>
Date: Tue, 20 Aug 2019 10:31:50 +0100
Subject: bpf: add new BPF_BTF_GET_NEXT_ID syscall command
Patch-mainline: v5.4-rc1
Git-commit: 1b9ed84ecf268904d89edf2908426a8eb3b5a4ba
References: bsc#1154353

Add a new command for the bpf() system call: BPF_BTF_GET_NEXT_ID is used
to cycle through all BTF objects loaded on the system.

The motivation is to be able to inspect (list) all BTF objects presents
on the system.

Signed-off-by: Quentin Monnet <quentin.monnet@netronome.com>
Reviewed-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
 include/linux/bpf.h      |    3 +++
 include/uapi/linux/bpf.h |    1 +
 kernel/bpf/btf.c         |    4 ++--
 kernel/bpf/syscall.c     |    4 ++++
 4 files changed, 10 insertions(+), 2 deletions(-)

--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -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) */
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -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 {
--- a/kernel/bpf/btf.c
+++ b/kernel/bpf/btf.c
@@ -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;
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -2890,6 +2890,10 @@ SYSCALL_DEFINE3(bpf, int, cmd, union bpf
 		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;