bpf: Fix bpf-next builds without CONFIG_BPF_EVENTS

This commit fixes linker errors along the lines of:

    s390-linux-ld: task_iter.c:(.init.text+0xa4): undefined reference to `btf_task_struct_ids'`

Fix by defining btf_task_struct_ids unconditionally in kernel/bpf/btf.c
since there exists code that unconditionally uses btf_task_struct_ids.

Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Daniel Xu <dxu@dxuuu.xyz>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/05d94748d9f4b3eecedc4fddd6875418a396e23c.1629942444.git.dxu@dxuuu.xyz

diff --git a/include/linux/btf_ids.h b/include/linux/btf_ids.h
index 93d881a..47d9abf 100644 (file)
--- a/include/linux/btf_ids.h
+++ b/include/linux/btf_ids.h
@@ -151,6 +151,7 @@ extern struct btf_id_set name;
 #define BTF_ID_UNUSED
 #define BTF_ID_LIST_GLOBAL(name) u32 name[1];
 #define BTF_ID_LIST_SINGLE(name, prefix, typename) static u32 name[1];
+#define BTF_ID_LIST_GLOBAL_SINGLE(name, prefix, typename) u32 name[1];
 #define BTF_SET_START(name) static struct btf_id_set name = { 0 };
 #define BTF_SET_START_GLOBAL(name) static struct btf_id_set name = { 0 };
 #define BTF_SET_END(name)

diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
index c395024..dfe61df 100644 (file)
--- a/kernel/bpf/btf.c
+++ b/kernel/bpf/btf.c
@@ -6213,3 +6213,5 @@ const struct bpf_func_proto bpf_btf_find_by_name_kind_proto = {
        .arg3_type      = ARG_ANYTHING,
        .arg4_type      = ARG_ANYTHING,
 };
+
+BTF_ID_LIST_GLOBAL_SINGLE(btf_task_struct_ids, struct, task_struct)

diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index 580e14e..8e2eb95 100644 (file)
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -714,8 +714,6 @@ BPF_CALL_0(bpf_get_current_task_btf)
        return (unsigned long) current;
 }
 
-BTF_ID_LIST_GLOBAL_SINGLE(btf_task_struct_ids, struct, task_struct)
-
 const struct bpf_func_proto bpf_get_current_task_btf_proto = {
        .func           = bpf_get_current_task_btf,
        .gpl_only       = true,