bpf: btf: support proper non-jit func info

Commit 838e96904ff3 ("bpf: Introduce bpf_func_info")
added bpf func info support. The userspace is able
to get better ksym's for bpf programs with jit, and
is able to print out func prototypes.

For a program containing func-to-func calls, the existing
implementation returns user specified number of function
calls and BTF types if jit is enabled. If the jit is not
enabled, it only returns the type for the main function.

This is undesirable. Interpreter may still be used
and we should keep feature identical regardless of
whether jit is enabled or not.
This patch fixed this discrepancy.

Fixes: 838e96904ff3 ("bpf: Introduce bpf_func_info")
Signed-off-by: Yonghong Song <yhs@fb.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

1 files changed, 8 insertions, 25 deletions

diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index 998377808102..85cbeec06e50 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -1214,6 +1214,7 @@ static void __bpf_prog_put(struct bpf_prog *prog, bool do_idr_lock)
                 bpf_prog_free_id(prog, do_idr_lock);
                 bpf_prog_kallsyms_del_all(prog);
                 btf_put(prog->aux->btf);
+                kvfree(prog->aux->func_info);
 
                 call_rcu(&prog->aux->rcu, __bpf_prog_put_rcu);
         }
@@ -2219,46 +2220,28 @@ static int bpf_prog_get_info_by_fd(struct bpf_prog *prog,
         }
 
         if (prog->aux->btf) {
+                u32 krec_size = sizeof(struct bpf_func_info);
                 u32 ucnt, urec_size;
 
                 info.btf_id = btf_id(prog->aux->btf);
 
                 ucnt = info.func_info_cnt;
-                info.func_info_cnt = prog->aux->func_cnt ? : 1;
+                info.func_info_cnt = prog->aux->func_info_cnt;
                 urec_size = info.func_info_rec_size;
-                info.func_info_rec_size = sizeof(struct bpf_func_info);
+                info.func_info_rec_size = krec_size;
                 if (ucnt) {
                         /* expect passed-in urec_size is what the kernel expects */
                         if (urec_size != info.func_info_rec_size)
                                 return -EINVAL;
 
                         if (bpf_dump_raw_ok()) {
-                                struct bpf_func_info kern_finfo;
                                 char __user *user_finfo;
-                                u32 i, insn_offset;
 
                                 user_finfo = u64_to_user_ptr(info.func_info);
-                                if (prog->aux->func_cnt) {
-                                        ucnt = min_t(u32, info.func_info_cnt, ucnt);
-                                        insn_offset = 0;
-                                        for (i = 0; i < ucnt; i++) {
-                                                kern_finfo.insn_offset = insn_offset;
-                                                kern_finfo.type_id = prog->aux->func[i]->aux->type_id;
-                                                if (copy_to_user(user_finfo, &kern_finfo,
-                                                                 sizeof(kern_finfo)))
-                                                        return -EFAULT;
-
-                                                /* func[i]->len holds the prog len */
-                                                insn_offset += prog->aux->func[i]->len;
-                                                user_finfo += urec_size;
-                                        }
-                                } else {
-                                        kern_finfo.insn_offset = 0;
-                                        kern_finfo.type_id = prog->aux->type_id;
-                                        if (copy_to_user(user_finfo, &kern_finfo,
-                                                         sizeof(kern_finfo)))
-                                                return -EFAULT;
-                                }
+                                ucnt = min_t(u32, info.func_info_cnt, ucnt);
+                                if (copy_to_user(user_finfo, prog->aux->func_info,
+                                                 krec_size * ucnt))
+                                        return -EFAULT;
                         } else {
                                 info.func_info_cnt = 0;
                         }