[PATCH v2 bpf 3/3] bpf: show main program address and length in bpf_prog_info

[Song Liu]

Currently, when there is no subprog (prog->aux->func_cnt == 0),
bpf_prog_info does not return any jited_ksyms or jited_func_lens. This
patch adds main program address (prog->bpf_func) and main program
length (prog->jited_len) to bpf_prog_info.

Signed-off-by: Song Liu <songliubrav...@fb.com>
---
 kernel/bpf/syscall.c | 33 ++++++++++++++++++++++++---------
 1 file changed, 24 insertions(+), 9 deletions(-)

diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index 34a9eef5992c..9418174c276c 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -2158,11 +2158,11 @@ static int bpf_prog_get_info_by_fd(struct bpf_prog 
*prog,
        }
 
        ulen = info.nr_jited_ksyms;
-       info.nr_jited_ksyms = prog->aux->func_cnt;
+       info.nr_jited_ksyms = prog->aux->func_cnt ? : 1;
        if (info.nr_jited_ksyms && ulen) {
                if (bpf_dump_raw_ok()) {
+                       unsigned long ksym_addr;
                        u64 __user *user_ksyms;
-                       ulong ksym_addr;
                        u32 i;
 
                        /* copy the address of the kernel symbol
@@ -2170,9 +2170,17 @@ static int bpf_prog_get_info_by_fd(struct bpf_prog *prog,
                         */
                        ulen = min_t(u32, info.nr_jited_ksyms, ulen);
                        user_ksyms = u64_to_user_ptr(info.jited_ksyms);
-                       for (i = 0; i < ulen; i++) {
-                               ksym_addr = (ulong) 
prog->aux->func[i]->bpf_func;
-                               if (put_user((u64) ksym_addr, &user_ksyms[i]))
+                       if (prog->aux->func_cnt) {
+                               for (i = 0; i < ulen; i++) {
+                                       ksym_addr = (unsigned long)
+                                               prog->aux->func[i]->bpf_func;
+                                       if (put_user((u64) ksym_addr,
+                                                    &user_ksyms[i]))
+                                               return -EFAULT;
+                               }
+                       } else {
+                               ksym_addr = (unsigned long) prog->bpf_func;
+                               if (put_user((u64) ksym_addr, &user_ksyms[0]))
                                        return -EFAULT;
                        }
                } else {
@@ -2181,7 +2189,7 @@ static int bpf_prog_get_info_by_fd(struct bpf_prog *prog,
        }
 
        ulen = info.nr_jited_func_lens;
-       info.nr_jited_func_lens = prog->aux->func_cnt;
+       info.nr_jited_func_lens = prog->aux->func_cnt ? : 1;
        if (info.nr_jited_func_lens && ulen) {
                if (bpf_dump_raw_ok()) {
                        u32 __user *user_lens;
@@ -2190,9 +2198,16 @@ static int bpf_prog_get_info_by_fd(struct bpf_prog *prog,
                        /* copy the JITed image lengths for each function */
                        ulen = min_t(u32, info.nr_jited_func_lens, ulen);
                        user_lens = u64_to_user_ptr(info.jited_func_lens);
-                       for (i = 0; i < ulen; i++) {
-                               func_len = prog->aux->func[i]->jited_len;
-                               if (put_user(func_len, &user_lens[i]))
+                       if (prog->aux->func_cnt) {
+                               for (i = 0; i < ulen; i++) {
+                                       func_len =
+                                               prog->aux->func[i]->jited_len;
+                                       if (put_user(func_len, &user_lens[i]))
+                                               return -EFAULT;
+                               }
+                       } else {
+                               func_len = prog->jited_len;
+                               if (put_user(func_len, &user_lens[0]))
                                        return -EFAULT;
                        }
                } else {
-- 
2.17.1