Currently, for multi-function programs, we cannot get the JITed
instructions using the bpf system call's BPF_OBJ_GET_INFO_BY_FD
command. Because of this, userspace tools such as bpftool fail
to identify a multi-function program as being JITed or not.
With the JIT enabled and the test program running, this can be
verified as follows:
# cat /proc/sys/net/core/bpf_jit_enable
1
Before applying this patch:
# bpftool prog list
1: kprobe name foo tag b811aab41a39ad3d gpl
loaded_at 2018-05-16T11:43:38+0530 uid 0
xlated 216B not jited memlock 65536B
...
# bpftool prog dump jited id 1
no instructions returned
After applying this patch:
# bpftool prog list
1: kprobe name foo tag b811aab41a39ad3d gpl
loaded_at 2018-05-16T12:13:01+0530 uid 0
xlated 216B jited 308B memlock 65536B
...
# bpftool prog dump jited id 1
0: nop
4: nop
8: mflr r0
c: std r0,16(r1)
10: stdu r1,-112(r1)
14: std r31,104(r1)
18: addi r31,r1,48
1c: li r3,10
...
Signed-off-by: Sandipan Das <sandi...@linux.vnet.ibm.com>
---
kernel/bpf/syscall.c | 38 ++++++++++++++++++++++++++++++++------
1 file changed, 32 insertions(+), 6 deletions(-)
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index 03c8437a2990..b2f70718aca7 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -1896,7 +1896,7 @@ static int bpf_prog_get_info_by_fd(struct bpf_prog *prog,
struct bpf_prog_info info = {};
u32 info_len = attr->info.info_len;
char __user *uinsns;
- u32 ulen;
+ u32 ulen, i;
int err;
err = check_uarg_tail_zero(uinfo, sizeof(info), info_len);
@@ -1922,7 +1922,6 @@ static int bpf_prog_get_info_by_fd(struct bpf_prog *prog,
ulen = min_t(u32, info.nr_map_ids, ulen);
if (ulen) {
u32 __user *user_map_ids = u64_to_user_ptr(info.map_ids);
- u32 i;
for (i = 0; i < ulen; i++)
if (put_user(prog->aux->used_maps[i]->id,
@@ -1970,13 +1969,41 @@ static int bpf_prog_get_info_by_fd(struct bpf_prog
*prog,
* for offload.
*/
ulen = info.jited_prog_len;
- info.jited_prog_len = prog->jited_len;
+ if (prog->aux->func_cnt) {
+ info.jited_prog_len = 0;
+ for (i = 0; i < prog->aux->func_cnt; i++)
+ info.jited_prog_len += prog->aux->func[i]->jited_len;
+ } else {
+ info.jited_prog_len = prog->jited_len;
+ }
+
if (info.jited_prog_len && ulen) {
if (bpf_dump_raw_ok()) {
uinsns = u64_to_user_ptr(info.jited_prog_insns);
ulen = min_t(u32, info.jited_prog_len, ulen);
- if (copy_to_user(uinsns, prog->bpf_func, ulen))
- return -EFAULT;
+
+ /* for multi-function programs, copy the JITed
+ * instructions for all the functions
+ */
+ if (prog->aux->func_cnt) {
+ u32 len, free;
+ u8 *img;
+
+ free = ulen;
+ for (i = 0; i < prog->aux->func_cnt; i++) {
+ len = prog->aux->func[i]->jited_len;
+ img = (u8 *)
prog->aux->func[i]->bpf_func;
+ if (len > free)
+ break;
+ if (copy_to_user(uinsns, img, len))
+ return -EFAULT;
+ uinsns += len;
+ free -= len;
+ }
+ } else {
+ if (copy_to_user(uinsns, prog->bpf_func, ulen))
+ return -EFAULT;
+ }
} else {
info.jited_prog_insns = 0;
}
@@ -1987,7 +2014,6 @@ static int bpf_prog_get_info_by_fd(struct bpf_prog *prog,
if (info.nr_jited_ksyms && ulen) {
u64 __user *user_jited_ksyms =
u64_to_user_ptr(info.jited_ksyms);
ulong ksym_addr;
- u32 i;
/* copy the address of the kernel symbol corresponding to
* each function
--
2.14.3
