On Thu, 11 Jan 2018 16:47:47 -0800, Jakub Kicinski wrote:
> Hi!
>
> Jiong is working on dumping JITed NFP image via bpftool, Francois will be
> submitting support for NFP in binutils soon (whoop! :)).
>
> We would appreciate if you could weigh in on the uAPI. Is it OK to reuse
> the existing jited_prog_len/jited_prog_insns or should we add separate
> 2 new fields (plus the arch name) to avoid confusing old user space?
Ah, I skipped one chunk of Jiong's patch here, this would also be
necessary if we reuse fields:
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index 2bac0dc..c7831cd 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -1673,19 +1673,6 @@ static int bpf_prog_get_info_by_fd(struct bpf_prog *prog,
goto done;
}
- ulen = info.jited_prog_len;
- 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;
- } else {
- info.jited_prog_insns = 0;
- }
- }
-
ulen = info.xlated_prog_len;
info.xlated_prog_len = bpf_prog_insn_size(prog);
if (info.xlated_prog_len && ulen) {
@@ -1711,6 +1698,21 @@ static int bpf_prog_get_info_by_fd(struct bpf_prog *prog,
err = bpf_prog_offload_info_fill(&info, prog);
if (err)
return err;
+ else
+ goto done;
+ }
+
+ ulen = info.jited_prog_len;
+ 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;
+ } else {
+ info.jited_prog_insns = 0;
+ }
}
done:
info.jited_prog_len is an in/out parameter, so we can't write it twice
if we share fields.. Sorry for messing up.
