bpf: get JITed image lengths of functions via syscall (815581c1) · Commits · 戴 / test

This adds new two new fields to struct bpf_prog_info. For multi-function programs, these fields can be used to pass a list of the JITed image lengths of each function for a given program to userspace using the bpf system call with the BPF_OBJ_GET_INFO_BY_FD command. This can be used by userspace applications like bpftool to split up the contiguous JITed dump, also obtained via the system call, into more relatable chunks corresponding to each function. Signed-off-by:

Sandipan Das <sandipan@linux.vnet.ibm.com> Signed-off-by:

Daniel Borkmann <daniel@iogearbox.net>

include/uapi/linux/bpf.h

+2 −0

Original line number	Diff line number	Diff line
		@@ -2206,7 +2206,9 @@ struct bpf_prog_info {
		__u64 netns_dev;
		__u64 netns_ino;
		__u32 nr_jited_ksyms;
		__u32 nr_jited_func_lens;
		__aligned_u64 jited_ksyms;
		__aligned_u64 jited_func_lens;
		} __attribute__((aligned(8)));

		struct bpf_map_info {

kernel/bpf/syscall.c

+20 −0

Original line number	Diff line number	Diff line
		@@ -2037,6 +2037,26 @@ 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;
		if (info.nr_jited_func_lens && ulen) {
		if (bpf_dump_raw_ok()) {
		u32 __user *user_lens;
		u32 func_len, i;

		/* 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]))
		return -EFAULT;
		}
		} else {
		info.jited_func_lens = 0;
		}
		}

		done:
		if (copy_to_user(uinfo, &info, info_len) \|\|
		put_user(info_len, &uattr->info.info_len))

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