diff mbox series

[bpf-next,v3,08/10] bpf: get JITed image lengths of functions via syscall

Message ID 9a23d3341776cc1ae6568a21e24428a8aa75b320.1527008647.git.sandipan@linux.vnet.ibm.com (mailing list archive)
State Not Applicable
Headers show
Series bpf: enhancements for multi-function programs | expand

Commit Message

Sandipan Das May 22, 2018, 5:16 p.m. UTC 
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>
---
 include/uapi/linux/bpf.h |  2 ++
 kernel/bpf/syscall.c     | 20 ++++++++++++++++++++
 2 files changed, 22 insertions(+)
diff mbox series

Patch

diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index c44105f27da9..8c3109b5d6d3 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -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 {
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index 1c4cba91e523..faadbcd90191 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -2036,6 +2036,26 @@  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))