bpf: Add bpf_line_info support

This patch adds bpf_line_info support.

It accepts an array of bpf_line_info objects during BPF_PROG_LOAD.
The "line_info", "line_info_cnt" and "line_info_rec_size" are added
to the "union bpf_attr".  The "line_info_rec_size" makes
bpf_line_info extensible in the future.

The new "check_btf_line()" ensures the userspace line_info is valid
for the kernel to use.

When the verifier is translating/patching the bpf_prog (through
"bpf_patch_insn_single()"), the line_infos' insn_off is also
adjusted by the newly added "bpf_adj_linfo()".

If the bpf_prog is jited, this patch also provides the jited addrs (in
aux->jited_linfo) for the corresponding line_info.insn_off.
"bpf_prog_fill_jited_linfo()" is added to fill the aux->jited_linfo.
It is currently called by the x86 jit.  Other jits can also use
"bpf_prog_fill_jited_linfo()" and it will be done in the followup patches.
In the future, if it deemed necessary, a particular jit could also provide
its own "bpf_prog_fill_jited_linfo()" implementation.

A few "*line_info*" fields are added to the bpf_prog_info such
that the user can get the xlated line_info back (i.e. the line_info
with its insn_off reflecting the translated prog).  The jited_line_info
is available if the prog is jited.  It is an array of __u64.
If the prog is not jited, jited_line_info_cnt is 0.

The verifier's verbose log with line_info will be done in
a follow up patch.

Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Acked-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

1 files changed, 19 insertions, 0 deletions

diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index a84fd232d934..7a66db8d15d5 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -356,6 +356,9 @@ union bpf_attr {
 		__u32		func_info_rec_size;	/* userspace bpf_func_info size */
 		__aligned_u64	func_info;	/* func info */
 		__u32		func_info_cnt;	/* number of bpf_func_info records */
+		__u32		line_info_rec_size;	/* userspace bpf_line_info size */
+		__aligned_u64	line_info;	/* line info */
+		__u32		line_info_cnt;	/* number of bpf_line_info records */
 	};
 
 	struct { /* anonymous struct used by BPF_OBJ_* commands */
@@ -2679,6 +2682,12 @@ struct bpf_prog_info {
 	__u32 func_info_rec_size;
 	__aligned_u64 func_info;
 	__u32 func_info_cnt;
+	__u32 line_info_cnt;
+	__aligned_u64 line_info;
+	__aligned_u64 jited_line_info;
+	__u32 jited_line_info_cnt;
+	__u32 line_info_rec_size;
+	__u32 jited_line_info_rec_size;
 } __attribute__((aligned(8)));
 
 struct bpf_map_info {
@@ -2995,4 +3004,14 @@ struct bpf_func_info {
 	__u32	type_id;
 };
 
+#define BPF_LINE_INFO_LINE_NUM(line_col)	((line_col) >> 10)
+#define BPF_LINE_INFO_LINE_COL(line_col)	((line_col) & 0x3ff)
+
+struct bpf_line_info {
+	__u32	insn_off;
+	__u32	file_name_off;
+	__u32	line_off;
+	__u32	line_col;
+};
+
 #endif /* _UAPI__LINUX_BPF_H__ */