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, 7 insertions, 0 deletions

diff --git a/include/linux/filter.h b/include/linux/filter.h
index d16deead65c6..29f21f9d7f68 100644
--- a/include/linux/filter.h
+++ b/include/linux/filter.h
@@ -718,6 +718,13 @@ void bpf_prog_free(struct bpf_prog *fp);
 
 bool bpf_opcode_in_insntable(u8 code);
 
+void bpf_prog_free_linfo(struct bpf_prog *prog);
+void bpf_prog_fill_jited_linfo(struct bpf_prog *prog,
+			       const u32 *insn_to_jit_off);
+int bpf_prog_alloc_jited_linfo(struct bpf_prog *prog);
+void bpf_prog_free_jited_linfo(struct bpf_prog *prog);
+void bpf_prog_free_unused_jited_linfo(struct bpf_prog *prog);
+
 struct bpf_prog *bpf_prog_alloc(unsigned int size, gfp_t gfp_extra_flags);
 struct bpf_prog *bpf_prog_realloc(struct bpf_prog *fp_old, unsigned int size,
 				  gfp_t gfp_extra_flags);