bpf: Add bpf_line_info support
authorMartin KaFai Lau <kafai@fb.com>
Sat, 8 Dec 2018 00:42:25 +0000 (16:42 -0800)
committerAlexei Starovoitov <ast@kernel.org>
Sun, 9 Dec 2018 21:54:38 +0000 (13:54 -0800)
commitc454a46b5efd8eff8880e88ece2976e60a26bf35
treefa0791a8524e5a13b2798ba6fee34d517df3dfa4
parent6baefa1aa46f0e90aefbd13b8c926e89068fabba
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>
arch/x86/net/bpf_jit_comp.c
include/linux/bpf.h
include/linux/bpf_verifier.h
include/linux/btf.h
include/linux/filter.h
include/uapi/linux/bpf.h
kernel/bpf/btf.c
kernel/bpf/core.c
kernel/bpf/syscall.c
kernel/bpf/verifier.c