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bpf: Add bpf_line_info support

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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>
This commit is contained in:
Martin KaFai Lau 2018-12-07 16:42:25 -08:00 • committed by Alexei Starovoitov
parent 6baefa1aa4
commit c454a46b5e
10 changed files with 419 additions and 33 deletions
Download patch file Download diff file Expand all files Collapse all files

83
kernel/bpf/syscall.c
View file

@ -1215,6 +1215,7 @@ static void __bpf_prog_put(struct bpf_prog *prog, bool do_idr_lock)
bpf_prog_kallsyms_del_all(prog);
btf_put(prog->aux->btf);
kvfree(prog->aux->func_info);
bpf_prog_free_linfo(prog);
call_rcu(&prog->aux->rcu, __bpf_prog_put_rcu);
}
@ -1439,7 +1440,7 @@ bpf_prog_load_check_attach_type(enum bpf_prog_type prog_type,
}
/* last field in 'union bpf_attr' used by this command */
#define BPF_PROG_LOAD_LAST_FIELD func_info_cnt
#define BPF_PROG_LOAD_LAST_FIELD line_info_cnt
static int bpf_prog_load(union bpf_attr *attr, union bpf_attr __user *uattr)
{
@ -1560,6 +1561,7 @@ static int bpf_prog_load(union bpf_attr *attr, union bpf_attr __user *uattr)
return err;
free_used_maps:
bpf_prog_free_linfo(prog);
kvfree(prog->aux->func_info);
btf_put(prog->aux->btf);
bpf_prog_kallsyms_del_subprogs(prog);
@ -2041,6 +2043,37 @@ static struct bpf_insn *bpf_insn_prepare_dump(const struct bpf_prog *prog)
return insns;
}
static int set_info_rec_size(struct bpf_prog_info *info)
{
/*
* Ensure info.*_rec_size is the same as kernel expected size
*
* or
*
* Only allow zero *_rec_size if both _rec_size and _cnt are
* zero. In this case, the kernel will set the expected
* _rec_size back to the info.
*/
if ((info->func_info_cnt || info->func_info_rec_size) &&
info->func_info_rec_size != sizeof(struct bpf_func_info))
return -EINVAL;
if ((info->line_info_cnt || info->line_info_rec_size) &&
info->line_info_rec_size != sizeof(struct bpf_line_info))
return -EINVAL;
if ((info->jited_line_info_cnt || info->jited_line_info_rec_size) &&
info->jited_line_info_rec_size != sizeof(__u64))
return -EINVAL;
info->func_info_rec_size = sizeof(struct bpf_func_info);
info->line_info_rec_size = sizeof(struct bpf_line_info);
info->jited_line_info_rec_size = sizeof(__u64);
return 0;
}
static int bpf_prog_get_info_by_fd(struct bpf_prog *prog,
const union bpf_attr *attr,
union bpf_attr __user *uattr)
@ -2083,11 +2116,9 @@ static int bpf_prog_get_info_by_fd(struct bpf_prog *prog,
return -EFAULT;
}
if ((info.func_info_cnt || info.func_info_rec_size) &&
info.func_info_rec_size != sizeof(struct bpf_func_info))
return -EINVAL;
info.func_info_rec_size = sizeof(struct bpf_func_info);
err = set_info_rec_size(&info);
if (err)
return err;
if (!capable(CAP_SYS_ADMIN)) {
info.jited_prog_len = 0;
@ -2095,6 +2126,8 @@ static int bpf_prog_get_info_by_fd(struct bpf_prog *prog,
info.nr_jited_ksyms = 0;
info.nr_jited_func_lens = 0;
info.func_info_cnt = 0;
info.line_info_cnt = 0;
info.jited_line_info_cnt = 0;
goto done;
}
@ -2251,6 +2284,44 @@ static int bpf_prog_get_info_by_fd(struct bpf_prog *prog,
}
}
ulen = info.line_info_cnt;
info.line_info_cnt = prog->aux->nr_linfo;
if (info.line_info_cnt && ulen) {
if (bpf_dump_raw_ok()) {
__u8 __user *user_linfo;
user_linfo = u64_to_user_ptr(info.line_info);
ulen = min_t(u32, info.line_info_cnt, ulen);
if (copy_to_user(user_linfo, prog->aux->linfo,
info.line_info_rec_size * ulen))
return -EFAULT;
} else {
info.line_info = 0;
}
}
ulen = info.jited_line_info_cnt;
if (prog->aux->jited_linfo)
info.jited_line_info_cnt = prog->aux->nr_linfo;
else
info.jited_line_info_cnt = 0;
if (info.jited_line_info_cnt && ulen) {
if (bpf_dump_raw_ok()) {
__u64 __user *user_linfo;
u32 i;
user_linfo = u64_to_user_ptr(info.jited_line_info);
ulen = min_t(u32, info.jited_line_info_cnt, ulen);
for (i = 0; i < ulen; i++) {
if (put_user((__u64)(long)prog->aux->jited_linfo[i],
&user_linfo[i]))
return -EFAULT;
}
} else {
info.jited_line_info = 0;
}
}
done:
if (copy_to_user(uinfo, &info, info_len) ||
put_user(info_len, &uattr->info.info_len))