diff options
| author | Yonghong Song <yhs@fb.com> | 2020-06-23 17:10:54 -0700 |
|---|---|---|
| committer | Alexei Starovoitov <ast@kernel.org> | 2020-06-23 17:27:37 -0700 |
| commit | c4c0bdc0d2d084ed847c7066bdf59fe2cd25aa17 (patch) | |
| tree | 111b9157be6a6cf063521db22c32d2c7ea14f67a /kernel/bpf | |
| parent | 9c82a63cf3701b78cd092c69c3e75ff806837194 (diff) | |
bpf: Set the number of exception entries properly for subprograms
Currently, if a bpf program has more than one subprograms, each program will be
jitted separately. For programs with bpf-to-bpf calls the
prog->aux->num_exentries is not setup properly. For example, with
bpf_iter_netlink.c modified to force one function to be not inlined and with
CONFIG_BPF_JIT_ALWAYS_ON the following error is seen:
$ ./test_progs -n 3/3
...
libbpf: failed to load program 'iter/netlink'
libbpf: failed to load object 'bpf_iter_netlink'
libbpf: failed to load BPF skeleton 'bpf_iter_netlink': -4007
test_netlink:FAIL:bpf_iter_netlink__open_and_load skeleton open_and_load failed
#3/3 netlink:FAIL
The dmesg shows the following errors:
ex gen bug
which is triggered by the following code in arch/x86/net/bpf_jit_comp.c:
if (excnt >= bpf_prog->aux->num_exentries) {
pr_err("ex gen bug\n");
return -EFAULT;
}
This patch fixes the issue by computing proper num_exentries for each
subprogram before calling JIT.
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Diffstat (limited to 'kernel/bpf')
| -rw-r--r-- | kernel/bpf/verifier.c | 10 |
1 files changed, 9 insertions, 1 deletions
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 34cde841ab68..8911d0576399 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -9801,7 +9801,7 @@ static int jit_subprogs(struct bpf_verifier_env *env) int i, j, subprog_start, subprog_end = 0, len, subprog; struct bpf_insn *insn; void *old_bpf_func; - int err; + int err, num_exentries; if (env->subprog_cnt <= 1) return 0; @@ -9876,6 +9876,14 @@ static int jit_subprogs(struct bpf_verifier_env *env) func[i]->aux->nr_linfo = prog->aux->nr_linfo; func[i]->aux->jited_linfo = prog->aux->jited_linfo; func[i]->aux->linfo_idx = env->subprog_info[i].linfo_idx; + num_exentries = 0; + insn = func[i]->insnsi; + for (j = 0; j < func[i]->len; j++, insn++) { + if (BPF_CLASS(insn->code) == BPF_LDX && + BPF_MODE(insn->code) == BPF_PROBE_MEM) + num_exentries++; + } + func[i]->aux->num_exentries = num_exentries; func[i] = bpf_int_jit_compile(func[i]); if (!func[i]->jited) { err = -ENOTSUPP; |