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authorYonghong Song <yhs@fb.com>2020-06-23 17:10:54 -0700
committerAlexei Starovoitov <ast@kernel.org>2020-06-23 17:27:37 -0700
commitc4c0bdc0d2d084ed847c7066bdf59fe2cd25aa17 (patch)
tree111b9157be6a6cf063521db22c32d2c7ea14f67a /kernel/bpf
parent9c82a63cf3701b78cd092c69c3e75ff806837194 (diff)
downloadlwn-c4c0bdc0d2d084ed847c7066bdf59fe2cd25aa17.tar.gz
lwn-c4c0bdc0d2d084ed847c7066bdf59fe2cd25aa17.zip
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.c10
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;