d923021c2c
Add two tests for PTR_TO_BTF_ID vs. null ptr comparison,
one for PTR_TO_BTF_ID in the ctx structure and the
other for PTR_TO_BTF_ID after one level pointer chasing.
In both cases, the test ensures condition is not
removed.
For example, for this test
struct bpf_fentry_test_t {
struct bpf_fentry_test_t *a;
};
int BPF_PROG(test7, struct bpf_fentry_test_t *arg)
{
if (arg == 0)
test7_result = 1;
return 0;
}
Before the previous verifier change, we have xlated codes:
int test7(long long unsigned int * ctx):
; int BPF_PROG(test7, struct bpf_fentry_test_t *arg)
0: (79) r1 = *(u64 *)(r1 +0)
; int BPF_PROG(test7, struct bpf_fentry_test_t *arg)
1: (b4) w0 = 0
2: (95) exit
After the previous verifier change, we have:
int test7(long long unsigned int * ctx):
; int BPF_PROG(test7, struct bpf_fentry_test_t *arg)
0: (79) r1 = *(u64 *)(r1 +0)
; if (arg == 0)
1: (55) if r1 != 0x0 goto pc+4
; test7_result = 1;
2: (18) r1 = map[id:6][0]+48
4: (b7) r2 = 1
5: (7b) *(u64 *)(r1 +0) = r2
; int BPF_PROG(test7, struct bpf_fentry_test_t *arg)
6: (b4) w0 = 0
7: (95) exit
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/20200630171241.2523875-1-yhs@fb.com
================== BPF Selftest Notes ================== General instructions on running selftests can be found in `Documentation/bpf/bpf_devel_QA.rst`_. Additional information about selftest failures are documented here. bpf_iter test failures with clang/llvm 10.0.0 ============================================= With clang/llvm 10.0.0, the following two bpf_iter tests failed: * ``bpf_iter/ipv6_route`` * ``bpf_iter/netlink`` The symptom for ``bpf_iter/ipv6_route`` looks like .. code-block:: c 2: (79) r8 = *(u64 *)(r1 +8) ... 14: (bf) r2 = r8 15: (0f) r2 += r1 ; BPF_SEQ_PRINTF(seq, "%pi6 %02x ", &rt->fib6_dst.addr, rt->fib6_dst.plen); 16: (7b) *(u64 *)(r8 +64) = r2 only read is supported The symptom for ``bpf_iter/netlink`` looks like .. code-block:: c ; struct netlink_sock *nlk = ctx->sk; 2: (79) r7 = *(u64 *)(r1 +8) ... 15: (bf) r2 = r7 16: (0f) r2 += r1 ; BPF_SEQ_PRINTF(seq, "%pK %-3d ", s, s->sk_protocol); 17: (7b) *(u64 *)(r7 +0) = r2 only read is supported This is due to a llvm BPF backend bug. The fix https://reviews.llvm.org/D78466 has been pushed to llvm 10.x release branch and will be available in 10.0.1. The fix is available in llvm 11.0.0 trunk.