On 6/30/20 12:23 PM, Andrii Nakryiko wrote:
On Tue, Jun 30, 2020 at 11:46 AM Yonghong Song <yhs@xxxxxx> wrote:
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
Cc: Andrii Nakryiko <andriin@xxxxxx>
Cc: John Fastabend <john.fastabend@xxxxxxxxx>
Cc: Wenbo Zhang <ethercflow@xxxxxxxxx>
Signed-off-by: Yonghong Song <yhs@xxxxxx>
---
LGTM, two nits below.
Acked-by: Andrii Nakryiko <andriin@xxxxxx>
net/bpf/test_run.c | 19 +++++++++++++++-
.../selftests/bpf/prog_tests/fentry_fexit.c | 2 +-
.../testing/selftests/bpf/progs/fentry_test.c | 22 +++++++++++++++++++
.../testing/selftests/bpf/progs/fexit_test.c | 22 +++++++++++++++++++
4 files changed, 63 insertions(+), 2 deletions(-)
[...]
diff --git a/tools/testing/selftests/bpf/progs/fentry_test.c b/tools/testing/selftests/bpf/progs/fentry_test.c
index 9365b686f84b..5f645fdaba6f 100644
--- a/tools/testing/selftests/bpf/progs/fentry_test.c
+++ b/tools/testing/selftests/bpf/progs/fentry_test.c
@@ -55,3 +55,25 @@ int BPF_PROG(test6, __u64 a, void *b, short c, int d, void * e, __u64 f)
e == (void *)20 && f == 21;
return 0;
}
+
+struct bpf_fentry_test_t {
+ struct bpf_fentry_test_t *a;
+};
nit: __attribute__((preserve_access_index)) ?
Yes. Why not. Will send a followup once the patch circulates back to
bpf-next.
+
+__u64 test7_result = 0;
+SEC("fentry/bpf_fentry_test7")
+int BPF_PROG(test7, struct bpf_fentry_test_t *arg)
+{
+ if (arg == 0)
+ test7_result = 1;
+ return 0;
+}
+
[...]
