On 4/27/20 7:56 PM, Ma Xinjian wrote:
Hi Yonghong.
During our team's test, we find a similar issue. when run test_sysctl of
bpf, we met error:
```
libbpf: -- END LOG --
libbpf: failed to load program 'cgroup/sysctl'
libbpf: failed to load object './test_sysctl_prog.o'
(test_sysctl.c:1490: errno: Permission denied) >>> Loading program
(./test_sysctl_prog.o) error.
```
Testing env: "Debian GNU/Linux 9 (stretch)"
kernel: 5.6 5.7-rc1 5.7-rc2 5.7-rc3
clang/llvm version: v11.0.0.
we have tested a log of commits, following commits are part of them
drwxrwxr-x 2 root root 1 Apr 28 07:01
f30416fdde922eaa655934e050026930fefbd260
drwxrwxr-x 2 root root 2 Apr 26 11:38
10bc12588dac532fad044b2851dde8e7b9121e88
drwxrwxr-x 2 root root 1 Apr 26 07:01
969e7edd88ceb4791eb1cac22828290f0ae30b3d
drwxrwxr-x 2 root root 1 Apr 23 13:51
bbf386f02b05db017fda66875cc5edef70779244
drwxrwxr-x 2 root root 1 Apr 22 10:01
2de52422acf04662b45599f77c14ce1b2cec2b81
drwxrwxr-x 2 root root 1 Apr 21 07:07
a9b137f9ffba8cb25dfd7dd1fb613e8aac121b37
drwxrwxr-x 2 root root 1 Apr 17 07:01
40d139c620f83509fe18acbff5ec358298e99def
drwxrwxr-x 2 root root 1 Apr 16 07:02
bee6c234ed28ae7349cb83afa322dfd8394590ee
And I have tested, If I add following patch like you did, test_sysctl pass:
diff --git a/tools/testing/selftests/bpf/progs/test_sysctl_prog.c
b/tools/testing/selftests/bpf/progs/test_sysctl_prog.c
index 2d0b0b82a78a..8e3da8d2e7c9 100644
--- a/tools/testing/selftests/bpf/progs/test_sysctl_prog.c
+++ b/tools/testing/selftests/bpf/progs/test_sysctl_prog.c
@@ -45,7 +45,10 @@ int sysctl_tcp_mem(struct bpf_sysctl *ctx)
unsigned long tcp_mem[3] = {0, 0, 0};
char value[MAX_VALUE_STR_LEN];
unsigned char i, off = 0;
- int ret;
+ /* a workaround to prevent compiler from generating
+ * codes verifier cannot handle yet.
+ */
+ volatile int ret;
if (ctx->write)
return 0;
Right. This is related to alu32 mode. The detailed description
https://lore.kernel.org/bpf/20191107170045.2503480-1-yhs@xxxxxx/
We are still working on this, either a verifier solution or a compiler
workaround.
root@vm-snb-15
/usr/src/perf_selftests-x86_64-rhel-7.6-kselftests-6a8b55ed4056ea5559ebe4f6a4b247f627870d4c/tools/testing/selftests/bpf#
./test_sysctl
...
Summary: 40 PASSED, 0 FAILED
