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tools/bpf: add log_level to bpf_load_program_attr

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The kernel verifier has three levels of logs:
    0: no logs
    1: logs mostly useful
  > 1: verbose

Current libbpf API functions bpf_load_program_xattr() and
bpf_load_program() cannot specify log_level.
The bcc, however, provides an interface for user to
specify log_level 2 for verbose output.

This patch added log_level into structure
bpf_load_program_attr, so users, including bcc, can use
bpf_load_program_xattr() to change log_level. The
supported log_level is 0, 1, and 2.

The bpf selftest test_sock.c is modified to enable log_level = 2.
If the "verbose" in test_sock.c is changed to true,
the test will output logs like below:
  $ ./test_sock
  func#0 @0
  0: R1=ctx(id=0,off=0,imm=0) R10=fp0,call_-1
  0: (bf) r6 = r1
  1: R1=ctx(id=0,off=0,imm=0) R6_w=ctx(id=0,off=0,imm=0) R10=fp0,call_-1
  1: (61) r7 = *(u32 *)(r6 +28)
  invalid bpf_context access off=28 size=4

  Test case: bind4 load with invalid access: src_ip6 .. [PASS]
  ...
  Test case: bind6 allow all .. [PASS]
  Summary: 16 PASSED, 0 FAILED

Some test_sock tests are negative tests and verbose verifier
log will be printed out as shown in the above.

Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Yonghong Song
2019-02-07 09:34:51 -08:00
committed by Alexei Starovoitov
parent 62b8cea62e
commit a4021a3579
3 changed files with 26 additions and 6 deletions
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9
tools/testing/selftests/bpf/test_sock.c
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@@ -20,6 +20,7 @@
#define MAX_INSNS 512
char bpf_log_buf[BPF_LOG_BUF_SIZE];
static bool verbose = false;
struct sock_test {
const char *descr;
@@ -325,6 +326,7 @@ static int load_sock_prog(const struct bpf_insn *prog,
enum bpf_attach_type attach_type)
{
struct bpf_load_program_attr attr;
int ret;
memset(&attr, 0, sizeof(struct bpf_load_program_attr));
attr.prog_type = BPF_PROG_TYPE_CGROUP_SOCK;
@@ -332,8 +334,13 @@ static int load_sock_prog(const struct bpf_insn *prog,
attr.insns = prog;
attr.insns_cnt = probe_prog_length(attr.insns);
attr.license = "GPL";
attr.log_level = 2;
return bpf_load_program_xattr(&attr, bpf_log_buf, BPF_LOG_BUF_SIZE);
ret = bpf_load_program_xattr(&attr, bpf_log_buf, BPF_LOG_BUF_SIZE);
if (verbose && ret < 0)
fprintf(stderr, "%s\n", bpf_log_buf);
return ret;
}
static int attach_sock_prog(int cgfd, int progfd,