On Thu, Feb 07, 2019 at 09:34:51AM -0800, Yonghong Song wrote:
> 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 <y...@fb.com>
> ---
> tools/lib/bpf/bpf.c | 22 +++++++++++++++++-----
> tools/lib/bpf/bpf.h | 1 +
> tools/testing/selftests/bpf/test_sock.c | 9 ++++++++-
> 3 files changed, 26 insertions(+), 6 deletions(-)
>
> Changelog:
> v2 -> v3:
> . returning error immediately for inconsistent
> log_level/log_buf/log_buf_sz
> values
> . for log_level=1/2, always doing logging during bpf_prog_load.
> v1 -> v2:
> . make log_level as the last member of struct bpf_load_program_attr.
> . return -EINVAL if bpf_load_program_attr.log_level > 2.
>
> diff --git a/tools/lib/bpf/bpf.c b/tools/lib/bpf/bpf.c
> index 3defad77dc7a..3f5290ee1b47 100644
> --- a/tools/lib/bpf/bpf.c
> +++ b/tools/lib/bpf/bpf.c
> @@ -214,10 +214,15 @@ int bpf_load_program_xattr(const struct
> bpf_load_program_attr *load_attr,
> {
> void *finfo = NULL, *linfo = NULL;
> union bpf_attr attr;
> + __u32 log_level;
> __u32 name_len;
> int fd;
>
> - if (!load_attr)
> + if (!load_attr || !log_buf != !log_buf_sz)
> + return -EINVAL;
> +
> + log_level = load_attr->log_level;
> + if (log_level > 2 || (log_level && !log_buf))
> return -EINVAL;
>
> name_len = load_attr->name ? strlen(load_attr->name) : 0;
> @@ -228,9 +233,16 @@ int bpf_load_program_xattr(const struct
> bpf_load_program_attr *load_attr,
> attr.insn_cnt = (__u32)load_attr->insns_cnt;
> attr.insns = ptr_to_u64(load_attr->insns);
> attr.license = ptr_to_u64(load_attr->license);
> - attr.log_buf = ptr_to_u64(NULL);
> - attr.log_size = 0;
> - attr.log_level = 0;
> +
> + attr.log_level = log_level;
> + if (log_level) {
> + attr.log_buf = ptr_to_u64(log_buf);
> + attr.log_size = log_buf_sz;
> + } else {
> + attr.log_buf = ptr_to_u64(NULL);
> + attr.log_size = 0;
> + }
> +
> attr.kern_version = load_attr->kern_version;
> attr.prog_ifindex = load_attr->prog_ifindex;
> attr.prog_btf_fd = load_attr->prog_btf_fd;
> @@ -286,7 +298,7 @@ int bpf_load_program_xattr(const struct
> bpf_load_program_attr *load_attr,
> goto done;
> }
>
> - if (!log_buf || !log_buf_sz)
> + if (log_level || !log_buf)
> goto done;
>
> /* Try again with log */
> diff --git a/tools/lib/bpf/bpf.h b/tools/lib/bpf/bpf.h
> index ed09eed2dc3b..6ffdd79bea89 100644
> --- a/tools/lib/bpf/bpf.h
> +++ b/tools/lib/bpf/bpf.h
> @@ -85,6 +85,7 @@ struct bpf_load_program_attr {
> __u32 line_info_rec_size;
> const void *line_info;
> __u32 line_info_cnt;
> + __u32 log_level;
> };
>
> /* Flags to direct loading requirements */
> diff --git a/tools/testing/selftests/bpf/test_sock.c
> b/tools/testing/selftests/bpf/test_sock.c
> index 561ffb6d6433..fb679ac3d4b0 100644
> --- a/tools/testing/selftests/bpf/test_sock.c
> +++ b/tools/testing/selftests/bpf/test_sock.c
> @@ -20,6 +20,7 @@
> #define MAX_INSNS 512
>
> char bpf_log_buf[BPF_LOG_BUF_SIZE];
> +static bool verbose = false;
If there was a command line flag to toggle 'verbose' it would have made it
easier to test. In this form test_sock.c needs to be manually edited
to see that log_level=2 is actually working.
Applied to bpf-next anyway.
