Commit a4021a35 authored by Yonghong Song's avatar Yonghong Song Committed by Alexei Starovoitov
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tools/bpf: add log_level to bpf_load_program_attr 



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: default avatarYonghong Song <yhs@fb.com>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent 62b8cea6

tools/lib/bpf/bpf.c

+17 −5
Original line number Diff line number Diff line
@@ -215,10 +215,15 @@ 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;
@@ -229,9 +234,16 @@ 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_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.log_level = 0;

	}



	attr.kern_version = load_attr->kern_version;

	attr.prog_ifindex = load_attr->prog_ifindex;

	attr.prog_btf_fd = load_attr->prog_btf_fd;
@@ -287,7 +299,7 @@ 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 */

tools/lib/bpf/bpf.h

+1 −0
Original line number Diff line number Diff line
@@ -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 */

tools/testing/selftests/bpf/test_sock.c

+8 −1
Original line number Diff line number Diff line
@@ -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,

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