Commit b72091bd authored by Alan Maguire's avatar Alan Maguire Committed by Alexei Starovoitov
Browse files

selftests/bpf: Add test for bpf_seq_printf_btf helper 



Add a test verifying iterating over tasks and displaying BTF
representation of task_struct succeeds.

Suggested-by: default avatarAlexei Starovoitov <alexei.starovoitov@gmail.com>
Signed-off-by: default avatarAlan Maguire <alan.maguire@oracle.com>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/1601292670-1616-9-git-send-email-alan.maguire@oracle.com
parent eb411377

tools/testing/selftests/bpf/prog_tests/bpf_iter.c

+74 −0
Original line number Diff line number Diff line
@@ -7,6 +7,7 @@ 
#include "bpf_iter_task.skel.h"

#include "bpf_iter_task_stack.skel.h"

#include "bpf_iter_task_file.skel.h"

#include "bpf_iter_task_btf.skel.h"

#include "bpf_iter_tcp4.skel.h"

#include "bpf_iter_tcp6.skel.h"

#include "bpf_iter_udp4.skel.h"
@@ -167,6 +168,77 @@ static void test_task_file(void) 
	bpf_iter_task_file__destroy(skel);

}



#define TASKBUFSZ		32768



static char taskbuf[TASKBUFSZ];



static void do_btf_read(struct bpf_iter_task_btf *skel)

{

	struct bpf_program *prog = skel->progs.dump_task_struct;

	struct bpf_iter_task_btf__bss *bss = skel->bss;

	int iter_fd = -1, len = 0, bufleft = TASKBUFSZ;

	struct bpf_link *link;

	char *buf = taskbuf;



	link = bpf_program__attach_iter(prog, NULL);

	if (CHECK(IS_ERR(link), "attach_iter", "attach_iter failed\n"))

		return;



	iter_fd = bpf_iter_create(bpf_link__fd(link));

	if (CHECK(iter_fd < 0, "create_iter", "create_iter failed\n"))

		goto free_link;



	do {

		len = read(iter_fd, buf, bufleft);

		if (len > 0) {

			buf += len;

			bufleft -= len;

		}

	} while (len > 0);



	if (bss->skip) {

		printf("%s:SKIP:no __builtin_btf_type_id\n", __func__);

		test__skip();

		goto free_link;

	}



	if (CHECK(len < 0, "read", "read failed: %s\n", strerror(errno)))

		goto free_link;



	CHECK(strstr(taskbuf, "(struct task_struct)") == NULL,

	      "check for btf representation of task_struct in iter data",

	      "struct task_struct not found");

free_link:

	if (iter_fd > 0)

		close(iter_fd);

	bpf_link__destroy(link);

}



static void test_task_btf(void)

{

	struct bpf_iter_task_btf__bss *bss;

	struct bpf_iter_task_btf *skel;



	skel = bpf_iter_task_btf__open_and_load();

	if (CHECK(!skel, "bpf_iter_task_btf__open_and_load",

		  "skeleton open_and_load failed\n"))

		return;



	bss = skel->bss;



	do_btf_read(skel);



	if (CHECK(bss->tasks == 0, "check if iterated over tasks",

		  "no task iteration, did BPF program run?\n"))

		goto cleanup;



	CHECK(bss->seq_err != 0, "check for unexpected err",

	      "bpf_seq_printf_btf returned %ld", bss->seq_err);



cleanup:

	bpf_iter_task_btf__destroy(skel);

}



static void test_tcp4(void)

{

	struct bpf_iter_tcp4 *skel;
@@ -957,6 +1029,8 @@ void test_bpf_iter(void) 
		test_task_stack();

	if (test__start_subtest("task_file"))

		test_task_file();

	if (test__start_subtest("task_btf"))

		test_task_btf();

	if (test__start_subtest("tcp4"))

		test_tcp4();

	if (test__start_subtest("tcp6"))

tools/testing/selftests/bpf/progs/bpf_iter_task_btf.c

0 → 100644
+50 −0
Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0

/* Copyright (c) 2020, Oracle and/or its affiliates. */

#include "bpf_iter.h"

#include <bpf/bpf_helpers.h>

#include <bpf/bpf_tracing.h>

#include <bpf/bpf_core_read.h>



#include <errno.h>



char _license[] SEC("license") = "GPL";



long tasks = 0;

long seq_err = 0;

bool skip = false;



SEC("iter/task")

int dump_task_struct(struct bpf_iter__task *ctx)

{

	struct seq_file *seq = ctx->meta->seq;

	struct task_struct *task = ctx->task;

	static struct btf_ptr ptr = { };

	long ret;



#if __has_builtin(__builtin_btf_type_id)

	ptr.type_id = bpf_core_type_id_kernel(struct task_struct);

	ptr.ptr = task;



	if (ctx->meta->seq_num == 0)

		BPF_SEQ_PRINTF(seq, "Raw BTF task\n");



	ret = bpf_seq_printf_btf(seq, &ptr, sizeof(ptr), 0);

	switch (ret) {

	case 0:

		tasks++;

		break;

	case -ERANGE:

		/* NULL task or task->fs, don't count it as an error. */

		break;

	case -E2BIG:

		return 1;

	default:

		seq_err = ret;

		break;

	}

#else

	skip = true;

#endif



	return 0;

}