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selftests/bpf: Add test for bpf_seq_printf_btf helper

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

Suggested-by: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Signed-off-by: Alan Maguire <alan.maguire@oracle.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/1601292670-1616-9-git-send-email-alan.maguire@oracle.com
This commit is contained in:
Alan Maguire 2020-09-28 12:31:10 +01:00 committed by Alexei Starovoitov
parent eb411377ae
commit b72091bd4e
2 changed files with 124 additions and 0 deletions
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74
tools/testing/selftests/bpf/prog_tests/bpf_iter.c
View File

@ -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 @@ done:
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"))

50
tools/testing/selftests/bpf/progs/bpf_iter_task_btf.c Normal file
View File

@ -0,0 +1,50 @@
// 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;
}