selftests/bpf: Add test for sleepable bpf iterator programs

This adds a test for bpf iterator programs to make use of sleepable
bpf helpers.

Signed-off-by: Kenny Yu <kennyyu@fb.com>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20220124185403.468466-5-kennyyu@fb.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

diff --git a/tools/testing/selftests/bpf/prog_tests/bpf_iter.c b/tools/testing/selftests/bpf/prog_tests/bpf_iter.c
index b84f859..5142a7d 100644 (file)
--- a/tools/testing/selftests/bpf/prog_tests/bpf_iter.c
+++ b/tools/testing/selftests/bpf/prog_tests/bpf_iter.c
@@ -138,6 +138,24 @@ static void test_task(void)
        bpf_iter_task__destroy(skel);
 }
 
+static void test_task_sleepable(void)
+{
+       struct bpf_iter_task *skel;
+
+       skel = bpf_iter_task__open_and_load();
+       if (!ASSERT_OK_PTR(skel, "bpf_iter_task__open_and_load"))
+               return;
+
+       do_dummy_read(skel->progs.dump_task_sleepable);
+
+       ASSERT_GT(skel->bss->num_expected_failure_copy_from_user_task, 0,
+                 "num_expected_failure_copy_from_user_task");
+       ASSERT_GT(skel->bss->num_success_copy_from_user_task, 0,
+                 "num_success_copy_from_user_task");
+
+       bpf_iter_task__destroy(skel);
+}
+
 static void test_task_stack(void)
 {
        struct bpf_iter_task_stack *skel;
@@ -1252,6 +1270,8 @@ void test_bpf_iter(void)
                test_bpf_map();
        if (test__start_subtest("task"))
                test_task();
+       if (test__start_subtest("task_sleepable"))
+               test_task_sleepable();
        if (test__start_subtest("task_stack"))
                test_task_stack();
        if (test__start_subtest("task_file"))

diff --git a/tools/testing/selftests/bpf/progs/bpf_iter_task.c b/tools/testing/selftests/bpf/progs/bpf_iter_task.c
index c86b93f..d227412 100644 (file)
--- a/tools/testing/selftests/bpf/progs/bpf_iter_task.c
+++ b/tools/testing/selftests/bpf/progs/bpf_iter_task.c
@@ -2,6 +2,7 @@
 /* Copyright (c) 2020 Facebook */
 #include "bpf_iter.h"
 #include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
 
 char _license[] SEC("license") = "GPL";
 
@@ -23,3 +24,56 @@ int dump_task(struct bpf_iter__task *ctx)
        BPF_SEQ_PRINTF(seq, "%8d %8d\n", task->tgid, task->pid);
        return 0;
 }
+
+int num_expected_failure_copy_from_user_task = 0;
+int num_success_copy_from_user_task = 0;
+
+SEC("iter.s/task")
+int dump_task_sleepable(struct bpf_iter__task *ctx)
+{
+       struct seq_file *seq = ctx->meta->seq;
+       struct task_struct *task = ctx->task;
+       static const char info[] = "    === END ===";
+       struct pt_regs *regs;
+       void *ptr;
+       uint32_t user_data = 0;
+       int ret;
+
+       if (task == (void *)0) {
+               BPF_SEQ_PRINTF(seq, "%s\n", info);
+               return 0;
+       }
+
+       /* Read an invalid pointer and ensure we get an error */
+       ptr = NULL;
+       ret = bpf_copy_from_user_task(&user_data, sizeof(uint32_t), ptr, task, 0);
+       if (ret) {
+               ++num_expected_failure_copy_from_user_task;
+       } else {
+               BPF_SEQ_PRINTF(seq, "%s\n", info);
+               return 0;
+       }
+
+       /* Try to read the contents of the task's instruction pointer from the
+        * remote task's address space.
+        */
+       regs = (struct pt_regs *)bpf_task_pt_regs(task);
+       if (regs == (void *)0) {
+               BPF_SEQ_PRINTF(seq, "%s\n", info);
+               return 0;
+       }
+       ptr = (void *)PT_REGS_IP(regs);
+
+       ret = bpf_copy_from_user_task(&user_data, sizeof(uint32_t), ptr, task, 0);
+       if (ret) {
+               BPF_SEQ_PRINTF(seq, "%s\n", info);
+               return 0;
+       }
+       ++num_success_copy_from_user_task;
+
+       if (ctx->meta->seq_num == 0)
+               BPF_SEQ_PRINTF(seq, "    tgid      gid     data\n");
+
+       BPF_SEQ_PRINTF(seq, "%8d %8d %8d\n", task->tgid, task->pid, user_data);
+       return 0;
+}