selftests/bpf: Add test for sleepable program tailcalls

Adding test that makes sure we can't mix sleepable and non-sleepable
bpf programs in the BPF_MAP_TYPE_PROG_ARRAY map and that we can do
tail call in the sleepable program.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Link: https://lore.kernel.org/r/20260130081208.1130204-3-jolsa@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

diff --git a/tools/testing/selftests/bpf/prog_tests/tailcalls.c b/tools/testing/selftests/bpf/prog_tests/tailcalls.c
index 0ab36503c3b213fbcbc5b0792c4011cecba2895e..7d534fde0af9bf0d7640e69ff5ced39b1b4b2ac9 100644 (file)
--- a/tools/testing/selftests/bpf/prog_tests/tailcalls.c
+++ b/tools/testing/selftests/bpf/prog_tests/tailcalls.c
@@ -8,6 +8,7 @@
 #include "tailcall_freplace.skel.h"
 #include "tc_bpf2bpf.skel.h"
 #include "tailcall_fail.skel.h"
+#include "tailcall_sleepable.skel.h"
 
 /* test_tailcall_1 checks basic functionality by patching multiple locations
  * in a single program for a single tail call slot with nop->jmp, jmp->nop
@@ -1653,6 +1654,77 @@ static void test_tailcall_failure()
        RUN_TESTS(tailcall_fail);
 }
 
+noinline void uprobe_sleepable_trigger(void)
+{
+       asm volatile ("");
+}
+
+static void test_tailcall_sleepable(void)
+{
+       LIBBPF_OPTS(bpf_uprobe_opts, opts);
+       struct tailcall_sleepable *skel;
+       int prog_fd, map_fd;
+       int err, key;
+
+       skel = tailcall_sleepable__open();
+       if (!ASSERT_OK_PTR(skel, "tailcall_sleepable__open"))
+               return;
+
+       /*
+        * Test that we can't load uprobe_normal and uprobe_sleepable_1,
+        * because they share tailcall map.
+        */
+       bpf_program__set_autoload(skel->progs.uprobe_normal, true);
+       bpf_program__set_autoload(skel->progs.uprobe_sleepable_1, true);
+
+       err = tailcall_sleepable__load(skel);
+       if (!ASSERT_ERR(err, "tailcall_sleepable__load"))
+               goto out;
+
+       tailcall_sleepable__destroy(skel);
+
+       /*
+        * Test that we can tail call from sleepable to sleepable program.
+        */
+       skel = tailcall_sleepable__open();
+       if (!ASSERT_OK_PTR(skel, "tailcall_sleepable__open"))
+               return;
+
+       bpf_program__set_autoload(skel->progs.uprobe_sleepable_1, true);
+       bpf_program__set_autoload(skel->progs.uprobe_sleepable_2, true);
+
+       err = tailcall_sleepable__load(skel);
+       if (!ASSERT_OK(err, "tailcall_sleepable__load"))
+               goto out;
+
+       /* Add sleepable uprobe_sleepable_2 to jmp_table[0]. */
+       key = 0;
+       prog_fd = bpf_program__fd(skel->progs.uprobe_sleepable_2);
+       map_fd = bpf_map__fd(skel->maps.jmp_table);
+       err = bpf_map_update_elem(map_fd, &key, &prog_fd, BPF_ANY);
+       if (!ASSERT_OK(err, "update jmp_table"))
+               goto out;
+
+       skel->bss->my_pid = getpid();
+
+       /* Attach uprobe_sleepable_1 to uprobe_sleepable_trigger and hit it.  */
+       opts.func_name = "uprobe_sleepable_trigger";
+       skel->links.uprobe_sleepable_1 = bpf_program__attach_uprobe_opts(
+                                               skel->progs.uprobe_sleepable_1,
+                                               -1,
+                                               "/proc/self/exe",
+                                               0 /* offset */,
+                                               &opts);
+       if (!ASSERT_OK_PTR(skel->links.uprobe_sleepable_1, "bpf_program__attach_uprobe_opts"))
+               goto out;
+
+       uprobe_sleepable_trigger();
+       ASSERT_EQ(skel->bss->executed, 1, "executed");
+
+out:
+       tailcall_sleepable__destroy(skel);
+}
+
 void test_tailcalls(void)
 {
        if (test__start_subtest("tailcall_1"))
@@ -1707,4 +1779,6 @@ void test_tailcalls(void)
                test_tailcall_bpf2bpf_freplace();
        if (test__start_subtest("tailcall_failure"))
                test_tailcall_failure();
+       if (test__start_subtest("tailcall_sleepable"))
+               test_tailcall_sleepable();
 }

diff --git a/tools/testing/selftests/bpf/progs/tailcall_sleepable.c b/tools/testing/selftests/bpf/progs/tailcall_sleepable.c
new file mode 100644 (file)
index 0000000..d959a9e
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/tailcall_sleepable.c
@@ -0,0 +1,43 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/bpf.h>
+#include <bpf/bpf_helpers.h>
+#include "bpf_misc.h"
+#include "bpf_test_utils.h"
+
+struct {
+       __uint(type, BPF_MAP_TYPE_PROG_ARRAY);
+       __uint(max_entries, 1);
+       __uint(key_size, sizeof(__u32));
+       __array(values, void (void));
+} jmp_table SEC(".maps");
+
+SEC("?uprobe")
+int uprobe_normal(void *ctx)
+{
+       bpf_tail_call_static(ctx, &jmp_table, 0);
+       return 0;
+}
+
+SEC("?uprobe.s")
+int uprobe_sleepable_1(void *ctx)
+{
+       bpf_tail_call_static(ctx, &jmp_table, 0);
+       return 0;
+}
+
+int executed = 0;
+int my_pid = 0;
+
+SEC("?uprobe.s")
+int uprobe_sleepable_2(void *ctx)
+{
+       int pid = bpf_get_current_pid_tgid() >> 32;
+
+       if (pid != my_pid)
+               return 0;
+
+       executed++;
+       return 0;
+}
+
+char __license[] SEC("license") = "GPL";