selftests/bpf: Test subprog jit when toggle bpf_jit_harden repeatedly

When bpf_jit_harden is toggled between 0 and 2, subprog jit may fail
due to inconsistent twice read values of bpf_jit_harden during jit. So
add a test to ensure the problem is fixed.

Signed-off-by: Hou Tao <houtao1@huawei.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20220309123321.2400262-5-houtao1@huawei.com

diff --git a/tools/testing/selftests/bpf/prog_tests/subprogs.c b/tools/testing/selftests/bpf/prog_tests/subprogs.c
index 3f3d2ac..903f35a 100644 (file)
--- a/tools/testing/selftests/bpf/prog_tests/subprogs.c
+++ b/tools/testing/selftests/bpf/prog_tests/subprogs.c
@@ -1,32 +1,83 @@
 // SPDX-License-Identifier: GPL-2.0
 /* Copyright (c) 2020 Facebook */
 #include <test_progs.h>
-#include <time.h>
 #include "test_subprogs.skel.h"
 #include "test_subprogs_unused.skel.h"
 
-static int duration;
+struct toggler_ctx {
+       int fd;
+       bool stop;
+};
 
-void test_subprogs(void)
+static void *toggle_jit_harden(void *arg)
+{
+       struct toggler_ctx *ctx = arg;
+       char two = '2';
+       char zero = '0';
+
+       while (!ctx->stop) {
+               lseek(ctx->fd, SEEK_SET, 0);
+               write(ctx->fd, &two, sizeof(two));
+               lseek(ctx->fd, SEEK_SET, 0);
+               write(ctx->fd, &zero, sizeof(zero));
+       }
+
+       return NULL;
+}
+
+static void test_subprogs_with_jit_harden_toggling(void)
+{
+       struct toggler_ctx ctx;
+       pthread_t toggler;
+       int err;
+       unsigned int i, loop = 10;
+
+       ctx.fd = open("/proc/sys/net/core/bpf_jit_harden", O_RDWR);
+       if (!ASSERT_GE(ctx.fd, 0, "open bpf_jit_harden"))
+               return;
+
+       ctx.stop = false;
+       err = pthread_create(&toggler, NULL, toggle_jit_harden, &ctx);
+       if (!ASSERT_OK(err, "new toggler"))
+               goto out;
+
+       /* Make toggler thread to run */
+       usleep(1);
+
+       for (i = 0; i < loop; i++) {
+               struct test_subprogs *skel = test_subprogs__open_and_load();
+
+               if (!ASSERT_OK_PTR(skel, "skel open"))
+                       break;
+               test_subprogs__destroy(skel);
+       }
+
+       ctx.stop = true;
+       pthread_join(toggler, NULL);
+out:
+       close(ctx.fd);
+}
+
+static void test_subprogs_alone(void)
 {
        struct test_subprogs *skel;
        struct test_subprogs_unused *skel2;
        int err;
 
        skel = test_subprogs__open_and_load();
-       if (CHECK(!skel, "skel_open", "failed to open skeleton\n"))
+       if (!ASSERT_OK_PTR(skel, "skel_open"))
                return;
 
        err = test_subprogs__attach(skel);
-       if (CHECK(err, "skel_attach", "failed to attach skeleton: %d\n", err))
+       if (!ASSERT_OK(err, "skel attach"))
                goto cleanup;
 
        usleep(1);
 
-       CHECK(skel->bss->res1 != 12, "res1", "got %d, exp %d\n", skel->bss->res1, 12);
-       CHECK(skel->bss->res2 != 17, "res2", "got %d, exp %d\n", skel->bss->res2, 17);
-       CHECK(skel->bss->res3 != 19, "res3", "got %d, exp %d\n", skel->bss->res3, 19);
-       CHECK(skel->bss->res4 != 36, "res4", "got %d, exp %d\n", skel->bss->res4, 36);
+       ASSERT_EQ(skel->bss->res1, 12, "res1");
+       ASSERT_EQ(skel->bss->res2, 17, "res2");
+       ASSERT_EQ(skel->bss->res3, 19, "res3");
+       ASSERT_EQ(skel->bss->res4, 36, "res4");
 
        skel2 = test_subprogs_unused__open_and_load();
        ASSERT_OK_PTR(skel2, "unused_progs_skel");
@@ -35,3 +86,11 @@ void test_subprogs(void)
 cleanup:
        test_subprogs__destroy(skel);
 }
+
+void test_subprogs(void)
+{
+       if (test__start_subtest("subprogs_alone"))
+               test_subprogs_alone();
+       if (test__start_subtest("subprogs_and_jit_harden"))
+               test_subprogs_with_jit_harden_toggling();
+}