selftests/bpf: Add tailcall_bpf2bpf tests

Add four tests to tailcalls selftest explicitly named
"tailcall_bpf2bpf_X" as their purpose is to validate that combination
of tailcalls with bpf2bpf calls are working properly.
These tests also validate LD_ABS from subprograms.

Signed-off-by: Maciej Fijalkowski <maciej.fijalkowski@intel.com>
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 bb8fe646dd9f052dc647b32d354fbd595e7ec32e..ee27d68d2a1c6e41e8cf735ab4be29e40ebd0fc1 100644 (file)
--- a/tools/testing/selftests/bpf/prog_tests/tailcalls.c
+++ b/tools/testing/selftests/bpf/prog_tests/tailcalls.c
@@ -1,5 +1,6 @@
 // SPDX-License-Identifier: GPL-2.0
 #include <test_progs.h>
+#include <network_helpers.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
@@ -472,6 +473,329 @@ out:
        bpf_object__close(obj);
 }
 
+/* test_tailcall_bpf2bpf_1 purpose is to make sure that tailcalls are working
+ * correctly in correlation with BPF subprograms
+ */
+static void test_tailcall_bpf2bpf_1(void)
+{
+       int err, map_fd, prog_fd, main_fd, i;
+       struct bpf_map *prog_array;
+       struct bpf_program *prog;
+       struct bpf_object *obj;
+       __u32 retval, duration;
+       char prog_name[32];
+
+       err = bpf_prog_load("tailcall_bpf2bpf1.o", BPF_PROG_TYPE_SCHED_CLS,
+                           &obj, &prog_fd);
+       if (CHECK_FAIL(err))
+               return;
+
+       prog = bpf_object__find_program_by_title(obj, "classifier");
+       if (CHECK_FAIL(!prog))
+               goto out;
+
+       main_fd = bpf_program__fd(prog);
+       if (CHECK_FAIL(main_fd < 0))
+               goto out;
+
+       prog_array = bpf_object__find_map_by_name(obj, "jmp_table");
+       if (CHECK_FAIL(!prog_array))
+               goto out;
+
+       map_fd = bpf_map__fd(prog_array);
+       if (CHECK_FAIL(map_fd < 0))
+               goto out;
+
+       /* nop -> jmp */
+       for (i = 0; i < bpf_map__def(prog_array)->max_entries; i++) {
+               snprintf(prog_name, sizeof(prog_name), "classifier/%i", i);
+
+               prog = bpf_object__find_program_by_title(obj, prog_name);
+               if (CHECK_FAIL(!prog))
+                       goto out;
+
+               prog_fd = bpf_program__fd(prog);
+               if (CHECK_FAIL(prog_fd < 0))
+                       goto out;
+
+               err = bpf_map_update_elem(map_fd, &i, &prog_fd, BPF_ANY);
+               if (CHECK_FAIL(err))
+                       goto out;
+       }
+
+       err = bpf_prog_test_run(main_fd, 1, &pkt_v4, sizeof(pkt_v4), 0,
+                               0, &retval, &duration);
+       CHECK(err || retval != 1, "tailcall",
+             "err %d errno %d retval %d\n", err, errno, retval);
+
+       /* jmp -> nop, call subprog that will do tailcall */
+       i = 1;
+       err = bpf_map_delete_elem(map_fd, &i);
+       if (CHECK_FAIL(err))
+               goto out;
+
+       err = bpf_prog_test_run(main_fd, 1, &pkt_v4, sizeof(pkt_v4), 0,
+                               0, &retval, &duration);
+       CHECK(err || retval != 0, "tailcall", "err %d errno %d retval %d\n",
+             err, errno, retval);
+
+       /* make sure that subprog can access ctx and entry prog that
+        * called this subprog can properly return
+        */
+       i = 0;
+       err = bpf_map_delete_elem(map_fd, &i);
+       if (CHECK_FAIL(err))
+               goto out;
+
+       err = bpf_prog_test_run(main_fd, 1, &pkt_v4, sizeof(pkt_v4), 0,
+                               0, &retval, &duration);
+       CHECK(err || retval != sizeof(pkt_v4) * 2,
+             "tailcall", "err %d errno %d retval %d\n",
+             err, errno, retval);
+out:
+       bpf_object__close(obj);
+}
+
+/* test_tailcall_bpf2bpf_2 checks that the count value of the tail call limit
+ * enforcement matches with expectations when tailcall is preceded with
+ * bpf2bpf call.
+ */
+static void test_tailcall_bpf2bpf_2(void)
+{
+       int err, map_fd, prog_fd, main_fd, data_fd, i, val;
+       struct bpf_map *prog_array, *data_map;
+       struct bpf_program *prog;
+       struct bpf_object *obj;
+       __u32 retval, duration;
+       char buff[128] = {};
+
+       err = bpf_prog_load("tailcall_bpf2bpf2.o", BPF_PROG_TYPE_SCHED_CLS,
+                           &obj, &prog_fd);
+       if (CHECK_FAIL(err))
+               return;
+
+       prog = bpf_object__find_program_by_title(obj, "classifier");
+       if (CHECK_FAIL(!prog))
+               goto out;
+
+       main_fd = bpf_program__fd(prog);
+       if (CHECK_FAIL(main_fd < 0))
+               goto out;
+
+       prog_array = bpf_object__find_map_by_name(obj, "jmp_table");
+       if (CHECK_FAIL(!prog_array))
+               goto out;
+
+       map_fd = bpf_map__fd(prog_array);
+       if (CHECK_FAIL(map_fd < 0))
+               goto out;
+
+       prog = bpf_object__find_program_by_title(obj, "classifier/0");
+       if (CHECK_FAIL(!prog))
+               goto out;
+
+       prog_fd = bpf_program__fd(prog);
+       if (CHECK_FAIL(prog_fd < 0))
+               goto out;
+
+       i = 0;
+       err = bpf_map_update_elem(map_fd, &i, &prog_fd, BPF_ANY);
+       if (CHECK_FAIL(err))
+               goto out;
+
+       err = bpf_prog_test_run(main_fd, 1, buff, sizeof(buff), 0,
+                               &duration, &retval, NULL);
+       CHECK(err || retval != 1, "tailcall", "err %d errno %d retval %d\n",
+             err, errno, retval);
+
+       data_map = bpf_object__find_map_by_name(obj, "tailcall.bss");
+       if (CHECK_FAIL(!data_map || !bpf_map__is_internal(data_map)))
+               return;
+
+       data_fd = bpf_map__fd(data_map);
+       if (CHECK_FAIL(map_fd < 0))
+               return;
+
+       i = 0;
+       err = bpf_map_lookup_elem(data_fd, &i, &val);
+       CHECK(err || val != 33, "tailcall count", "err %d errno %d count %d\n",
+             err, errno, val);
+
+       i = 0;
+       err = bpf_map_delete_elem(map_fd, &i);
+       if (CHECK_FAIL(err))
+               goto out;
+
+       err = bpf_prog_test_run(main_fd, 1, buff, sizeof(buff), 0,
+                               &duration, &retval, NULL);
+       CHECK(err || retval != 0, "tailcall", "err %d errno %d retval %d\n",
+             err, errno, retval);
+out:
+       bpf_object__close(obj);
+}
+
+/* test_tailcall_bpf2bpf_3 checks that non-trivial amount of stack (up to
+ * 256 bytes) can be used within bpf subprograms that have the tailcalls
+ * in them
+ */
+static void test_tailcall_bpf2bpf_3(void)
+{
+       int err, map_fd, prog_fd, main_fd, i;
+       struct bpf_map *prog_array;
+       struct bpf_program *prog;
+       struct bpf_object *obj;
+       __u32 retval, duration;
+       char prog_name[32];
+
+       err = bpf_prog_load("tailcall_bpf2bpf3.o", BPF_PROG_TYPE_SCHED_CLS,
+                           &obj, &prog_fd);
+       if (CHECK_FAIL(err))
+               return;
+
+       prog = bpf_object__find_program_by_title(obj, "classifier");
+       if (CHECK_FAIL(!prog))
+               goto out;
+
+       main_fd = bpf_program__fd(prog);
+       if (CHECK_FAIL(main_fd < 0))
+               goto out;
+
+       prog_array = bpf_object__find_map_by_name(obj, "jmp_table");
+       if (CHECK_FAIL(!prog_array))
+               goto out;
+
+       map_fd = bpf_map__fd(prog_array);
+       if (CHECK_FAIL(map_fd < 0))
+               goto out;
+
+       for (i = 0; i < bpf_map__def(prog_array)->max_entries; i++) {
+               snprintf(prog_name, sizeof(prog_name), "classifier/%i", i);
+
+               prog = bpf_object__find_program_by_title(obj, prog_name);
+               if (CHECK_FAIL(!prog))
+                       goto out;
+
+               prog_fd = bpf_program__fd(prog);
+               if (CHECK_FAIL(prog_fd < 0))
+                       goto out;
+
+               err = bpf_map_update_elem(map_fd, &i, &prog_fd, BPF_ANY);
+               if (CHECK_FAIL(err))
+                       goto out;
+       }
+
+       err = bpf_prog_test_run(main_fd, 1, &pkt_v4, sizeof(pkt_v4), 0,
+                               &duration, &retval, NULL);
+       CHECK(err || retval != sizeof(pkt_v4) * 3,
+             "tailcall", "err %d errno %d retval %d\n",
+             err, errno, retval);
+
+       i = 1;
+       err = bpf_map_delete_elem(map_fd, &i);
+       if (CHECK_FAIL(err))
+               goto out;
+
+       err = bpf_prog_test_run(main_fd, 1, &pkt_v4, sizeof(pkt_v4), 0,
+                               &duration, &retval, NULL);
+       CHECK(err || retval != sizeof(pkt_v4),
+             "tailcall", "err %d errno %d retval %d\n",
+             err, errno, retval);
+
+       i = 0;
+       err = bpf_map_delete_elem(map_fd, &i);
+       if (CHECK_FAIL(err))
+               goto out;
+
+       err = bpf_prog_test_run(main_fd, 1, &pkt_v4, sizeof(pkt_v4), 0,
+                               &duration, &retval, NULL);
+       CHECK(err || retval != sizeof(pkt_v4) * 2,
+             "tailcall", "err %d errno %d retval %d\n",
+             err, errno, retval);
+out:
+       bpf_object__close(obj);
+}
+
+/* test_tailcall_bpf2bpf_4 checks that tailcall counter is correctly preserved
+ * across tailcalls combined with bpf2bpf calls. for making sure that tailcall
+ * counter behaves correctly, bpf program will go through following flow:
+ *
+ * entry -> entry_subprog -> tailcall0 -> bpf_func0 -> subprog0 ->
+ * -> tailcall1 -> bpf_func1 -> subprog1 -> tailcall2 -> bpf_func2 ->
+ * subprog2 [here bump global counter] --------^
+ *
+ * We go through first two tailcalls and start counting from the subprog2 where
+ * the loop begins. At the end of the test make sure that the global counter is
+ * equal to 31, because tailcall counter includes the first two tailcalls
+ * whereas global counter is incremented only on loop presented on flow above.
+ */
+static void test_tailcall_bpf2bpf_4(void)
+{
+       int err, map_fd, prog_fd, main_fd, data_fd, i, val;
+       struct bpf_map *prog_array, *data_map;
+       struct bpf_program *prog;
+       struct bpf_object *obj;
+       __u32 retval, duration;
+       char prog_name[32];
+
+       err = bpf_prog_load("tailcall_bpf2bpf4.o", BPF_PROG_TYPE_SCHED_CLS,
+                           &obj, &prog_fd);
+       if (CHECK_FAIL(err))
+               return;
+
+       prog = bpf_object__find_program_by_title(obj, "classifier");
+       if (CHECK_FAIL(!prog))
+               goto out;
+
+       main_fd = bpf_program__fd(prog);
+       if (CHECK_FAIL(main_fd < 0))
+               goto out;
+
+       prog_array = bpf_object__find_map_by_name(obj, "jmp_table");
+       if (CHECK_FAIL(!prog_array))
+               goto out;
+
+       map_fd = bpf_map__fd(prog_array);
+       if (CHECK_FAIL(map_fd < 0))
+               goto out;
+
+       for (i = 0; i < bpf_map__def(prog_array)->max_entries; i++) {
+               snprintf(prog_name, sizeof(prog_name), "classifier/%i", i);
+
+               prog = bpf_object__find_program_by_title(obj, prog_name);
+               if (CHECK_FAIL(!prog))
+                       goto out;
+
+               prog_fd = bpf_program__fd(prog);
+               if (CHECK_FAIL(prog_fd < 0))
+                       goto out;
+
+               err = bpf_map_update_elem(map_fd, &i, &prog_fd, BPF_ANY);
+               if (CHECK_FAIL(err))
+                       goto out;
+       }
+
+       err = bpf_prog_test_run(main_fd, 1, &pkt_v4, sizeof(pkt_v4), 0,
+                               &duration, &retval, NULL);
+       CHECK(err || retval != sizeof(pkt_v4) * 3, "tailcall", "err %d errno %d retval %d\n",
+             err, errno, retval);
+
+       data_map = bpf_object__find_map_by_name(obj, "tailcall.bss");
+       if (CHECK_FAIL(!data_map || !bpf_map__is_internal(data_map)))
+               return;
+
+       data_fd = bpf_map__fd(data_map);
+       if (CHECK_FAIL(map_fd < 0))
+               return;
+
+       i = 0;
+       err = bpf_map_lookup_elem(data_fd, &i, &val);
+       CHECK(err || val != 31, "tailcall count", "err %d errno %d count %d\n",
+             err, errno, val);
+
+out:
+       bpf_object__close(obj);
+}
+
 void test_tailcalls(void)
 {
        if (test__start_subtest("tailcall_1"))
@@ -484,4 +808,12 @@ void test_tailcalls(void)
                test_tailcall_4();
        if (test__start_subtest("tailcall_5"))
                test_tailcall_5();
+       if (test__start_subtest("tailcall_bpf2bpf_1"))
+               test_tailcall_bpf2bpf_1();
+       if (test__start_subtest("tailcall_bpf2bpf_2"))
+               test_tailcall_bpf2bpf_2();
+       if (test__start_subtest("tailcall_bpf2bpf_3"))
+               test_tailcall_bpf2bpf_3();
+       if (test__start_subtest("tailcall_bpf2bpf_4"))
+               test_tailcall_bpf2bpf_4();
 }

diff --git a/tools/testing/selftests/bpf/progs/tailcall_bpf2bpf1.c b/tools/testing/selftests/bpf/progs/tailcall_bpf2bpf1.c
new file mode 100644 (file)
index 0000000..b5d9c8e
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/tailcall_bpf2bpf1.c
@@ -0,0 +1,38 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/bpf.h>
+#include <bpf/bpf_helpers.h>
+
+struct {
+       __uint(type, BPF_MAP_TYPE_PROG_ARRAY);
+       __uint(max_entries, 2);
+       __uint(key_size, sizeof(__u32));
+       __uint(value_size, sizeof(__u32));
+} jmp_table SEC(".maps");
+
+#define TAIL_FUNC(x)                           \
+       SEC("classifier/" #x)                   \
+       int bpf_func_##x(struct __sk_buff *skb) \
+       {                                       \
+               return x;                       \
+       }
+TAIL_FUNC(0)
+TAIL_FUNC(1)
+
+static __noinline
+int subprog_tail(struct __sk_buff *skb)
+{
+       bpf_tail_call(skb, &jmp_table, 0);
+
+       return skb->len * 2;
+}
+
+SEC("classifier")
+int entry(struct __sk_buff *skb)
+{
+       bpf_tail_call(skb, &jmp_table, 1);
+
+       return subprog_tail(skb);
+}
+
+char __license[] SEC("license") = "GPL";
+int _version SEC("version") = 1;

diff --git a/tools/testing/selftests/bpf/progs/tailcall_bpf2bpf2.c b/tools/testing/selftests/bpf/progs/tailcall_bpf2bpf2.c
new file mode 100644 (file)
index 0000000..a004ab2
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/tailcall_bpf2bpf2.c
@@ -0,0 +1,41 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/bpf.h>
+#include <bpf/bpf_helpers.h>
+#include "bpf_legacy.h"
+
+struct {
+       __uint(type, BPF_MAP_TYPE_PROG_ARRAY);
+       __uint(max_entries, 1);
+       __uint(key_size, sizeof(__u32));
+       __uint(value_size, sizeof(__u32));
+} jmp_table SEC(".maps");
+
+static __noinline
+int subprog_tail(struct __sk_buff *skb)
+{
+       if (load_byte(skb, 0))
+               bpf_tail_call(skb, &jmp_table, 1);
+       else
+               bpf_tail_call(skb, &jmp_table, 0);
+       return 1;
+}
+
+static volatile int count;
+
+SEC("classifier/0")
+int bpf_func_0(struct __sk_buff *skb)
+{
+       count++;
+       return subprog_tail(skb);
+}
+
+SEC("classifier")
+int entry(struct __sk_buff *skb)
+{
+       bpf_tail_call(skb, &jmp_table, 0);
+
+       return 0;
+}
+
+char __license[] SEC("license") = "GPL";
+int _version SEC("version") = 1;

diff --git a/tools/testing/selftests/bpf/progs/tailcall_bpf2bpf3.c b/tools/testing/selftests/bpf/progs/tailcall_bpf2bpf3.c
new file mode 100644 (file)
index 0000000..96dbef2
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/tailcall_bpf2bpf3.c
@@ -0,0 +1,61 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/bpf.h>
+#include <bpf/bpf_helpers.h>
+#include "bpf_legacy.h"
+
+struct {
+       __uint(type, BPF_MAP_TYPE_PROG_ARRAY);
+       __uint(max_entries, 2);
+       __uint(key_size, sizeof(__u32));
+       __uint(value_size, sizeof(__u32));
+} jmp_table SEC(".maps");
+
+__noinline
+int subprog_tail2(struct __sk_buff *skb)
+{
+       volatile char arr[64] = {};
+
+       if (load_word(skb, 0) || load_half(skb, 0))
+               bpf_tail_call(skb, &jmp_table, 10);
+       else
+               bpf_tail_call(skb, &jmp_table, 1);
+
+       return skb->len;
+}
+
+static __noinline
+int subprog_tail(struct __sk_buff *skb)
+{
+       volatile char arr[64] = {};
+
+       bpf_tail_call(skb, &jmp_table, 0);
+
+       return skb->len * 2;
+}
+
+SEC("classifier/0")
+int bpf_func_0(struct __sk_buff *skb)
+{
+       volatile char arr[128] = {};
+
+       return subprog_tail2(skb);
+}
+
+SEC("classifier/1")
+int bpf_func_1(struct __sk_buff *skb)
+{
+       volatile char arr[128] = {};
+
+       return skb->len * 3;
+}
+
+SEC("classifier")
+int entry(struct __sk_buff *skb)
+{
+       volatile char arr[128] = {};
+
+       return subprog_tail(skb);
+}
+
+char __license[] SEC("license") = "GPL";
+int _version SEC("version") = 1;

diff --git a/tools/testing/selftests/bpf/progs/tailcall_bpf2bpf4.c b/tools/testing/selftests/bpf/progs/tailcall_bpf2bpf4.c
new file mode 100644 (file)
index 0000000..98b40a9
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/tailcall_bpf2bpf4.c
@@ -0,0 +1,61 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/bpf.h>
+#include <bpf/bpf_helpers.h>
+
+struct {
+       __uint(type, BPF_MAP_TYPE_PROG_ARRAY);
+       __uint(max_entries, 3);
+       __uint(key_size, sizeof(__u32));
+       __uint(value_size, sizeof(__u32));
+} jmp_table SEC(".maps");
+
+static volatile int count;
+
+__noinline
+int subprog_tail_2(struct __sk_buff *skb)
+{
+       bpf_tail_call(skb, &jmp_table, 2);
+       return skb->len * 3;
+}
+
+__noinline
+int subprog_tail_1(struct __sk_buff *skb)
+{
+       bpf_tail_call(skb, &jmp_table, 1);
+       return skb->len * 2;
+}
+
+__noinline
+int subprog_tail(struct __sk_buff *skb)
+{
+       bpf_tail_call(skb, &jmp_table, 0);
+       return skb->len;
+}
+
+SEC("classifier/1")
+int bpf_func_1(struct __sk_buff *skb)
+{
+       return subprog_tail_2(skb);
+}
+
+SEC("classifier/2")
+int bpf_func_2(struct __sk_buff *skb)
+{
+       count++;
+       return subprog_tail_2(skb);
+}
+
+SEC("classifier/0")
+int bpf_func_0(struct __sk_buff *skb)
+{
+       return subprog_tail_1(skb);
+}
+
+SEC("classifier")
+int entry(struct __sk_buff *skb)
+{
+       return subprog_tail(skb);
+}
+
+char __license[] SEC("license") = "GPL";
+int _version SEC("version") = 1;