On 6/15/22 5:17 PM, Jakub Sitnicki wrote:
Cover the case when tail call count needs to be passed from BPF function to
BPF function, and the caller has data on stack. Specifically when the size
of data allocated on BPF stack is not a multiple on 8.
Signed-off-by: Jakub Sitnicki <jakub@xxxxxxxxxxxxxx>
---
.../selftests/bpf/prog_tests/tailcalls.c | 55 +++++++++++++++++++
.../selftests/bpf/progs/tailcall_bpf2bpf6.c | 42 ++++++++++++++
2 files changed, 97 insertions(+)
create mode 100644 tools/testing/selftests/bpf/progs/tailcall_bpf2bpf6.c
diff --git a/tools/testing/selftests/bpf/prog_tests/tailcalls.c b/tools/testing/selftests/bpf/prog_tests/tailcalls.c
index c4da87ec3ba4..19c70880cfb3 100644
--- a/tools/testing/selftests/bpf/prog_tests/tailcalls.c
+++ b/tools/testing/selftests/bpf/prog_tests/tailcalls.c
@@ -831,6 +831,59 @@ static void test_tailcall_bpf2bpf_4(bool noise)
bpf_object__close(obj);
}
+#include "tailcall_bpf2bpf6.skel.h"
+
+/* Tail call counting works even when there is data on stack which is
+ * not aligned to 8 bytes.
+ */
+static void test_tailcall_bpf2bpf_6(void)
+{
+ struct tailcall_bpf2bpf6 *obj;
+ int err, map_fd, prog_fd, main_fd, data_fd, i, val;
+ LIBBPF_OPTS(bpf_test_run_opts, topts,
+ .data_in = &pkt_v4,
+ .data_size_in = sizeof(pkt_v4),
+ .repeat = 1,
+ );
+
+ obj = tailcall_bpf2bpf6__open_and_load();
+ if (!ASSERT_OK_PTR(obj, "open and load"))
+ return;
+
+ main_fd = bpf_program__fd(obj->progs.entry);
+ if (!ASSERT_GE(main_fd, 0, "entry prog fd"))
+ goto out;
+
+ map_fd = bpf_map__fd(obj->maps.jmp_table);
+ if (!ASSERT_GE(map_fd, 0, "jmp_table map fd"))
+ goto out;
+
+ prog_fd = bpf_program__fd(obj->progs.classifier_0);
+ if (!ASSERT_GE(prog_fd, 0, "classifier_0 prog fd"))
+ goto out;
+
+ i = 0;
+ err = bpf_map_update_elem(map_fd, &i, &prog_fd, BPF_ANY);
+ if (!ASSERT_OK(err, "jmp_table map update"))
+ goto out;
+
+ err = bpf_prog_test_run_opts(main_fd, &topts);
+ ASSERT_OK(err, "entry prog test run");
+ ASSERT_EQ(topts.retval, 0, "tailcall retval");
+
+ data_fd = bpf_map__fd(obj->maps.bss);
+ if (!ASSERT_GE(map_fd, 0, "bss map fd"))
+ goto out;
+
+ i = 0;
+ err = bpf_map_lookup_elem(data_fd, &i, &val);
+ ASSERT_OK(err, "bss map lookup");
+ ASSERT_EQ(val, 1, "done flag is set");
+
+out:
+ tailcall_bpf2bpf6__destroy(obj);
+}
+
void test_tailcalls(void)
{
if (test__start_subtest("tailcall_1"))
@@ -855,4 +908,6 @@ void test_tailcalls(void)
test_tailcall_bpf2bpf_4(false);
if (test__start_subtest("tailcall_bpf2bpf_5"))
test_tailcall_bpf2bpf_4(true);
+ if (test__start_subtest("tailcall_bpf2bpf_6"))
+ test_tailcall_bpf2bpf_6();
}
diff --git a/tools/testing/selftests/bpf/progs/tailcall_bpf2bpf6.c b/tools/testing/selftests/bpf/progs/tailcall_bpf2bpf6.c
new file mode 100644
index 000000000000..256de9bcc621
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/tailcall_bpf2bpf6.c
@@ -0,0 +1,42 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/bpf.h>
+#include <bpf/bpf_helpers.h>
+
+#define __unused __attribute__((always_unused))
+
+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");
+
+int done = 0;
+
+SEC("tc")
+int classifier_0(struct __sk_buff *skb __unused)
+{
+ done = 1;
+ return 0;
+}
Looks like this fails CI with:
progs/tailcall_bpf2bpf6.c:17:40: error: unknown attribute 'always_unused' ignored [-Werror,-Wunknown-attributes]
int classifier_0(struct __sk_buff *skb __unused)
^~~~~~~~
progs/tailcall_bpf2bpf6.c:5:33: note: expanded from macro '__unused'
#define __unused __attribute__((always_unused))
^~~~~~~~~~~~~
1 error generated.
make: *** [Makefile:509: /tmp/runner/work/bpf/bpf/tools/testing/selftests/bpf/tailcall_bpf2bpf6.o] Error 1
make: *** Waiting for unfinished jobs....
Error: Process completed with exit code 2.
