selftests/bpf: Test a uptr struct spanning across pages.

This patch tests the case when uptr has a struct spanning across two
pages. It is not supported now and EOPNOTSUPP is expected from the
syscall update_elem.

It also tests the whole uptr struct located exactly at the
end of a page and ensures that this case is accepted by update_elem.

Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Link: https://lore.kernel.org/r/20241023234759.860539-10-martin.lau@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

diff --git a/tools/testing/selftests/bpf/prog_tests/task_local_storage.c b/tools/testing/selftests/bpf/prog_tests/task_local_storage.c
index 4c8eadd1f083c807dd1a115e52c106ea232ffc4e..b7af0921b3da91be367645ca48534a2d837e90a7 100644 (file)
--- a/tools/testing/selftests/bpf/prog_tests/task_local_storage.c
+++ b/tools/testing/selftests/bpf/prog_tests/task_local_storage.c
@@ -8,6 +8,7 @@
 #include <sys/syscall.h>   /* For SYS_xxx definitions */
 #include <sys/types.h>
 #include <sys/eventfd.h>
+#include <sys/mman.h>
 #include <test_progs.h>
 #include "task_local_storage_helpers.h"
 #include "task_local_storage.skel.h"
@@ -367,6 +368,46 @@ out:
        close(parent_task_fd);
 }
 
+static void test_uptr_across_pages(void)
+{
+       int page_size = getpagesize();
+       struct value_type value = {};
+       struct task_ls_uptr *skel;
+       int err, task_fd, map_fd;
+       void *mem;
+
+       task_fd = sys_pidfd_open(getpid(), 0);
+       if (!ASSERT_OK_FD(task_fd, "task_fd"))
+               return;
+
+       mem = mmap(NULL, page_size * 2, PROT_READ | PROT_WRITE,
+                  MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+       if (!ASSERT_OK_PTR(mem, "mmap(page_size * 2)")) {
+               close(task_fd);
+               return;
+       }
+
+       skel = task_ls_uptr__open_and_load();
+       if (!ASSERT_OK_PTR(skel, "skel_open_and_load"))
+               goto out;
+
+       map_fd = bpf_map__fd(skel->maps.datamap);
+       value.udata = mem + page_size - offsetof(struct user_data, b);
+       err = bpf_map_update_elem(map_fd, &task_fd, &value, 0);
+       if (!ASSERT_ERR(err, "update_elem(udata)"))
+               goto out;
+       ASSERT_EQ(errno, EOPNOTSUPP, "errno");
+
+       value.udata = mem + page_size - sizeof(struct user_data);
+       err = bpf_map_update_elem(map_fd, &task_fd, &value, 0);
+       ASSERT_OK(err, "update_elem(udata)");
+
+out:
+       task_ls_uptr__destroy(skel);
+       close(task_fd);
+       munmap(mem, page_size * 2);
+}
+
 void test_task_local_storage(void)
 {
        if (test__start_subtest("sys_enter_exit"))
@@ -379,4 +420,6 @@ void test_task_local_storage(void)
                test_nodeadlock();
        if (test__start_subtest("uptr_basic"))
                test_uptr_basic();
+       if (test__start_subtest("uptr_across_pages"))
+               test_uptr_across_pages();
 }