tjh.dev / kernel
Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel os linux
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selftests: Add test for overriding global data value before load

This adds a test to exercise the new bpf_map__set_initial_value() function.
The test simply overrides the global data section with all zeroes, and
checks that the new value makes it into the kernel map on load.

Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/20200329132253.232541-2-toke@redhat.com

authored by

Toke Høiland-Jørgensen and committed by
Daniel Borkmann e5fb60ee e2842be5

+62 -1
+61
tools/testing/selftests/bpf/prog_tests/global_data_init.c
··· 1 + // SPDX-License-Identifier: GPL-2.0 2 + #include <test_progs.h> 3 + 4 + void test_global_data_init(void) 5 + { 6 + const char *file = "./test_global_data.o"; 7 + int err = -ENOMEM, map_fd, zero = 0; 8 + __u8 *buff = NULL, *newval = NULL; 9 + struct bpf_object *obj; 10 + struct bpf_map *map; 11 + __u32 duration = 0; 12 + size_t sz; 13 + 14 + obj = bpf_object__open_file(file, NULL); 15 + if (CHECK_FAIL(!obj)) 16 + return; 17 + 18 + map = bpf_object__find_map_by_name(obj, "test_glo.rodata"); 19 + if (CHECK_FAIL(!map || !bpf_map__is_internal(map))) 20 + goto out; 21 + 22 + sz = bpf_map__def(map)->value_size; 23 + newval = malloc(sz); 24 + if (CHECK_FAIL(!newval)) 25 + goto out; 26 + 27 + memset(newval, 0, sz); 28 + /* wrong size, should fail */ 29 + err = bpf_map__set_initial_value(map, newval, sz - 1); 30 + if (CHECK(!err, "reject set initial value wrong size", "err %d\n", err)) 31 + goto out; 32 + 33 + err = bpf_map__set_initial_value(map, newval, sz); 34 + if (CHECK(err, "set initial value", "err %d\n", err)) 35 + goto out; 36 + 37 + err = bpf_object__load(obj); 38 + if (CHECK_FAIL(err)) 39 + goto out; 40 + 41 + map_fd = bpf_map__fd(map); 42 + if (CHECK_FAIL(map_fd < 0)) 43 + goto out; 44 + 45 + buff = malloc(sz); 46 + if (buff) 47 + err = bpf_map_lookup_elem(map_fd, &zero, buff); 48 + if (CHECK(!buff || err || memcmp(buff, newval, sz), 49 + "compare .rodata map data override", 50 + "err %d errno %d\n", err, errno)) 51 + goto out; 52 + 53 + memset(newval, 1, sz); 54 + /* object loaded - should fail */ 55 + err = bpf_map__set_initial_value(map, newval, sz); 56 + CHECK(!err, "reject set initial value after load", "err %d\n", err); 57 + out: 58 + free(buff); 59 + free(newval); 60 + bpf_object__close(obj); 61 + }
+1 -1
tools/testing/selftests/bpf/progs/test_global_data.c
··· 68 68 bpf_map_update_elem(&result_##map, &key, var, 0); \ 69 69 } while (0) 70 70 71 - SEC("static_data_load") 71 + SEC("classifier/static_data_load") 72 72 int load_static_data(struct __sk_buff *skb) 73 73 { 74 74 static const __u64 bar = ~0;