selftests/bpf: Additional test for CO-RE in the kernel.

Add a test where randmap() function is appended to three different bpf
programs. That action checks struct bpf_core_relo replication logic
and offset adjustment in gen loader part of libbpf.

Fourth bpf program has 360 CO-RE relocations from vmlinux, bpf_testmod,
and non-existing type. It tests candidate cache logic.

Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20211201181040.23337-16-alexei.starovoitov@gmail.com

diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile
index 200ebcc..8981369 100644 (file)
--- a/tools/testing/selftests/bpf/Makefile
+++ b/tools/testing/selftests/bpf/Makefile
@@ -326,7 +326,7 @@ LINKED_SKELS := test_static_linked.skel.h linked_funcs.skel.h               \
 
 LSKELS := kfunc_call_test.c fentry_test.c fexit_test.c fexit_sleep.c \
        test_ringbuf.c atomics.c trace_printk.c trace_vprintk.c \
-       map_ptr_kern.c
+       map_ptr_kern.c core_kern.c
 # Generate both light skeleton and libbpf skeleton for these
 LSKELS_EXTRA := test_ksyms_module.c test_ksyms_weak.c kfunc_call_test_subprog.c
 SKEL_BLACKLIST += $$(LSKELS)

diff --git a/tools/testing/selftests/bpf/prog_tests/core_kern.c b/tools/testing/selftests/bpf/prog_tests/core_kern.c
new file mode 100644 (file)
index 0000000..561c518
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/core_kern.c
@@ -0,0 +1,14 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2021 Facebook */
+
+#include "test_progs.h"
+#include "core_kern.lskel.h"
+
+void test_core_kern_lskel(void)
+{
+       struct core_kern_lskel *skel;
+
+       skel = core_kern_lskel__open_and_load();
+       ASSERT_OK_PTR(skel, "open_and_load");
+       core_kern_lskel__destroy(skel);
+}

diff --git a/tools/testing/selftests/bpf/progs/core_kern.c b/tools/testing/selftests/bpf/progs/core_kern.c
new file mode 100644 (file)
index 0000000..13499cc
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/core_kern.c
@@ -0,0 +1,104 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2021 Facebook */
+#include "vmlinux.h"
+
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+#include <bpf/bpf_core_read.h>
+
+#define ATTR __always_inline
+#include "test_jhash.h"
+
+struct {
+       __uint(type, BPF_MAP_TYPE_ARRAY);
+       __type(key, u32);
+       __type(value, u32);
+       __uint(max_entries, 256);
+} array1 SEC(".maps");
+
+struct {
+       __uint(type, BPF_MAP_TYPE_ARRAY);
+       __type(key, u32);
+       __type(value, u32);
+       __uint(max_entries, 256);
+} array2 SEC(".maps");
+
+static __noinline int randmap(int v, const struct net_device *dev)
+{
+       struct bpf_map *map = (struct bpf_map *)&array1;
+       int key = bpf_get_prandom_u32() & 0xff;
+       int *val;
+
+       if (bpf_get_prandom_u32() & 1)
+               map = (struct bpf_map *)&array2;
+
+       val = bpf_map_lookup_elem(map, &key);
+       if (val)
+               *val = bpf_get_prandom_u32() + v + dev->mtu;
+
+       return 0;
+}
+
+SEC("tp_btf/xdp_devmap_xmit")
+int BPF_PROG(tp_xdp_devmap_xmit_multi, const struct net_device
+            *from_dev, const struct net_device *to_dev, int sent, int drops,
+            int err)
+{
+       return randmap(from_dev->ifindex, from_dev);
+}
+
+SEC("fentry/eth_type_trans")
+int BPF_PROG(fentry_eth_type_trans, struct sk_buff *skb,
+            struct net_device *dev, unsigned short protocol)
+{
+       return randmap(dev->ifindex + skb->len, dev);
+}
+
+SEC("fexit/eth_type_trans")
+int BPF_PROG(fexit_eth_type_trans, struct sk_buff *skb,
+            struct net_device *dev, unsigned short protocol)
+{
+       return randmap(dev->ifindex + skb->len, dev);
+}
+
+volatile const int never;
+
+struct __sk_bUfF /* it will not exist in vmlinux */ {
+       int len;
+} __attribute__((preserve_access_index));
+
+struct bpf_testmod_test_read_ctx /* it exists in bpf_testmod */ {
+       size_t len;
+} __attribute__((preserve_access_index));
+
+SEC("tc")
+int balancer_ingress(struct __sk_buff *ctx)
+{
+       void *data_end = (void *)(long)ctx->data_end;
+       void *data = (void *)(long)ctx->data;
+       void *ptr;
+       int ret = 0, nh_off, i = 0;
+
+       nh_off = 14;
+
+       /* pragma unroll doesn't work on large loops */
+#define C do { \
+       ptr = data + i; \
+       if (ptr + nh_off > data_end) \
+               break; \
+       ctx->tc_index = jhash(ptr, nh_off, ctx->cb[0] + i++); \
+       if (never) { \
+               /* below is a dead code with unresolvable CO-RE relo */ \
+               i += ((struct __sk_bUfF *)ctx)->len; \
+               /* this CO-RE relo may or may not resolve
+                * depending on whether bpf_testmod is loaded.
+                */ \
+               i += ((struct bpf_testmod_test_read_ctx *)ctx)->len; \
+       } \
+       } while (0);
+#define C30 C;C;C;C;C;C;C;C;C;C;C;C;C;C;C;C;C;C;C;C;C;C;C;C;C;C;C;C;C;C;
+       C30;C30;C30; /* 90 calls */
+       return 0;
+}
+
+char LICENSE[] SEC("license") = "GPL";