bpf: selftests: Add verifier tests for CO-RE bitfield writes

Add some tests that exercise BPF_CORE_WRITE_BITFIELD() macro. Since some
non-trivial bit fiddling is going on, make sure various edge cases (such
as adjacent bitfields and bitfields at the edge of structs) are
exercised.

Acked-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Xu <dxu@dxuuu.xyz>
Link: https://lore.kernel.org/r/72698a1080fa565f541d5654705255984ea2a029.1702325874.git.dxu@dxuuu.xyz
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>

diff --git a/tools/testing/selftests/bpf/prog_tests/verifier.c b/tools/testing/selftests/bpf/prog_tests/verifier.c
index 8d746642cbd7e6706278083d283bbfe8339f3642..ac49ec25211d1d2ba15f025314c3dd31c6d96251 100644 (file)
--- a/tools/testing/selftests/bpf/prog_tests/verifier.c
+++ b/tools/testing/selftests/bpf/prog_tests/verifier.c
@@ -6,6 +6,7 @@
 #include "verifier_and.skel.h"
 #include "verifier_array_access.skel.h"
 #include "verifier_basic_stack.skel.h"
+#include "verifier_bitfield_write.skel.h"
 #include "verifier_bounds.skel.h"
 #include "verifier_bounds_deduction.skel.h"
 #include "verifier_bounds_deduction_non_const.skel.h"
@@ -116,6 +117,7 @@ static void run_tests_aux(const char *skel_name,
 
 void test_verifier_and(void)                  { RUN(verifier_and); }
 void test_verifier_basic_stack(void)          { RUN(verifier_basic_stack); }
+void test_verifier_bitfield_write(void)       { RUN(verifier_bitfield_write); }
 void test_verifier_bounds(void)               { RUN(verifier_bounds); }
 void test_verifier_bounds_deduction(void)     { RUN(verifier_bounds_deduction); }
 void test_verifier_bounds_deduction_non_const(void)     { RUN(verifier_bounds_deduction_non_const); }

diff --git a/tools/testing/selftests/bpf/progs/verifier_bitfield_write.c b/tools/testing/selftests/bpf/progs/verifier_bitfield_write.c
new file mode 100644 (file)
index 0000000..623f130
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/verifier_bitfield_write.c
@@ -0,0 +1,100 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/bpf.h>
+#include <stdint.h>
+
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_core_read.h>
+
+#include "bpf_misc.h"
+
+struct core_reloc_bitfields {
+       /* unsigned bitfields */
+       uint8_t         ub1: 1;
+       uint8_t         ub2: 2;
+       uint32_t        ub7: 7;
+       /* signed bitfields */
+       int8_t          sb4: 4;
+       int32_t         sb20: 20;
+       /* non-bitfields */
+       uint32_t        u32;
+       int32_t         s32;
+} __attribute__((preserve_access_index));
+
+SEC("tc")
+__description("single CO-RE bitfield roundtrip")
+__btf_path("btf__core_reloc_bitfields.bpf.o")
+__success
+__retval(3)
+int single_field_roundtrip(struct __sk_buff *ctx)
+{
+       struct core_reloc_bitfields bitfields;
+
+       __builtin_memset(&bitfields, 0, sizeof(bitfields));
+       BPF_CORE_WRITE_BITFIELD(&bitfields, ub2, 3);
+       return BPF_CORE_READ_BITFIELD(&bitfields, ub2);
+}
+
+SEC("tc")
+__description("multiple CO-RE bitfield roundtrip")
+__btf_path("btf__core_reloc_bitfields.bpf.o")
+__success
+__retval(0x3FD)
+int multiple_field_roundtrip(struct __sk_buff *ctx)
+{
+       struct core_reloc_bitfields bitfields;
+       uint8_t ub2;
+       int8_t sb4;
+
+       __builtin_memset(&bitfields, 0, sizeof(bitfields));
+       BPF_CORE_WRITE_BITFIELD(&bitfields, ub2, 1);
+       BPF_CORE_WRITE_BITFIELD(&bitfields, sb4, -1);
+
+       ub2 = BPF_CORE_READ_BITFIELD(&bitfields, ub2);
+       sb4 = BPF_CORE_READ_BITFIELD(&bitfields, sb4);
+
+       return (((uint8_t)sb4) << 2) | ub2;
+}
+
+SEC("tc")
+__description("adjacent CO-RE bitfield roundtrip")
+__btf_path("btf__core_reloc_bitfields.bpf.o")
+__success
+__retval(7)
+int adjacent_field_roundtrip(struct __sk_buff *ctx)
+{
+       struct core_reloc_bitfields bitfields;
+       uint8_t ub1, ub2;
+
+       __builtin_memset(&bitfields, 0, sizeof(bitfields));
+       BPF_CORE_WRITE_BITFIELD(&bitfields, ub1, 1);
+       BPF_CORE_WRITE_BITFIELD(&bitfields, ub2, 3);
+
+       ub1 = BPF_CORE_READ_BITFIELD(&bitfields, ub1);
+       ub2 = BPF_CORE_READ_BITFIELD(&bitfields, ub2);
+
+       return (ub2 << 1) | ub1;
+}
+
+SEC("tc")
+__description("multibyte CO-RE bitfield roundtrip")
+__btf_path("btf__core_reloc_bitfields.bpf.o")
+__success
+__retval(0x21)
+int multibyte_field_roundtrip(struct __sk_buff *ctx)
+{
+       struct core_reloc_bitfields bitfields;
+       uint32_t ub7;
+       uint8_t ub1;
+
+       __builtin_memset(&bitfields, 0, sizeof(bitfields));
+       BPF_CORE_WRITE_BITFIELD(&bitfields, ub1, 1);
+       BPF_CORE_WRITE_BITFIELD(&bitfields, ub7, 16);
+
+       ub1 = BPF_CORE_READ_BITFIELD(&bitfields, ub1);
+       ub7 = BPF_CORE_READ_BITFIELD(&bitfields, ub7);
+
+       return (ub7 << 1) | ub1;
+}
+
+char _license[] SEC("license") = "GPL";