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

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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>
This commit is contained in:
Daniel Xu 2023-12-11 13:20:09 -07:00 committed by Martin KaFai Lau
parent 7d19c00e9a
commit f04f2ce601
2 changed files with 102 additions and 0 deletions
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2
tools/testing/selftests/bpf/prog_tests/verifier.c
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@ -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); }

100
tools/testing/selftests/bpf/progs/verifier_bitfield_write.c Normal file
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@ -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";