Commit f04f2ce6 authored by Daniel Xu's avatar Daniel Xu Committed by Martin KaFai Lau
Browse files

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: default avatarAndrii Nakryiko <andrii@kernel.org>
Signed-off-by: default avatarDaniel Xu <dxu@dxuuu.xyz>
Link: https://lore.kernel.org/r/72698a1080fa565f541d5654705255984ea2a029.1702325874.git.dxu@dxuuu.xyz


Signed-off-by: default avatarMartin KaFai Lau <martin.lau@kernel.org>
parent 7d19c00e

tools/testing/selftests/bpf/prog_tests/verifier.c

+2 −0
Original line number Diff line number Diff line
@@ -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); }

tools/testing/selftests/bpf/progs/verifier_bitfield_write.c

0 → 100644
+100 −0
Original line number Diff line number Diff line 
// 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";