Commit 5a30eb23 authored by Andrii Nakryiko's avatar Andrii Nakryiko Committed by Alexei Starovoitov
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selftests/bpf: Fix field existence CO-RE reloc tests 



Negative field existence cases for have a broken assumption that FIELD_EXISTS
CO-RE relo will fail for fields that match the name but have incompatible type
signature. That's not how CO-RE relocations generally behave. Types and fields
that match by name but not by expected type are treated as non-matching
candidates and are skipped. Error later is reported if no matching candidate
was found. That's what happens for most relocations, but existence relocations
(FIELD_EXISTS and TYPE_EXISTS) are more permissive and they are designed to
return 0 or 1, depending if a match is found. This allows to handle
name-conflicting but incompatible types in BPF code easily. Combined with
___flavor suffixes, it's possible to handle pretty much any structural type
changes in kernel within the compiled once BPF source code.

So, long story short, negative field existence test cases are invalid in their
assumptions, so this patch reworks them into a single consolidated positive
case that doesn't match any of the fields.

Fixes: c7566a69 ("selftests/bpf: Add field existence CO-RE relocs tests")
Reported-by: default avatarLorenz Bauer <lmb@cloudflare.com>
Signed-off-by: default avatarAndrii Nakryiko <andrii@kernel.org>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Acked-by: default avatarLorenz Bauer <lmb@cloudflare.com>
Link: https://lore.kernel.org/bpf/20210426192949.416837-5-andrii@kernel.org
parent 0f20615d

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

+19 −12
Original line number Diff line number Diff line
@@ -210,11 +210,6 @@ static int duration = 0; 
	.bpf_obj_file = "test_core_reloc_existence.o",			\

	.btf_src_file = "btf__core_reloc_" #name ".o"			\



#define FIELD_EXISTS_ERR_CASE(name) {					\

	FIELD_EXISTS_CASE_COMMON(name),					\

	.fails = true,							\

}



#define BITFIELDS_CASE_COMMON(objfile, test_name_prefix,  name)		\

	.case_name = test_name_prefix#name,				\

	.bpf_obj_file = objfile,					\
@@ -643,13 +638,25 @@ static struct core_reloc_test_case test_cases[] = { 
		},

		.output_len = sizeof(struct core_reloc_existence_output),

	},



	FIELD_EXISTS_ERR_CASE(existence__err_int_sz),

	FIELD_EXISTS_ERR_CASE(existence__err_int_type),

	FIELD_EXISTS_ERR_CASE(existence__err_int_kind),

	FIELD_EXISTS_ERR_CASE(existence__err_arr_kind),

	FIELD_EXISTS_ERR_CASE(existence__err_arr_value_type),

	FIELD_EXISTS_ERR_CASE(existence__err_struct_type),

	{

		FIELD_EXISTS_CASE_COMMON(existence___wrong_field_defs),

		.input = STRUCT_TO_CHAR_PTR(core_reloc_existence___wrong_field_defs) {

		},

		.input_len = sizeof(struct core_reloc_existence___wrong_field_defs),

		.output = STRUCT_TO_CHAR_PTR(core_reloc_existence_output) {

			.a_exists = 0,

			.b_exists = 0,

			.c_exists = 0,

			.arr_exists = 0,

			.s_exists = 0,

			.a_value = 0xff000001u,

			.b_value = 0xff000002u,

			.c_value = 0xff000003u,

			.arr_value = 0xff000004u,

			.s_value = 0xff000005u,

		},

		.output_len = sizeof(struct core_reloc_existence_output),

	},



	/* bitfield relocation checks */

	BITFIELDS_CASE(bitfields, {

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

deleted100644 → 0
+0 −3
Original line number Diff line number Diff line 
#include "core_reloc_types.h"



void f(struct core_reloc_existence___err_wrong_arr_kind x) {}

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

deleted100644 → 0
+0 −3
Original line number Diff line number Diff line 
#include "core_reloc_types.h"



void f(struct core_reloc_existence___err_wrong_arr_value_type x) {}

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

deleted100644 → 0
+0 −3
Original line number Diff line number Diff line 
#include "core_reloc_types.h"



void f(struct core_reloc_existence___err_wrong_int_kind x) {}

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

deleted100644 → 0
+0 −3
Original line number Diff line number Diff line 
#include "core_reloc_types.h"



void f(struct core_reloc_existence___err_wrong_int_type x) {}