Commit 49f67f39 authored by Ilya Leoshkevich's avatar Ilya Leoshkevich Committed by Alexei Starovoitov
Browse files

bpf: btf: Add BTF_FMODEL_SIGNED_ARG flag 



s390x eBPF JIT needs to know whether a function return value is signed
and which function arguments are signed, in order to generate code
compliant with the s390x ABI.

Signed-off-by: default avatarIlya Leoshkevich <iii@linux.ibm.com>
Link: https://lore.kernel.org/r/20230128000650.1516334-26-iii@linux.ibm.com


Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent 0f0e5f5b

include/linux/bpf.h

+4 −0
Original line number Diff line number Diff line
@@ -899,8 +899,12 @@ enum bpf_cgroup_storage_type { 
/* The argument is a structure. */

#define BTF_FMODEL_STRUCT_ARG		BIT(0)



/* The argument is signed. */

#define BTF_FMODEL_SIGNED_ARG		BIT(1)



struct btf_func_model {

	u8 ret_size;

	u8 ret_flags;

	u8 nr_args;

	u8 arg_size[MAX_BPF_FUNC_ARGS];

	u8 arg_flags[MAX_BPF_FUNC_ARGS];

include/linux/btf.h

+10 −5
Original line number Diff line number Diff line
@@ -236,6 +236,16 @@ static inline bool btf_type_is_small_int(const struct btf_type *t) 
	return btf_type_is_int(t) && t->size <= sizeof(u64);

}



static inline u8 btf_int_encoding(const struct btf_type *t)

{

	return BTF_INT_ENCODING(*(u32 *)(t + 1));

}



static inline bool btf_type_is_signed_int(const struct btf_type *t)

{

	return btf_type_is_int(t) && (btf_int_encoding(t) & BTF_INT_SIGNED);

}



static inline bool btf_type_is_enum(const struct btf_type *t)

{

	return BTF_INFO_KIND(t->info) == BTF_KIND_ENUM;
@@ -306,11 +316,6 @@ static inline u8 btf_int_offset(const struct btf_type *t) 
	return BTF_INT_OFFSET(*(u32 *)(t + 1));

}



static inline u8 btf_int_encoding(const struct btf_type *t)

{

	return BTF_INT_ENCODING(*(u32 *)(t + 1));

}



static inline bool btf_type_is_scalar(const struct btf_type *t)

{

	return btf_type_is_int(t) || btf_type_is_enum(t);

kernel/bpf/btf.c

+15 −1
Original line number Diff line number Diff line
@@ -6453,6 +6453,18 @@ static int __get_type_size(struct btf *btf, u32 btf_id, 
	return -EINVAL;

}



static u8 __get_type_fmodel_flags(const struct btf_type *t)

{

	u8 flags = 0;



	if (__btf_type_is_struct(t))

		flags |= BTF_FMODEL_STRUCT_ARG;

	if (btf_type_is_signed_int(t))

		flags |= BTF_FMODEL_SIGNED_ARG;



	return flags;

}



int btf_distill_func_proto(struct bpf_verifier_log *log,

			   struct btf *btf,

			   const struct btf_type *func,
@@ -6473,6 +6485,7 @@ int btf_distill_func_proto(struct bpf_verifier_log *log, 
			m->arg_flags[i] = 0;

		}

		m->ret_size = 8;

		m->ret_flags = 0;

		m->nr_args = MAX_BPF_FUNC_REG_ARGS;

		return 0;

	}
@@ -6492,6 +6505,7 @@ int btf_distill_func_proto(struct bpf_verifier_log *log, 
		return -EINVAL;

	}

	m->ret_size = ret;

	m->ret_flags = __get_type_fmodel_flags(t);



	for (i = 0; i < nargs; i++) {

		if (i == nargs - 1 && args[i].type == 0) {
@@ -6516,7 +6530,7 @@ int btf_distill_func_proto(struct bpf_verifier_log *log, 
			return -EINVAL;

		}

		m->arg_size[i] = ret;

		m->arg_flags[i] = __btf_type_is_struct(t) ? BTF_FMODEL_STRUCT_ARG : 0;

		m->arg_flags[i] = __get_type_fmodel_flags(t);

	}

	m->nr_args = nargs;

	return 0;