[v4,dwarves] btf: Add support for the floating-point types

Message ID	20210310201550.170599-1-iii@linux.ibm.com (mailing list archive)
State	Not Applicable
Delegated to:	BPF
Headers	show Return-Path: <bpf-owner@kernel.org> From: Ilya Leoshkevich <iii@linux.ibm.com> To: Arnaldo Carvalho de Melo <acme@redhat.com>, Andrii Nakryiko <andrii@kernel.org> Cc: dwarves@vger.kernel.org, bpf@vger.kernel.org, Alexei Starovoitov <ast@kernel.org>, Daniel Borkmann <daniel@iogearbox.net>, Yonghong Song <yhs@fb.com>, Heiko Carstens <hca@linux.ibm.com>, Vasily Gorbik <gor@linux.ibm.com>, Ilya Leoshkevich <iii@linux.ibm.com> Subject: [PATCH v4 dwarves] btf: Add support for the floating-point types Date: Wed, 10 Mar 2021 21:15:50 +0100 Message-Id: <20210310201550.170599-1-iii@linux.ibm.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk
Series	[v4,dwarves] btf: Add support for the floating-point types \| expand [v4,dwarves] btf: Add support for the floating-point types

Context	Check	Description
netdev/tree_selection	success	Not a local patch

diff --git a/btf_loader.c b/btf_loader.c index ec286f4..7cc39aa 100644 --- a/btf_loader.c +++ b/btf_loader.c @@ -160,7 +160,7 @@ static struct variable *variable__new(strings_t name, uint32_t linkage) return var; } -static int create_new_base_type(struct btf_elf *btfe, const struct btf_type *tp, uint32_t id) +static int create_new_int_type(struct btf_elf *btfe, const struct btf_type *tp, uint32_t id) { uint32_t attrs = btf_int_encoding(tp); strings_t name = tp->name_off; @@ -175,6 +175,20 @@ static int create_new_base_type(struct btf_elf *btfe, const struct btf_type *tp, return 0; } +static int create_new_float_type(struct btf_elf *btfe, const struct btf_type *tp, uint32_t id) +{ + strings_t name = tp->name_off; + struct base_type *base = base_type__new(name, 0, BT_FP_SINGLE, tp->size * 8); + + if (base == NULL) + return -ENOMEM; + + base->tag.tag = DW_TAG_base_type; + cu__add_tag_with_id(btfe->priv, &base->tag, id); + + return 0; +} + static int create_new_array(struct btf_elf *btfe, const struct btf_type *tp, uint32_t id) { struct btf_array *ap = btf_array(tp); @@ -397,7 +411,7 @@ static int btf_elf__load_types(struct btf_elf *btfe) switch (type) { case BTF_KIND_INT: - err = create_new_base_type(btfe, type_ptr, type_index); + err = create_new_int_type(btfe, type_ptr, type_index); break; case BTF_KIND_ARRAY: err = create_new_array(btfe, type_ptr, type_index); @@ -442,6 +456,9 @@ static int btf_elf__load_types(struct btf_elf *btfe) // BTF_KIND_FUNC corresponding to a defined subprogram. err = create_new_function(btfe, type_ptr, type_index); break; + case BTF_KIND_FLOAT: + err = create_new_float_type(btfe, type_ptr, type_index); + break; default: fprintf(stderr, "BTF: idx: %d, Unknown kind %d\n", type_index, type); fflush(stderr); diff --git a/dwarf_loader.c b/dwarf_loader.c index b73d786..c5e6681 100644 --- a/dwarf_loader.c +++ b/dwarf_loader.c @@ -461,6 +461,16 @@ static struct ptr_to_member_type *ptr_to_member_type__new(Dwarf_Die *die, return ptr; } +static uint8_t encoding_to_float_type(uint64_t encoding) +{ + switch (encoding) { + case DW_ATE_complex_float: return BT_FP_CMPLX; + case DW_ATE_float: return BT_FP_SINGLE; + case DW_ATE_imaginary_float: return BT_FP_IMGRY; + default: return 0; + } +} + static struct base_type *base_type__new(Dwarf_Die *die, struct cu *cu) { struct base_type *bt = tag__alloc(cu, sizeof(*bt)); @@ -474,6 +484,7 @@ static struct base_type *base_type__new(Dwarf_Die *die, struct cu *cu) bt->is_signed = encoding == DW_ATE_signed; bt->is_varargs = false; bt->name_has_encoding = true; + bt->float_type = encoding_to_float_type(encoding); } return bt; diff --git a/lib/bpf b/lib/bpf index 5af3d86..986962f 160000 --- a/lib/bpf +++ b/lib/bpf @@ -1 +1 @@ -Subproject commit 5af3d86b5a2c5fecdc3ab83822d083edd32b4396 +Subproject commit 986962fade5dfa89c2890f3854eb040d2a64ab38 diff --git a/libbtf.c b/libbtf.c index 9f76283..7ad7e9c 100644 --- a/libbtf.c +++ b/libbtf.c @@ -30,6 +30,7 @@ struct btf *base_btf; uint8_t btf_elf__verbose; uint8_t btf_elf__force; +bool btf_gen_floats = false; static int btf_var_secinfo_cmp(const void *a, const void *b) { @@ -227,6 +228,7 @@ static const char * const btf_kind_str[NR_BTF_KINDS] = { [BTF_KIND_FUNC_PROTO] = "FUNC_PROTO", [BTF_KIND_VAR] = "VAR", [BTF_KIND_DATASEC] = "DATASEC", + [BTF_KIND_FLOAT] = "FLOAT", }; static const char *btf_elf__printable_name(const struct btf_elf *btfe, uint32_t offset) @@ -367,6 +369,27 @@ static void btf_log_func_param(const struct btf_elf *btfe, } } +static int32_t btf_elf__add_float_type(struct btf_elf *btfe, + const struct base_type *bt, + const char *name) +{ + int32_t id; + + id = btf__add_float(btfe->btf, name, BITS_ROUNDUP_BYTES(bt->bit_size)); + if (id < 0) { + btf_elf__log_err(btfe, BTF_KIND_FLOAT, name, true, "Error emitting BTF type"); + } else { + const struct btf_type *t; + + t = btf__type_by_id(btfe->btf, id); + btf_elf__log_type(btfe, t, false, true, + "size=%u nr_bits=%u", + t->size, bt->bit_size); + } + + return id; +} + int32_t btf_elf__add_base_type(struct btf_elf *btfe, const struct base_type *bt, const char *name) { @@ -379,8 +402,17 @@ int32_t btf_elf__add_base_type(struct btf_elf *btfe, const struct base_type *bt, encoding = BTF_INT_SIGNED; } else if (bt->is_bool) { encoding = BTF_INT_BOOL; - } else if (bt->float_type) { - fprintf(stderr, "float_type is not supported\n"); + } else if (bt->float_type && btf_gen_floats) { + /* + * Encode floats as BTF_KIND_FLOAT if allowed, otherwise (in + * compatibility mode) encode them as BTF_KIND_INT - that's not + * fully correct, but that's what it used to be. + */ + if (bt->float_type == BT_FP_SINGLE || + bt->float_type == BT_FP_DOUBLE || + bt->float_type == BT_FP_LDBL) + return btf_elf__add_float_type(btfe, bt, name); + fprintf(stderr, "Complex, interval and imaginary float types are not supported\n"); return -1; } diff --git a/libbtf.h b/libbtf.h index 191f586..c7cbe6e 100644 --- a/libbtf.h +++ b/libbtf.h @@ -35,6 +35,7 @@ extern struct btf *base_btf; extern uint8_t btf_elf__verbose; extern uint8_t btf_elf__force; #define btf_elf__verbose_log(fmt, ...) { if (btf_elf__verbose) printf(fmt, __VA_ARGS__); } +extern bool btf_gen_floats; #define PERCPU_SECTION ".data..percpu" diff --git a/man-pages/pahole.1 b/man-pages/pahole.1 index 352bb5e..e292b2c 100644 --- a/man-pages/pahole.1 +++ b/man-pages/pahole.1 @@ -199,6 +199,11 @@ Path to the base BTF file, for instance: vmlinux when encoding kernel module BTF This may be inferred when asking for a /sys/kernel/btf/MODULE, when it will be autoconfigured to "/sys/kernel/btf/vmlinux". +.TP +.B \-\-btf_gen_floats +Allow producing BTF_KIND_FLOAT entries in systems where the vmlinux DWARF +information has float types. + .TP .B \-l, \-\-show_first_biggest_size_base_type_member Show first biggest size base_type member. diff --git a/pahole.c b/pahole.c index 4a34ba5..c8d38f5 100644 --- a/pahole.c +++ b/pahole.c @@ -825,6 +825,7 @@ ARGP_PROGRAM_VERSION_HOOK_DEF = dwarves_print_version; #define ARGP_just_packed_structs 319 #define ARGP_numeric_version 320 #define ARGP_btf_base 321 +#define ARGP_btf_gen_floats 322 static const struct argp_option pahole__options[] = { { @@ -1119,6 +1120,11 @@ static const struct argp_option pahole__options[] = { .key = ARGP_btf_encode_force, .doc = "Ignore those symbols found invalid when encoding BTF." }, + { + .name = "btf_gen_floats", + .key = ARGP_btf_gen_floats, + .doc = "Allow producing BTF_KIND_FLOAT entries." + }, { .name = "structs", .key = ARGP_just_structs, @@ -1254,6 +1260,8 @@ static error_t pahole__options_parser(int key, char *arg, base_btf_file = arg; break; case ARGP_numeric_version: print_numeric_version = true; break; + case ARGP_btf_gen_floats: + btf_gen_floats = true; break; default: return ARGP_ERR_UNKNOWN; }

[v4,dwarves] btf: Add support for the floating-point types

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