Add a BTF dumper for typed data, so that the user can dump a typed version of the data provided.
The API is
int btf_dump__dump_type_data(struct btf_dump *d, __u32 id, void *data, size_t data_sz, const struct btf_dump_type_data_opts *opts);
...where the id is the BTF id of the data pointed to by the "void *" argument; for example the BTF id of "struct sk_buff" for a "struct skb *" data pointer. Options supported are
- a starting indent level (indent_lvl) - a user-specified indent string which will be printed once per indent level; by default tab is chosen but any string <= 4 chars can be provided. - a set of boolean options to control dump display, similar to those used for BPF helper bpf_snprintf_btf(). Options are - compact : omit newlines and other indentation - skip_names: omit member names - emit_zeroes: show zero-value members
Default output format is identical to that dumped by bpf_snprintf_btf(), for example a "struct sk_buff" representation would look like this:
struct sk_buff){ (union){ (struct){ .next = (struct sk_buff *)0xffffffffffffffff, .prev = (struct sk_buff *)0xffffffffffffffff, (union){ .dev = (struct net_device *)0xffffffffffffffff, .dev_scratch = (long unsigned int)18446744073709551615, }, }, ...
If the data structure is larger than the *data_sz* number of bytes that are available in *data*, as much of the data as possible will be dumped and -E2BIG will be returned. This is useful as tracers will sometimes not be able to capture all of the data associated with a type; for example a "struct task_struct" is ~16k. Being able to specify that only a subset is available is important for such cases. On success, the amount of data dumped is returned.
Signed-off-by: Alan Maguire alan.maguire@oracle.com --- tools/lib/bpf/btf.h | 22 + tools/lib/bpf/btf_dump.c | 1008 +++++++++++++++++++++++++++++++++++++++++++++- tools/lib/bpf/libbpf.map | 1 + 3 files changed, 1029 insertions(+), 2 deletions(-)
diff --git a/tools/lib/bpf/btf.h b/tools/lib/bpf/btf.h index b54f1c3..10470e0 100644 --- a/tools/lib/bpf/btf.h +++ b/tools/lib/bpf/btf.h @@ -184,6 +184,28 @@ struct btf_dump_emit_type_decl_opts { btf_dump__emit_type_decl(struct btf_dump *d, __u32 id, const struct btf_dump_emit_type_decl_opts *opts);
+ +/* indent string length; one indent string is added for each indent level */ +#define BTF_DATA_INDENT_STR_LEN 4 + +struct btf_dump_type_data_opts { + /* size of this struct, for forward/backward compatibility */ + size_t sz; + int indent_level; + char indent_str[BTF_DATA_INDENT_STR_LEN + 1]; + /* below match "show" flags for bpf_show_snprintf() */ + bool compact; /* no newlines/tabs */ + bool skip_names; /* skip member/type names */ + bool emit_zeroes; /* show 0-valued fields */ + size_t :0; +}; +#define btf_dump_type_data_opts__last_field emit_zeroes + +LIBBPF_API int +btf_dump__dump_type_data(struct btf_dump *d, __u32 id, + const void *data, size_t data_sz, + const struct btf_dump_type_data_opts *opts); + /* * A set of helpers for easier BTF types handling */ diff --git a/tools/lib/bpf/btf_dump.c b/tools/lib/bpf/btf_dump.c index 5dc6b517..b1b356a 100644 --- a/tools/lib/bpf/btf_dump.c +++ b/tools/lib/bpf/btf_dump.c @@ -10,6 +10,8 @@ #include <stddef.h> #include <stdlib.h> #include <string.h> +#include <ctype.h> +#include <endian.h> #include <errno.h> #include <linux/err.h> #include <linux/btf.h> @@ -19,6 +21,12 @@ #include "libbpf.h" #include "libbpf_internal.h"
+#define BITS_PER_U128 128 +#define BITS_PER_BYTE_MASK (8 - 1) +#define BITS_PER_BYTE_MASKED(bits) ((bits) & BITS_PER_BYTE_MASK) +#define BITS_ROUNDDOWN_BYTES(bits) ((bits) / 8) +#define BITS_ROUNDUP_BYTES(bits) (roundup(bits, 8)) + static const char PREFIXES[] = "\t\t\t\t\t\t\t\t\t\t\t\t\t"; static const size_t PREFIX_CNT = sizeof(PREFIXES) - 1;
@@ -53,6 +61,26 @@ struct btf_dump_type_aux_state { __u8 referenced: 1; };
+/* + * Common internal data for BTF type data dump operations. + */ +struct btf_dump_data { + const void *data_end; /* end of valid data to show */ + bool compact; + bool skip_names; + bool emit_zeroes; + __u8 indent_lvl; /* base indent level */ + char indent_str[BTF_DATA_INDENT_STR_LEN + 1]; + /* below are used during iteration */ + struct { + __u8 depth; + __u8 array_member:1, + array_terminated:1, + array_ischar:1; + __u32 bitfield_size; + } state; +}; + struct btf_dump { const struct btf *btf; const struct btf_ext *btf_ext; @@ -89,6 +117,10 @@ struct btf_dump { * name occurrences */ struct hashmap *ident_names; + /* + * data for typed display; allocated if needed. + */ + struct btf_dump_data *data; };
static size_t str_hash_fn(const void *key, void *ctx) @@ -765,11 +797,11 @@ static void btf_dump_emit_type(struct btf_dump *d, __u32 id, __u32 cont_id) break; case BTF_KIND_FUNC_PROTO: { const struct btf_param *p = btf_params(t); - __u16 vlen = btf_vlen(t); + __u16 n = btf_vlen(t); int i;
btf_dump_emit_type(d, t->type, cont_id); - for (i = 0; i < vlen; i++, p++) + for (i = 0; i < n; i++, p++) btf_dump_emit_type(d, p->type, cont_id);
break; @@ -1392,6 +1424,112 @@ static void btf_dump_emit_type_chain(struct btf_dump *d, btf_dump_emit_name(d, fname, last_was_ptr); }
+/* show type name as (type_name) */ +static void btf_dump_emit_type_name(struct btf_dump *d, __u32 id, + int lvl, bool toplevel) +{ + + const struct btf_type *t, *child; + const char *name; + __u16 kind; + + /* for array members, we don't bother emitting type name for each + * member to avoid the redundancy of + * .name = (char[])[(char)'f',(char)'o',(char)'o',] + */ + if (d->data->state.array_member) + return; + + t = btf__type_by_id(d->btf, id); + kind = btf_kind(t); + + /* avoid type name specification for variable/section; it will be done + * for the associated variable value(s). + */ + switch (kind) { + case BTF_KIND_VAR: + case BTF_KIND_DATASEC: + return; + default: + break; + } + + if (toplevel) + btf_dump_printf(d, "("); + + if (id == 0) { + btf_dump_printf(d, "void"); + goto done; + } + + switch (kind) { + case BTF_KIND_INT: + case BTF_KIND_FLOAT: + name = btf_name_of(d, t->name_off); + btf_dump_printf(d, "%s", name); + break; + case BTF_KIND_STRUCT: + case BTF_KIND_UNION: + name = btf_dump_type_name(d, id); + btf_dump_printf(d, "%s%s%s", + btf_is_struct(t) ? "struct" : "union", + strlen(name) > 0 ? " " : "", + name); + break; + case BTF_KIND_ENUM: + btf_dump_emit_enum_fwd(d, id, t); + break; + case BTF_KIND_TYPEDEF: + btf_dump_printf(d, "%s", btf_dump_ident_name(d, id)); + break; + case BTF_KIND_VOLATILE: + case BTF_KIND_CONST: + case BTF_KIND_RESTRICT: + /* modifiers are omitted from the cast to save space */ + btf_dump_emit_type_name(d, t->type, lvl, false); + break; + case BTF_KIND_PTR: + btf_dump_emit_type_name(d, t->type, lvl, false); + child = btf__type_by_id(d->btf, t->type); + /* no need for '*' suffix for function prototype */ + if (btf_kind(child) == BTF_KIND_FUNC_PROTO) + break; + btf_dump_printf(d, + btf_kind(child) == BTF_KIND_PTR ? "*" : " *"); + break; + case BTF_KIND_ARRAY: { + const struct btf_array *a = btf_array(t); + + btf_dump_emit_type_name(d, a->type, lvl, false); + btf_dump_printf(d, "[]"); + break; + } + case BTF_KIND_FUNC_PROTO: { + const struct btf_param *p = btf_params(t); + __u16 n = btf_vlen(t); + int i; + + btf_dump_emit_type_name(d, t->type, 0, false); + btf_dump_printf(d, "(*)("); + + for (i = 0; i < n; i++, p++) { + if (i > 0) + btf_dump_printf(d, ", "); + btf_dump_emit_type_name(d, p->type, 0, false); + } + btf_dump_printf(d, ")"); + break; + } + default: + pr_warn("unexpected type when emitting type name, kind %u, id:[%u]\n", + kind, id); + break; + } +done: + if (toplevel) + btf_dump_printf(d, ")"); +} + /* return number of duplicates (occurrences) of a given name */ static size_t btf_dump_name_dups(struct btf_dump *d, struct hashmap *name_map, const char *orig_name) @@ -1442,3 +1580,869 @@ static const char *btf_dump_ident_name(struct btf_dump *d, __u32 id) { return btf_dump_resolve_name(d, id, d->ident_names); } + +static int btf_dump_dump_type_data(struct btf_dump *d, + const char *fname, + const struct btf_type *t, + __u32 id, + const void *data, + __u8 bits_offset); + +static const char *btf_dump_data_newline(struct btf_dump *d) +{ + return d->data->compact ? "" : "\n"; +} + +static const char *btf_dump_data_delim(struct btf_dump *d) +{ + return d->data->state.depth == 0 ? "" : ","; +} + +static void btf_dump_data_pfx(struct btf_dump *d) +{ + int i, lvl = d->data->indent_lvl + d->data->state.depth; + + if (d->data->compact) + lvl = 0; + + for (i = 0; i < lvl; i++) + btf_dump_printf(d, "%s", d->data->indent_str); +} + +/* A macro is used here as btf_type_value[s]() appends format specifiers + * to the format specifier passed in; these do the work of appending + * delimiters etc while the caller simply has to specify the type values + * in the format specifier + value(s). + */ +#define btf_dump_type_values(d, fmt, ...) \ + btf_dump_printf(d, fmt "%s%s", \ + __VA_ARGS__, \ + btf_dump_data_delim(d), \ + btf_dump_data_newline(d)) + +static int btf_dump_unsupported_data(struct btf_dump *d, + const struct btf_type *t, + __u32 id, + const void *data) +{ + btf_dump_printf(d, "<unsupported kind:%u>", + BTF_INFO_KIND(t->info)); + return -ENOTSUP; +} + +static void btf_dump_int128(struct btf_dump *d, + const struct btf_type *t, + const void *data) +{ + /* data points to a __int128 number. + * Suppose + * int128_num = *(__int128 *)data; + * The below formulas shows what upper_num and lower_num represents: + * upper_num = int128_num >> 64; + * lower_num = int128_num & 0xffffffffFFFFFFFFULL; + */ + __u64 upper_num, lower_num; + +#ifdef __BIG_ENDIAN_BITFIELD + upper_num = *(__u64 *)data; + lower_num = *(__u64 *)(data + 8); +#else + upper_num = *(__u64 *)(data + 8); + lower_num = *(__u64 *)data; +#endif + if (upper_num == 0) + btf_dump_type_values(d, "0x%llx", (long long)lower_num); + else + btf_dump_type_values(d, "0x%llx%016llx", (long long)upper_num, + (long long)lower_num); +} + +static void btf_int128_shift(__u64 *print_num, __u16 left_shift_bits, + __u16 right_shift_bits) +{ + __u64 upper_num, lower_num; + +#ifdef __BIG_ENDIAN_BITFIELD + upper_num = print_num[0]; + lower_num = print_num[1]; +#else + upper_num = print_num[1]; + lower_num = print_num[0]; +#endif + + /* shake out un-needed bits by shift/or operations */ + if (left_shift_bits >= 64) { + upper_num = lower_num << (left_shift_bits - 64); + lower_num = 0; + } else { + upper_num = (upper_num << left_shift_bits) | + (lower_num >> (64 - left_shift_bits)); + lower_num = lower_num << left_shift_bits; + } + + if (right_shift_bits >= 64) { + lower_num = upper_num >> (right_shift_bits - 64); + upper_num = 0; + } else { + lower_num = (lower_num >> right_shift_bits) | + (upper_num << (64 - right_shift_bits)); + upper_num = upper_num >> right_shift_bits; + } + +#ifdef __BIG_ENDIAN_BITFIELD + print_num[0] = upper_num; + print_num[1] = lower_num; +#else + print_num[0] = lower_num; + print_num[1] = upper_num; +#endif +} + +static int btf_dump_bitfield_get_data(struct btf_dump *d, + const void *data, + __u8 bits_offset, + __u8 nr_bits, + __u64 *print_num) +{ + __u16 left_shift_bits, right_shift_bits; + __u8 nr_copy_bytes; + __u8 nr_copy_bits; + + nr_copy_bits = nr_bits + bits_offset; + nr_copy_bytes = BITS_ROUNDUP_BYTES(nr_copy_bits); + + memcpy(print_num, data, nr_copy_bytes); + +#ifdef __BIG_ENDIAN_BITFIELD + left_shift_bits = bits_offset; +#else + left_shift_bits = BITS_PER_U128 - nr_copy_bits; +#endif + right_shift_bits = BITS_PER_U128 - nr_bits; + + btf_int128_shift(print_num, left_shift_bits, right_shift_bits); + + return 0; +} + +static int btf_dump_bitfield_data(struct btf_dump *d, + const struct btf_type *t, + const void *data, + __u8 bits_offset, + __u8 nr_bits) +{ + __u64 print_num[2]; + + btf_dump_bitfield_get_data(d, data, bits_offset, nr_bits, print_num); + btf_dump_int128(d, t, print_num); + + return 0; +} + +static int btf_dump_int_bits(struct btf_dump *d, + const struct btf_type *t, + const void *data, + __u8 bits_offset) +{ + __u8 nr_bits = d->data->state.bitfield_size ?: btf_int_bits(t); + + data += BITS_ROUNDDOWN_BYTES(bits_offset); + return btf_dump_bitfield_data(d, t, data, bits_offset, nr_bits); +} + +static int btf_dump_int_bits_check_zero(struct btf_dump *d, + const struct btf_type *t, + const void *data, + __u8 bits_offset) +{ + __u64 print_num[2], zero[2] = { }; + __u8 nr_bits = d->data->state.bitfield_size ?: btf_int_bits(t); + + data += BITS_ROUNDDOWN_BYTES(bits_offset); + btf_dump_bitfield_get_data(d, data, bits_offset, nr_bits, + (__u64 *)&print_num); + if (memcmp(print_num, zero, sizeof(zero)) == 0) + return -ENODATA; + return 0; +} + +static int btf_dump_int_check_zero(struct btf_dump *d, + const struct btf_type *t, + const void *data, + __u8 bits_offset) +{ + __u8 nr_bits = btf_int_bits(t); + bool zero = false; + + if (bits_offset || BITS_PER_BYTE_MASKED(nr_bits)) + return btf_dump_int_bits_check_zero(d, t, data, bits_offset); + + switch (nr_bits) { + case 128: + zero = *(__int128 *)data == 0; + break; + case 64: + zero = *(__s64 *)data == 0; + break; + case 32: + zero = *(__s32 *)data == 0; + break; + case 16: + zero = *(__s16 *)data == 0; + break; + case 8: + zero = *(__s8 *)data == 0; + break; + default: + break; + } + if (zero) + return -ENODATA; + return 0; +} + +static int btf_dump_int_data(struct btf_dump *d, + const struct btf_type *t, + __u32 type_id, + const void *data, + __u8 bits_offset) +{ + __u8 encoding = btf_int_encoding(t); + bool sign = encoding & BTF_INT_SIGNED; + __u8 nr_bits = btf_int_bits(t); + + if (bits_offset || BITS_PER_BYTE_MASKED(nr_bits)) + return btf_dump_int_bits(d, t, data, bits_offset); + + switch (nr_bits) { + case 128: + btf_dump_int128(d, t, data); + break; + case 64: + if (sign) + btf_dump_type_values(d, "%lld", *(long long *)data); + else + btf_dump_type_values(d, "%llu", + *(unsigned long long *)data); + break; + case 32: + if (sign) + btf_dump_type_values(d, "%d", *(__s32 *)data); + else + btf_dump_type_values(d, "%u", *(__u32 *)data); + break; + case 16: + if (sign) + btf_dump_type_values(d, "%d", *(__s16 *)data); + else + btf_dump_type_values(d, "%u", *(__u16 *)data); + break; + case 8: + if (d->data->state.array_ischar) { + /* check for null terminator */ + if (d->data->state.array_terminated) + break; + if (*(char *)data == '\0') { + d->data->state.array_terminated = 1; + break; + } + if (isprint(*(char *)data)) { + btf_dump_type_values(d, "'%c'", + *(char *)data); + break; + } + } + if (sign) + btf_dump_type_values(d, "%d", *(__s8 *)data); + else + btf_dump_type_values(d, "%u", *(__u8 *)data); + break; + default: + pr_warn("unexpected nr_bits %d for id [%u]\n", + nr_bits, type_id); + return -EINVAL; + } + return 0; +} + +static int btf_dump_float_check_zero(struct btf_dump *d, + const struct btf_type *t, + const void *data) +{ + __u8 bytecmp[16] = { 0 }; + int nr_bytes = t->size; + + if (nr_bytes > 16 || nr_bytes < 2) { + pr_warn("unexpected size %d for float\n", nr_bytes); + return -EINVAL; + } + if (memcmp(data, bytecmp, nr_bytes) == 0) + return -ENOMSG; + + return 0; +} + +static int btf_dump_float_data(struct btf_dump *d, + const struct btf_type *t, + __u32 type_id, + const void *data, + __u8 bits_offset) +{ + int nr_bytes = t->size; + + fprintf(stderr, "printing float size %d\n", nr_bytes); + switch (nr_bytes) { + case 16: + btf_dump_type_values(d, "%Lf", *(long double *)data); + break; + case 8: + btf_dump_type_values(d, "%f", *(double *)data); + break; + case 4: + btf_dump_type_values(d, "%f", *(float *)data); + break; + case 12: + case 2: + /* although 2 and 12 are valid BTF_KIND_FLOAT sizes, + * display is not supported yet. + */ + pr_warn("unsupported size %d for id [%u]\n", + nr_bytes, type_id); + return -ENOTSUP; + default: + pr_warn("unexpected size %d for id [%u]\n", + nr_bytes, type_id); + return -EINVAL; + } + return 0; +} + +static int btf_dump_var_data(struct btf_dump *d, + const struct btf_type *v, + __u32 id, + const void *data) +{ + enum btf_func_linkage linkage = btf_var(v)->linkage; + const struct btf_type *t; + const char *l = ""; + __u32 type_id; + + switch (linkage) { + case BTF_FUNC_STATIC: + l = "static "; + break; + case BTF_FUNC_EXTERN: + l = "extern "; + break; + case BTF_FUNC_GLOBAL: + default: + break; + } + + /* format of output here is [linkage] [type] [varname] = (type)value, + * for example "static int cpu_profile_flip = (int)1" + */ + btf_dump_printf(d, "%s", l); + type_id = v->type; + t = btf__type_by_id(d->btf, type_id); + btf_dump_emit_type_name(d, type_id, 0, false); + btf_dump_printf(d, " %s = ", btf_name_of(d, v->name_off)); + return btf_dump_dump_type_data(d, NULL, + t, type_id, data, 0); +} + +static int btf_dump_array_data(struct btf_dump *d, + const struct btf_type *t, + __u32 id, + const void *data) +{ + const struct btf_array *array = btf_array(t); + const struct btf_type *elem_type; + __u32 i, elem_size = 0, elem_type_id; + int array_member; + + elem_type_id = array->type; + elem_type = skip_mods_and_typedefs(d->btf, elem_type_id, NULL); + elem_size = btf__resolve_size(d->btf, elem_type_id); + if (elem_size <= 0) { + pr_warn("unexpected elem size %d for array type [%u]\n", + elem_size, id); + return -EINVAL; + } + + if (btf_is_int(elem_type)) { + /* + * BTF_INT_CHAR encoding never seems to be set for + * char arrays, so if size is 1 and element is + * printable as a char, we'll do that. + */ + if (elem_size == 1) + d->data->state.array_ischar = true; + } + + btf_dump_printf(d, "[%s", btf_dump_data_newline(d)); + d->data->state.depth++; + + /* may be a multidimensional array, so store current "is array member" + * status so we can restore it correctly later. + */ + array_member = d->data->state.array_member; + d->data->state.array_member = 1; + for (i = 0; i < array->nelems && !d->data->state.array_terminated; i++) { + + btf_dump_dump_type_data(d, NULL, elem_type, elem_type_id, + data, 0); + data += elem_size; + } + d->data->state.array_member = array_member; + d->data->state.depth--; + btf_dump_data_pfx(d); + btf_dump_printf(d, "]%s%s", + btf_dump_data_delim(d), + btf_dump_data_newline(d)); + + return 0; +} + +static int btf_dump_struct_data(struct btf_dump *d, + const struct btf_type *t, + __u32 id, + const void *data) +{ + const struct btf_member *m = btf_members(t); + __u16 n = btf_vlen(t); + int i, err; + + btf_dump_printf(d, "{%s", + btf_dump_data_newline(d)); + d->data->state.depth++; + for (i = 0; i < n; i++, m++) { + const struct btf_type *mtype; + __u32 bytes_offset, moffset; + const char *mname; + __u8 bits8_offset; + + mtype = btf__type_by_id(d->btf, m->type); + mname = btf_name_of(d, m->name_off); + moffset = btf_member_bit_offset(t, i); + bytes_offset = BITS_ROUNDDOWN_BYTES(moffset); + bits8_offset = BITS_PER_BYTE_MASKED(moffset); + + /* btf_int_bits() does not store member bitfield size; + * bitfield size needs to be stored here so int display + * of member can retrieve it. + */ + d->data->state.bitfield_size = + btf_member_bitfield_size(t, i); + err = btf_dump_dump_type_data(d, + mname, + mtype, + m->type, + data + bytes_offset, + bits8_offset); + d->data->state.bitfield_size = 0; + if (err < 0) + return err; + } + d->data->state.depth--; + btf_dump_data_pfx(d); + btf_dump_printf(d, "}%s%s", + btf_dump_data_delim(d), + btf_dump_data_newline(d)); + return err; +} + +static int btf_dump_ptr_data(struct btf_dump *d, + const struct btf_type *t, + __u32 id, + const void *data) +{ + btf_dump_type_values(d, "%p", *(void **)data); + return 0; +} + +static int btf_dump_get_enum_value(const struct btf_type *t, + const void *data, + __u32 id, + __s64 *value) +{ + switch (t->size) { + case 8: + *value = *(__s64 *)data; + return 0; + case 4: + *value = *(__s32 *)data; + return 0; + case 2: + *value = *(__s16 *)data; + return 0; + case 1: + *value = *(__s8 *)data; + default: + pr_warn("unexpected size %d for enum, id:[%u]\n", + t->size, id); + return -EINVAL; + } +} + +static int btf_dump_enum_data(struct btf_dump *d, + const struct btf_type *t, + __u32 id, + const void *data) +{ + const struct btf_enum *e; + __s64 value; + int i, err; + + err = btf_dump_get_enum_value(t, data, id, &value); + if (err) + return err; + + for (i = 0, e = btf_enum(t); i < btf_vlen(t); i++, e++) { + if (value != e->val) + continue; + btf_dump_type_values(d, "%s", + btf_name_of(d, e->name_off)); + return 0; + } + + btf_dump_type_values(d, "%d", value); + return 0; +} + +static int btf_dump_datasec_data(struct btf_dump *d, + const struct btf_type *t, + __u32 id, + const void *data) +{ + const struct btf_var_secinfo *vsi; + const struct btf_type *var; + __u32 i; + int err; + + btf_dump_type_values(d, "SEC("%s") ", + btf_name_of(d, t->name_off)); + for (i = 0, vsi = btf_var_secinfos(t); + i < btf_vlen(t); + i++, vsi++) { + var = btf__type_by_id(d->btf, vsi->type); + err = btf_dump_dump_type_data(d, NULL, var, + vsi->type, + data + vsi->offset, + 0); + if (err < 0) + return err; + btf_dump_printf(d, ";"); + } + return 0; +} + +/* return size of type, or if base type overflows, return -E2BIG. */ +static int btf_dump_type_data_check_overflow(struct btf_dump *d, + const struct btf_type *t, + __u32 id, + const void *data, + __u8 bits_offset) +{ + __s64 size = btf__resolve_size(d->btf, id); + + if (size < 0 || size >= INT_MAX) { + pr_warn("unexpected size [%lld] for id [%u]\n", + size, id); + return -EINVAL; + } + + /* Only do overflow checking for base types; we do not want to + * avoid showing part of a struct, union or array, even if we + * do not have enough data to show the full object. By + * restricting overflow checking to base types we can ensure + * that partial display succeeds, while avoiding overflowing + * and using bogus data for display. + */ + t = skip_mods_and_typedefs(d->btf, id, NULL); + if (!t) { + pr_warn("unexpected error skipping mods/typedefs for id [%u]\n", + id); + return -EINVAL; + } + + switch (BTF_INFO_KIND(t->info)) { + case BTF_KIND_INT: + case BTF_KIND_PTR: + case BTF_KIND_ENUM: + if (data + (bits_offset/8) + size > d->data->data_end) + return -E2BIG; + break; + default: + break; + } + return (int)size; +} + +static int btf_dump_type_data_check_zero(struct btf_dump *d, + const struct btf_type *t, + __u32 id, + const void *data, + __u8 bits_offset) +{ + __s64 value; + int i, err; + + /* toplevel exceptions; we show zero values if + * - we ask for them (emit_zeros) + * - if we are at top-level so we see "struct empty { }" + * - or if we are an array member and the array is non-empty and + * not a char array; we don't want to be in a situation where we + * have an integer array 0, 1, 0, 1 and only show non-zero values. + * If the array contains zeroes only, or is a char array starting + * with a '\0', the array-level check_zero() will prevent showing it; + * we are concerned with determining zero value at the array member + * level here. + */ + if (d->data->emit_zeroes || d->data->state.depth == 0 || + (d->data->state.array_member && !d->data->state.array_ischar)) + return 0; + + t = skip_mods_and_typedefs(d->btf, id, NULL); + if (!t) { + pr_warn("unexpected error skipping mods/typedefs for id [%u]\n", + id); + return -EINVAL; + } + + + switch (BTF_INFO_KIND(t->info)) { + case BTF_KIND_INT: + if (d->data->state.bitfield_size) + return btf_dump_int_bits_check_zero(d, t, data, + bits_offset); + return btf_dump_int_check_zero(d, t, data, bits_offset); + case BTF_KIND_FLOAT: + return btf_dump_float_check_zero(d, t, data); + case BTF_KIND_PTR: + if (*((void **)data) == NULL) + return -ENODATA; + return 0; + case BTF_KIND_ARRAY: { + const struct btf_array *array = btf_array(t); + const struct btf_type *elem_type; + __u32 elem_type_id, elem_size; + bool ischar; + + elem_type_id = array->type; + elem_size = btf__resolve_size(d->btf, elem_type_id); + elem_type = btf__type_by_id(d->btf, elem_type_id); + + ischar = btf_is_int(elem_type) && elem_size == 1; + + /* check all elements; if _any_ element is nonzero, all + * of array is displayed. We make an exception however + * for char arrays where the first element is 0; these + * are considered zeroed also, even if later elements are + * non-zero because the string is terminated. + */ + for (i = 0; i < array->nelems; i++) { + if (i == 0 && ischar && *(char *)data == 0) + return -ENODATA; + err = btf_dump_type_data_check_zero(d, elem_type, + elem_type_id, + data + + (i * elem_size), + bits_offset); + if (err != -ENODATA) + return err; + } + return -ENODATA; + } + case BTF_KIND_STRUCT: + case BTF_KIND_UNION: { + const struct btf_member *m = btf_members(t); + __u16 n = btf_vlen(t); + + /* if any struct/union member is non-zero, the struct/union + * is considered non-zero and dumped. + */ + for (i = 0; i < n; i++, m++) { + const struct btf_type *mtype; + __u32 bytes_offset, moffset; + __u8 bits8_offset; + + mtype = btf__type_by_id(d->btf, m->type); + moffset = btf_member_bit_offset(t, i); + bytes_offset = BITS_ROUNDDOWN_BYTES(moffset); + bits8_offset = BITS_PER_BYTE_MASKED(moffset); + + /* btf_int_bits() does not store member bitfield size; + * bitfield size needs to be stored here so int display + * of member can retrieve it. + */ + d->data->state.bitfield_size = + btf_member_bitfield_size(t, i); + + err = btf_dump_type_data_check_zero(d, mtype, + m->type, + data + bytes_offset, + bits8_offset); + d->data->state.bitfield_size = 0; + if (err != ENODATA) + return err; + } + return -ENODATA; + } + case BTF_KIND_ENUM: + if (btf_dump_get_enum_value(t, data, id, &value)) + return 0; + if (value == 0) + return -ENODATA; + return 0; + default: + return 0; + } +} + +/* returns size of data dumped, or error. */ +static int btf_dump_dump_type_data(struct btf_dump *d, + const char *fname, + const struct btf_type *t, + __u32 id, + const void *data, + __u8 bits_offset) +{ + int size, err; + + size = btf_dump_type_data_check_overflow(d, t, id, data, bits_offset); + if (size < 0) + return size; + err = btf_dump_type_data_check_zero(d, t, id, data, bits_offset); + if (err) { + /* zeroed data is expected and not an error, so simply skip + * dumping such data. Record other errors however. + */ + if (err == -ENODATA) + return size; + return err; + } + btf_dump_data_pfx(d); + if (!d->data->skip_names) { + if (fname && strlen(fname) > 0) + btf_dump_printf(d, ".%s = ", fname); + btf_dump_emit_type_name(d, id, 0, true); + } + + t = skip_mods_and_typedefs(d->btf, id, NULL); + if (!t) { + pr_warn("unexpected error skipping mods/typedefs for id [%u]\n", + id); + return -EINVAL; + } + + switch (BTF_INFO_KIND(t->info)) { + case BTF_KIND_UNKN: + case BTF_KIND_FWD: + case BTF_KIND_FUNC: + case BTF_KIND_FUNC_PROTO: + err = btf_dump_unsupported_data(d, t, id, data); + break; + case BTF_KIND_INT: + if (d->data->state.bitfield_size) + err = btf_dump_bitfield_data(d, t, data, + bits_offset, + d->data->state.bitfield_size); + else + err = btf_dump_int_data(d, t, id, data, bits_offset); + break; + case BTF_KIND_FLOAT: + err = btf_dump_float_data(d, t, id, data, bits_offset); + break; + case BTF_KIND_PTR: + err = btf_dump_ptr_data(d, t, id, data); + break; + case BTF_KIND_ARRAY: + err = btf_dump_array_data(d, t, id, data); + break; + case BTF_KIND_STRUCT: + case BTF_KIND_UNION: + err = btf_dump_struct_data(d, t, id, data); + break; + case BTF_KIND_ENUM: + /* handle bitfield and int enum values */ + if (d->data->state.bitfield_size) { + __u64 print_num[2], upper_num; + __s64 enum_val; + + err = btf_dump_bitfield_get_data(d, data, bits_offset, + d->data->state.bitfield_size, + print_num); + if (err) + break; +#ifdef __BIG_ENDIAN_BITFIELD + upper_num = print_num[0]; + enum_val = (__s64)print_num[1]; +#else + upper_num = print_num[1]; + enum_val = (__s64)print_num[0]; +#endif + if (upper_num != 0) { + pr_warn("enum value too big for id [%u]\n", id); + err = -EINVAL; + break; + } + err = btf_dump_enum_data(d, t, id, &enum_val); + } else + err = btf_dump_enum_data(d, t, id, data); + break; + case BTF_KIND_VAR: + err = btf_dump_var_data(d, t, id, data); + break; + case BTF_KIND_DATASEC: + err = btf_dump_datasec_data(d, t, id, data); + break; + default: + pr_warn("unexpected kind [%u] for id [%u]\n", + BTF_INFO_KIND(t->info), id); + return -EINVAL; + } + if (err < 0) + return err; + return size; +} + +int btf_dump__dump_type_data(struct btf_dump *d, __u32 id, + const void *data, size_t data_sz, + const struct btf_dump_type_data_opts *opts) +{ + const struct btf_type *t; + int ret; + + if (!OPTS_VALID(opts, btf_dump_type_data_opts)) + return libbpf_err(-EINVAL); + + t = btf__type_by_id(d->btf, id); + if (!t) + return libbpf_err(-ENOENT); + + d->data = calloc(1, sizeof(struct btf_dump_data)); + if (!d->data) + return libbpf_err(-ENOMEM); + + d->data->data_end = data + data_sz; + d->data->indent_lvl = OPTS_GET(opts, indent_level, 0); + /* default indent string is a tab */ + if (strlen(opts->indent_str) == 0) + d->data->indent_str[0] = '\t'; + else + strncpy(d->data->indent_str, opts->indent_str, + sizeof(d->data->indent_str)); + + d->data->compact = OPTS_GET(opts, compact, false); + d->data->skip_names = OPTS_GET(opts, skip_names, false); + d->data->emit_zeroes = OPTS_GET(opts, emit_zeroes, false); + + ret = btf_dump_dump_type_data(d, NULL, t, id, data, 0); + + free(d->data); + + if (ret < 0) + return libbpf_err(ret); + return ret; +} diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map index bbe99b1..dfdf51e0 100644 --- a/tools/lib/bpf/libbpf.map +++ b/tools/lib/bpf/libbpf.map @@ -374,4 +374,5 @@ LIBBPF_0.4.0 { LIBBPF_0.5.0 { global: libbpf_set_strict_mode; + btf_dump__dump_type_data; } LIBBPF_0.4.0;