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Message-Id: <1622558220-2849-2-git-send-email-alan.maguire@oracle.com>
Date: Tue, 1 Jun 2021 15:36:59 +0100
From: Alan Maguire <alan.maguire@...cle.com>
To: ast@...nel.org, daniel@...earbox.net, andrii@...nel.org
Cc: kafai@...com, songliubraving@...com, yhs@...com,
john.fastabend@...il.com, kpsingh@...nel.org, morbo@...gle.com,
shuah@...nel.org, bpf@...r.kernel.org, netdev@...r.kernel.org,
linux-kselftest@...r.kernel.org, linux-kernel@...r.kernel.org,
Alan Maguire <alan.maguire@...cle.com>
Subject: [PATCH v4 bpf-next 1/2] libbpf: BTF dumper support for typed data
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@...cle.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;
--
1.8.3.1
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