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linux/tools/lib/bpf/btf_dump.c
Xu Kuohai 4226961b00 libbpf: Skip forward declaration when counting duplicated type names 
Currently if a declaration appears in the BTF before the definition, the
definition is dumped as a conflicting name, e.g.:

    $ bpftool btf dump file vmlinux format raw | grep "'unix_sock'"
    [81287] FWD 'unix_sock' fwd_kind=struct
    [89336] STRUCT 'unix_sock' size=1024 vlen=14

    $ bpftool btf dump file vmlinux format c | grep "struct unix_sock"
    struct unix_sock;
    struct unix_sock___2 {	<--- conflict, the "___2" is unexpected
		    struct unix_sock___2 *unix_sk;

This causes a compilation error if the dump output is used as a header file.

Fix it by skipping declaration when counting duplicated type names.

Fixes: 351131b51c ("libbpf: add btf_dump API for BTF-to-C conversion")
Signed-off-by: Xu Kuohai <xukuohai@huawei.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Song Liu <songliubraving@fb.com>
Link: https://lore.kernel.org/bpf/20220301053250.1464204-2-xukuohai@huawei.com
2022-03-01 13:40:57 +01:00

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// SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)
/*
* BTF-to-C type converter.
*
* Copyright (c) 2019 Facebook
*/
#include <stdbool.h>
#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>
#include <linux/kernel.h>
#include "btf.h"
#include "hashmap.h"
#include "libbpf.h"
#include "libbpf_internal.h"
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;
static const char *pfx(int lvl)
{
return lvl >= PREFIX_CNT ? PREFIXES : &PREFIXES[PREFIX_CNT - lvl];
}
enum btf_dump_type_order_state {
NOT_ORDERED,
ORDERING,
ORDERED,
};
enum btf_dump_type_emit_state {
NOT_EMITTED,
EMITTING,
EMITTED,
};
/* per-type auxiliary state */
struct btf_dump_type_aux_state {
/* topological sorting state */
enum btf_dump_type_order_state order_state: 2;
/* emitting state used to determine the need for forward declaration */
enum btf_dump_type_emit_state emit_state: 2;
/* whether forward declaration was already emitted */
__u8 fwd_emitted: 1;
/* whether unique non-duplicate name was already assigned */
__u8 name_resolved: 1;
/* whether type is referenced from any other type */
__u8 referenced: 1;
};
/* indent string length; one indent string is added for each indent level */
#define BTF_DATA_INDENT_STR_LEN 32
/*
* 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];
/* below are used during iteration */
int depth;
bool is_array_member;
bool is_array_terminated;
bool is_array_char;
};
struct btf_dump {
const struct btf *btf;
btf_dump_printf_fn_t printf_fn;
void *cb_ctx;
int ptr_sz;
bool strip_mods;
bool skip_anon_defs;
int last_id;
/* per-type auxiliary state */
struct btf_dump_type_aux_state *type_states;
size_t type_states_cap;
/* per-type optional cached unique name, must be freed, if present */
const char **cached_names;
size_t cached_names_cap;
/* topo-sorted list of dependent type definitions */
__u32 *emit_queue;
int emit_queue_cap;
int emit_queue_cnt;
/*
* stack of type declarations (e.g., chain of modifiers, arrays,
* funcs, etc)
*/
__u32 *decl_stack;
int decl_stack_cap;
int decl_stack_cnt;
/* maps struct/union/enum name to a number of name occurrences */
struct hashmap *type_names;
/*
* maps typedef identifiers and enum value names to a number of such
* name occurrences
*/
struct hashmap *ident_names;
/*
* data for typed display; allocated if needed.
*/
struct btf_dump_data *typed_dump;
};
static size_t str_hash_fn(const void *key, void *ctx)
{
return str_hash(key);
}
static bool str_equal_fn(const void *a, const void *b, void *ctx)
{
return strcmp(a, b) == 0;
}
static const char *btf_name_of(const struct btf_dump *d, __u32 name_off)
{
return btf__name_by_offset(d->btf, name_off);
}
static void btf_dump_printf(const struct btf_dump *d, const char *fmt, ...)
{
va_list args;
va_start(args, fmt);
d->printf_fn(d->cb_ctx, fmt, args);
va_end(args);
}
static int btf_dump_mark_referenced(struct btf_dump *d);
static int btf_dump_resize(struct btf_dump *d);
DEFAULT_VERSION(btf_dump__new_v0_6_0, btf_dump__new, LIBBPF_0.6.0)
struct btf_dump *btf_dump__new_v0_6_0(const struct btf *btf,
btf_dump_printf_fn_t printf_fn,
void *ctx,
const struct btf_dump_opts *opts)
{
struct btf_dump *d;
int err;
if (!printf_fn)
return libbpf_err_ptr(-EINVAL);
d = calloc(1, sizeof(struct btf_dump));
if (!d)
return libbpf_err_ptr(-ENOMEM);
d->btf = btf;
d->printf_fn = printf_fn;
d->cb_ctx = ctx;
d->ptr_sz = btf__pointer_size(btf) ? : sizeof(void *);
d->type_names = hashmap__new(str_hash_fn, str_equal_fn, NULL);
if (IS_ERR(d->type_names)) {
err = PTR_ERR(d->type_names);
d->type_names = NULL;
goto err;
}
d->ident_names = hashmap__new(str_hash_fn, str_equal_fn, NULL);
if (IS_ERR(d->ident_names)) {
err = PTR_ERR(d->ident_names);
d->ident_names = NULL;
goto err;
}
err = btf_dump_resize(d);
if (err)
goto err;
return d;
err:
btf_dump__free(d);
return libbpf_err_ptr(err);
}
COMPAT_VERSION(btf_dump__new_deprecated, btf_dump__new, LIBBPF_0.0.4)
struct btf_dump *btf_dump__new_deprecated(const struct btf *btf,
const struct btf_ext *btf_ext,
const struct btf_dump_opts *opts,
btf_dump_printf_fn_t printf_fn)
{
if (!printf_fn)
return libbpf_err_ptr(-EINVAL);
return btf_dump__new_v0_6_0(btf, printf_fn, opts ? opts->ctx : NULL, opts);
}
static int btf_dump_resize(struct btf_dump *d)
{
int err, last_id = btf__type_cnt(d->btf) - 1;
if (last_id <= d->last_id)
return 0;
if (libbpf_ensure_mem((void **)&d->type_states, &d->type_states_cap,
sizeof(*d->type_states), last_id + 1))
return -ENOMEM;
if (libbpf_ensure_mem((void **)&d->cached_names, &d->cached_names_cap,
sizeof(*d->cached_names), last_id + 1))
return -ENOMEM;
if (d->last_id == 0) {
/* VOID is special */
d->type_states[0].order_state = ORDERED;
d->type_states[0].emit_state = EMITTED;
}
/* eagerly determine referenced types for anon enums */
err = btf_dump_mark_referenced(d);
if (err)
return err;
d->last_id = last_id;
return 0;
}
void btf_dump__free(struct btf_dump *d)
{
int i;
if (IS_ERR_OR_NULL(d))
return;
free(d->type_states);
if (d->cached_names) {
/* any set cached name is owned by us and should be freed */
for (i = 0; i <= d->last_id; i++) {
if (d->cached_names[i])
free((void *)d->cached_names[i]);
}
}
free(d->cached_names);
free(d->emit_queue);
free(d->decl_stack);
hashmap__free(d->type_names);
hashmap__free(d->ident_names);
free(d);
}
static int btf_dump_order_type(struct btf_dump *d, __u32 id, bool through_ptr);
static void btf_dump_emit_type(struct btf_dump *d, __u32 id, __u32 cont_id);
/*
* Dump BTF type in a compilable C syntax, including all the necessary
* dependent types, necessary for compilation. If some of the dependent types
* were already emitted as part of previous btf_dump__dump_type() invocation
* for another type, they won't be emitted again. This API allows callers to
* filter out BTF types according to user-defined criterias and emitted only
* minimal subset of types, necessary to compile everything. Full struct/union
* definitions will still be emitted, even if the only usage is through
* pointer and could be satisfied with just a forward declaration.
*
* Dumping is done in two high-level passes:
* 1. Topologically sort type definitions to satisfy C rules of compilation.
* 2. Emit type definitions in C syntax.
*
* Returns 0 on success; <0, otherwise.
*/
int btf_dump__dump_type(struct btf_dump *d, __u32 id)
{
int err, i;
if (id >= btf__type_cnt(d->btf))
return libbpf_err(-EINVAL);
err = btf_dump_resize(d);
if (err)
return libbpf_err(err);
d->emit_queue_cnt = 0;
err = btf_dump_order_type(d, id, false);
if (err < 0)
return libbpf_err(err);
for (i = 0; i < d->emit_queue_cnt; i++)
btf_dump_emit_type(d, d->emit_queue[i], 0 /*top-level*/);
return 0;
}
/*
* Mark all types that are referenced from any other type. This is used to
* determine top-level anonymous enums that need to be emitted as an
* independent type declarations.
* Anonymous enums come in two flavors: either embedded in a struct's field
* definition, in which case they have to be declared inline as part of field
* type declaration; or as a top-level anonymous enum, typically used for
* declaring global constants. It's impossible to distinguish between two
* without knowning whether given enum type was referenced from other type:
* top-level anonymous enum won't be referenced by anything, while embedded
* one will.
*/
static int btf_dump_mark_referenced(struct btf_dump *d)
{
int i, j, n = btf__type_cnt(d->btf);
const struct btf_type *t;
__u16 vlen;
for (i = d->last_id + 1; i < n; i++) {
t = btf__type_by_id(d->btf, i);
vlen = btf_vlen(t);
switch (btf_kind(t)) {
case BTF_KIND_INT:
case BTF_KIND_ENUM:
case BTF_KIND_FWD:
case BTF_KIND_FLOAT:
break;
case BTF_KIND_VOLATILE:
case BTF_KIND_CONST:
case BTF_KIND_RESTRICT:
case BTF_KIND_PTR:
case BTF_KIND_TYPEDEF:
case BTF_KIND_FUNC:
case BTF_KIND_VAR:
case BTF_KIND_DECL_TAG:
case BTF_KIND_TYPE_TAG:
d->type_states[t->type].referenced = 1;
break;
case BTF_KIND_ARRAY: {
const struct btf_array *a = btf_array(t);
d->type_states[a->index_type].referenced = 1;
d->type_states[a->type].referenced = 1;
break;
}
case BTF_KIND_STRUCT:
case BTF_KIND_UNION: {
const struct btf_member *m = btf_members(t);
for (j = 0; j < vlen; j++, m++)
d->type_states[m->type].referenced = 1;
break;
}
case BTF_KIND_FUNC_PROTO: {
const struct btf_param *p = btf_params(t);
for (j = 0; j < vlen; j++, p++)
d->type_states[p->type].referenced = 1;
break;
}
case BTF_KIND_DATASEC: {
const struct btf_var_secinfo *v = btf_var_secinfos(t);
for (j = 0; j < vlen; j++, v++)
d->type_states[v->type].referenced = 1;
break;
}
default:
return -EINVAL;
}
}
return 0;
}
static int btf_dump_add_emit_queue_id(struct btf_dump *d, __u32 id)
{
__u32 *new_queue;
size_t new_cap;
if (d->emit_queue_cnt >= d->emit_queue_cap) {
new_cap = max(16, d->emit_queue_cap * 3 / 2);
new_queue = libbpf_reallocarray(d->emit_queue, new_cap, sizeof(new_queue[0]));
if (!new_queue)
return -ENOMEM;
d->emit_queue = new_queue;
d->emit_queue_cap = new_cap;
}
d->emit_queue[d->emit_queue_cnt++] = id;
return 0;
}
/*
* Determine order of emitting dependent types and specified type to satisfy
* C compilation rules. This is done through topological sorting with an
* additional complication which comes from C rules. The main idea for C is
* that if some type is "embedded" into a struct/union, it's size needs to be
* known at the time of definition of containing type. E.g., for:
*
* struct A {};
* struct B { struct A x; }
*
* struct A *HAS* to be defined before struct B, because it's "embedded",
* i.e., it is part of struct B layout. But in the following case:
*
* struct A;
* struct B { struct A *x; }
* struct A {};
*
* it's enough to just have a forward declaration of struct A at the time of
* struct B definition, as struct B has a pointer to struct A, so the size of
* field x is known without knowing struct A size: it's sizeof(void *).
*
* Unfortunately, there are some trickier cases we need to handle, e.g.:
*
* struct A {}; // if this was forward-declaration: compilation error
* struct B {
* struct { // anonymous struct
* struct A y;
* } *x;
* };
*
* In this case, struct B's field x is a pointer, so it's size is known
* regardless of the size of (anonymous) struct it points to. But because this
* struct is anonymous and thus defined inline inside struct B, *and* it
* embeds struct A, compiler requires full definition of struct A to be known
* before struct B can be defined. This creates a transitive dependency
* between struct A and struct B. If struct A was forward-declared before
* struct B definition and fully defined after struct B definition, that would
* trigger compilation error.
*
* All this means that while we are doing topological sorting on BTF type
* graph, we need to determine relationships between different types (graph
* nodes):
* - weak link (relationship) between X and Y, if Y *CAN* be
* forward-declared at the point of X definition;
* - strong link, if Y *HAS* to be fully-defined before X can be defined.
*
* The rule is as follows. Given a chain of BTF types from X to Y, if there is
* BTF_KIND_PTR type in the chain and at least one non-anonymous type
* Z (excluding X, including Y), then link is weak. Otherwise, it's strong.
* Weak/strong relationship is determined recursively during DFS traversal and
* is returned as a result from btf_dump_order_type().
*
* btf_dump_order_type() is trying to avoid unnecessary forward declarations,
* but it is not guaranteeing that no extraneous forward declarations will be
* emitted.
*
* To avoid extra work, algorithm marks some of BTF types as ORDERED, when
* it's done with them, but not for all (e.g., VOLATILE, CONST, RESTRICT,
* ARRAY, FUNC_PROTO), as weak/strong semantics for those depends on the
* entire graph path, so depending where from one came to that BTF type, it
* might cause weak or strong ordering. For types like STRUCT/UNION/INT/ENUM,
* once they are processed, there is no need to do it again, so they are
* marked as ORDERED. We can mark PTR as ORDERED as well, as it semi-forces
* weak link, unless subsequent referenced STRUCT/UNION/ENUM is anonymous. But
* in any case, once those are processed, no need to do it again, as the
* result won't change.
*
* Returns:
* - 1, if type is part of strong link (so there is strong topological
* ordering requirements);
* - 0, if type is part of weak link (so can be satisfied through forward
* declaration);
* - <0, on error (e.g., unsatisfiable type loop detected).
*/
static int btf_dump_order_type(struct btf_dump *d, __u32 id, bool through_ptr)
{
/*
* Order state is used to detect strong link cycles, but only for BTF
* kinds that are or could be an independent definition (i.e.,
* stand-alone fwd decl, enum, typedef, struct, union). Ptrs, arrays,
* func_protos, modifiers are just means to get to these definitions.
* Int/void don't need definitions, they are assumed to be always
* properly defined. We also ignore datasec, var, and funcs for now.
* So for all non-defining kinds, we never even set ordering state,
* for defining kinds we set ORDERING and subsequently ORDERED if it
* forms a strong link.
*/
struct btf_dump_type_aux_state *tstate = &d->type_states[id];
const struct btf_type *t;
__u16 vlen;
int err, i;
/* return true, letting typedefs know that it's ok to be emitted */
if (tstate->order_state == ORDERED)
return 1;
t = btf__type_by_id(d->btf, id);
if (tstate->order_state == ORDERING) {
/* type loop, but resolvable through fwd declaration */
if (btf_is_composite(t) && through_ptr && t->name_off != 0)
return 0;
pr_warn("unsatisfiable type cycle, id:[%u]\n", id);
return -ELOOP;
}
switch (btf_kind(t)) {
case BTF_KIND_INT:
case BTF_KIND_FLOAT:
tstate->order_state = ORDERED;
return 0;
case BTF_KIND_PTR:
err = btf_dump_order_type(d, t->type, true);
tstate->order_state = ORDERED;
return err;
case BTF_KIND_ARRAY:
return btf_dump_order_type(d, btf_array(t)->type, false);
case BTF_KIND_STRUCT:
case BTF_KIND_UNION: {
const struct btf_member *m = btf_members(t);
/*
* struct/union is part of strong link, only if it's embedded
* (so no ptr in a path) or it's anonymous (so has to be
* defined inline, even if declared through ptr)
*/
if (through_ptr && t->name_off != 0)
return 0;
tstate->order_state = ORDERING;
vlen = btf_vlen(t);
for (i = 0; i < vlen; i++, m++) {
err = btf_dump_order_type(d, m->type, false);
if (err < 0)
return err;
}
if (t->name_off != 0) {
err = btf_dump_add_emit_queue_id(d, id);
if (err < 0)
return err;
}
tstate->order_state = ORDERED;
return 1;
}
case BTF_KIND_ENUM:
case BTF_KIND_FWD:
/*
* non-anonymous or non-referenced enums are top-level
* declarations and should be emitted. Same logic can be
* applied to FWDs, it won't hurt anyways.
*/
if (t->name_off != 0 || !tstate->referenced) {
err = btf_dump_add_emit_queue_id(d, id);
if (err)
return err;
}
tstate->order_state = ORDERED;
return 1;
case BTF_KIND_TYPEDEF: {
int is_strong;
is_strong = btf_dump_order_type(d, t->type, through_ptr);
if (is_strong < 0)
return is_strong;
/* typedef is similar to struct/union w.r.t. fwd-decls */
if (through_ptr && !is_strong)
return 0;
/* typedef is always a named definition */
err = btf_dump_add_emit_queue_id(d, id);
if (err)
return err;
d->type_states[id].order_state = ORDERED;
return 1;
}
case BTF_KIND_VOLATILE:
case BTF_KIND_CONST:
case BTF_KIND_RESTRICT:
case BTF_KIND_TYPE_TAG:
return btf_dump_order_type(d, t->type, through_ptr);
case BTF_KIND_FUNC_PROTO: {
const struct btf_param *p = btf_params(t);
bool is_strong;
err = btf_dump_order_type(d, t->type, through_ptr);
if (err < 0)
return err;
is_strong = err > 0;
vlen = btf_vlen(t);
for (i = 0; i < vlen; i++, p++) {
err = btf_dump_order_type(d, p->type, through_ptr);
if (err < 0)
return err;
if (err > 0)
is_strong = true;
}
return is_strong;
}
case BTF_KIND_FUNC:
case BTF_KIND_VAR:
case BTF_KIND_DATASEC:
case BTF_KIND_DECL_TAG:
d->type_states[id].order_state = ORDERED;
return 0;
default:
return -EINVAL;
}
}
static void btf_dump_emit_missing_aliases(struct btf_dump *d, __u32 id,
const struct btf_type *t);
static void btf_dump_emit_struct_fwd(struct btf_dump *d, __u32 id,
const struct btf_type *t);
static void btf_dump_emit_struct_def(struct btf_dump *d, __u32 id,
const struct btf_type *t, int lvl);
static void btf_dump_emit_enum_fwd(struct btf_dump *d, __u32 id,
const struct btf_type *t);
static void btf_dump_emit_enum_def(struct btf_dump *d, __u32 id,
const struct btf_type *t, int lvl);
static void btf_dump_emit_fwd_def(struct btf_dump *d, __u32 id,
const struct btf_type *t);
static void btf_dump_emit_typedef_def(struct btf_dump *d, __u32 id,
const struct btf_type *t, int lvl);
/* a local view into a shared stack */
struct id_stack {
const __u32 *ids;
int cnt;
};
static void btf_dump_emit_type_decl(struct btf_dump *d, __u32 id,
const char *fname, int lvl);
static void btf_dump_emit_type_chain(struct btf_dump *d,
struct id_stack *decl_stack,
const char *fname, int lvl);
static const char *btf_dump_type_name(struct btf_dump *d, __u32 id);
static const char *btf_dump_ident_name(struct btf_dump *d, __u32 id);
static size_t btf_dump_name_dups(struct btf_dump *d, struct hashmap *name_map,
const char *orig_name);
static bool btf_dump_is_blacklisted(struct btf_dump *d, __u32 id)
{
const struct btf_type *t = btf__type_by_id(d->btf, id);
/* __builtin_va_list is a compiler built-in, which causes compilation
* errors, when compiling w/ different compiler, then used to compile
* original code (e.g., GCC to compile kernel, Clang to use generated
* C header from BTF). As it is built-in, it should be already defined
* properly internally in compiler.
*/
if (t->name_off == 0)
return false;
return strcmp(btf_name_of(d, t->name_off), "__builtin_va_list") == 0;
}
/*
* Emit C-syntax definitions of types from chains of BTF types.
*
* High-level handling of determining necessary forward declarations are handled
* by btf_dump_emit_type() itself, but all nitty-gritty details of emitting type
* declarations/definitions in C syntax are handled by a combo of
* btf_dump_emit_type_decl()/btf_dump_emit_type_chain() w/ delegation to
* corresponding btf_dump_emit_*_{def,fwd}() functions.
*
* We also keep track of "containing struct/union type ID" to determine when
* we reference it from inside and thus can avoid emitting unnecessary forward
* declaration.
*
* This algorithm is designed in such a way, that even if some error occurs
* (either technical, e.g., out of memory, or logical, i.e., malformed BTF
* that doesn't comply to C rules completely), algorithm will try to proceed
* and produce as much meaningful output as possible.
*/
static void btf_dump_emit_type(struct btf_dump *d, __u32 id, __u32 cont_id)
{
struct btf_dump_type_aux_state *tstate = &d->type_states[id];
bool top_level_def = cont_id == 0;
const struct btf_type *t;
__u16 kind;
if (tstate->emit_state == EMITTED)
return;
t = btf__type_by_id(d->btf, id);
kind = btf_kind(t);
if (tstate->emit_state == EMITTING) {
if (tstate->fwd_emitted)
return;
switch (kind) {
case BTF_KIND_STRUCT:
case BTF_KIND_UNION:
/*
* if we are referencing a struct/union that we are
* part of - then no need for fwd declaration
*/
if (id == cont_id)
return;
if (t->name_off == 0) {
pr_warn("anonymous struct/union loop, id:[%u]\n",
id);
return;
}
btf_dump_emit_struct_fwd(d, id, t);
btf_dump_printf(d, ";\n\n");
tstate->fwd_emitted = 1;
break;
case BTF_KIND_TYPEDEF:
/*
* for typedef fwd_emitted means typedef definition
* was emitted, but it can be used only for "weak"
* references through pointer only, not for embedding
*/
if (!btf_dump_is_blacklisted(d, id)) {
btf_dump_emit_typedef_def(d, id, t, 0);
btf_dump_printf(d, ";\n\n");
}
tstate->fwd_emitted = 1;
break;
default:
break;
}
return;
}
switch (kind) {
case BTF_KIND_INT:
/* Emit type alias definitions if necessary */
btf_dump_emit_missing_aliases(d, id, t);
tstate->emit_state = EMITTED;
break;
case BTF_KIND_ENUM:
if (top_level_def) {
btf_dump_emit_enum_def(d, id, t, 0);
btf_dump_printf(d, ";\n\n");
}
tstate->emit_state = EMITTED;
break;
case BTF_KIND_PTR:
case BTF_KIND_VOLATILE:
case BTF_KIND_CONST:
case BTF_KIND_RESTRICT:
case BTF_KIND_TYPE_TAG:
btf_dump_emit_type(d, t->type, cont_id);
break;
case BTF_KIND_ARRAY:
btf_dump_emit_type(d, btf_array(t)->type, cont_id);
break;
case BTF_KIND_FWD:
btf_dump_emit_fwd_def(d, id, t);
btf_dump_printf(d, ";\n\n");
tstate->emit_state = EMITTED;
break;
case BTF_KIND_TYPEDEF:
tstate->emit_state = EMITTING;
btf_dump_emit_type(d, t->type, id);
/*
* typedef can server as both definition and forward
* declaration; at this stage someone depends on
* typedef as a forward declaration (refers to it
* through pointer), so unless we already did it,
* emit typedef as a forward declaration
*/
if (!tstate->fwd_emitted && !btf_dump_is_blacklisted(d, id)) {
btf_dump_emit_typedef_def(d, id, t, 0);
btf_dump_printf(d, ";\n\n");
}
tstate->emit_state = EMITTED;
break;
case BTF_KIND_STRUCT:
case BTF_KIND_UNION:
tstate->emit_state = EMITTING;
/* if it's a top-level struct/union definition or struct/union
* is anonymous, then in C we'll be emitting all fields and
* their types (as opposed to just `struct X`), so we need to
* make sure that all types, referenced from struct/union
* members have necessary forward-declarations, where
* applicable
*/
if (top_level_def || t->name_off == 0) {
const struct btf_member *m = btf_members(t);
__u16 vlen = btf_vlen(t);
int i, new_cont_id;
new_cont_id = t->name_off == 0 ? cont_id : id;
for (i = 0; i < vlen; i++, m++)
btf_dump_emit_type(d, m->type, new_cont_id);
} else if (!tstate->fwd_emitted && id != cont_id) {
btf_dump_emit_struct_fwd(d, id, t);
btf_dump_printf(d, ";\n\n");
tstate->fwd_emitted = 1;
}
if (top_level_def) {
btf_dump_emit_struct_def(d, id, t, 0);
btf_dump_printf(d, ";\n\n");
tstate->emit_state = EMITTED;
} else {
tstate->emit_state = NOT_EMITTED;
}
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(d, t->type, cont_id);
for (i = 0; i < n; i++, p++)
btf_dump_emit_type(d, p->type, cont_id);
break;
}
default:
break;
}
}
static bool btf_is_struct_packed(const struct btf *btf, __u32 id,
const struct btf_type *t)
{
const struct btf_member *m;
int align, i, bit_sz;
__u16 vlen;
align = btf__align_of(btf, id);
/* size of a non-packed struct has to be a multiple of its alignment*/
if (align && t->size % align)
return true;
m = btf_members(t);
vlen = btf_vlen(t);
/* all non-bitfield fields have to be naturally aligned */
for (i = 0; i < vlen; i++, m++) {
align = btf__align_of(btf, m->type);
bit_sz = btf_member_bitfield_size(t, i);
if (align && bit_sz == 0 && m->offset % (8 * align) != 0)
return true;
}
/*
* if original struct was marked as packed, but its layout is
* naturally aligned, we'll detect that it's not packed
*/
return false;
}
static int chip_away_bits(int total, int at_most)
{
return total % at_most ? : at_most;
}
static void btf_dump_emit_bit_padding(const struct btf_dump *d,
int cur_off, int m_off, int m_bit_sz,
int align, int lvl)
{
int off_diff = m_off - cur_off;
int ptr_bits = d->ptr_sz * 8;
if (off_diff <= 0)
/* no gap */
return;
if (m_bit_sz == 0 && off_diff < align * 8)
/* natural padding will take care of a gap */
return;
while (off_diff > 0) {
const char *pad_type;
int pad_bits;
if (ptr_bits > 32 && off_diff > 32) {
pad_type = "long";
pad_bits = chip_away_bits(off_diff, ptr_bits);
} else if (off_diff > 16) {
pad_type = "int";
pad_bits = chip_away_bits(off_diff, 32);
} else if (off_diff > 8) {
pad_type = "short";
pad_bits = chip_away_bits(off_diff, 16);
} else {
pad_type = "char";
pad_bits = chip_away_bits(off_diff, 8);
}
btf_dump_printf(d, "\n%s%s: %d;", pfx(lvl), pad_type, pad_bits);
off_diff -= pad_bits;
}
}
static void btf_dump_emit_struct_fwd(struct btf_dump *d, __u32 id,
const struct btf_type *t)
{
btf_dump_printf(d, "%s%s%s",
btf_is_struct(t) ? "struct" : "union",
t->name_off ? " " : "",
btf_dump_type_name(d, id));
}
static void btf_dump_emit_struct_def(struct btf_dump *d,
__u32 id,
const struct btf_type *t,
int lvl)
{
const struct btf_member *m = btf_members(t);
bool is_struct = btf_is_struct(t);
int align, i, packed, off = 0;
__u16 vlen = btf_vlen(t);
packed = is_struct ? btf_is_struct_packed(d->btf, id, t) : 0;
btf_dump_printf(d, "%s%s%s {",
is_struct ? "struct" : "union",
t->name_off ? " " : "",
btf_dump_type_name(d, id));
for (i = 0; i < vlen; i++, m++) {
const char *fname;
int m_off, m_sz;
fname = btf_name_of(d, m->name_off);
m_sz = btf_member_bitfield_size(t, i);
m_off = btf_member_bit_offset(t, i);
align = packed ? 1 : btf__align_of(d->btf, m->type);
btf_dump_emit_bit_padding(d, off, m_off, m_sz, align, lvl + 1);
btf_dump_printf(d, "\n%s", pfx(lvl + 1));
btf_dump_emit_type_decl(d, m->type, fname, lvl + 1);
if (m_sz) {
btf_dump_printf(d, ": %d", m_sz);
off = m_off + m_sz;
} else {
m_sz = max((__s64)0, btf__resolve_size(d->btf, m->type));
off = m_off + m_sz * 8;
}
btf_dump_printf(d, ";");
}
/* pad at the end, if necessary */
if (is_struct) {
align = packed ? 1 : btf__align_of(d->btf, id);
btf_dump_emit_bit_padding(d, off, t->size * 8, 0, align,
lvl + 1);
}
if (vlen)
btf_dump_printf(d, "\n");
btf_dump_printf(d, "%s}", pfx(lvl));
if (packed)
btf_dump_printf(d, " __attribute__((packed))");
}
static const char *missing_base_types[][2] = {
/*
* GCC emits typedefs to its internal __PolyX_t types when compiling Arm
* SIMD intrinsics. Alias them to standard base types.
*/
{ "__Poly8_t", "unsigned char" },
{ "__Poly16_t", "unsigned short" },
{ "__Poly64_t", "unsigned long long" },
{ "__Poly128_t", "unsigned __int128" },
};
static void btf_dump_emit_missing_aliases(struct btf_dump *d, __u32 id,
const struct btf_type *t)
{
const char *name = btf_dump_type_name(d, id);
int i;
for (i = 0; i < ARRAY_SIZE(missing_base_types); i++) {
if (strcmp(name, missing_base_types[i][0]) == 0) {
btf_dump_printf(d, "typedef %s %s;\n\n",
missing_base_types[i][1], name);
break;
}
}
}
static void btf_dump_emit_enum_fwd(struct btf_dump *d, __u32 id,
const struct btf_type *t)
{
btf_dump_printf(d, "enum %s", btf_dump_type_name(d, id));
}
static void btf_dump_emit_enum_def(struct btf_dump *d, __u32 id,
const struct btf_type *t,
int lvl)
{
const struct btf_enum *v = btf_enum(t);
__u16 vlen = btf_vlen(t);
const char *name;
size_t dup_cnt;
int i;
btf_dump_printf(d, "enum%s%s",
t->name_off ? " " : "",
btf_dump_type_name(d, id));
if (vlen) {
btf_dump_printf(d, " {");
for (i = 0; i < vlen; i++, v++) {
name = btf_name_of(d, v->name_off);
/* enumerators share namespace with typedef idents */
dup_cnt = btf_dump_name_dups(d, d->ident_names, name);
if (dup_cnt > 1) {
btf_dump_printf(d, "\n%s%s___%zu = %u,",
pfx(lvl + 1), name, dup_cnt,
(__u32)v->val);
} else {
btf_dump_printf(d, "\n%s%s = %u,",
pfx(lvl + 1), name,
(__u32)v->val);
}
}
btf_dump_printf(d, "\n%s}", pfx(lvl));
}
}
static void btf_dump_emit_fwd_def(struct btf_dump *d, __u32 id,
const struct btf_type *t)
{
const char *name = btf_dump_type_name(d, id);
if (btf_kflag(t))
btf_dump_printf(d, "union %s", name);
else
btf_dump_printf(d, "struct %s", name);
}
static void btf_dump_emit_typedef_def(struct btf_dump *d, __u32 id,
const struct btf_type *t, int lvl)
{
const char *name = btf_dump_ident_name(d, id);
/*
* Old GCC versions are emitting invalid typedef for __gnuc_va_list
* pointing to VOID. This generates warnings from btf_dump() and
* results in uncompilable header file, so we are fixing it up here
* with valid typedef into __builtin_va_list.
*/
if (t->type == 0 && strcmp(name, "__gnuc_va_list") == 0) {
btf_dump_printf(d, "typedef __builtin_va_list __gnuc_va_list");
return;
}
btf_dump_printf(d, "typedef ");
btf_dump_emit_type_decl(d, t->type, name, lvl);
}
static int btf_dump_push_decl_stack_id(struct btf_dump *d, __u32 id)
{
__u32 *new_stack;
size_t new_cap;
if (d->decl_stack_cnt >= d->decl_stack_cap) {
new_cap = max(16, d->decl_stack_cap * 3 / 2);
new_stack = libbpf_reallocarray(d->decl_stack, new_cap, sizeof(new_stack[0]));
if (!new_stack)
return -ENOMEM;
d->decl_stack = new_stack;
d->decl_stack_cap = new_cap;
}
d->decl_stack[d->decl_stack_cnt++] = id;
return 0;
}
/*
* Emit type declaration (e.g., field type declaration in a struct or argument
* declaration in function prototype) in correct C syntax.
*
* For most types it's trivial, but there are few quirky type declaration
* cases worth mentioning:
* - function prototypes (especially nesting of function prototypes);
* - arrays;
* - const/volatile/restrict for pointers vs other types.
*
* For a good discussion of *PARSING* C syntax (as a human), see
* Peter van der Linden's "Expert C Programming: Deep C Secrets",
* Ch.3 "Unscrambling Declarations in C".
*
* It won't help with BTF to C conversion much, though, as it's an opposite
* problem. So we came up with this algorithm in reverse to van der Linden's
* parsing algorithm. It goes from structured BTF representation of type
* declaration to a valid compilable C syntax.
*
* For instance, consider this C typedef:
* typedef const int * const * arr[10] arr_t;
* It will be represented in BTF with this chain of BTF types:
* [typedef] -> [array] -> [ptr] -> [const] -> [ptr] -> [const] -> [int]
*
* Notice how [const] modifier always goes before type it modifies in BTF type
* graph, but in C syntax, const/volatile/restrict modifiers are written to
* the right of pointers, but to the left of other types. There are also other
* quirks, like function pointers, arrays of them, functions returning other
* functions, etc.
*
* We handle that by pushing all the types to a stack, until we hit "terminal"
* type (int/enum/struct/union/fwd). Then depending on the kind of a type on
* top of a stack, modifiers are handled differently. Array/function pointers
* have also wildly different syntax and how nesting of them are done. See
* code for authoritative definition.
*
* To avoid allocating new stack for each independent chain of BTF types, we
* share one bigger stack, with each chain working only on its own local view
* of a stack frame. Some care is required to "pop" stack frames after
* processing type declaration chain.
*/
int btf_dump__emit_type_decl(struct btf_dump *d, __u32 id,
const struct btf_dump_emit_type_decl_opts *opts)
{
const char *fname;
int lvl, err;
if (!OPTS_VALID(opts, btf_dump_emit_type_decl_opts))
return libbpf_err(-EINVAL);
err = btf_dump_resize(d);
if (err)
return libbpf_err(err);
fname = OPTS_GET(opts, field_name, "");
lvl = OPTS_GET(opts, indent_level, 0);
d->strip_mods = OPTS_GET(opts, strip_mods, false);
btf_dump_emit_type_decl(d, id, fname, lvl);
d->strip_mods = false;
return 0;
}
static void btf_dump_emit_type_decl(struct btf_dump *d, __u32 id,
const char *fname, int lvl)
{
struct id_stack decl_stack;
const struct btf_type *t;
int err, stack_start;
stack_start = d->decl_stack_cnt;
for (;;) {
t = btf__type_by_id(d->btf, id);
if (d->strip_mods && btf_is_mod(t))
goto skip_mod;
err = btf_dump_push_decl_stack_id(d, id);
if (err < 0) {
/*
* if we don't have enough memory for entire type decl
* chain, restore stack, emit warning, and try to
* proceed nevertheless
*/
pr_warn("not enough memory for decl stack:%d", err);
d->decl_stack_cnt = stack_start;
return;
}
skip_mod:
/* VOID */
if (id == 0)
break;
switch (btf_kind(t)) {
case BTF_KIND_PTR:
case BTF_KIND_VOLATILE:
case BTF_KIND_CONST:
case BTF_KIND_RESTRICT:
case BTF_KIND_FUNC_PROTO:
case BTF_KIND_TYPE_TAG:
id = t->type;
break;
case BTF_KIND_ARRAY:
id = btf_array(t)->type;
break;
case BTF_KIND_INT:
case BTF_KIND_ENUM:
case BTF_KIND_FWD:
case BTF_KIND_STRUCT:
case BTF_KIND_UNION:
case BTF_KIND_TYPEDEF:
case BTF_KIND_FLOAT:
goto done;
default:
pr_warn("unexpected type in decl chain, kind:%u, id:[%u]\n",
btf_kind(t), id);
goto done;
}
}
done:
/*
* We might be inside a chain of declarations (e.g., array of function
* pointers returning anonymous (so inlined) structs, having another
* array field). Each of those needs its own "stack frame" to handle
* emitting of declarations. Those stack frames are non-overlapping
* portions of shared btf_dump->decl_stack. To make it a bit nicer to
* handle this set of nested stacks, we create a view corresponding to
* our own "stack frame" and work with it as an independent stack.
* We'll need to clean up after emit_type_chain() returns, though.
*/
decl_stack.ids = d->decl_stack + stack_start;
decl_stack.cnt = d->decl_stack_cnt - stack_start;
btf_dump_emit_type_chain(d, &decl_stack, fname, lvl);
/*
* emit_type_chain() guarantees that it will pop its entire decl_stack
* frame before returning. But it works with a read-only view into
* decl_stack, so it doesn't actually pop anything from the
* perspective of shared btf_dump->decl_stack, per se. We need to
* reset decl_stack state to how it was before us to avoid it growing
* all the time.
*/
d->decl_stack_cnt = stack_start;
}
static void btf_dump_emit_mods(struct btf_dump *d, struct id_stack *decl_stack)
{
const struct btf_type *t;
__u32 id;
while (decl_stack->cnt) {
id = decl_stack->ids[decl_stack->cnt - 1];
t = btf__type_by_id(d->btf, id);
switch (btf_kind(t)) {
case BTF_KIND_VOLATILE:
btf_dump_printf(d, "volatile ");
break;
case BTF_KIND_CONST:
btf_dump_printf(d, "const ");
break;
case BTF_KIND_RESTRICT:
btf_dump_printf(d, "restrict ");
break;
default:
return;
}
decl_stack->cnt--;
}
}
static void btf_dump_drop_mods(struct btf_dump *d, struct id_stack *decl_stack)
{
const struct btf_type *t;
__u32 id;
while (decl_stack->cnt) {
id = decl_stack->ids[decl_stack->cnt - 1];
t = btf__type_by_id(d->btf, id);
if (!btf_is_mod(t))
return;
decl_stack->cnt--;
}
}
static void btf_dump_emit_name(const struct btf_dump *d,
const char *name, bool last_was_ptr)
{
bool separate = name[0] && !last_was_ptr;
btf_dump_printf(d, "%s%s", separate ? " " : "", name);
}
static void btf_dump_emit_type_chain(struct btf_dump *d,
struct id_stack *decls,
const char *fname, int lvl)
{
/*
* last_was_ptr is used to determine if we need to separate pointer
* asterisk (*) from previous part of type signature with space, so
* that we get `int ***`, instead of `int * * *`. We default to true
* for cases where we have single pointer in a chain. E.g., in ptr ->
* func_proto case. func_proto will start a new emit_type_chain call
* with just ptr, which should be emitted as (*) or (*<fname>), so we
* don't want to prepend space for that last pointer.
*/
bool last_was_ptr = true;
const struct btf_type *t;
const char *name;
__u16 kind;
__u32 id;
while (decls->cnt) {
id = decls->ids[--decls->cnt];
if (id == 0) {
/* VOID is a special snowflake */
btf_dump_emit_mods(d, decls);
btf_dump_printf(d, "void");
last_was_ptr = false;
continue;
}
t = btf__type_by_id(d->btf, id);
kind = btf_kind(t);
switch (kind) {
case BTF_KIND_INT:
case BTF_KIND_FLOAT:
btf_dump_emit_mods(d, decls);
name = btf_name_of(d, t->name_off);
btf_dump_printf(d, "%s", name);
break;
case BTF_KIND_STRUCT:
case BTF_KIND_UNION:
btf_dump_emit_mods(d, decls);
/* inline anonymous struct/union */
if (t->name_off == 0 && !d->skip_anon_defs)
btf_dump_emit_struct_def(d, id, t, lvl);
else
btf_dump_emit_struct_fwd(d, id, t);
break;
case BTF_KIND_ENUM:
btf_dump_emit_mods(d, decls);
/* inline anonymous enum */
if (t->name_off == 0 && !d->skip_anon_defs)
btf_dump_emit_enum_def(d, id, t, lvl);
else
btf_dump_emit_enum_fwd(d, id, t);
break;
case BTF_KIND_FWD:
btf_dump_emit_mods(d, decls);
btf_dump_emit_fwd_def(d, id, t);
break;
case BTF_KIND_TYPEDEF:
btf_dump_emit_mods(d, decls);
btf_dump_printf(d, "%s", btf_dump_ident_name(d, id));
break;
case BTF_KIND_PTR:
btf_dump_printf(d, "%s", last_was_ptr ? "*" : " *");
break;
case BTF_KIND_VOLATILE:
btf_dump_printf(d, " volatile");
break;
case BTF_KIND_CONST:
btf_dump_printf(d, " const");
break;
case BTF_KIND_RESTRICT:
btf_dump_printf(d, " restrict");
break;
case BTF_KIND_TYPE_TAG:
btf_dump_emit_mods(d, decls);
name = btf_name_of(d, t->name_off);
btf_dump_printf(d, " __attribute__((btf_type_tag(\"%s\")))", name);
break;
case BTF_KIND_ARRAY: {
const struct btf_array *a = btf_array(t);
const struct btf_type *next_t;
__u32 next_id;
bool multidim;
/*
* GCC has a bug
* (https://gcc.gnu.org/bugzilla/show_bug.cgi?id=8354)
* which causes it to emit extra const/volatile
* modifiers for an array, if array's element type has
* const/volatile modifiers. Clang doesn't do that.
* In general, it doesn't seem very meaningful to have
* a const/volatile modifier for array, so we are
* going to silently skip them here.
*/
btf_dump_drop_mods(d, decls);
if (decls->cnt == 0) {
btf_dump_emit_name(d, fname, last_was_ptr);
btf_dump_printf(d, "[%u]", a->nelems);
return;
}
next_id = decls->ids[decls->cnt - 1];
next_t = btf__type_by_id(d->btf, next_id);
multidim = btf_is_array(next_t);
/* we need space if we have named non-pointer */
if (fname[0] && !last_was_ptr)
btf_dump_printf(d, " ");
/* no parentheses for multi-dimensional array */
if (!multidim)
btf_dump_printf(d, "(");
btf_dump_emit_type_chain(d, decls, fname, lvl);
if (!multidim)
btf_dump_printf(d, ")");
btf_dump_printf(d, "[%u]", a->nelems);
return;
}
case BTF_KIND_FUNC_PROTO: {
const struct btf_param *p = btf_params(t);
__u16 vlen = btf_vlen(t);
int i;
/*
* GCC emits extra volatile qualifier for
* __attribute__((noreturn)) function pointers. Clang
* doesn't do it. It's a GCC quirk for backwards
* compatibility with code written for GCC <2.5. So,
* similarly to extra qualifiers for array, just drop
* them, instead of handling them.
*/
btf_dump_drop_mods(d, decls);
if (decls->cnt) {
btf_dump_printf(d, " (");
btf_dump_emit_type_chain(d, decls, fname, lvl);
btf_dump_printf(d, ")");
} else {
btf_dump_emit_name(d, fname, last_was_ptr);
}
btf_dump_printf(d, "(");
/*
* Clang for BPF target generates func_proto with no
* args as a func_proto with a single void arg (e.g.,
* `int (*f)(void)` vs just `int (*f)()`). We are
* going to pretend there are no args for such case.
*/
if (vlen == 1 && p->type == 0) {
btf_dump_printf(d, ")");
return;
}
for (i = 0; i < vlen; i++, p++) {
if (i > 0)
btf_dump_printf(d, ", ");
/* last arg of type void is vararg */
if (i == vlen - 1 && p->type == 0) {
btf_dump_printf(d, "...");
break;
}
name = btf_name_of(d, p->name_off);
btf_dump_emit_type_decl(d, p->type, name, lvl);
}
btf_dump_printf(d, ")");
return;
}
default:
pr_warn("unexpected type in decl chain, kind:%u, id:[%u]\n",
kind, id);
return;
}
last_was_ptr = kind == BTF_KIND_PTR;
}
btf_dump_emit_name(d, fname, last_was_ptr);
}
/* show type name as (type_name) */
static void btf_dump_emit_type_cast(struct btf_dump *d, __u32 id,
bool top_level)
{
const struct btf_type *t;
/* for array members, we don't bother emitting type name for each
* member to avoid the redundancy of
* .name = (char[4])[(char)'f',(char)'o',(char)'o',]
*/
if (d->typed_dump->is_array_member)
return;
/* avoid type name specification for variable/section; it will be done
* for the associated variable value(s).
*/
t = btf__type_by_id(d->btf, id);
if (btf_is_var(t) || btf_is_datasec(t))
return;
if (top_level)
btf_dump_printf(d, "(");
d->skip_anon_defs = true;
d->strip_mods = true;
btf_dump_emit_type_decl(d, id, "", 0);
d->strip_mods = false;
d->skip_anon_defs = false;
if (top_level)
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)
{
size_t dup_cnt = 0;
hashmap__find(name_map, orig_name, (void **)&dup_cnt);
dup_cnt++;
hashmap__set(name_map, orig_name, (void *)dup_cnt, NULL, NULL);
return dup_cnt;
}
static const char *btf_dump_resolve_name(struct btf_dump *d, __u32 id,
struct hashmap *name_map)
{
struct btf_dump_type_aux_state *s = &d->type_states[id];
const struct btf_type *t = btf__type_by_id(d->btf, id);
const char *orig_name = btf_name_of(d, t->name_off);
const char **cached_name = &d->cached_names[id];
size_t dup_cnt;
if (t->name_off == 0)
return "";
if (s->name_resolved)
return *cached_name ? *cached_name : orig_name;
if (btf_is_fwd(t) || (btf_is_enum(t) && btf_vlen(t) == 0)) {
s->name_resolved = 1;
return orig_name;
}
dup_cnt = btf_dump_name_dups(d, name_map, orig_name);
if (dup_cnt > 1) {
const size_t max_len = 256;
char new_name[max_len];
snprintf(new_name, max_len, "%s___%zu", orig_name, dup_cnt);
*cached_name = strdup(new_name);
}
s->name_resolved = 1;
return *cached_name ? *cached_name : orig_name;
}
static const char *btf_dump_type_name(struct btf_dump *d, __u32 id)
{
return btf_dump_resolve_name(d, id, d->type_names);
}
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,
__u8 bit_sz);
static const char *btf_dump_data_newline(struct btf_dump *d)
{
return d->typed_dump->compact || d->typed_dump->depth == 0 ? "" : "\n";
}
static const char *btf_dump_data_delim(struct btf_dump *d)
{
return d->typed_dump->depth == 0 ? "" : ",";
}
static void btf_dump_data_pfx(struct btf_dump *d)
{
int i, lvl = d->typed_dump->indent_lvl + d->typed_dump->depth;
if (d->typed_dump->compact)
return;
for (i = 0; i < lvl; i++)
btf_dump_printf(d, "%s", d->typed_dump->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)
{
btf_dump_printf(d, "<unsupported kind:%u>", btf_kind(t));
return -ENOTSUP;
}
static int btf_dump_get_bitfield_value(struct btf_dump *d,
const struct btf_type *t,
const void *data,
__u8 bits_offset,
__u8 bit_sz,
__u64 *value)
{
__u16 left_shift_bits, right_shift_bits;
const __u8 *bytes = data;
__u8 nr_copy_bits;
__u64 num = 0;
int i;
/* Maximum supported bitfield size is 64 bits */
if (t->size > 8) {
pr_warn("unexpected bitfield size %d\n", t->size);
return -EINVAL;
}
/* Bitfield value retrieval is done in two steps; first relevant bytes are
* stored in num, then we left/right shift num to eliminate irrelevant bits.
*/
#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
for (i = t->size - 1; i >= 0; i--)
num = num * 256 + bytes[i];
nr_copy_bits = bit_sz + bits_offset;
#elif __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
for (i = 0; i < t->size; i++)
num = num * 256 + bytes[i];
nr_copy_bits = t->size * 8 - bits_offset;
#else
# error "Unrecognized __BYTE_ORDER__"
#endif
left_shift_bits = 64 - nr_copy_bits;
right_shift_bits = 64 - bit_sz;
*value = (num << left_shift_bits) >> right_shift_bits;
return 0;
}
static int btf_dump_bitfield_check_zero(struct btf_dump *d,
const struct btf_type *t,
const void *data,
__u8 bits_offset,
__u8 bit_sz)
{
__u64 check_num;
int err;
err = btf_dump_get_bitfield_value(d, t, data, bits_offset, bit_sz, &check_num);
if (err)
return err;
if (check_num == 0)
return -ENODATA;
return 0;
}
static int btf_dump_bitfield_data(struct btf_dump *d,
const struct btf_type *t,
const void *data,
__u8 bits_offset,
__u8 bit_sz)
{
__u64 print_num;
int err;
err = btf_dump_get_bitfield_value(d, t, data, bits_offset, bit_sz, &print_num);
if (err)
return err;
btf_dump_type_values(d, "0x%llx", (unsigned long long)print_num);
return 0;
}
/* ints, floats and ptrs */
static int btf_dump_base_type_check_zero(struct btf_dump *d,
const struct btf_type *t,
__u32 id,
const void *data)
{
static __u8 bytecmp[16] = {};
int nr_bytes;
/* For pointer types, pointer size is not defined on a per-type basis.
* On dump creation however, we store the pointer size.
*/
if (btf_kind(t) == BTF_KIND_PTR)
nr_bytes = d->ptr_sz;
else
nr_bytes = t->size;
if (nr_bytes < 1 || nr_bytes > 16) {
pr_warn("unexpected size %d for id [%u]\n", nr_bytes, id);
return -EINVAL;
}
if (memcmp(data, bytecmp, nr_bytes) == 0)
return -ENODATA;
return 0;
}
static bool ptr_is_aligned(const struct btf *btf, __u32 type_id,
const void *data)
{
int alignment = btf__align_of(btf, type_id);
if (alignment == 0)
return false;
return ((uintptr_t)data) % alignment == 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;
char buf[16] __attribute__((aligned(16)));
int sz = t->size;
if (sz == 0 || sz > sizeof(buf)) {
pr_warn("unexpected size %d for id [%u]\n", sz, type_id);
return -EINVAL;
}
/* handle packed int data - accesses of integers not aligned on
* int boundaries can cause problems on some platforms.
*/
if (!ptr_is_aligned(d->btf, type_id, data)) {
memcpy(buf, data, sz);
data = buf;
}
switch (sz) {
case 16: {
const __u64 *ints = data;
__u64 lsi, msi;
/* avoid use of __int128 as some 32-bit platforms do not
* support it.
*/
#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
lsi = ints[0];
msi = ints[1];
#elif __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
lsi = ints[1];
msi = ints[0];
#else
# error "Unrecognized __BYTE_ORDER__"
#endif
if (msi == 0)
btf_dump_type_values(d, "0x%llx", (unsigned long long)lsi);
else
btf_dump_type_values(d, "0x%llx%016llx", (unsigned long long)msi,
(unsigned long long)lsi);
break;
}
case 8:
if (sign)
btf_dump_type_values(d, "%lld", *(long long *)data);
else
btf_dump_type_values(d, "%llu", *(unsigned long long *)data);
break;
case 4:
if (sign)
btf_dump_type_values(d, "%d", *(__s32 *)data);
else
btf_dump_type_values(d, "%u", *(__u32 *)data);
break;
case 2:
if (sign)
btf_dump_type_values(d, "%d", *(__s16 *)data);
else
btf_dump_type_values(d, "%u", *(__u16 *)data);
break;
case 1:
if (d->typed_dump->is_array_char) {
/* check for null terminator */
if (d->typed_dump->is_array_terminated)
break;
if (*(char *)data == '\0') {
d->typed_dump->is_array_terminated = true;
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 sz %d for id [%u]\n", sz, type_id);
return -EINVAL;
}
return 0;
}
union float_data {
long double ld;
double d;
float f;
};
static int btf_dump_float_data(struct btf_dump *d,
const struct btf_type *t,
__u32 type_id,
const void *data)
{
const union float_data *flp = data;
union float_data fl;
int sz = t->size;
/* handle unaligned data; copy to local union */
if (!ptr_is_aligned(d->btf, type_id, data)) {
memcpy(&fl, data, sz);
flp = &fl;
}
switch (sz) {
case 16:
btf_dump_type_values(d, "%Lf", flp->ld);
break;
case 8:
btf_dump_type_values(d, "%lf", flp->d);
break;
case 4:
btf_dump_type_values(d, "%f", flp->f);
break;
default:
pr_warn("unexpected size %d for id [%u]\n", sz, 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:
l = "";
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_cast(d, type_id, 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, 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_type_id;
__s64 elem_size;
bool is_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 %zd for array type [%u]\n",
(ssize_t)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->typed_dump->is_array_char = true;
}
/* note that we increment depth before calling btf_dump_print() below;
* this is intentional. btf_dump_data_newline() will not print a
* newline for depth 0 (since this leaves us with trailing newlines
* at the end of typed display), so depth is incremented first.
* For similar reasons, we decrement depth before showing the closing
* parenthesis.
*/
d->typed_dump->depth++;
btf_dump_printf(d, "[%s", btf_dump_data_newline(d));
/* may be a multidimensional array, so store current "is array member"
* status so we can restore it correctly later.
*/
is_array_member = d->typed_dump->is_array_member;
d->typed_dump->is_array_member = true;
for (i = 0; i < array->nelems; i++, data += elem_size) {
if (d->typed_dump->is_array_terminated)
break;
btf_dump_dump_type_data(d, NULL, elem_type, elem_type_id, data, 0, 0);
}
d->typed_dump->is_array_member = is_array_member;
d->typed_dump->depth--;
btf_dump_data_pfx(d);
btf_dump_type_values(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;
/* note that we increment depth before calling btf_dump_print() below;
* this is intentional. btf_dump_data_newline() will not print a
* newline for depth 0 (since this leaves us with trailing newlines
* at the end of typed display), so depth is incremented first.
* For similar reasons, we decrement depth before showing the closing
* parenthesis.
*/
d->typed_dump->depth++;
btf_dump_printf(d, "{%s", btf_dump_data_newline(d));
for (i = 0; i < n; i++, m++) {
const struct btf_type *mtype;
const char *mname;
__u32 moffset;
__u8 bit_sz;
mtype = btf__type_by_id(d->btf, m->type);
mname = btf_name_of(d, m->name_off);
moffset = btf_member_bit_offset(t, i);
bit_sz = btf_member_bitfield_size(t, i);
err = btf_dump_dump_type_data(d, mname, mtype, m->type, data + moffset / 8,
moffset % 8, bit_sz);
if (err < 0)
return err;
}
d->typed_dump->depth--;
btf_dump_data_pfx(d);
btf_dump_type_values(d, "}");
return err;
}
union ptr_data {
unsigned int p;
unsigned long long lp;
};
static int btf_dump_ptr_data(struct btf_dump *d,
const struct btf_type *t,
__u32 id,
const void *data)
{
if (ptr_is_aligned(d->btf, id, data) && d->ptr_sz == sizeof(void *)) {
btf_dump_type_values(d, "%p", *(void **)data);
} else {
union ptr_data pt;
memcpy(&pt, data, d->ptr_sz);
if (d->ptr_sz == 4)
btf_dump_type_values(d, "0x%x", pt.p);
else
btf_dump_type_values(d, "0x%llx", pt.lp);
}
return 0;
}
static int btf_dump_get_enum_value(struct btf_dump *d,
const struct btf_type *t,
const void *data,
__u32 id,
__s64 *value)
{
/* handle unaligned enum value */
if (!ptr_is_aligned(d->btf, id, data)) {
__u64 val;
int err;
err = btf_dump_get_bitfield_value(d, t, data, 0, 0, &val);
if (err)
return err;
*value = (__s64)val;
return 0;
}
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;
return 0;
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(d, 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, 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 [%zu] for id [%u]\n",
(size_t)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_kind(t)) {
case BTF_KIND_INT:
case BTF_KIND_FLOAT:
case BTF_KIND_PTR:
case BTF_KIND_ENUM:
if (data + bits_offset / 8 + size > d->typed_dump->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,
__u8 bit_sz)
{
__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->typed_dump->emit_zeroes || d->typed_dump->depth == 0 ||
(d->typed_dump->is_array_member &&
!d->typed_dump->is_array_char))
return 0;
t = skip_mods_and_typedefs(d->btf, id, NULL);
switch (btf_kind(t)) {
case BTF_KIND_INT:
if (bit_sz)
return btf_dump_bitfield_check_zero(d, t, data, bits_offset, bit_sz);
return btf_dump_base_type_check_zero(d, t, id, data);
case BTF_KIND_FLOAT:
case BTF_KIND_PTR:
return btf_dump_base_type_check_zero(d, t, id, data);
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 = skip_mods_and_typedefs(d->btf, elem_type_id, NULL);
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, 0);
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 moffset;
mtype = btf__type_by_id(d->btf, m->type);
moffset = btf_member_bit_offset(t, i);
/* btf_int_bits() does not store member bitfield size;
* bitfield size needs to be stored here so int display
* of member can retrieve it.
*/
bit_sz = btf_member_bitfield_size(t, i);
err = btf_dump_type_data_check_zero(d, mtype, m->type, data + moffset / 8,
moffset % 8, bit_sz);
if (err != ENODATA)
return err;
}
return -ENODATA;
}
case BTF_KIND_ENUM:
err = btf_dump_get_enum_value(d, t, data, id, &value);
if (err)
return err;
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,
__u8 bit_sz)
{
int size, err = 0;
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, bit_sz);
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->typed_dump->skip_names) {
if (fname && strlen(fname) > 0)
btf_dump_printf(d, ".%s = ", fname);
btf_dump_emit_type_cast(d, id, true);
}
t = skip_mods_and_typedefs(d->btf, id, NULL);
switch (btf_kind(t)) {
case BTF_KIND_UNKN:
case BTF_KIND_FWD:
case BTF_KIND_FUNC:
case BTF_KIND_FUNC_PROTO:
case BTF_KIND_DECL_TAG:
err = btf_dump_unsupported_data(d, t, id);
break;
case BTF_KIND_INT:
if (bit_sz)
err = btf_dump_bitfield_data(d, t, data, bits_offset, bit_sz);
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);
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 (bit_sz) {
__u64 print_num;
__s64 enum_val;
err = btf_dump_get_bitfield_value(d, t, data, bits_offset, bit_sz,
&print_num);
if (err)
break;
enum_val = (__s64)print_num;
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)
{
struct btf_dump_data typed_dump = {};
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->typed_dump = &typed_dump;
d->typed_dump->data_end = data + data_sz;
d->typed_dump->indent_lvl = OPTS_GET(opts, indent_level, 0);
/* default indent string is a tab */
if (!opts->indent_str)
d->typed_dump->indent_str[0] = '\t';
else
libbpf_strlcpy(d->typed_dump->indent_str, opts->indent_str,
sizeof(d->typed_dump->indent_str));
d->typed_dump->compact = OPTS_GET(opts, compact, false);
d->typed_dump->skip_names = OPTS_GET(opts, skip_names, false);
d->typed_dump->emit_zeroes = OPTS_GET(opts, emit_zeroes, false);
ret = btf_dump_dump_type_data(d, NULL, t, id, data, 0, 0);
d->typed_dump = NULL;
return libbpf_err(ret);
}
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