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linux/tools/lib/bpf/btf_dump.c
Andrii Nakryiko 189f1a976e libbpf: Fix no-args func prototype BTF dumping syntax 
For all these years libbpf's BTF dumper has been emitting not strictly
valid syntax for function prototypes that have no input arguments.

Instead of `int (*blah)()` we should emit `int (*blah)(void)`.

This is not normally a problem, but it manifests when we get kfuncs in
vmlinux.h that have no input arguments. Due to compiler internal
specifics, we get no BTF information for such kfuncs, if they are not
declared with proper `(void)`.

The fix is trivial. We also need to adjust a few ancient tests that
happily assumed `()` is correct.

Fixes: 351131b51c ("libbpf: add btf_dump API for BTF-to-C conversion")
Reported-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Stanislav Fomichev <sdf@fomichev.me>
Link: https://lore.kernel.org/bpf/20240712224442.282823-1-andrii@kernel.org
2024-07-17 22:42:47 +02:00

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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 <limits.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(long key, void *ctx)
{
return str_hash((void *)key);
}
static bool str_equal_fn(long a, long b, void *ctx)
{
return strcmp((void *)a, (void *)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);
struct btf_dump *btf_dump__new(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 (!OPTS_VALID(opts, btf_dump_opts))
return libbpf_err_ptr(-EINVAL);
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);
}
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;
}
static void btf_dump_free_names(struct hashmap *map)
{
size_t bkt;
struct hashmap_entry *cur;
hashmap__for_each_entry(map, cur, bkt)
free((void *)cur->pkey);
hashmap__free(map);
}
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);
btf_dump_free_names(d->type_names);
btf_dump_free_names(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_ENUM64:
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_ENUM64:
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:
case BTF_KIND_ENUM64:
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 max_align = 1, align, i, bit_sz;
__u16 vlen;
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;
max_align = max(align, max_align);
}
/* size of a non-packed struct has to be a multiple of its alignment */
if (t->size % max_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 void btf_dump_emit_bit_padding(const struct btf_dump *d,
int cur_off, int next_off, int next_align,
bool in_bitfield, int lvl)
{
const struct {
const char *name;
int bits;
} pads[] = {
{"long", d->ptr_sz * 8}, {"int", 32}, {"short", 16}, {"char", 8}
};
int new_off, pad_bits, bits, i;
const char *pad_type;
if (cur_off >= next_off)
return; /* no gap */
/* For filling out padding we want to take advantage of
* natural alignment rules to minimize unnecessary explicit
* padding. First, we find the largest type (among long, int,
* short, or char) that can be used to force naturally aligned
* boundary. Once determined, we'll use such type to fill in
* the remaining padding gap. In some cases we can rely on
* compiler filling some gaps, but sometimes we need to force
* alignment to close natural alignment with markers like
* `long: 0` (this is always the case for bitfields). Note
* that even if struct itself has, let's say 4-byte alignment
* (i.e., it only uses up to int-aligned types), using `long:
* X;` explicit padding doesn't actually change struct's
* overall alignment requirements, but compiler does take into
* account that type's (long, in this example) natural
* alignment requirements when adding implicit padding. We use
* this fact heavily and don't worry about ruining correct
* struct alignment requirement.
*/
for (i = 0; i < ARRAY_SIZE(pads); i++) {
pad_bits = pads[i].bits;
pad_type = pads[i].name;
new_off = roundup(cur_off, pad_bits);
if (new_off <= next_off)
break;
}
if (new_off > cur_off && new_off <= next_off) {
/* We need explicit `<type>: 0` aligning mark if next
* field is right on alignment offset and its
* alignment requirement is less strict than <type>'s
* alignment (so compiler won't naturally align to the
* offset we expect), or if subsequent `<type>: X`,
* will actually completely fit in the remaining hole,
* making compiler basically ignore `<type>: X`
* completely.
*/
if (in_bitfield ||
(new_off == next_off && roundup(cur_off, next_align * 8) != new_off) ||
(new_off != next_off && next_off - new_off <= new_off - cur_off))
/* but for bitfields we'll emit explicit bit count */
btf_dump_printf(d, "\n%s%s: %d;", pfx(lvl), pad_type,
in_bitfield ? new_off - cur_off : 0);
cur_off = new_off;
}
/* Now we know we start at naturally aligned offset for a chosen
* padding type (long, int, short, or char), and so the rest is just
* a straightforward filling of remaining padding gap with full
* `<type>: sizeof(<type>);` markers, except for the last one, which
* might need smaller than sizeof(<type>) padding.
*/
while (cur_off != next_off) {
bits = min(next_off - cur_off, pad_bits);
if (bits == pad_bits) {
btf_dump_printf(d, "\n%s%s: %d;", pfx(lvl), pad_type, pad_bits);
cur_off += bits;
continue;
}
/* For the remainder padding that doesn't cover entire
* pad_type bit length, we pick the smallest necessary type.
* This is pure aesthetics, we could have just used `long`,
* but having smallest necessary one communicates better the
* scale of the padding gap.
*/
for (i = ARRAY_SIZE(pads) - 1; i >= 0; i--) {
pad_type = pads[i].name;
pad_bits = pads[i].bits;
if (pad_bits < bits)
continue;
btf_dump_printf(d, "\n%s%s: %d;", pfx(lvl), pad_type, bits);
cur_off += bits;
break;
}
}
}
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);
bool packed, prev_bitfield = false;
int align, i, off = 0;
__u16 vlen = btf_vlen(t);
align = btf__align_of(d->btf, id);
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, m_align;
bool in_bitfield;
fname = btf_name_of(d, m->name_off);
m_sz = btf_member_bitfield_size(t, i);
m_off = btf_member_bit_offset(t, i);
m_align = packed ? 1 : btf__align_of(d->btf, m->type);
in_bitfield = prev_bitfield && m_sz != 0;
btf_dump_emit_bit_padding(d, off, m_off, m_align, in_bitfield, 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;
prev_bitfield = true;
} else {
m_sz = max((__s64)0, btf__resolve_size(d->btf, m->type));
off = m_off + m_sz * 8;
prev_bitfield = false;
}
btf_dump_printf(d, ";");
}
/* pad at the end, if necessary */
if (is_struct)
btf_dump_emit_bit_padding(d, off, t->size * 8, align, false, lvl + 1);
/*
* Keep `struct empty {}` on a single line,
* only print newline when there are regular or padding fields.
*/
if (vlen || t->size) {
btf_dump_printf(d, "\n");
btf_dump_printf(d, "%s}", pfx(lvl));
} else {
btf_dump_printf(d, "}");
}
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_enum32_val(struct btf_dump *d,
const struct btf_type *t,
int lvl, __u16 vlen)
{
const struct btf_enum *v = btf_enum(t);
bool is_signed = btf_kflag(t);
const char *fmt_str;
const char *name;
size_t dup_cnt;
int i;
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) {
fmt_str = is_signed ? "\n%s%s___%zd = %d," : "\n%s%s___%zd = %u,";
btf_dump_printf(d, fmt_str, pfx(lvl + 1), name, dup_cnt, v->val);
} else {
fmt_str = is_signed ? "\n%s%s = %d," : "\n%s%s = %u,";
btf_dump_printf(d, fmt_str, pfx(lvl + 1), name, v->val);
}
}
}
static void btf_dump_emit_enum64_val(struct btf_dump *d,
const struct btf_type *t,
int lvl, __u16 vlen)
{
const struct btf_enum64 *v = btf_enum64(t);
bool is_signed = btf_kflag(t);
const char *fmt_str;
const char *name;
size_t dup_cnt;
__u64 val;
int i;
for (i = 0; i < vlen; i++, v++) {
name = btf_name_of(d, v->name_off);
dup_cnt = btf_dump_name_dups(d, d->ident_names, name);
val = btf_enum64_value(v);
if (dup_cnt > 1) {
fmt_str = is_signed ? "\n%s%s___%zd = %lldLL,"
: "\n%s%s___%zd = %lluULL,";
btf_dump_printf(d, fmt_str,
pfx(lvl + 1), name, dup_cnt,
(unsigned long long)val);
} else {
fmt_str = is_signed ? "\n%s%s = %lldLL,"
: "\n%s%s = %lluULL,";
btf_dump_printf(d, fmt_str,
pfx(lvl + 1), name,
(unsigned long long)val);
}
}
}
static void btf_dump_emit_enum_def(struct btf_dump *d, __u32 id,
const struct btf_type *t,
int lvl)
{
__u16 vlen = btf_vlen(t);
btf_dump_printf(d, "enum%s%s",
t->name_off ? " " : "",
btf_dump_type_name(d, id));
if (!vlen)
return;
btf_dump_printf(d, " {");
if (btf_is_enum(t))
btf_dump_emit_enum32_val(d, t, lvl, vlen);
else
btf_dump_emit_enum64_val(d, t, lvl, vlen);
btf_dump_printf(d, "\n%s}", pfx(lvl));
/* special case enums with special sizes */
if (t->size == 1) {
/* one-byte enums can be forced with mode(byte) attribute */
btf_dump_printf(d, " __attribute__((mode(byte)))");
} else if (t->size == 8 && d->ptr_sz == 8) {
/* enum can be 8-byte sized if one of the enumerator values
* doesn't fit in 32-bit integer, or by adding mode(word)
* attribute (but probably only on 64-bit architectures); do
* our best here to try to satisfy the contract without adding
* unnecessary attributes
*/
bool needs_word_mode;
if (btf_is_enum(t)) {
/* enum can't represent 64-bit values, so we need word mode */
needs_word_mode = true;
} else {
/* enum64 needs mode(word) if none of its values has
* non-zero upper 32-bits (which means that all values
* fit in 32-bit integers and won't cause compiler to
* bump enum to be 64-bit naturally
*/
int i;
needs_word_mode = true;
for (i = 0; i < vlen; i++) {
if (btf_enum64(t)[i].val_hi32 != 0) {
needs_word_mode = false;
break;
}
}
}
if (needs_word_mode)
btf_dump_printf(d, " __attribute__((mode(word)))");
}
}
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_ENUM64:
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:
case BTF_KIND_ENUM64:
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 emit valid empty args (void) syntax for
* such case. Similarly and conveniently, valid
* no args case can be special-cased here as well.
*/
if (vlen == 0 || (vlen == 1 && p->type == 0)) {
btf_dump_printf(d, "void)");
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)
{
char *old_name, *new_name;
size_t dup_cnt = 0;
int err;
new_name = strdup(orig_name);
if (!new_name)
return 1;
(void)hashmap__find(name_map, orig_name, &dup_cnt);
dup_cnt++;
err = hashmap__set(name_map, new_name, dup_cnt, &old_name, NULL);
if (err)
free(new_name);
free(old_name);
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') {
btf_dump_type_values(d, "'\\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;
bool is_array_terminated;
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;
is_array_terminated = d->typed_dump->is_array_terminated;
d->typed_dump->is_array_terminated = false;
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->is_array_terminated = is_array_terminated;
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 = 0;
/* 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)
{
bool is_signed = btf_kflag(t);
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 = is_signed ? (__s64)*(__s32 *)data : *(__u32 *)data;
return 0;
case 2:
*value = is_signed ? *(__s16 *)data : *(__u16 *)data;
return 0;
case 1:
*value = is_signed ? *(__s8 *)data : *(__u8 *)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)
{
bool is_signed;
__s64 value;
int i, err;
err = btf_dump_get_enum_value(d, t, data, id, &value);
if (err)
return err;
is_signed = btf_kflag(t);
if (btf_is_enum(t)) {
const struct btf_enum *e;
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, is_signed ? "%d" : "%u", value);
} else {
const struct btf_enum64 *e;
for (i = 0, e = btf_enum64(t); i < btf_vlen(t); i++, e++) {
if (value != btf_enum64_value(e))
continue;
btf_dump_type_values(d, "%s", btf_name_of(d, e->name_off));
return 0;
}
btf_dump_type_values(d, is_signed ? "%lldLL" : "%lluULL",
(unsigned long long)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,
__u8 bit_sz)
{
__s64 size;
if (bit_sz) {
/* bits_offset is at most 7. bit_sz is at most 128. */
__u8 nr_bytes = (bits_offset + bit_sz + 7) / 8;
/* When bit_sz is non zero, it is called from
* btf_dump_struct_data() where it only cares about
* negative error value.
* Return nr_bytes in success case to make it
* consistent as the regular integer case below.
*/
return data + nr_bytes > d->typed_dump->data_end ? -E2BIG : nr_bytes;
}
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:
case BTF_KIND_ENUM64:
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:
case BTF_KIND_ENUM64:
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, bit_sz);
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:
case BTF_KIND_ENUM64:
/* 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_GET(opts, indent_str, NULL))
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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