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btf_encoder.c
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btf_encoder.c
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/*
SPDX-License-Identifier: GPL-2.0-only
Copyright (C) 2019 Facebook
Derived from ctf_encoder.c, which is:
Copyright (C) Arnaldo Carvalho de Melo <[email protected]>
Copyright (C) Red Hat Inc
*/
#include "dwarves.h"
#include "elf_symtab.h"
#include "btf_encoder.h"
#include "gobuffer.h"
#include <linux/btf.h>
#include <bpf/btf.h>
#include <bpf/libbpf.h>
#include <ctype.h> /* for isalpha() and isalnum() */
#include <stdlib.h> /* for qsort() and bsearch() */
#include <inttypes.h>
#include <limits.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <errno.h>
#include <stdint.h>
struct elf_function {
const char *name;
bool generated;
};
#define MAX_PERCPU_VAR_CNT 4096
struct var_info {
uint64_t addr;
const char *name;
uint32_t sz;
};
struct btf_encoder {
struct list_head node;
struct btf *btf;
struct gobuffer percpu_secinfo;
const char *filename;
struct elf_symtab *symtab;
bool has_index_type,
need_index_type,
skip_encoding_vars,
raw_output,
verbose,
force,
gen_floats,
is_rel;
uint32_t array_index_id;
struct {
struct var_info vars[MAX_PERCPU_VAR_CNT];
int var_cnt;
uint32_t shndx;
uint64_t base_addr;
uint64_t sec_sz;
} percpu;
struct {
struct elf_function *entries;
int allocated;
int cnt;
} functions;
};
void btf_encoders__add(struct list_head *encoders, struct btf_encoder *encoder)
{
list_add_tail(&encoder->node, encoders);
}
struct btf_encoder *btf_encoders__first(struct list_head *encoders)
{
return list_first_entry(encoders, struct btf_encoder, node);
}
struct btf_encoder *btf_encoders__next(struct btf_encoder *encoder)
{
return list_next_entry(encoder, node);
}
#define PERCPU_SECTION ".data..percpu"
/*
* This depends on the GNU extension to eliminate the stray comma in the zero
* arguments case.
*
* The difference between elf_errmsg(-1) and elf_errmsg(elf_errno()) is that the
* latter clears the current error.
*/
#define elf_error(fmt, ...) \
fprintf(stderr, "%s: " fmt ": %s.\n", __func__, ##__VA_ARGS__, elf_errmsg(-1))
/*
* This depends on the GNU extension to eliminate the stray comma in the zero
* arguments case.
*
* The difference between elf_errmsg(-1) and elf_errmsg(elf_errno()) is that the
* latter clears the current error.
*/
#define elf_error(fmt, ...) \
fprintf(stderr, "%s: " fmt ": %s.\n", __func__, ##__VA_ARGS__, elf_errmsg(-1))
static int btf_var_secinfo_cmp(const void *a, const void *b)
{
const struct btf_var_secinfo *av = a;
const struct btf_var_secinfo *bv = b;
return av->offset - bv->offset;
}
#define BITS_PER_BYTE 8
#define BITS_PER_BYTE_MASK (BITS_PER_BYTE - 1)
#define BITS_PER_BYTE_MASKED(bits) ((bits) & BITS_PER_BYTE_MASK)
#define BITS_ROUNDDOWN_BYTES(bits) ((bits) >> 3)
#define BITS_ROUNDUP_BYTES(bits) (BITS_ROUNDDOWN_BYTES(bits) + !!BITS_PER_BYTE_MASKED(bits))
static const char * const btf_kind_str[NR_BTF_KINDS] = {
[BTF_KIND_UNKN] = "UNKNOWN",
[BTF_KIND_INT] = "INT",
[BTF_KIND_PTR] = "PTR",
[BTF_KIND_ARRAY] = "ARRAY",
[BTF_KIND_STRUCT] = "STRUCT",
[BTF_KIND_UNION] = "UNION",
[BTF_KIND_ENUM] = "ENUM",
[BTF_KIND_FWD] = "FWD",
[BTF_KIND_TYPEDEF] = "TYPEDEF",
[BTF_KIND_VOLATILE] = "VOLATILE",
[BTF_KIND_CONST] = "CONST",
[BTF_KIND_RESTRICT] = "RESTRICT",
[BTF_KIND_FUNC] = "FUNC",
[BTF_KIND_FUNC_PROTO] = "FUNC_PROTO",
[BTF_KIND_VAR] = "VAR",
[BTF_KIND_DATASEC] = "DATASEC",
[BTF_KIND_FLOAT] = "FLOAT",
[BTF_KIND_DECL_TAG] = "DECL_TAG",
[BTF_KIND_TYPE_TAG] = "TYPE_TAG",
};
static const char *btf__printable_name(const struct btf *btf, uint32_t offset)
{
if (!offset)
return "(anon)";
else
return btf__str_by_offset(btf, offset);
}
static const char * btf__int_encoding_str(uint8_t encoding)
{
if (encoding == 0)
return "(none)";
else if (encoding == BTF_INT_SIGNED)
return "SIGNED";
else if (encoding == BTF_INT_CHAR)
return "CHAR";
else if (encoding == BTF_INT_BOOL)
return "BOOL";
else
return "UNKN";
}
__attribute ((format (printf, 5, 6)))
static void btf__log_err(const struct btf *btf, int kind, const char *name,
bool output_cr, const char *fmt, ...)
{
fprintf(stderr, "[%u] %s %s", btf__get_nr_types(btf) + 1,
btf_kind_str[kind], name ?: "(anon)");
if (fmt && *fmt) {
va_list ap;
fprintf(stderr, " ");
va_start(ap, fmt);
vfprintf(stderr, fmt, ap);
va_end(ap);
}
if (output_cr)
fprintf(stderr, "\n");
}
__attribute ((format (printf, 5, 6)))
static void btf_encoder__log_type(const struct btf_encoder *encoder, const struct btf_type *t,
bool err, bool output_cr, const char *fmt, ...)
{
const struct btf *btf = encoder->btf;
uint8_t kind;
FILE *out;
if (!encoder->verbose && !err)
return;
kind = BTF_INFO_KIND(t->info);
out = err ? stderr : stdout;
fprintf(out, "[%u] %s %s",
btf__get_nr_types(btf), btf_kind_str[kind],
btf__printable_name(btf, t->name_off));
if (fmt && *fmt) {
va_list ap;
fprintf(out, " ");
va_start(ap, fmt);
vfprintf(out, fmt, ap);
va_end(ap);
}
if (output_cr)
fprintf(out, "\n");
}
__attribute ((format (printf, 5, 6)))
static void btf_encoder__log_member(const struct btf_encoder *encoder, const struct btf_type *t,
const struct btf_member *member, bool err, const char *fmt, ...)
{
const struct btf *btf = encoder->btf;
FILE *out;
if (!encoder->verbose && !err)
return;
out = err ? stderr : stdout;
if (btf_kflag(t))
fprintf(out, "\t%s type_id=%u bitfield_size=%u bits_offset=%u",
btf__printable_name(btf, member->name_off),
member->type,
BTF_MEMBER_BITFIELD_SIZE(member->offset),
BTF_MEMBER_BIT_OFFSET(member->offset));
else
fprintf(out, "\t%s type_id=%u bits_offset=%u",
btf__printable_name(btf, member->name_off),
member->type,
member->offset);
if (fmt && *fmt) {
va_list ap;
fprintf(out, " ");
va_start(ap, fmt);
vfprintf(out, fmt, ap);
va_end(ap);
}
fprintf(out, "\n");
}
__attribute ((format (printf, 6, 7)))
static void btf_encoder__log_func_param(struct btf_encoder *encoder, const char *name, uint32_t type,
bool err, bool is_last_param, const char *fmt, ...)
{
FILE *out;
if (!encoder->verbose && !err)
return;
out = err ? stderr : stdout;
if (is_last_param && !type)
fprintf(out, "vararg)\n");
else
fprintf(out, "%u %s%s", type, name, is_last_param ? ")\n" : ", ");
if (fmt && *fmt) {
va_list ap;
fprintf(out, " ");
va_start(ap, fmt);
vfprintf(out, fmt, ap);
va_end(ap);
}
}
static int32_t btf_encoder__add_float(struct btf_encoder *encoder, const struct base_type *bt, const char *name)
{
int32_t id = btf__add_float(encoder->btf, name, BITS_ROUNDUP_BYTES(bt->bit_size));
if (id < 0) {
btf__log_err(encoder->btf, BTF_KIND_FLOAT, name, true, "Error emitting BTF type");
} else {
const struct btf_type *t;
t = btf__type_by_id(encoder->btf, id);
btf_encoder__log_type(encoder, t, false, true, "size=%u nr_bits=%u", t->size, bt->bit_size);
}
return id;
}
static int32_t btf_encoder__add_base_type(struct btf_encoder *encoder, const struct base_type *bt, const char *name)
{
const struct btf_type *t;
uint8_t encoding = 0;
uint16_t byte_sz;
int32_t id;
if (bt->is_signed) {
encoding = BTF_INT_SIGNED;
} else if (bt->is_bool) {
encoding = BTF_INT_BOOL;
} else if (bt->float_type && encoder->gen_floats) {
/*
* Encode floats as BTF_KIND_FLOAT if allowed, otherwise (in
* compatibility mode) encode them as BTF_KIND_INT - that's not
* fully correct, but that's what it used to be.
*/
if (bt->float_type == BT_FP_SINGLE ||
bt->float_type == BT_FP_DOUBLE ||
bt->float_type == BT_FP_LDBL)
return btf_encoder__add_float(encoder, bt, name);
fprintf(stderr, "Complex, interval and imaginary float types are not supported\n");
return -1;
}
/* dwarf5 may emit DW_ATE_[un]signed_{num} base types where
* {num} is not power of 2 and may exceed 128. Such attributes
* are mostly used to record operation for an actual parameter
* or variable.
* For example,
* DW_AT_location (indexed (0x3c) loclist = 0x00008fb0:
* [0xffffffff82808812, 0xffffffff82808817):
* DW_OP_breg0 RAX+0,
* DW_OP_convert (0x000e97d5) "DW_ATE_unsigned_64",
* DW_OP_convert (0x000e97df) "DW_ATE_unsigned_8",
* DW_OP_stack_value,
* DW_OP_piece 0x1,
* DW_OP_breg0 RAX+0,
* DW_OP_convert (0x000e97d5) "DW_ATE_unsigned_64",
* DW_OP_convert (0x000e97da) "DW_ATE_unsigned_32",
* DW_OP_lit8,
* DW_OP_shr,
* DW_OP_convert (0x000e97da) "DW_ATE_unsigned_32",
* DW_OP_convert (0x000e97e4) "DW_ATE_unsigned_24",
* DW_OP_stack_value, DW_OP_piece 0x3
* DW_AT_name ("ebx")
* DW_AT_decl_file ("/linux/arch/x86/events/intel/core.c")
*
* In the above example, at some point, one unsigned_32 value
* is right shifted by 8 and the result is converted to unsigned_32
* and then unsigned_24.
*
* BTF does not need such DW_OP_* information so let us sanitize
* these non-regular int types to avoid libbpf/kernel complaints.
*/
byte_sz = BITS_ROUNDUP_BYTES(bt->bit_size);
if (!byte_sz || (byte_sz & (byte_sz - 1))) {
name = "__SANITIZED_FAKE_INT__";
byte_sz = 4;
}
id = btf__add_int(encoder->btf, name, byte_sz, encoding);
if (id < 0) {
btf__log_err(encoder->btf, BTF_KIND_INT, name, true, "Error emitting BTF type");
} else {
t = btf__type_by_id(encoder->btf, id);
btf_encoder__log_type(encoder, t, false, true, "size=%u nr_bits=%u encoding=%s%s",
t->size, bt->bit_size, btf__int_encoding_str(encoding),
id < 0 ? " Error in emitting BTF" : "" );
}
return id;
}
static int32_t btf_encoder__add_ref_type(struct btf_encoder *encoder, uint16_t kind, uint32_t type,
const char *name, bool kind_flag)
{
struct btf *btf = encoder->btf;
const struct btf_type *t;
int32_t id;
switch (kind) {
case BTF_KIND_PTR:
id = btf__add_ptr(btf, type);
break;
case BTF_KIND_VOLATILE:
id = btf__add_volatile(btf, type);
break;
case BTF_KIND_CONST:
id = btf__add_const(btf, type);
break;
case BTF_KIND_RESTRICT:
id = btf__add_restrict(btf, type);
break;
case BTF_KIND_TYPEDEF:
id = btf__add_typedef(btf, name, type);
break;
case BTF_KIND_TYPE_TAG:
id = btf__add_type_tag(btf, name, type);
break;
case BTF_KIND_FWD:
id = btf__add_fwd(btf, name, kind_flag);
break;
case BTF_KIND_FUNC:
id = btf__add_func(btf, name, BTF_FUNC_STATIC, type);
break;
default:
btf__log_err(btf, kind, name, true, "Unexpected kind for reference");
return -1;
}
if (id > 0) {
t = btf__type_by_id(btf, id);
if (kind == BTF_KIND_FWD)
btf_encoder__log_type(encoder, t, false, true, "%s", kind_flag ? "union" : "struct");
else
btf_encoder__log_type(encoder, t, false, true, "type_id=%u", t->type);
} else {
btf__log_err(btf, kind, name, true, "Error emitting BTF type");
}
return id;
}
static int32_t btf_encoder__add_array(struct btf_encoder *encoder, uint32_t type, uint32_t index_type, uint32_t nelems)
{
struct btf *btf = encoder->btf;
const struct btf_type *t;
const struct btf_array *array;
int32_t id;
id = btf__add_array(btf, index_type, type, nelems);
if (id > 0) {
t = btf__type_by_id(btf, id);
array = btf_array(t);
btf_encoder__log_type(encoder, t, false, true, "type_id=%u index_type_id=%u nr_elems=%u",
array->type, array->index_type, array->nelems);
} else {
btf__log_err(btf, BTF_KIND_ARRAY, NULL, true,
"type_id=%u index_type_id=%u nr_elems=%u Error emitting BTF type",
type, index_type, nelems);
}
return id;
}
static int btf_encoder__add_field(struct btf_encoder *encoder, const char *name, uint32_t type, uint32_t bitfield_size, uint32_t offset)
{
struct btf *btf = encoder->btf;
const struct btf_type *t;
const struct btf_member *m;
int err;
err = btf__add_field(btf, name, type, offset, bitfield_size);
t = btf__type_by_id(btf, btf__get_nr_types(btf));
if (err) {
fprintf(stderr, "[%u] %s %s's field '%s' offset=%u bit_size=%u type=%u Error emitting field\n",
btf__get_nr_types(btf), btf_kind_str[btf_kind(t)],
btf__printable_name(btf, t->name_off),
name, offset, bitfield_size, type);
} else {
m = &btf_members(t)[btf_vlen(t) - 1];
btf_encoder__log_member(encoder, t, m, false, NULL);
}
return err;
}
static int32_t btf_encoder__add_struct(struct btf_encoder *encoder, uint8_t kind, const char *name, uint32_t size)
{
struct btf *btf = encoder->btf;
const struct btf_type *t;
int32_t id;
switch (kind) {
case BTF_KIND_STRUCT:
id = btf__add_struct(btf, name, size);
break;
case BTF_KIND_UNION:
id = btf__add_union(btf, name, size);
break;
default:
btf__log_err(btf, kind, name, true, "Unexpected kind of struct");
return -1;
}
if (id < 0) {
btf__log_err(btf, kind, name, true, "Error emitting BTF type");
} else {
t = btf__type_by_id(btf, id);
btf_encoder__log_type(encoder, t, false, true, "size=%u", t->size);
}
return id;
}
static int32_t btf_encoder__add_enum(struct btf_encoder *encoder, const char *name, uint32_t bit_size)
{
struct btf *btf = encoder->btf;
const struct btf_type *t;
int32_t id, size;
size = BITS_ROUNDUP_BYTES(bit_size);
id = btf__add_enum(btf, name, size);
if (id > 0) {
t = btf__type_by_id(btf, id);
btf_encoder__log_type(encoder, t, false, true, "size=%u", t->size);
} else {
btf__log_err(btf, BTF_KIND_ENUM, name, true,
"size=%u Error emitting BTF type", size);
}
return id;
}
static int btf_encoder__add_enum_val(struct btf_encoder *encoder, const char *name, int32_t value)
{
int err = btf__add_enum_value(encoder->btf, name, value);
if (!err) {
if (encoder->verbose)
printf("\t%s val=%d\n", name, value);
} else {
fprintf(stderr, "\t%s val=%d Error emitting BTF enum value\n",
name, value);
}
return err;
}
static int32_t btf_encoder__add_func_param(struct btf_encoder *encoder, const char *name, uint32_t type, bool is_last_param)
{
int err = btf__add_func_param(encoder->btf, name, type);
if (!err) {
btf_encoder__log_func_param(encoder, name, type, false, is_last_param, NULL);
return 0;
} else {
btf_encoder__log_func_param(encoder, name, type, true, is_last_param, "Error adding func param");
return -1;
}
}
static int32_t btf_encoder__add_func_proto(struct btf_encoder *encoder, struct ftype *ftype, uint32_t type_id_off)
{
struct btf *btf = encoder->btf;
const struct btf_type *t;
struct parameter *param;
uint16_t nr_params, param_idx;
int32_t id, type_id;
/* add btf_type for func_proto */
nr_params = ftype->nr_parms + (ftype->unspec_parms ? 1 : 0);
type_id = ftype->tag.type == 0 ? 0 : type_id_off + ftype->tag.type;
id = btf__add_func_proto(btf, type_id);
if (id > 0) {
t = btf__type_by_id(btf, id);
btf_encoder__log_type(encoder, t, false, false, "return=%u args=(%s", t->type, !nr_params ? "void)\n" : "");
} else {
btf__log_err(btf, BTF_KIND_FUNC_PROTO, NULL, true,
"return=%u vlen=%u Error emitting BTF type",
type_id, nr_params);
return id;
}
/* add parameters */
param_idx = 0;
ftype__for_each_parameter(ftype, param) {
const char *name = parameter__name(param);
type_id = param->tag.type == 0 ? 0 : type_id_off + param->tag.type;
++param_idx;
if (btf_encoder__add_func_param(encoder, name, type_id, param_idx == nr_params))
return -1;
}
++param_idx;
if (ftype->unspec_parms)
if (btf_encoder__add_func_param(encoder, NULL, 0, param_idx == nr_params))
return -1;
return id;
}
static int32_t btf_encoder__add_var(struct btf_encoder *encoder, uint32_t type, const char *name, uint32_t linkage)
{
struct btf *btf = encoder->btf;
const struct btf_type *t;
int32_t id;
id = btf__add_var(btf, name, linkage, type);
if (id > 0) {
t = btf__type_by_id(btf, id);
btf_encoder__log_type(encoder, t, false, true, "type=%u linkage=%u", t->type, btf_var(t)->linkage);
} else {
btf__log_err(btf, BTF_KIND_VAR, name, true,
"type=%u linkage=%u Error emitting BTF type",
type, linkage);
}
return id;
}
static int32_t btf_encoder__add_var_secinfo(struct btf_encoder *encoder, uint32_t type,
uint32_t offset, uint32_t size)
{
struct btf_var_secinfo si = {
.type = type,
.offset = offset,
.size = size,
};
return gobuffer__add(&encoder->percpu_secinfo, &si, sizeof(si));
}
static int32_t btf_encoder__add_datasec(struct btf_encoder *encoder, const char *section_name)
{
struct gobuffer *var_secinfo_buf = &encoder->percpu_secinfo;
struct btf *btf = encoder->btf;
size_t sz = gobuffer__size(var_secinfo_buf);
uint16_t nr_var_secinfo = sz / sizeof(struct btf_var_secinfo);
struct btf_var_secinfo *last_vsi, *vsi;
const struct btf_type *t;
uint32_t datasec_sz;
int32_t err, id, i;
qsort(var_secinfo_buf->entries, nr_var_secinfo,
sizeof(struct btf_var_secinfo), btf_var_secinfo_cmp);
last_vsi = (struct btf_var_secinfo *)var_secinfo_buf->entries + nr_var_secinfo - 1;
datasec_sz = last_vsi->offset + last_vsi->size;
id = btf__add_datasec(btf, section_name, datasec_sz);
if (id < 0) {
btf__log_err(btf, BTF_KIND_DATASEC, section_name, true,
"size=%u vlen=%u Error emitting BTF type",
datasec_sz, nr_var_secinfo);
} else {
t = btf__type_by_id(btf, id);
btf_encoder__log_type(encoder, t, false, true, "size=%u vlen=%u", t->size, nr_var_secinfo);
}
for (i = 0; i < nr_var_secinfo; i++) {
vsi = (struct btf_var_secinfo *)var_secinfo_buf->entries + i;
err = btf__add_datasec_var_info(btf, vsi->type, vsi->offset, vsi->size);
if (!err) {
if (encoder->verbose)
printf("\ttype=%u offset=%u size=%u\n",
vsi->type, vsi->offset, vsi->size);
} else {
fprintf(stderr, "\ttype=%u offset=%u size=%u Error emitting BTF datasec var info\n",
vsi->type, vsi->offset, vsi->size);
return -1;
}
}
return id;
}
static int32_t btf_encoder__add_decl_tag(struct btf_encoder *encoder, const char *value, uint32_t type,
int component_idx)
{
struct btf *btf = encoder->btf;
const struct btf_type *t;
int32_t id;
id = btf__add_decl_tag(btf, value, type, component_idx);
if (id > 0) {
t = btf__type_by_id(btf, id);
btf_encoder__log_type(encoder, t, false, true, "type_id=%u component_idx=%d",
t->type, component_idx);
} else {
btf__log_err(btf, BTF_KIND_DECL_TAG, value, true, "component_idx=%d Error emitting BTF type",
component_idx);
}
return id;
}
/*
* This corresponds to the same macro defined in
* include/linux/kallsyms.h
*/
#define KSYM_NAME_LEN 128
static int functions_cmp(const void *_a, const void *_b)
{
const struct elf_function *a = _a;
const struct elf_function *b = _b;
return strcmp(a->name, b->name);
}
#ifndef max
#define max(x, y) ((x) < (y) ? (y) : (x))
#endif
static int btf_encoder__collect_function(struct btf_encoder *encoder, GElf_Sym *sym)
{
struct elf_function *new;
const char *name;
if (elf_sym__type(sym) != STT_FUNC)
return 0;
name = elf_sym__name(sym, encoder->symtab);
if (!name)
return 0;
if (encoder->functions.cnt == encoder->functions.allocated) {
encoder->functions.allocated = max(1000, encoder->functions.allocated * 3 / 2);
new = realloc(encoder->functions.entries, encoder->functions.allocated * sizeof(*encoder->functions.entries));
if (!new) {
/*
* The cleanup - delete_functions is called
* in btf_encoder__encode_cu error path.
*/
return -1;
}
encoder->functions.entries = new;
}
encoder->functions.entries[encoder->functions.cnt].name = name;
encoder->functions.entries[encoder->functions.cnt].generated = false;
encoder->functions.cnt++;
return 0;
}
static struct elf_function *btf_encoder__find_function(const struct btf_encoder *encoder, const char *name)
{
struct elf_function key = { .name = name };
return bsearch(&key, encoder->functions.entries, encoder->functions.cnt, sizeof(key), functions_cmp);
}
static bool btf_name_char_ok(char c, bool first)
{
if (c == '_' || c == '.')
return true;
return first ? isalpha(c) : isalnum(c);
}
/* Check whether the given name is valid in vmlinux btf. */
static bool btf_name_valid(const char *p)
{
const char *limit;
if (!btf_name_char_ok(*p, true))
return false;
/* set a limit on identifier length */
limit = p + KSYM_NAME_LEN;
p++;
while (*p && p < limit) {
if (!btf_name_char_ok(*p, false))
return false;
p++;
}
return !*p;
}
static void dump_invalid_symbol(const char *msg, const char *sym,
int verbose, bool force)
{
if (force) {
if (verbose)
fprintf(stderr, "PAHOLE: Warning: %s, ignored (sym: '%s').\n",
msg, sym);
return;
}
fprintf(stderr, "PAHOLE: Error: %s (sym: '%s').\n", msg, sym);
fprintf(stderr, "PAHOLE: Error: Use '--btf_encode_force' to ignore such symbols and force emit the btf.\n");
}
static int tag__check_id_drift(const struct tag *tag,
uint32_t core_id, uint32_t btf_type_id,
uint32_t type_id_off)
{
if (btf_type_id != (core_id + type_id_off)) {
fprintf(stderr,
"%s: %s id drift, core_id: %u, btf_type_id: %u, type_id_off: %u\n",
__func__, dwarf_tag_name(tag->tag),
core_id, btf_type_id, type_id_off);
return -1;
}
return 0;
}
static int32_t btf_encoder__add_struct_type(struct btf_encoder *encoder, struct tag *tag, uint32_t type_id_off)
{
struct type *type = tag__type(tag);
struct class_member *pos;
const char *name = type__name(type);
int32_t type_id;
uint8_t kind;
kind = (tag->tag == DW_TAG_union_type) ?
BTF_KIND_UNION : BTF_KIND_STRUCT;
type_id = btf_encoder__add_struct(encoder, kind, name, type->size);
if (type_id < 0)
return type_id;
type__for_each_data_member(type, pos) {
/*
* dwarf_loader uses DWARF's recommended bit offset addressing
* scheme, which conforms to BTF requirement, so no conversion
* is required.
*/
name = class_member__name(pos);
if (btf_encoder__add_field(encoder, name, type_id_off + pos->tag.type, pos->bitfield_size, pos->bit_offset))
return -1;
}
return type_id;
}
static uint32_t array_type__nelems(struct tag *tag)
{
int i;
uint32_t nelem = 1;
struct array_type *array = tag__array_type(tag);
for (i = array->dimensions - 1; i >= 0; --i)
nelem *= array->nr_entries[i];
return nelem;
}
static int32_t btf_encoder__add_enum_type(struct btf_encoder *encoder, struct tag *tag)
{
struct type *etype = tag__type(tag);
struct enumerator *pos;
const char *name = type__name(etype);
int32_t type_id;
type_id = btf_encoder__add_enum(encoder, name, etype->size);
if (type_id < 0)
return type_id;
type__for_each_enumerator(etype, pos) {
name = enumerator__name(pos);
if (btf_encoder__add_enum_val(encoder, name, pos->value))
return -1;
}
return type_id;
}
static int btf_encoder__encode_tag(struct btf_encoder *encoder, struct tag *tag, uint32_t type_id_off)
{
/* single out type 0 as it represents special type "void" */
uint32_t ref_type_id = tag->type == 0 ? 0 : type_id_off + tag->type;
struct base_type *bt;
const char *name;
switch (tag->tag) {
case DW_TAG_base_type:
bt = tag__base_type(tag);
name = __base_type__name(bt);
return btf_encoder__add_base_type(encoder, bt, name);
case DW_TAG_const_type:
return btf_encoder__add_ref_type(encoder, BTF_KIND_CONST, ref_type_id, NULL, false);
case DW_TAG_pointer_type:
return btf_encoder__add_ref_type(encoder, BTF_KIND_PTR, ref_type_id, NULL, false);
case DW_TAG_restrict_type:
return btf_encoder__add_ref_type(encoder, BTF_KIND_RESTRICT, ref_type_id, NULL, false);
case DW_TAG_volatile_type:
return btf_encoder__add_ref_type(encoder, BTF_KIND_VOLATILE, ref_type_id, NULL, false);
case DW_TAG_typedef:
name = namespace__name(tag__namespace(tag));
return btf_encoder__add_ref_type(encoder, BTF_KIND_TYPEDEF, ref_type_id, name, false);
case DW_TAG_LLVM_annotation:
name = tag__btf_type_tag(tag)->value;
return btf_encoder__add_ref_type(encoder, BTF_KIND_TYPE_TAG, ref_type_id, name, false);
case DW_TAG_structure_type:
case DW_TAG_union_type:
case DW_TAG_class_type:
name = namespace__name(tag__namespace(tag));
if (tag__type(tag)->declaration)
return btf_encoder__add_ref_type(encoder, BTF_KIND_FWD, 0, name, tag->tag == DW_TAG_union_type);
else
return btf_encoder__add_struct_type(encoder, tag, type_id_off);
case DW_TAG_array_type:
/* TODO: Encode one dimension at a time. */
encoder->need_index_type = true;
return btf_encoder__add_array(encoder, ref_type_id, encoder->array_index_id, array_type__nelems(tag));
case DW_TAG_enumeration_type:
return btf_encoder__add_enum_type(encoder, tag);
case DW_TAG_subroutine_type:
return btf_encoder__add_func_proto(encoder, tag__ftype(tag), type_id_off);
default:
fprintf(stderr, "Unsupported DW_TAG_%s(0x%x)\n",
dwarf_tag_name(tag->tag), tag->tag);
return -1;
}
}
static int btf_encoder__write_raw_file(struct btf_encoder *encoder)
{
const char *filename = encoder->filename;
uint32_t raw_btf_size;
const void *raw_btf_data;
int fd, err;
raw_btf_data = btf__get_raw_data(encoder->btf, &raw_btf_size);
if (raw_btf_data == NULL) {
fprintf(stderr, "%s: btf__get_raw_data failed!\n", __func__);
return -1;
}
fd = open(filename, O_WRONLY | O_CREAT, 0640);
if (fd < 0) {
fprintf(stderr, "%s: Couldn't open %s for writing the raw BTF info: %s\n", __func__, filename, strerror(errno));
return -1;
}
err = write(fd, raw_btf_data, raw_btf_size);
if (err < 0)
fprintf(stderr, "%s: Couldn't write the raw BTF info to %s: %s\n", __func__, filename, strerror(errno));
close(fd);
if ((uint32_t)err != raw_btf_size) {
fprintf(stderr, "%s: Could only write %d bytes to %s of raw BTF info out of %d, aborting\n", __func__, err, filename, raw_btf_size);
unlink(filename);
err = -1;
} else {
/* go from bytes written == raw_btf_size to an indication that all went fine */
err = 0;
}
return err;
}
static int btf_encoder__write_elf(struct btf_encoder *encoder)
{
struct btf *btf = encoder->btf;
const char *filename = encoder->filename;
GElf_Shdr shdr_mem, *shdr;
Elf_Data *btf_data = NULL;
Elf_Scn *scn = NULL;
Elf *elf = NULL;
const void *raw_btf_data;
uint32_t raw_btf_size;
int fd, err = -1;
size_t strndx;
fd = open(filename, O_RDWR);
if (fd < 0) {
fprintf(stderr, "Cannot open %s\n", filename);
return -1;
}
if (elf_version(EV_CURRENT) == EV_NONE) {
elf_error("Cannot set libelf version");
goto out;
}
elf = elf_begin(fd, ELF_C_RDWR, NULL);
if (elf == NULL) {
elf_error("Cannot update ELF file");
goto out;
}
elf_flagelf(elf, ELF_C_SET, ELF_F_DIRTY);
/*
* First we look if there was already a .BTF section to overwrite.
*/
elf_getshdrstrndx(elf, &strndx);
while ((scn = elf_nextscn(elf, scn)) != NULL) {
shdr = gelf_getshdr(scn, &shdr_mem);
if (shdr == NULL)
continue;
char *secname = elf_strptr(elf, strndx, shdr->sh_name);
if (strcmp(secname, ".BTF") == 0) {
btf_data = elf_getdata(scn, btf_data);
break;
}
}
raw_btf_data = btf__get_raw_data(btf, &raw_btf_size);
if (btf_data) {
/* Existing .BTF section found */
btf_data->d_buf = (void *)raw_btf_data;
btf_data->d_size = raw_btf_size;
elf_flagdata(btf_data, ELF_C_SET, ELF_F_DIRTY);
if (elf_update(elf, ELF_C_NULL) >= 0 &&
elf_update(elf, ELF_C_WRITE) >= 0)
err = 0;
else
elf_error("elf_update failed");
} else {
const char *llvm_objcopy;
char tmp_fn[PATH_MAX];
char cmd[PATH_MAX * 2];
llvm_objcopy = getenv("LLVM_OBJCOPY");
if (!llvm_objcopy)
llvm_objcopy = "llvm-objcopy";