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linuxdebug/tools/bpf/bpftool/gen.c

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null pointer error
2024-07-16 15:50:57 +02:00
// SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
/* Copyright (C) 2019 Facebook */
#ifndef _GNU_SOURCE
#define _GNU_SOURCE
#endif
#include <ctype.h>
#include <errno.h>
#include <fcntl.h>
#include <linux/err.h>
#include <stdbool.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <bpf/bpf.h>
#include <bpf/libbpf.h>
#include <bpf/libbpf_internal.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/mman.h>
#include <bpf/btf.h>
#include "json_writer.h"
#include "main.h"
#define MAX_OBJ_NAME_LEN 64
static void sanitize_identifier(char *name)
{
int i;
for (i = 0; name[i]; i++)
if (!isalnum(name[i]) && name[i] != '_')
name[i] = '_';
}
static bool str_has_prefix(const char *str, const char *prefix)
{
return strncmp(str, prefix, strlen(prefix)) == 0;
}
static bool str_has_suffix(const char *str, const char *suffix)
{
size_t i, n1 = strlen(str), n2 = strlen(suffix);
if (n1 < n2)
return false;
for (i = 0; i < n2; i++) {
if (str[n1 - i - 1] != suffix[n2 - i - 1])
return false;
}
return true;
}
static void get_obj_name(char *name, const char *file)
{
/* Using basename() GNU version which doesn't modify arg. */
strncpy(name, basename(file), MAX_OBJ_NAME_LEN - 1);
name[MAX_OBJ_NAME_LEN - 1] = '\0';
if (str_has_suffix(name, ".o"))
name[strlen(name) - 2] = '\0';
sanitize_identifier(name);
}
static void get_header_guard(char *guard, const char *obj_name, const char *suffix)
{
int i;
sprintf(guard, "__%s_%s__", obj_name, suffix);
for (i = 0; guard[i]; i++)
guard[i] = toupper(guard[i]);
}
static bool get_map_ident(const struct bpf_map *map, char *buf, size_t buf_sz)
{
static const char *sfxs[] = { ".data", ".rodata", ".bss", ".kconfig" };
const char *name = bpf_map__name(map);
int i, n;
if (!bpf_map__is_internal(map)) {
snprintf(buf, buf_sz, "%s", name);
return true;
}
for (i = 0, n = ARRAY_SIZE(sfxs); i < n; i++) {
const char *sfx = sfxs[i], *p;
p = strstr(name, sfx);
if (p) {
snprintf(buf, buf_sz, "%s", p + 1);
sanitize_identifier(buf);
return true;
}
}
return false;
}
static bool get_datasec_ident(const char *sec_name, char *buf, size_t buf_sz)
{
static const char *pfxs[] = { ".data", ".rodata", ".bss", ".kconfig" };
int i, n;
for (i = 0, n = ARRAY_SIZE(pfxs); i < n; i++) {
const char *pfx = pfxs[i];
if (str_has_prefix(sec_name, pfx)) {
snprintf(buf, buf_sz, "%s", sec_name + 1);
sanitize_identifier(buf);
return true;
}
}
return false;
}
static void codegen_btf_dump_printf(void *ctx, const char *fmt, va_list args)
{
vprintf(fmt, args);
}
static int codegen_datasec_def(struct bpf_object *obj,
struct btf *btf,
struct btf_dump *d,
const struct btf_type *sec,
const char *obj_name)
{
const char *sec_name = btf__name_by_offset(btf, sec->name_off);
const struct btf_var_secinfo *sec_var = btf_var_secinfos(sec);
int i, err, off = 0, pad_cnt = 0, vlen = btf_vlen(sec);
char var_ident[256], sec_ident[256];
bool strip_mods = false;
if (!get_datasec_ident(sec_name, sec_ident, sizeof(sec_ident)))
return 0;
if (strcmp(sec_name, ".kconfig") != 0)
strip_mods = true;
printf(" struct %s__%s {\n", obj_name, sec_ident);
for (i = 0; i < vlen; i++, sec_var++) {
const struct btf_type *var = btf__type_by_id(btf, sec_var->type);
const char *var_name = btf__name_by_offset(btf, var->name_off);
DECLARE_LIBBPF_OPTS(btf_dump_emit_type_decl_opts, opts,
.field_name = var_ident,
.indent_level = 2,
.strip_mods = strip_mods,
);
int need_off = sec_var->offset, align_off, align;
__u32 var_type_id = var->type;
/* static variables are not exposed through BPF skeleton */
if (btf_var(var)->linkage == BTF_VAR_STATIC)
continue;
if (off > need_off) {
p_err("Something is wrong for %s's variable #%d: need offset %d, already at %d.\n",
sec_name, i, need_off, off);
return -EINVAL;
}
align = btf__align_of(btf, var->type);
if (align <= 0) {
p_err("Failed to determine alignment of variable '%s': %d",
var_name, align);
return -EINVAL;
}
/* Assume 32-bit architectures when generating data section
* struct memory layout. Given bpftool can't know which target
* host architecture it's emitting skeleton for, we need to be
* conservative and assume 32-bit one to ensure enough padding
* bytes are generated for pointer and long types. This will
* still work correctly for 64-bit architectures, because in
* the worst case we'll generate unnecessary padding field,
* which on 64-bit architectures is not strictly necessary and
* would be handled by natural 8-byte alignment. But it still
* will be a correct memory layout, based on recorded offsets
* in BTF.
*/
if (align > 4)
align = 4;
align_off = (off + align - 1) / align * align;
if (align_off != need_off) {
printf("\t\tchar __pad%d[%d];\n",
pad_cnt, need_off - off);
pad_cnt++;
}
/* sanitize variable name, e.g., for static vars inside
* a function, it's name is '<function name>.<variable name>',
* which we'll turn into a '<function name>_<variable name>'
*/
var_ident[0] = '\0';
strncat(var_ident, var_name, sizeof(var_ident) - 1);
sanitize_identifier(var_ident);
printf("\t\t");
err = btf_dump__emit_type_decl(d, var_type_id, &opts);
if (err)
return err;
printf(";\n");
off = sec_var->offset + sec_var->size;
}
printf(" } *%s;\n", sec_ident);
return 0;
}
static const struct btf_type *find_type_for_map(struct btf *btf, const char *map_ident)
{
int n = btf__type_cnt(btf), i;
char sec_ident[256];
for (i = 1; i < n; i++) {
const struct btf_type *t = btf__type_by_id(btf, i);
const char *name;
if (!btf_is_datasec(t))
continue;
name = btf__str_by_offset(btf, t->name_off);
if (!get_datasec_ident(name, sec_ident, sizeof(sec_ident)))
continue;
if (strcmp(sec_ident, map_ident) == 0)
return t;
}
return NULL;
}
static bool is_internal_mmapable_map(const struct bpf_map *map, char *buf, size_t sz)
{
if (!bpf_map__is_internal(map) || !(bpf_map__map_flags(map) & BPF_F_MMAPABLE))
return false;
if (!get_map_ident(map, buf, sz))
return false;
return true;
}
static int codegen_datasecs(struct bpf_object *obj, const char *obj_name)
{
struct btf *btf = bpf_object__btf(obj);
struct btf_dump *d;
struct bpf_map *map;
const struct btf_type *sec;
char map_ident[256];
int err = 0;
d = btf_dump__new(btf, codegen_btf_dump_printf, NULL, NULL);
err = libbpf_get_error(d);
if (err)
return err;
bpf_object__for_each_map(map, obj) {
/* only generate definitions for memory-mapped internal maps */
if (!is_internal_mmapable_map(map, map_ident, sizeof(map_ident)))
continue;
sec = find_type_for_map(btf, map_ident);
/* In some cases (e.g., sections like .rodata.cst16 containing
* compiler allocated string constants only) there will be
* special internal maps with no corresponding DATASEC BTF
* type. In such case, generate empty structs for each such
* map. It will still be memory-mapped and its contents
* accessible from user-space through BPF skeleton.
*/
if (!sec) {
printf(" struct %s__%s {\n", obj_name, map_ident);
printf(" } *%s;\n", map_ident);
} else {
err = codegen_datasec_def(obj, btf, d, sec, obj_name);
if (err)
goto out;
}
}
out:
btf_dump__free(d);
return err;
}
static bool btf_is_ptr_to_func_proto(const struct btf *btf,
const struct btf_type *v)
{
return btf_is_ptr(v) && btf_is_func_proto(btf__type_by_id(btf, v->type));
}
static int codegen_subskel_datasecs(struct bpf_object *obj, const char *obj_name)
{
struct btf *btf = bpf_object__btf(obj);
struct btf_dump *d;
struct bpf_map *map;
const struct btf_type *sec, *var;
const struct btf_var_secinfo *sec_var;
int i, err = 0, vlen;
char map_ident[256], sec_ident[256];
bool strip_mods = false, needs_typeof = false;
const char *sec_name, *var_name;
__u32 var_type_id;
d = btf_dump__new(btf, codegen_btf_dump_printf, NULL, NULL);
if (!d)
return -errno;
bpf_object__for_each_map(map, obj) {
/* only generate definitions for memory-mapped internal maps */
if (!is_internal_mmapable_map(map, map_ident, sizeof(map_ident)))
continue;
sec = find_type_for_map(btf, map_ident);
if (!sec)
continue;
sec_name = btf__name_by_offset(btf, sec->name_off);
if (!get_datasec_ident(sec_name, sec_ident, sizeof(sec_ident)))
continue;
strip_mods = strcmp(sec_name, ".kconfig") != 0;
printf(" struct %s__%s {\n", obj_name, sec_ident);
sec_var = btf_var_secinfos(sec);
vlen = btf_vlen(sec);
for (i = 0; i < vlen; i++, sec_var++) {
DECLARE_LIBBPF_OPTS(btf_dump_emit_type_decl_opts, opts,
.indent_level = 2,
.strip_mods = strip_mods,
/* we'll print the name separately */
.field_name = "",
);
var = btf__type_by_id(btf, sec_var->type);
var_name = btf__name_by_offset(btf, var->name_off);
var_type_id = var->type;
/* static variables are not exposed through BPF skeleton */
if (btf_var(var)->linkage == BTF_VAR_STATIC)
continue;
/* The datasec member has KIND_VAR but we want the
* underlying type of the variable (e.g. KIND_INT).
*/
var = skip_mods_and_typedefs(btf, var->type, NULL);
printf("\t\t");
/* Func and array members require special handling.
* Instead of producing `typename *var`, they produce
* `typeof(typename) *var`. This allows us to keep a
* similar syntax where the identifier is just prefixed
* by *, allowing us to ignore C declaration minutiae.
*/
needs_typeof = btf_is_array(var) || btf_is_ptr_to_func_proto(btf, var);
if (needs_typeof)
printf("typeof(");
err = btf_dump__emit_type_decl(d, var_type_id, &opts);
if (err)
goto out;
if (needs_typeof)
printf(")");
printf(" *%s;\n", var_name);
}
printf(" } %s;\n", sec_ident);
}
out:
btf_dump__free(d);
return err;
}
static void codegen(const char *template, ...)
{
const char *src, *end;
int skip_tabs = 0, n;
char *s, *dst;
va_list args;
char c;
n = strlen(template);
s = malloc(n + 1);
if (!s)
exit(-1);
src = template;
dst = s;
/* find out "baseline" indentation to skip */
while ((c = *src++)) {
if (c == '\t') {
skip_tabs++;
} else if (c == '\n') {
break;
} else {
p_err("unrecognized character at pos %td in template '%s': '%c'",
src - template - 1, template, c);
free(s);
exit(-1);
}
}
while (*src) {
/* skip baseline indentation tabs */
for (n = skip_tabs; n > 0; n--, src++) {
if (*src != '\t') {
p_err("not enough tabs at pos %td in template '%s'",
src - template - 1, template);
free(s);
exit(-1);
}
}
/* trim trailing whitespace */
end = strchrnul(src, '\n');
for (n = end - src; n > 0 && isspace(src[n - 1]); n--)
;
memcpy(dst, src, n);
dst += n;
if (*end)
*dst++ = '\n';
src = *end ? end + 1 : end;
}
*dst++ = '\0';
/* print out using adjusted template */
va_start(args, template);
n = vprintf(s, args);
va_end(args);
free(s);
}
static void print_hex(const char *data, int data_sz)
{
int i, len;
for (i = 0, len = 0; i < data_sz; i++) {
int w = data[i] ? 4 : 2;
len += w;
if (len > 78) {
printf("\\\n");
len = w;
}
if (!data[i])
printf("\\0");
else
printf("\\x%02x", (unsigned char)data[i]);
}
}
static size_t bpf_map_mmap_sz(const struct bpf_map *map)
{
long page_sz = sysconf(_SC_PAGE_SIZE);
size_t map_sz;
map_sz = (size_t)roundup(bpf_map__value_size(map), 8) * bpf_map__max_entries(map);
map_sz = roundup(map_sz, page_sz);
return map_sz;
}
/* Emit type size asserts for all top-level fields in memory-mapped internal maps. */
static void codegen_asserts(struct bpf_object *obj, const char *obj_name)
{
struct btf *btf = bpf_object__btf(obj);
struct bpf_map *map;
struct btf_var_secinfo *sec_var;
int i, vlen;
const struct btf_type *sec;
char map_ident[256], var_ident[256];
if (!btf)
return;
codegen("\
\n\
__attribute__((unused)) static void \n\
%1$s__assert(struct %1$s *s __attribute__((unused))) \n\
{ \n\
#ifdef __cplusplus \n\
#define _Static_assert static_assert \n\
#endif \n\
", obj_name);
bpf_object__for_each_map(map, obj) {
if (!is_internal_mmapable_map(map, map_ident, sizeof(map_ident)))
continue;
sec = find_type_for_map(btf, map_ident);
if (!sec) {
/* best effort, couldn't find the type for this map */
continue;
}
sec_var = btf_var_secinfos(sec);
vlen = btf_vlen(sec);
for (i = 0; i < vlen; i++, sec_var++) {
const struct btf_type *var = btf__type_by_id(btf, sec_var->type);
const char *var_name = btf__name_by_offset(btf, var->name_off);
long var_size;
/* static variables are not exposed through BPF skeleton */
if (btf_var(var)->linkage == BTF_VAR_STATIC)
continue;
var_size = btf__resolve_size(btf, var->type);
if (var_size < 0)
continue;
var_ident[0] = '\0';
strncat(var_ident, var_name, sizeof(var_ident) - 1);
sanitize_identifier(var_ident);
printf("\t_Static_assert(sizeof(s->%s->%s) == %ld, \"unexpected size of '%s'\");\n",
map_ident, var_ident, var_size, var_ident);
}
}
codegen("\
\n\
#ifdef __cplusplus \n\
#undef _Static_assert \n\
#endif \n\
} \n\
");
}
static void codegen_attach_detach(struct bpf_object *obj, const char *obj_name)
{
struct bpf_program *prog;
bpf_object__for_each_program(prog, obj) {
const char *tp_name;
codegen("\
\n\
\n\
static inline int \n\
%1$s__%2$s__attach(struct %1$s *skel) \n\
{ \n\
int prog_fd = skel->progs.%2$s.prog_fd; \n\
", obj_name, bpf_program__name(prog));
switch (bpf_program__type(prog)) {
case BPF_PROG_TYPE_RAW_TRACEPOINT:
tp_name = strchr(bpf_program__section_name(prog), '/') + 1;
printf("\tint fd = skel_raw_tracepoint_open(\"%s\", prog_fd);\n", tp_name);
break;
case BPF_PROG_TYPE_TRACING:
case BPF_PROG_TYPE_LSM:
if (bpf_program__expected_attach_type(prog) == BPF_TRACE_ITER)
printf("\tint fd = skel_link_create(prog_fd, 0, BPF_TRACE_ITER);\n");
else
printf("\tint fd = skel_raw_tracepoint_open(NULL, prog_fd);\n");
break;
default:
printf("\tint fd = ((void)prog_fd, 0); /* auto-attach not supported */\n");
break;
}
codegen("\
\n\
\n\
if (fd > 0) \n\
skel->links.%1$s_fd = fd; \n\
return fd; \n\
} \n\
", bpf_program__name(prog));
}
codegen("\
\n\
\n\
static inline int \n\
%1$s__attach(struct %1$s *skel) \n\
{ \n\
int ret = 0; \n\
\n\
", obj_name);
bpf_object__for_each_program(prog, obj) {
codegen("\
\n\
ret = ret < 0 ? ret : %1$s__%2$s__attach(skel); \n\
", obj_name, bpf_program__name(prog));
}
codegen("\
\n\
return ret < 0 ? ret : 0; \n\
} \n\
\n\
static inline void \n\
%1$s__detach(struct %1$s *skel) \n\
{ \n\
", obj_name);
bpf_object__for_each_program(prog, obj) {
codegen("\
\n\
skel_closenz(skel->links.%1$s_fd); \n\
", bpf_program__name(prog));
}
codegen("\
\n\
} \n\
");
}
static void codegen_destroy(struct bpf_object *obj, const char *obj_name)
{
struct bpf_program *prog;
struct bpf_map *map;
char ident[256];
codegen("\
\n\
static void \n\
%1$s__destroy(struct %1$s *skel) \n\
{ \n\
if (!skel) \n\
return; \n\
%1$s__detach(skel); \n\
",
obj_name);
bpf_object__for_each_program(prog, obj) {
codegen("\
\n\
skel_closenz(skel->progs.%1$s.prog_fd); \n\
", bpf_program__name(prog));
}
bpf_object__for_each_map(map, obj) {
if (!get_map_ident(map, ident, sizeof(ident)))
continue;
if (bpf_map__is_internal(map) &&
(bpf_map__map_flags(map) & BPF_F_MMAPABLE))
printf("\tskel_free_map_data(skel->%1$s, skel->maps.%1$s.initial_value, %2$zd);\n",
ident, bpf_map_mmap_sz(map));
codegen("\
\n\
skel_closenz(skel->maps.%1$s.map_fd); \n\
", ident);
}
codegen("\
\n\
skel_free(skel); \n\
} \n\
",
obj_name);
}
static int gen_trace(struct bpf_object *obj, const char *obj_name, const char *header_guard)
{
DECLARE_LIBBPF_OPTS(gen_loader_opts, opts);
struct bpf_map *map;
char ident[256];
int err = 0;
err = bpf_object__gen_loader(obj, &opts);
if (err)
return err;
err = bpf_object__load(obj);
if (err) {
p_err("failed to load object file");
goto out;
}
/* If there was no error during load then gen_loader_opts
* are populated with the loader program.
*/
/* finish generating 'struct skel' */
codegen("\
\n\
}; \n\
", obj_name);
codegen_attach_detach(obj, obj_name);
codegen_destroy(obj, obj_name);
codegen("\
\n\
static inline struct %1$s * \n\
%1$s__open(void) \n\
{ \n\
struct %1$s *skel; \n\
\n\
skel = skel_alloc(sizeof(*skel)); \n\
if (!skel) \n\
goto cleanup; \n\
skel->ctx.sz = (void *)&skel->links - (void *)skel; \n\
",
obj_name, opts.data_sz);
bpf_object__for_each_map(map, obj) {
const void *mmap_data = NULL;
size_t mmap_size = 0;
if (!is_internal_mmapable_map(map, ident, sizeof(ident)))
continue;
codegen("\
\n\
skel->%1$s = skel_prep_map_data((void *)\"\\ \n\
", ident);
mmap_data = bpf_map__initial_value(map, &mmap_size);
print_hex(mmap_data, mmap_size);
codegen("\
\n\
\", %1$zd, %2$zd); \n\
if (!skel->%3$s) \n\
goto cleanup; \n\
skel->maps.%3$s.initial_value = (__u64) (long) skel->%3$s;\n\
", bpf_map_mmap_sz(map), mmap_size, ident);
}
codegen("\
\n\
return skel; \n\
cleanup: \n\
%1$s__destroy(skel); \n\
return NULL; \n\
} \n\
\n\
static inline int \n\
%1$s__load(struct %1$s *skel) \n\
{ \n\
struct bpf_load_and_run_opts opts = {}; \n\
int err; \n\
\n\
opts.ctx = (struct bpf_loader_ctx *)skel; \n\
opts.data_sz = %2$d; \n\
opts.data = (void *)\"\\ \n\
",
obj_name, opts.data_sz);
print_hex(opts.data, opts.data_sz);
codegen("\
\n\
\"; \n\
");
codegen("\
\n\
opts.insns_sz = %d; \n\
opts.insns = (void *)\"\\ \n\
",
opts.insns_sz);
print_hex(opts.insns, opts.insns_sz);
codegen("\
\n\
\"; \n\
err = bpf_load_and_run(&opts); \n\
if (err < 0) \n\
return err; \n\
", obj_name);
bpf_object__for_each_map(map, obj) {
const char *mmap_flags;
if (!is_internal_mmapable_map(map, ident, sizeof(ident)))
continue;
if (bpf_map__map_flags(map) & BPF_F_RDONLY_PROG)
mmap_flags = "PROT_READ";
else
mmap_flags = "PROT_READ | PROT_WRITE";
codegen("\
\n\
skel->%1$s = skel_finalize_map_data(&skel->maps.%1$s.initial_value, \n\
%2$zd, %3$s, skel->maps.%1$s.map_fd);\n\
if (!skel->%1$s) \n\
return -ENOMEM; \n\
",
ident, bpf_map_mmap_sz(map), mmap_flags);
}
codegen("\
\n\
return 0; \n\
} \n\
\n\
static inline struct %1$s * \n\
%1$s__open_and_load(void) \n\
{ \n\
struct %1$s *skel; \n\
\n\
skel = %1$s__open(); \n\
if (!skel) \n\
return NULL; \n\
if (%1$s__load(skel)) { \n\
%1$s__destroy(skel); \n\
return NULL; \n\
} \n\
return skel; \n\
} \n\
\n\
", obj_name);
codegen_asserts(obj, obj_name);
codegen("\
\n\
\n\
#endif /* %s */ \n\
",
header_guard);
err = 0;
out:
return err;
}
static void
codegen_maps_skeleton(struct bpf_object *obj, size_t map_cnt, bool mmaped)
{
struct bpf_map *map;
char ident[256];
size_t i;
if (!map_cnt)
return;
codegen("\
\n\
\n\
/* maps */ \n\
s->map_cnt = %zu; \n\
s->map_skel_sz = sizeof(*s->maps); \n\
s->maps = (struct bpf_map_skeleton *)calloc(s->map_cnt, s->map_skel_sz);\n\
if (!s->maps) { \n\
err = -ENOMEM; \n\
goto err; \n\
} \n\
",
map_cnt
);
i = 0;
bpf_object__for_each_map(map, obj) {
if (!get_map_ident(map, ident, sizeof(ident)))
continue;
codegen("\
\n\
\n\
s->maps[%zu].name = \"%s\"; \n\
s->maps[%zu].map = &obj->maps.%s; \n\
",
i, bpf_map__name(map), i, ident);
/* memory-mapped internal maps */
if (mmaped && is_internal_mmapable_map(map, ident, sizeof(ident))) {
printf("\ts->maps[%zu].mmaped = (void **)&obj->%s;\n",
i, ident);
}
i++;
}
}
static void
codegen_progs_skeleton(struct bpf_object *obj, size_t prog_cnt, bool populate_links)
{
struct bpf_program *prog;
int i;
if (!prog_cnt)
return;
codegen("\
\n\
\n\
/* programs */ \n\
s->prog_cnt = %zu; \n\
s->prog_skel_sz = sizeof(*s->progs); \n\
s->progs = (struct bpf_prog_skeleton *)calloc(s->prog_cnt, s->prog_skel_sz);\n\
if (!s->progs) { \n\
err = -ENOMEM; \n\
goto err; \n\
} \n\
",
prog_cnt
);
i = 0;
bpf_object__for_each_program(prog, obj) {
codegen("\
\n\
\n\
s->progs[%1$zu].name = \"%2$s\"; \n\
s->progs[%1$zu].prog = &obj->progs.%2$s;\n\
",
i, bpf_program__name(prog));
if (populate_links) {
codegen("\
\n\
s->progs[%1$zu].link = &obj->links.%2$s;\n\
",
i, bpf_program__name(prog));
}
i++;
}
}
static int do_skeleton(int argc, char **argv)
{
char header_guard[MAX_OBJ_NAME_LEN + sizeof("__SKEL_H__")];
size_t map_cnt = 0, prog_cnt = 0, file_sz, mmap_sz;
DECLARE_LIBBPF_OPTS(bpf_object_open_opts, opts);
char obj_name[MAX_OBJ_NAME_LEN] = "", *obj_data;
struct bpf_object *obj = NULL;
const char *file;
char ident[256];
struct bpf_program *prog;
int fd, err = -1;
struct bpf_map *map;
struct btf *btf;
struct stat st;
if (!REQ_ARGS(1)) {
usage();
return -1;
}
file = GET_ARG();
while (argc) {
if (!REQ_ARGS(2))
return -1;
if (is_prefix(*argv, "name")) {
NEXT_ARG();
if (obj_name[0] != '\0') {
p_err("object name already specified");
return -1;
}
strncpy(obj_name, *argv, MAX_OBJ_NAME_LEN - 1);
obj_name[MAX_OBJ_NAME_LEN - 1] = '\0';
} else {
p_err("unknown arg %s", *argv);
return -1;
}
NEXT_ARG();
}
if (argc) {
p_err("extra unknown arguments");
return -1;
}
if (stat(file, &st)) {
p_err("failed to stat() %s: %s", file, strerror(errno));
return -1;
}
file_sz = st.st_size;
mmap_sz = roundup(file_sz, sysconf(_SC_PAGE_SIZE));
fd = open(file, O_RDONLY);
if (fd < 0) {
p_err("failed to open() %s: %s", file, strerror(errno));
return -1;
}
obj_data = mmap(NULL, mmap_sz, PROT_READ, MAP_PRIVATE, fd, 0);
if (obj_data == MAP_FAILED) {
obj_data = NULL;
p_err("failed to mmap() %s: %s", file, strerror(errno));
goto out;
}
if (obj_name[0] == '\0')
get_obj_name(obj_name, file);
opts.object_name = obj_name;
if (verifier_logs)
/* log_level1 + log_level2 + stats, but not stable UAPI */
opts.kernel_log_level = 1 + 2 + 4;
obj = bpf_object__open_mem(obj_data, file_sz, &opts);
err = libbpf_get_error(obj);
if (err) {
char err_buf[256];
libbpf_strerror(err, err_buf, sizeof(err_buf));
p_err("failed to open BPF object file: %s", err_buf);
obj = NULL;
goto out;
}
bpf_object__for_each_map(map, obj) {
if (!get_map_ident(map, ident, sizeof(ident))) {
p_err("ignoring unrecognized internal map '%s'...",
bpf_map__name(map));
continue;
}
map_cnt++;
}
bpf_object__for_each_program(prog, obj) {
prog_cnt++;
}
get_header_guard(header_guard, obj_name, "SKEL_H");
if (use_loader) {
codegen("\
\n\
/* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */ \n\
/* THIS FILE IS AUTOGENERATED BY BPFTOOL! */ \n\
#ifndef %2$s \n\
#define %2$s \n\
\n\
#include <bpf/skel_internal.h> \n\
\n\
struct %1$s { \n\
struct bpf_loader_ctx ctx; \n\
",
obj_name, header_guard
);
} else {
codegen("\
\n\
/* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */ \n\
\n\
/* THIS FILE IS AUTOGENERATED BY BPFTOOL! */ \n\
#ifndef %2$s \n\
#define %2$s \n\
\n\
#include <errno.h> \n\
#include <stdlib.h> \n\
#include <bpf/libbpf.h> \n\
\n\
struct %1$s { \n\
struct bpf_object_skeleton *skeleton; \n\
struct bpf_object *obj; \n\
",
obj_name, header_guard
);
}
if (map_cnt) {
printf("\tstruct {\n");
bpf_object__for_each_map(map, obj) {
if (!get_map_ident(map, ident, sizeof(ident)))
continue;
if (use_loader)
printf("\t\tstruct bpf_map_desc %s;\n", ident);
else
printf("\t\tstruct bpf_map *%s;\n", ident);
}
printf("\t} maps;\n");
}
if (prog_cnt) {
printf("\tstruct {\n");
bpf_object__for_each_program(prog, obj) {
if (use_loader)
printf("\t\tstruct bpf_prog_desc %s;\n",
bpf_program__name(prog));
else
printf("\t\tstruct bpf_program *%s;\n",
bpf_program__name(prog));
}
printf("\t} progs;\n");
printf("\tstruct {\n");
bpf_object__for_each_program(prog, obj) {
if (use_loader)
printf("\t\tint %s_fd;\n",
bpf_program__name(prog));
else
printf("\t\tstruct bpf_link *%s;\n",
bpf_program__name(prog));
}
printf("\t} links;\n");
}
btf = bpf_object__btf(obj);
if (btf) {
err = codegen_datasecs(obj, obj_name);
if (err)
goto out;
}
if (use_loader) {
err = gen_trace(obj, obj_name, header_guard);
goto out;
}
codegen("\
\n\
\n\
#ifdef __cplusplus \n\
static inline struct %1$s *open(const struct bpf_object_open_opts *opts = nullptr);\n\
static inline struct %1$s *open_and_load(); \n\
static inline int load(struct %1$s *skel); \n\
static inline int attach(struct %1$s *skel); \n\
static inline void detach(struct %1$s *skel); \n\
static inline void destroy(struct %1$s *skel); \n\
static inline const void *elf_bytes(size_t *sz); \n\
#endif /* __cplusplus */ \n\
}; \n\
\n\
static void \n\
%1$s__destroy(struct %1$s *obj) \n\
{ \n\
if (!obj) \n\
return; \n\
if (obj->skeleton) \n\
bpf_object__destroy_skeleton(obj->skeleton);\n\
free(obj); \n\
} \n\
\n\
static inline int \n\
%1$s__create_skeleton(struct %1$s *obj); \n\
\n\
static inline struct %1$s * \n\
%1$s__open_opts(const struct bpf_object_open_opts *opts) \n\
{ \n\
struct %1$s *obj; \n\
int err; \n\
\n\
obj = (struct %1$s *)calloc(1, sizeof(*obj)); \n\
if (!obj) { \n\
errno = ENOMEM; \n\
return NULL; \n\
} \n\
\n\
err = %1$s__create_skeleton(obj); \n\
if (err) \n\
goto err_out; \n\
\n\
err = bpf_object__open_skeleton(obj->skeleton, opts);\n\
if (err) \n\
goto err_out; \n\
\n\
return obj; \n\
err_out: \n\
%1$s__destroy(obj); \n\
errno = -err; \n\
return NULL; \n\
} \n\
\n\
static inline struct %1$s * \n\
%1$s__open(void) \n\
{ \n\
return %1$s__open_opts(NULL); \n\
} \n\
\n\
static inline int \n\
%1$s__load(struct %1$s *obj) \n\
{ \n\
return bpf_object__load_skeleton(obj->skeleton); \n\
} \n\
\n\
static inline struct %1$s * \n\
%1$s__open_and_load(void) \n\
{ \n\
struct %1$s *obj; \n\
int err; \n\
\n\
obj = %1$s__open(); \n\
if (!obj) \n\
return NULL; \n\
err = %1$s__load(obj); \n\
if (err) { \n\
%1$s__destroy(obj); \n\
errno = -err; \n\
return NULL; \n\
} \n\
return obj; \n\
} \n\
\n\
static inline int \n\
%1$s__attach(struct %1$s *obj) \n\
{ \n\
return bpf_object__attach_skeleton(obj->skeleton); \n\
} \n\
\n\
static inline void \n\
%1$s__detach(struct %1$s *obj) \n\
{ \n\
bpf_object__detach_skeleton(obj->skeleton); \n\
} \n\
",
obj_name
);
codegen("\
\n\
\n\
static inline const void *%1$s__elf_bytes(size_t *sz); \n\
\n\
static inline int \n\
%1$s__create_skeleton(struct %1$s *obj) \n\
{ \n\
struct bpf_object_skeleton *s; \n\
int err; \n\
\n\
s = (struct bpf_object_skeleton *)calloc(1, sizeof(*s));\n\
if (!s) { \n\
err = -ENOMEM; \n\
goto err; \n\
} \n\
\n\
s->sz = sizeof(*s); \n\
s->name = \"%1$s\"; \n\
s->obj = &obj->obj; \n\
",
obj_name
);
codegen_maps_skeleton(obj, map_cnt, true /*mmaped*/);
codegen_progs_skeleton(obj, prog_cnt, true /*populate_links*/);
codegen("\
\n\
\n\
s->data = (void *)%2$s__elf_bytes(&s->data_sz); \n\
\n\
obj->skeleton = s; \n\
return 0; \n\
err: \n\
bpf_object__destroy_skeleton(s); \n\
return err; \n\
} \n\
\n\
static inline const void *%2$s__elf_bytes(size_t *sz) \n\
{ \n\
*sz = %1$d; \n\
return (const void *)\"\\ \n\
"
, file_sz, obj_name);
/* embed contents of BPF object file */
print_hex(obj_data, file_sz);
codegen("\
\n\
\"; \n\
} \n\
\n\
#ifdef __cplusplus \n\
struct %1$s *%1$s::open(const struct bpf_object_open_opts *opts) { return %1$s__open_opts(opts); }\n\
struct %1$s *%1$s::open_and_load() { return %1$s__open_and_load(); } \n\
int %1$s::load(struct %1$s *skel) { return %1$s__load(skel); } \n\
int %1$s::attach(struct %1$s *skel) { return %1$s__attach(skel); } \n\
void %1$s::detach(struct %1$s *skel) { %1$s__detach(skel); } \n\
void %1$s::destroy(struct %1$s *skel) { %1$s__destroy(skel); } \n\
const void *%1$s::elf_bytes(size_t *sz) { return %1$s__elf_bytes(sz); } \n\
#endif /* __cplusplus */ \n\
\n\
",
obj_name);
codegen_asserts(obj, obj_name);
codegen("\
\n\
\n\
#endif /* %1$s */ \n\
",
header_guard);
err = 0;
out:
bpf_object__close(obj);
if (obj_data)
munmap(obj_data, mmap_sz);
close(fd);
return err;
}
/* Subskeletons are like skeletons, except they don't own the bpf_object,
* associated maps, links, etc. Instead, they know about the existence of
* variables, maps, programs and are able to find their locations
* _at runtime_ from an already loaded bpf_object.
*
* This allows for library-like BPF objects to have userspace counterparts
* with access to their own items without having to know anything about the
* final BPF object that the library was linked into.
*/
static int do_subskeleton(int argc, char **argv)
{
char header_guard[MAX_OBJ_NAME_LEN + sizeof("__SUBSKEL_H__")];
size_t i, len, file_sz, map_cnt = 0, prog_cnt = 0, mmap_sz, var_cnt = 0, var_idx = 0;
DECLARE_LIBBPF_OPTS(bpf_object_open_opts, opts);
char obj_name[MAX_OBJ_NAME_LEN] = "", *obj_data;
struct bpf_object *obj = NULL;
const char *file, *var_name;
char ident[256];
int fd, err = -1, map_type_id;
const struct bpf_map *map;
struct bpf_program *prog;
struct btf *btf;
const struct btf_type *map_type, *var_type;
const struct btf_var_secinfo *var;
struct stat st;
if (!REQ_ARGS(1)) {
usage();
return -1;
}
file = GET_ARG();
while (argc) {
if (!REQ_ARGS(2))
return -1;
if (is_prefix(*argv, "name")) {
NEXT_ARG();
if (obj_name[0] != '\0') {
p_err("object name already specified");
return -1;
}
strncpy(obj_name, *argv, MAX_OBJ_NAME_LEN - 1);
obj_name[MAX_OBJ_NAME_LEN - 1] = '\0';
} else {
p_err("unknown arg %s", *argv);
return -1;
}
NEXT_ARG();
}
if (argc) {
p_err("extra unknown arguments");
return -1;
}
if (use_loader) {
p_err("cannot use loader for subskeletons");
return -1;
}
if (stat(file, &st)) {
p_err("failed to stat() %s: %s", file, strerror(errno));
return -1;
}
file_sz = st.st_size;
mmap_sz = roundup(file_sz, sysconf(_SC_PAGE_SIZE));
fd = open(file, O_RDONLY);
if (fd < 0) {
p_err("failed to open() %s: %s", file, strerror(errno));
return -1;
}
obj_data = mmap(NULL, mmap_sz, PROT_READ, MAP_PRIVATE, fd, 0);
if (obj_data == MAP_FAILED) {
obj_data = NULL;
p_err("failed to mmap() %s: %s", file, strerror(errno));
goto out;
}
if (obj_name[0] == '\0')
get_obj_name(obj_name, file);
/* The empty object name allows us to use bpf_map__name and produce
* ELF section names out of it. (".data" instead of "obj.data")
*/
opts.object_name = "";
obj = bpf_object__open_mem(obj_data, file_sz, &opts);
if (!obj) {
char err_buf[256];
libbpf_strerror(errno, err_buf, sizeof(err_buf));
p_err("failed to open BPF object file: %s", err_buf);
obj = NULL;
goto out;
}
btf = bpf_object__btf(obj);
if (!btf) {
err = -1;
p_err("need btf type information for %s", obj_name);
goto out;
}
bpf_object__for_each_program(prog, obj) {
prog_cnt++;
}
/* First, count how many variables we have to find.
* We need this in advance so the subskel can allocate the right
* amount of storage.
*/
bpf_object__for_each_map(map, obj) {
if (!get_map_ident(map, ident, sizeof(ident)))
continue;
/* Also count all maps that have a name */
map_cnt++;
if (!is_internal_mmapable_map(map, ident, sizeof(ident)))
continue;
map_type_id = bpf_map__btf_value_type_id(map);
if (map_type_id <= 0) {
err = map_type_id;
goto out;
}
map_type = btf__type_by_id(btf, map_type_id);
var = btf_var_secinfos(map_type);
len = btf_vlen(map_type);
for (i = 0; i < len; i++, var++) {
var_type = btf__type_by_id(btf, var->type);
if (btf_var(var_type)->linkage == BTF_VAR_STATIC)
continue;
var_cnt++;
}
}
get_header_guard(header_guard, obj_name, "SUBSKEL_H");
codegen("\
\n\
/* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */ \n\
\n\
/* THIS FILE IS AUTOGENERATED! */ \n\
#ifndef %2$s \n\
#define %2$s \n\
\n\
#include <errno.h> \n\
#include <stdlib.h> \n\
#include <bpf/libbpf.h> \n\
\n\
struct %1$s { \n\
struct bpf_object *obj; \n\
struct bpf_object_subskeleton *subskel; \n\
", obj_name, header_guard);
if (map_cnt) {
printf("\tstruct {\n");
bpf_object__for_each_map(map, obj) {
if (!get_map_ident(map, ident, sizeof(ident)))
continue;
printf("\t\tstruct bpf_map *%s;\n", ident);
}
printf("\t} maps;\n");
}
if (prog_cnt) {
printf("\tstruct {\n");
bpf_object__for_each_program(prog, obj) {
printf("\t\tstruct bpf_program *%s;\n",
bpf_program__name(prog));
}
printf("\t} progs;\n");
}
err = codegen_subskel_datasecs(obj, obj_name);
if (err)
goto out;
/* emit code that will allocate enough storage for all symbols */
codegen("\
\n\
\n\
#ifdef __cplusplus \n\
static inline struct %1$s *open(const struct bpf_object *src);\n\
static inline void destroy(struct %1$s *skel); \n\
#endif /* __cplusplus */ \n\
}; \n\
\n\
static inline void \n\
%1$s__destroy(struct %1$s *skel) \n\
{ \n\
if (!skel) \n\
return; \n\
if (skel->subskel) \n\
bpf_object__destroy_subskeleton(skel->subskel);\n\
free(skel); \n\
} \n\
\n\
static inline struct %1$s * \n\
%1$s__open(const struct bpf_object *src) \n\
{ \n\
struct %1$s *obj; \n\
struct bpf_object_subskeleton *s; \n\
int err; \n\
\n\
obj = (struct %1$s *)calloc(1, sizeof(*obj)); \n\
if (!obj) { \n\
err = -ENOMEM; \n\
goto err; \n\
} \n\
s = (struct bpf_object_subskeleton *)calloc(1, sizeof(*s));\n\
if (!s) { \n\
err = -ENOMEM; \n\
goto err; \n\
} \n\
s->sz = sizeof(*s); \n\
s->obj = src; \n\
s->var_skel_sz = sizeof(*s->vars); \n\
obj->subskel = s; \n\
\n\
/* vars */ \n\
s->var_cnt = %2$d; \n\
s->vars = (struct bpf_var_skeleton *)calloc(%2$d, sizeof(*s->vars));\n\
if (!s->vars) { \n\
err = -ENOMEM; \n\
goto err; \n\
} \n\
",
obj_name, var_cnt
);
/* walk through each symbol and emit the runtime representation */
bpf_object__for_each_map(map, obj) {
if (!is_internal_mmapable_map(map, ident, sizeof(ident)))
continue;
map_type_id = bpf_map__btf_value_type_id(map);
if (map_type_id <= 0)
/* skip over internal maps with no type*/
continue;
map_type = btf__type_by_id(btf, map_type_id);
var = btf_var_secinfos(map_type);
len = btf_vlen(map_type);
for (i = 0; i < len; i++, var++) {
var_type = btf__type_by_id(btf, var->type);
var_name = btf__name_by_offset(btf, var_type->name_off);
if (btf_var(var_type)->linkage == BTF_VAR_STATIC)
continue;
/* Note that we use the dot prefix in .data as the
* field access operator i.e. maps%s becomes maps.data
*/
codegen("\
\n\
\n\
s->vars[%3$d].name = \"%1$s\"; \n\
s->vars[%3$d].map = &obj->maps.%2$s; \n\
s->vars[%3$d].addr = (void **) &obj->%2$s.%1$s;\n\
", var_name, ident, var_idx);
var_idx++;
}
}
codegen_maps_skeleton(obj, map_cnt, false /*mmaped*/);
codegen_progs_skeleton(obj, prog_cnt, false /*links*/);
codegen("\
\n\
\n\
err = bpf_object__open_subskeleton(s); \n\
if (err) \n\
goto err; \n\
\n\
return obj; \n\
err: \n\
%1$s__destroy(obj); \n\
errno = -err; \n\
return NULL; \n\
} \n\
\n\
#ifdef __cplusplus \n\
struct %1$s *%1$s::open(const struct bpf_object *src) { return %1$s__open(src); }\n\
void %1$s::destroy(struct %1$s *skel) { %1$s__destroy(skel); }\n\
#endif /* __cplusplus */ \n\
\n\
#endif /* %2$s */ \n\
",
obj_name, header_guard);
err = 0;
out:
bpf_object__close(obj);
if (obj_data)
munmap(obj_data, mmap_sz);
close(fd);
return err;
}
static int do_object(int argc, char **argv)
{
struct bpf_linker *linker;
const char *output_file, *file;
int err = 0;
if (!REQ_ARGS(2)) {
usage();
return -1;
}
output_file = GET_ARG();
linker = bpf_linker__new(output_file, NULL);
if (!linker) {
p_err("failed to create BPF linker instance");
return -1;
}
while (argc) {
file = GET_ARG();
err = bpf_linker__add_file(linker, file, NULL);
if (err) {
p_err("failed to link '%s': %s (%d)", file, strerror(errno), errno);
goto out;
}
}
err = bpf_linker__finalize(linker);
if (err) {
p_err("failed to finalize ELF file: %s (%d)", strerror(errno), errno);
goto out;
}
err = 0;
out:
bpf_linker__free(linker);
return err;
}
static int do_help(int argc, char **argv)
{
if (json_output) {
jsonw_null(json_wtr);
return 0;
}
fprintf(stderr,
"Usage: %1$s %2$s object OUTPUT_FILE INPUT_FILE [INPUT_FILE...]\n"
" %1$s %2$s skeleton FILE [name OBJECT_NAME]\n"
" %1$s %2$s subskeleton FILE [name OBJECT_NAME]\n"
" %1$s %2$s min_core_btf INPUT OUTPUT OBJECT [OBJECT...]\n"
" %1$s %2$s help\n"
"\n"
" " HELP_SPEC_OPTIONS " |\n"
" {-L|--use-loader} }\n"
"",
bin_name, "gen");
return 0;
}
static int btf_save_raw(const struct btf *btf, const char *path)
{
const void *data;
FILE *f = NULL;
__u32 data_sz;
int err = 0;
data = btf__raw_data(btf, &data_sz);
if (!data)
return -ENOMEM;
f = fopen(path, "wb");
if (!f)
return -errno;
if (fwrite(data, 1, data_sz, f) != data_sz)
err = -errno;
fclose(f);
return err;
}
struct btfgen_info {
struct btf *src_btf;
struct btf *marked_btf; /* btf structure used to mark used types */
};
static size_t btfgen_hash_fn(const void *key, void *ctx)
{
return (size_t)key;
}
static bool btfgen_equal_fn(const void *k1, const void *k2, void *ctx)
{
return k1 == k2;
}
static void *u32_as_hash_key(__u32 x)
{
return (void *)(uintptr_t)x;
}
static void btfgen_free_info(struct btfgen_info *info)
{
if (!info)
return;
btf__free(info->src_btf);
btf__free(info->marked_btf);
free(info);
}
static struct btfgen_info *
btfgen_new_info(const char *targ_btf_path)
{
struct btfgen_info *info;
int err;
info = calloc(1, sizeof(*info));
if (!info)
return NULL;
info->src_btf = btf__parse(targ_btf_path, NULL);
if (!info->src_btf) {
err = -errno;
p_err("failed parsing '%s' BTF file: %s", targ_btf_path, strerror(errno));
goto err_out;
}
info->marked_btf = btf__parse(targ_btf_path, NULL);
if (!info->marked_btf) {
err = -errno;
p_err("failed parsing '%s' BTF file: %s", targ_btf_path, strerror(errno));
goto err_out;
}
return info;
err_out:
btfgen_free_info(info);
errno = -err;
return NULL;
}
#define MARKED UINT32_MAX
static void btfgen_mark_member(struct btfgen_info *info, int type_id, int idx)
{
const struct btf_type *t = btf__type_by_id(info->marked_btf, type_id);
struct btf_member *m = btf_members(t) + idx;
m->name_off = MARKED;
}
static int
btfgen_mark_type(struct btfgen_info *info, unsigned int type_id, bool follow_pointers)
{
const struct btf_type *btf_type = btf__type_by_id(info->src_btf, type_id);
struct btf_type *cloned_type;
struct btf_param *param;
struct btf_array *array;
int err, i;
if (type_id == 0)
return 0;
/* mark type on cloned BTF as used */
cloned_type = (struct btf_type *) btf__type_by_id(info->marked_btf, type_id);
cloned_type->name_off = MARKED;
/* recursively mark other types needed by it */
switch (btf_kind(btf_type)) {
case BTF_KIND_UNKN:
case BTF_KIND_INT:
case BTF_KIND_FLOAT:
case BTF_KIND_ENUM:
case BTF_KIND_ENUM64:
case BTF_KIND_STRUCT:
case BTF_KIND_UNION:
break;
case BTF_KIND_PTR:
if (follow_pointers) {
err = btfgen_mark_type(info, btf_type->type, follow_pointers);
if (err)
return err;
}
break;
case BTF_KIND_CONST:
case BTF_KIND_RESTRICT:
case BTF_KIND_VOLATILE:
case BTF_KIND_TYPEDEF:
err = btfgen_mark_type(info, btf_type->type, follow_pointers);
if (err)
return err;
break;
case BTF_KIND_ARRAY:
array = btf_array(btf_type);
/* mark array type */
err = btfgen_mark_type(info, array->type, follow_pointers);
/* mark array's index type */
err = err ? : btfgen_mark_type(info, array->index_type, follow_pointers);
if (err)
return err;
break;
case BTF_KIND_FUNC_PROTO:
/* mark ret type */
err = btfgen_mark_type(info, btf_type->type, follow_pointers);
if (err)
return err;
/* mark parameters types */
param = btf_params(btf_type);
for (i = 0; i < btf_vlen(btf_type); i++) {
err = btfgen_mark_type(info, param->type, follow_pointers);
if (err)
return err;
param++;
}
break;
/* tells if some other type needs to be handled */
default:
p_err("unsupported kind: %s (%d)", btf_kind_str(btf_type), type_id);
return -EINVAL;
}
return 0;
}
static int btfgen_record_field_relo(struct btfgen_info *info, struct bpf_core_spec *targ_spec)
{
struct btf *btf = info->src_btf;
const struct btf_type *btf_type;
struct btf_member *btf_member;
struct btf_array *array;
unsigned int type_id = targ_spec->root_type_id;
int idx, err;
/* mark root type */
btf_type = btf__type_by_id(btf, type_id);
err = btfgen_mark_type(info, type_id, false);
if (err)
return err;
/* mark types for complex types (arrays, unions, structures) */
for (int i = 1; i < targ_spec->raw_len; i++) {
/* skip typedefs and mods */
while (btf_is_mod(btf_type) || btf_is_typedef(btf_type)) {
type_id = btf_type->type;
btf_type = btf__type_by_id(btf, type_id);
}
switch (btf_kind(btf_type)) {
case BTF_KIND_STRUCT:
case BTF_KIND_UNION:
idx = targ_spec->raw_spec[i];
btf_member = btf_members(btf_type) + idx;
/* mark member */
btfgen_mark_member(info, type_id, idx);
/* mark member's type */
type_id = btf_member->type;
btf_type = btf__type_by_id(btf, type_id);
err = btfgen_mark_type(info, type_id, false);
if (err)
return err;
break;
case BTF_KIND_ARRAY:
array = btf_array(btf_type);
type_id = array->type;
btf_type = btf__type_by_id(btf, type_id);
break;
default:
p_err("unsupported kind: %s (%d)",
btf_kind_str(btf_type), btf_type->type);
return -EINVAL;
}
}
return 0;
}
/* Mark types, members, and member types. Compared to btfgen_record_field_relo,
* this function does not rely on the target spec for inferring members, but
* uses the associated BTF.
*
* The `behind_ptr` argument is used to stop marking of composite types reached
* through a pointer. This way, we can keep BTF size in check while providing
* reasonable match semantics.
*/
static int btfgen_mark_type_match(struct btfgen_info *info, __u32 type_id, bool behind_ptr)
{
const struct btf_type *btf_type;
struct btf *btf = info->src_btf;
struct btf_type *cloned_type;
int i, err;
if (type_id == 0)
return 0;
btf_type = btf__type_by_id(btf, type_id);
/* mark type on cloned BTF as used */
cloned_type = (struct btf_type *)btf__type_by_id(info->marked_btf, type_id);
cloned_type->name_off = MARKED;
switch (btf_kind(btf_type)) {
case BTF_KIND_UNKN:
case BTF_KIND_INT:
case BTF_KIND_FLOAT:
case BTF_KIND_ENUM:
case BTF_KIND_ENUM64:
break;
case BTF_KIND_STRUCT:
case BTF_KIND_UNION: {
struct btf_member *m = btf_members(btf_type);
__u16 vlen = btf_vlen(btf_type);
if (behind_ptr)
break;
for (i = 0; i < vlen; i++, m++) {
/* mark member */
btfgen_mark_member(info, type_id, i);
/* mark member's type */
err = btfgen_mark_type_match(info, m->type, false);
if (err)
return err;
}
break;
}
case BTF_KIND_CONST:
case BTF_KIND_FWD:
case BTF_KIND_RESTRICT:
case BTF_KIND_TYPEDEF:
case BTF_KIND_VOLATILE:
return btfgen_mark_type_match(info, btf_type->type, behind_ptr);
case BTF_KIND_PTR:
return btfgen_mark_type_match(info, btf_type->type, true);
case BTF_KIND_ARRAY: {
struct btf_array *array;
array = btf_array(btf_type);
/* mark array type */
err = btfgen_mark_type_match(info, array->type, false);
/* mark array's index type */
err = err ? : btfgen_mark_type_match(info, array->index_type, false);
if (err)
return err;
break;
}
case BTF_KIND_FUNC_PROTO: {
__u16 vlen = btf_vlen(btf_type);
struct btf_param *param;
/* mark ret type */
err = btfgen_mark_type_match(info, btf_type->type, false);
if (err)
return err;
/* mark parameters types */
param = btf_params(btf_type);
for (i = 0; i < vlen; i++) {
err = btfgen_mark_type_match(info, param->type, false);
if (err)
return err;
param++;
}
break;
}
/* tells if some other type needs to be handled */
default:
p_err("unsupported kind: %s (%d)", btf_kind_str(btf_type), type_id);
return -EINVAL;
}
return 0;
}
/* Mark types, members, and member types. Compared to btfgen_record_field_relo,
* this function does not rely on the target spec for inferring members, but
* uses the associated BTF.
*/
static int btfgen_record_type_match_relo(struct btfgen_info *info, struct bpf_core_spec *targ_spec)
{
return btfgen_mark_type_match(info, targ_spec->root_type_id, false);
}
static int btfgen_record_type_relo(struct btfgen_info *info, struct bpf_core_spec *targ_spec)
{
return btfgen_mark_type(info, targ_spec->root_type_id, true);
}
static int btfgen_record_enumval_relo(struct btfgen_info *info, struct bpf_core_spec *targ_spec)
{
return btfgen_mark_type(info, targ_spec->root_type_id, false);
}
static int btfgen_record_reloc(struct btfgen_info *info, struct bpf_core_spec *res)
{
switch (res->relo_kind) {
case BPF_CORE_FIELD_BYTE_OFFSET:
case BPF_CORE_FIELD_BYTE_SIZE:
case BPF_CORE_FIELD_EXISTS:
case BPF_CORE_FIELD_SIGNED:
case BPF_CORE_FIELD_LSHIFT_U64:
case BPF_CORE_FIELD_RSHIFT_U64:
return btfgen_record_field_relo(info, res);
case BPF_CORE_TYPE_ID_LOCAL: /* BPF_CORE_TYPE_ID_LOCAL doesn't require kernel BTF */
return 0;
case BPF_CORE_TYPE_ID_TARGET:
case BPF_CORE_TYPE_EXISTS:
case BPF_CORE_TYPE_SIZE:
return btfgen_record_type_relo(info, res);
case BPF_CORE_TYPE_MATCHES:
return btfgen_record_type_match_relo(info, res);
case BPF_CORE_ENUMVAL_EXISTS:
case BPF_CORE_ENUMVAL_VALUE:
return btfgen_record_enumval_relo(info, res);
default:
return -EINVAL;
}
}
static struct bpf_core_cand_list *
btfgen_find_cands(const struct btf *local_btf, const struct btf *targ_btf, __u32 local_id)
{
const struct btf_type *local_type;
struct bpf_core_cand_list *cands = NULL;
struct bpf_core_cand local_cand = {};
size_t local_essent_len;
const char *local_name;
int err;
local_cand.btf = local_btf;
local_cand.id = local_id;
local_type = btf__type_by_id(local_btf, local_id);
if (!local_type) {
err = -EINVAL;
goto err_out;
}
local_name = btf__name_by_offset(local_btf, local_type->name_off);
if (!local_name) {
err = -EINVAL;
goto err_out;
}
local_essent_len = bpf_core_essential_name_len(local_name);
cands = calloc(1, sizeof(*cands));
if (!cands)
return NULL;
err = bpf_core_add_cands(&local_cand, local_essent_len, targ_btf, "vmlinux", 1, cands);
if (err)
goto err_out;
return cands;
err_out:
bpf_core_free_cands(cands);
errno = -err;
return NULL;
}
/* Record relocation information for a single BPF object */
static int btfgen_record_obj(struct btfgen_info *info, const char *obj_path)
{
const struct btf_ext_info_sec *sec;
const struct bpf_core_relo *relo;
const struct btf_ext_info *seg;
struct hashmap_entry *entry;
struct hashmap *cand_cache = NULL;
struct btf_ext *btf_ext = NULL;
unsigned int relo_idx;
struct btf *btf = NULL;
size_t i;
int err;
btf = btf__parse(obj_path, &btf_ext);
if (!btf) {
err = -errno;
p_err("failed to parse BPF object '%s': %s", obj_path, strerror(errno));
return err;
}
if (!btf_ext) {
p_err("failed to parse BPF object '%s': section %s not found",
obj_path, BTF_EXT_ELF_SEC);
err = -EINVAL;
goto out;
}
if (btf_ext->core_relo_info.len == 0) {
err = 0;
goto out;
}
cand_cache = hashmap__new(btfgen_hash_fn, btfgen_equal_fn, NULL);
if (IS_ERR(cand_cache)) {
err = PTR_ERR(cand_cache);
goto out;
}
seg = &btf_ext->core_relo_info;
for_each_btf_ext_sec(seg, sec) {
for_each_btf_ext_rec(seg, sec, relo_idx, relo) {
struct bpf_core_spec specs_scratch[3] = {};
struct bpf_core_relo_res targ_res = {};
struct bpf_core_cand_list *cands = NULL;
const void *type_key = u32_as_hash_key(relo->type_id);
const char *sec_name = btf__name_by_offset(btf, sec->sec_name_off);
if (relo->kind != BPF_CORE_TYPE_ID_LOCAL &&
!hashmap__find(cand_cache, type_key, (void **)&cands)) {
cands = btfgen_find_cands(btf, info->src_btf, relo->type_id);
if (!cands) {
err = -errno;
goto out;
}
err = hashmap__set(cand_cache, type_key, cands, NULL, NULL);
if (err)
goto out;
}
err = bpf_core_calc_relo_insn(sec_name, relo, relo_idx, btf, cands,
specs_scratch, &targ_res);
if (err)
goto out;
/* specs_scratch[2] is the target spec */
err = btfgen_record_reloc(info, &specs_scratch[2]);
if (err)
goto out;
}
}
out:
btf__free(btf);
btf_ext__free(btf_ext);
if (!IS_ERR_OR_NULL(cand_cache)) {
hashmap__for_each_entry(cand_cache, entry, i) {
bpf_core_free_cands(entry->value);
}
hashmap__free(cand_cache);
}
return err;
}
static int btfgen_remap_id(__u32 *type_id, void *ctx)
{
unsigned int *ids = ctx;
*type_id = ids[*type_id];
return 0;
}
/* Generate BTF from relocation information previously recorded */
static struct btf *btfgen_get_btf(struct btfgen_info *info)
{
struct btf *btf_new = NULL;
unsigned int *ids = NULL;
unsigned int i, n = btf__type_cnt(info->marked_btf);
int err = 0;
btf_new = btf__new_empty();
if (!btf_new) {
err = -errno;
goto err_out;
}
ids = calloc(n, sizeof(*ids));
if (!ids) {
err = -errno;
goto err_out;
}
/* first pass: add all marked types to btf_new and add their new ids to the ids map */
for (i = 1; i < n; i++) {
const struct btf_type *cloned_type, *type;
const char *name;
int new_id;
cloned_type = btf__type_by_id(info->marked_btf, i);
if (cloned_type->name_off != MARKED)
continue;
type = btf__type_by_id(info->src_btf, i);
/* add members for struct and union */
if (btf_is_composite(type)) {
struct btf_member *cloned_m, *m;
unsigned short vlen;
int idx_src;
name = btf__str_by_offset(info->src_btf, type->name_off);
if (btf_is_struct(type))
err = btf__add_struct(btf_new, name, type->size);
else
err = btf__add_union(btf_new, name, type->size);
if (err < 0)
goto err_out;
new_id = err;
cloned_m = btf_members(cloned_type);
m = btf_members(type);
vlen = btf_vlen(cloned_type);
for (idx_src = 0; idx_src < vlen; idx_src++, cloned_m++, m++) {
/* add only members that are marked as used */
if (cloned_m->name_off != MARKED)
continue;
name = btf__str_by_offset(info->src_btf, m->name_off);
err = btf__add_field(btf_new, name, m->type,
btf_member_bit_offset(cloned_type, idx_src),
btf_member_bitfield_size(cloned_type, idx_src));
if (err < 0)
goto err_out;
}
} else {
err = btf__add_type(btf_new, info->src_btf, type);
if (err < 0)
goto err_out;
new_id = err;
}
/* add ID mapping */
ids[i] = new_id;
}
/* second pass: fix up type ids */
for (i = 1; i < btf__type_cnt(btf_new); i++) {
struct btf_type *btf_type = (struct btf_type *) btf__type_by_id(btf_new, i);
err = btf_type_visit_type_ids(btf_type, btfgen_remap_id, ids);
if (err)
goto err_out;
}
free(ids);
return btf_new;
err_out:
btf__free(btf_new);
free(ids);
errno = -err;
return NULL;
}
/* Create minimized BTF file for a set of BPF objects.
*
* The BTFGen algorithm is divided in two main parts: (1) collect the
* BTF types that are involved in relocations and (2) generate the BTF
* object using the collected types.
*
* In order to collect the types involved in the relocations, we parse
* the BTF and BTF.ext sections of the BPF objects and use
* bpf_core_calc_relo_insn() to get the target specification, this
* indicates how the types and fields are used in a relocation.
*
* Types are recorded in different ways according to the kind of the
* relocation. For field-based relocations only the members that are
* actually used are saved in order to reduce the size of the generated
* BTF file. For type-based relocations empty struct / unions are
* generated and for enum-based relocations the whole type is saved.
*
* The second part of the algorithm generates the BTF object. It creates
* an empty BTF object and fills it with the types recorded in the
* previous step. This function takes care of only adding the structure
* and union members that were marked as used and it also fixes up the
* type IDs on the generated BTF object.
*/
static int minimize_btf(const char *src_btf, const char *dst_btf, const char *objspaths[])
{
struct btfgen_info *info;
struct btf *btf_new = NULL;
int err, i;
info = btfgen_new_info(src_btf);
if (!info) {
err = -errno;
p_err("failed to allocate info structure: %s", strerror(errno));
goto out;
}
for (i = 0; objspaths[i] != NULL; i++) {
err = btfgen_record_obj(info, objspaths[i]);
if (err) {
p_err("error recording relocations for %s: %s", objspaths[i],
strerror(errno));
goto out;
}
}
btf_new = btfgen_get_btf(info);
if (!btf_new) {
err = -errno;
p_err("error generating BTF: %s", strerror(errno));
goto out;
}
err = btf_save_raw(btf_new, dst_btf);
if (err) {
p_err("error saving btf file: %s", strerror(errno));
goto out;
}
out:
btf__free(btf_new);
btfgen_free_info(info);
return err;
}
static int do_min_core_btf(int argc, char **argv)
{
const char *input, *output, **objs;
int i, err;
if (!REQ_ARGS(3)) {
usage();
return -1;
}
input = GET_ARG();
output = GET_ARG();
objs = (const char **) calloc(argc + 1, sizeof(*objs));
if (!objs) {
p_err("failed to allocate array for object names");
return -ENOMEM;
}
i = 0;
while (argc)
objs[i++] = GET_ARG();
err = minimize_btf(input, output, objs);
free(objs);
return err;
}
static const struct cmd cmds[] = {
{ "object", do_object },
{ "skeleton", do_skeleton },
{ "subskeleton", do_subskeleton },
{ "min_core_btf", do_min_core_btf},
{ "help", do_help },
{ 0 }
};
int do_gen(int argc, char **argv)
{
return cmd_select(cmds, argc, argv, do_help);
}