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bpf: libbpf: Add STRUCT_OPS support 

This patch adds BPF STRUCT_OPS support to libbpf.

The only sec_name convention is SEC(".struct_ops") to identify the
struct_ops implemented in BPF,
e.g. To implement a tcp_congestion_ops:

SEC(".struct_ops")
struct tcp_congestion_ops dctcp = {
	.init           = (void *)dctcp_init,  /* <-- a bpf_prog */
	/* ... some more func prts ... */
	.name           = "bpf_dctcp",
};

Each struct_ops is defined as a global variable under SEC(".struct_ops")
as above.  libbpf creates a map for each variable and the variable name
is the map's name.  Multiple struct_ops is supported under
SEC(".struct_ops").

In the bpf_object__open phase, libbpf will look for the SEC(".struct_ops")
section and find out what is the btf-type the struct_ops is
implementing.  Note that the btf-type here is referring to
a type in the bpf_prog.o's btf.  A "struct bpf_map" is added
by bpf_object__add_map() as other maps do.  It will then
collect (through SHT_REL) where are the bpf progs that the
func ptrs are referring to.  No btf_vmlinux is needed in
the open phase.

In the bpf_object__load phase, the map-fields, which depend
on the btf_vmlinux, are initialized (in bpf_map__init_kern_struct_ops()).
It will also set the prog->type, prog->attach_btf_id, and
prog->expected_attach_type.  Thus, the prog's properties do
not rely on its section name.
[ Currently, the bpf_prog's btf-type ==> btf_vmlinux's btf-type matching
  process is as simple as: member-name match + btf-kind match + size match.
  If these matching conditions fail, libbpf will reject.
  The current targeting support is "struct tcp_congestion_ops" which
  most of its members are function pointers.
  The member ordering of the bpf_prog's btf-type can be different from
  the btf_vmlinux's btf-type. ]

Then, all obj->maps are created as usual (in bpf_object__create_maps()).

Once the maps are created and prog's properties are all set,
the libbpf will proceed to load all the progs.

bpf_map__attach_struct_ops() is added to register a struct_ops
map to a kernel subsystem.

Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200109003514.3856730-1-kafai@fb.com
This commit is contained in:
Martin KaFai Lau 2020-01-08 16:35:14 -08:00 committed by Alexei Starovoitov
parent 17328d618c
commit 590a008882
6 changed files with 661 additions and 13 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

10
tools/lib/bpf/bpf.c
View File

@ -95,7 +95,11 @@ int bpf_create_map_xattr(const struct bpf_create_map_attr *create_attr)
attr.btf_key_type_id = create_attr->btf_key_type_id;
attr.btf_value_type_id = create_attr->btf_value_type_id;
attr.map_ifindex = create_attr->map_ifindex;
attr.inner_map_fd = create_attr->inner_map_fd;
if (attr.map_type == BPF_MAP_TYPE_STRUCT_OPS)
attr.btf_vmlinux_value_type_id =
create_attr->btf_vmlinux_value_type_id;
else
attr.inner_map_fd = create_attr->inner_map_fd;
return sys_bpf(BPF_MAP_CREATE, &attr, sizeof(attr));
}
@ -228,7 +232,9 @@ int bpf_load_program_xattr(const struct bpf_load_program_attr *load_attr,
memset(&attr, 0, sizeof(attr));
attr.prog_type = load_attr->prog_type;
attr.expected_attach_type = load_attr->expected_attach_type;
if (attr.prog_type == BPF_PROG_TYPE_TRACING) {
if (attr.prog_type == BPF_PROG_TYPE_STRUCT_OPS) {
attr.attach_btf_id = load_attr->attach_btf_id;
} else if (attr.prog_type == BPF_PROG_TYPE_TRACING) {
attr.attach_btf_id = load_attr->attach_btf_id;
attr.attach_prog_fd = load_attr->attach_prog_fd;
} else {

5
tools/lib/bpf/bpf.h
View File

@ -46,7 +46,10 @@ struct bpf_create_map_attr {
__u32 btf_key_type_id;
__u32 btf_value_type_id;
__u32 map_ifindex;
__u32 inner_map_fd;
union {
__u32 inner_map_fd;
__u32 btf_vmlinux_value_type_id;
};
};
LIBBPF_API int

649
tools/lib/bpf/libbpf.c
View File

@ -70,6 +70,13 @@
#define __printf(a, b) __attribute__((format(printf, a, b)))
static struct btf *bpf_find_kernel_btf(void);
static struct bpf_map *bpf_object__add_map(struct bpf_object *obj);
static struct bpf_program *bpf_object__find_prog_by_idx(struct bpf_object *obj,
int idx);
static const struct btf_type *
skip_mods_and_typedefs(const struct btf *btf, __u32 id, __u32 *res_id);
static int __base_pr(enum libbpf_print_level level, const char *format,
va_list args)
{
@ -229,10 +236,32 @@ struct bpf_program {
__u32 prog_flags;
};
struct bpf_struct_ops {
const char *tname;
const struct btf_type *type;
struct bpf_program **progs;
__u32 *kern_func_off;
/* e.g. struct tcp_congestion_ops in bpf_prog's btf format */
void *data;
/* e.g. struct bpf_struct_ops_tcp_congestion_ops in
* btf_vmlinux's format.
* struct bpf_struct_ops_tcp_congestion_ops {
* [... some other kernel fields ...]
* struct tcp_congestion_ops data;
* }
* kern_vdata-size == sizeof(struct bpf_struct_ops_tcp_congestion_ops)
* bpf_map__init_kern_struct_ops() will populate the "kern_vdata"
* from "data".
*/
void *kern_vdata;
__u32 type_id;
};
#define DATA_SEC ".data"
#define BSS_SEC ".bss"
#define RODATA_SEC ".rodata"
#define KCONFIG_SEC ".kconfig"
#define STRUCT_OPS_SEC ".struct_ops"
enum libbpf_map_type {
LIBBPF_MAP_UNSPEC,
@ -259,10 +288,12 @@ struct bpf_map {
struct bpf_map_def def;
__u32 btf_key_type_id;
__u32 btf_value_type_id;
__u32 btf_vmlinux_value_type_id;
void *priv;
bpf_map_clear_priv_t clear_priv;
enum libbpf_map_type libbpf_type;
void *mmaped;
struct bpf_struct_ops *st_ops;
char *pin_path;
bool pinned;
bool reused;
@ -326,6 +357,7 @@ struct bpf_object {
Elf_Data *data;
Elf_Data *rodata;
Elf_Data *bss;
Elf_Data *st_ops_data;
size_t strtabidx;
struct {
GElf_Shdr shdr;
@ -339,6 +371,7 @@ struct bpf_object {
int data_shndx;
int rodata_shndx;
int bss_shndx;
int st_ops_shndx;
} efile;
/*
* All loaded bpf_object is linked in a list, which is
@ -566,6 +599,359 @@ static __u32 get_kernel_version(void)
return KERNEL_VERSION(major, minor, patch);
}
static const struct btf_member *
find_member_by_offset(const struct btf_type *t, __u32 bit_offset)
{
struct btf_member *m;
int i;
for (i = 0, m = btf_members(t); i < btf_vlen(t); i++, m++) {
if (btf_member_bit_offset(t, i) == bit_offset)
return m;
}
return NULL;
}
static const struct btf_member *
find_member_by_name(const struct btf *btf, const struct btf_type *t,
const char *name)
{
struct btf_member *m;
int i;
for (i = 0, m = btf_members(t); i < btf_vlen(t); i++, m++) {
if (!strcmp(btf__name_by_offset(btf, m->name_off), name))
return m;
}
return NULL;
}
#define STRUCT_OPS_VALUE_PREFIX "bpf_struct_ops_"
#define STRUCT_OPS_VALUE_PREFIX_LEN (sizeof(STRUCT_OPS_VALUE_PREFIX) - 1)
static int
find_struct_ops_kern_types(const struct btf *btf, const char *tname,
const struct btf_type **type, __u32 *type_id,
const struct btf_type **vtype, __u32 *vtype_id,
const struct btf_member **data_member)
{
const struct btf_type *kern_type, *kern_vtype;
const struct btf_member *kern_data_member;
__s32 kern_vtype_id, kern_type_id;
char vtname[128] = STRUCT_OPS_VALUE_PREFIX;
__u32 i;
kern_type_id = btf__find_by_name_kind(btf, tname, BTF_KIND_STRUCT);
if (kern_type_id < 0) {
pr_warn("struct_ops init_kern: struct %s is not found in kernel BTF\n",
tname);
return kern_type_id;
}
kern_type = btf__type_by_id(btf, kern_type_id);
/* Find the corresponding "map_value" type that will be used
* in map_update(BPF_MAP_TYPE_STRUCT_OPS). For example,
* find "struct bpf_struct_ops_tcp_congestion_ops" from the
* btf_vmlinux.
*/
strncat(vtname + STRUCT_OPS_VALUE_PREFIX_LEN, tname,
sizeof(vtname) - STRUCT_OPS_VALUE_PREFIX_LEN - 1);
kern_vtype_id = btf__find_by_name_kind(btf, vtname,
BTF_KIND_STRUCT);
if (kern_vtype_id < 0) {
pr_warn("struct_ops init_kern: struct %s is not found in kernel BTF\n",
vtname);
return kern_vtype_id;
}
kern_vtype = btf__type_by_id(btf, kern_vtype_id);
/* Find "struct tcp_congestion_ops" from
* struct bpf_struct_ops_tcp_congestion_ops {
* [ ... ]
* struct tcp_congestion_ops data;
* }
*/
kern_data_member = btf_members(kern_vtype);
for (i = 0; i < btf_vlen(kern_vtype); i++, kern_data_member++) {
if (kern_data_member->type == kern_type_id)
break;
}
if (i == btf_vlen(kern_vtype)) {
pr_warn("struct_ops init_kern: struct %s data is not found in struct %s\n",
tname, vtname);
return -EINVAL;
}
*type = kern_type;
*type_id = kern_type_id;
*vtype = kern_vtype;
*vtype_id = kern_vtype_id;
*data_member = kern_data_member;
return 0;
}
static bool bpf_map__is_struct_ops(const struct bpf_map *map)
{
return map->def.type == BPF_MAP_TYPE_STRUCT_OPS;
}
/* Init the map's fields that depend on kern_btf */
static int bpf_map__init_kern_struct_ops(struct bpf_map *map,
const struct btf *btf,
const struct btf *kern_btf)
{
const struct btf_member *member, *kern_member, *kern_data_member;
const struct btf_type *type, *kern_type, *kern_vtype;
__u32 i, kern_type_id, kern_vtype_id, kern_data_off;
struct bpf_struct_ops *st_ops;
void *data, *kern_data;
const char *tname;
int err;
st_ops = map->st_ops;
type = st_ops->type;
tname = st_ops->tname;
err = find_struct_ops_kern_types(kern_btf, tname,
&kern_type, &kern_type_id,
&kern_vtype, &kern_vtype_id,
&kern_data_member);
if (err)
return err;
pr_debug("struct_ops init_kern %s: type_id:%u kern_type_id:%u kern_vtype_id:%u\n",
map->name, st_ops->type_id, kern_type_id, kern_vtype_id);
map->def.value_size = kern_vtype->size;
map->btf_vmlinux_value_type_id = kern_vtype_id;
st_ops->kern_vdata = calloc(1, kern_vtype->size);
if (!st_ops->kern_vdata)
return -ENOMEM;
data = st_ops->data;
kern_data_off = kern_data_member->offset / 8;
kern_data = st_ops->kern_vdata + kern_data_off;
member = btf_members(type);
for (i = 0; i < btf_vlen(type); i++, member++) {
const struct btf_type *mtype, *kern_mtype;
__u32 mtype_id, kern_mtype_id;
void *mdata, *kern_mdata;
__s64 msize, kern_msize;
__u32 moff, kern_moff;
__u32 kern_member_idx;
const char *mname;
mname = btf__name_by_offset(btf, member->name_off);
kern_member = find_member_by_name(kern_btf, kern_type, mname);
if (!kern_member) {
pr_warn("struct_ops init_kern %s: Cannot find member %s in kernel BTF\n",
map->name, mname);
return -ENOTSUP;
}
kern_member_idx = kern_member - btf_members(kern_type);
if (btf_member_bitfield_size(type, i) ||
btf_member_bitfield_size(kern_type, kern_member_idx)) {
pr_warn("struct_ops init_kern %s: bitfield %s is not supported\n",
map->name, mname);
return -ENOTSUP;
}
moff = member->offset / 8;
kern_moff = kern_member->offset / 8;
mdata = data + moff;
kern_mdata = kern_data + kern_moff;
mtype = skip_mods_and_typedefs(btf, member->type, &mtype_id);
kern_mtype = skip_mods_and_typedefs(kern_btf, kern_member->type,
&kern_mtype_id);
if (BTF_INFO_KIND(mtype->info) !=
BTF_INFO_KIND(kern_mtype->info)) {
pr_warn("struct_ops init_kern %s: Unmatched member type %s %u != %u(kernel)\n",
map->name, mname, BTF_INFO_KIND(mtype->info),
BTF_INFO_KIND(kern_mtype->info));
return -ENOTSUP;
}
if (btf_is_ptr(mtype)) {
struct bpf_program *prog;
mtype = skip_mods_and_typedefs(btf, mtype->type, &mtype_id);
kern_mtype = skip_mods_and_typedefs(kern_btf,
kern_mtype->type,
&kern_mtype_id);
if (!btf_is_func_proto(mtype) ||
!btf_is_func_proto(kern_mtype)) {
pr_warn("struct_ops init_kern %s: non func ptr %s is not supported\n",
map->name, mname);
return -ENOTSUP;
}
prog = st_ops->progs[i];
if (!prog) {
pr_debug("struct_ops init_kern %s: func ptr %s is not set\n",
map->name, mname);
continue;
}
prog->attach_btf_id = kern_type_id;
prog->expected_attach_type = kern_member_idx;
st_ops->kern_func_off[i] = kern_data_off + kern_moff;
pr_debug("struct_ops init_kern %s: func ptr %s is set to prog %s from data(+%u) to kern_data(+%u)\n",
map->name, mname, prog->name, moff,
kern_moff);
continue;
}
msize = btf__resolve_size(btf, mtype_id);
kern_msize = btf__resolve_size(kern_btf, kern_mtype_id);
if (msize < 0 || kern_msize < 0 || msize != kern_msize) {
pr_warn("struct_ops init_kern %s: Error in size of member %s: %zd != %zd(kernel)\n",
map->name, mname, (ssize_t)msize,
(ssize_t)kern_msize);
return -ENOTSUP;
}
pr_debug("struct_ops init_kern %s: copy %s %u bytes from data(+%u) to kern_data(+%u)\n",
map->name, mname, (unsigned int)msize,
moff, kern_moff);
memcpy(kern_mdata, mdata, msize);
}
return 0;
}
static int bpf_object__init_kern_struct_ops_maps(struct bpf_object *obj)
{
struct btf *kern_btf = NULL;
struct bpf_map *map;
size_t i;
int err;
for (i = 0; i < obj->nr_maps; i++) {
map = &obj->maps[i];
if (!bpf_map__is_struct_ops(map))
continue;
if (!kern_btf) {
kern_btf = bpf_find_kernel_btf();
if (IS_ERR(kern_btf))
return PTR_ERR(kern_btf);
}
err = bpf_map__init_kern_struct_ops(map, obj->btf, kern_btf);
if (err) {
btf__free(kern_btf);
return err;
}
}
btf__free(kern_btf);
return 0;
}
static int bpf_object__init_struct_ops_maps(struct bpf_object *obj)
{
const struct btf_type *type, *datasec;
const struct btf_var_secinfo *vsi;
struct bpf_struct_ops *st_ops;
const char *tname, *var_name;
__s32 type_id, datasec_id;
const struct btf *btf;
struct bpf_map *map;
__u32 i;
if (obj->efile.st_ops_shndx == -1)
return 0;
btf = obj->btf;
datasec_id = btf__find_by_name_kind(btf, STRUCT_OPS_SEC,
BTF_KIND_DATASEC);
if (datasec_id < 0) {
pr_warn("struct_ops init: DATASEC %s not found\n",
STRUCT_OPS_SEC);
return -EINVAL;
}
datasec = btf__type_by_id(btf, datasec_id);
vsi = btf_var_secinfos(datasec);
for (i = 0; i < btf_vlen(datasec); i++, vsi++) {
type = btf__type_by_id(obj->btf, vsi->type);
var_name = btf__name_by_offset(obj->btf, type->name_off);
type_id = btf__resolve_type(obj->btf, vsi->type);
if (type_id < 0) {
pr_warn("struct_ops init: Cannot resolve var type_id %u in DATASEC %s\n",
vsi->type, STRUCT_OPS_SEC);
return -EINVAL;
}
type = btf__type_by_id(obj->btf, type_id);
tname = btf__name_by_offset(obj->btf, type->name_off);
if (!tname[0]) {
pr_warn("struct_ops init: anonymous type is not supported\n");
return -ENOTSUP;
}
if (!btf_is_struct(type)) {
pr_warn("struct_ops init: %s is not a struct\n", tname);
return -EINVAL;
}
map = bpf_object__add_map(obj);
if (IS_ERR(map))
return PTR_ERR(map);
map->sec_idx = obj->efile.st_ops_shndx;
map->sec_offset = vsi->offset;
map->name = strdup(var_name);
if (!map->name)
return -ENOMEM;
map->def.type = BPF_MAP_TYPE_STRUCT_OPS;
map->def.key_size = sizeof(int);
map->def.value_size = type->size;
map->def.max_entries = 1;
map->st_ops = calloc(1, sizeof(*map->st_ops));
if (!map->st_ops)
return -ENOMEM;
st_ops = map->st_ops;
st_ops->data = malloc(type->size);
st_ops->progs = calloc(btf_vlen(type), sizeof(*st_ops->progs));
st_ops->kern_func_off = malloc(btf_vlen(type) *
sizeof(*st_ops->kern_func_off));
if (!st_ops->data || !st_ops->progs || !st_ops->kern_func_off)
return -ENOMEM;
if (vsi->offset + type->size > obj->efile.st_ops_data->d_size) {
pr_warn("struct_ops init: var %s is beyond the end of DATASEC %s\n",
var_name, STRUCT_OPS_SEC);
return -EINVAL;
}
memcpy(st_ops->data,
obj->efile.st_ops_data->d_buf + vsi->offset,
type->size);
st_ops->tname = tname;
st_ops->type = type;
st_ops->type_id = type_id;
pr_debug("struct_ops init: struct %s(type_id=%u) %s found at offset %u\n",
tname, type_id, var_name, vsi->offset);
}
return 0;
}
static struct bpf_object *bpf_object__new(const char *path,
const void *obj_buf,
size_t obj_buf_sz,
@ -607,6 +993,7 @@ static struct bpf_object *bpf_object__new(const char *path,
obj->efile.data_shndx = -1;
obj->efile.rodata_shndx = -1;
obj->efile.bss_shndx = -1;
obj->efile.st_ops_shndx = -1;
obj->kconfig_map_idx = -1;
obj->kern_version = get_kernel_version();
@ -630,6 +1017,7 @@ static void bpf_object__elf_finish(struct bpf_object *obj)
obj->efile.data = NULL;
obj->efile.rodata = NULL;
obj->efile.bss = NULL;
obj->efile.st_ops_data = NULL;
zfree(&obj->efile.reloc_sects);
obj->efile.nr_reloc_sects = 0;
@ -815,6 +1203,9 @@ int bpf_object__section_size(const struct bpf_object *obj, const char *name,
} else if (!strcmp(name, RODATA_SEC)) {
if (obj->efile.rodata)
*size = obj->efile.rodata->d_size;
} else if (!strcmp(name, STRUCT_OPS_SEC)) {
if (obj->efile.st_ops_data)
*size = obj->efile.st_ops_data->d_size;
} else {
ret = bpf_object_search_section_size(obj, name, &d_size);
if (!ret)
@ -1440,6 +1831,20 @@ skip_mods_and_typedefs(const struct btf *btf, __u32 id, __u32 *res_id)
return t;
}
static const struct btf_type *
resolve_func_ptr(const struct btf *btf, __u32 id, __u32 *res_id)
{
const struct btf_type *t;
t = skip_mods_and_typedefs(btf, id, NULL);
if (!btf_is_ptr(t))
return NULL;
t = skip_mods_and_typedefs(btf, t->type, res_id);
return btf_is_func_proto(t) ? t : NULL;
}
/*
* Fetch integer attribute of BTF map definition. Such attributes are
* represented using a pointer to an array, in which dimensionality of array
@ -1787,6 +2192,7 @@ static int bpf_object__init_maps(struct bpf_object *obj,
err = err ?: bpf_object__init_user_btf_maps(obj, strict, pin_root_path);
err = err ?: bpf_object__init_global_data_maps(obj);
err = err ?: bpf_object__init_kconfig_map(obj);
err = err ?: bpf_object__init_struct_ops_maps(obj);
if (err)
return err;
@ -1889,7 +2295,8 @@ static void bpf_object__sanitize_btf_ext(struct bpf_object *obj)
static bool bpf_object__is_btf_mandatory(const struct bpf_object *obj)
{
return obj->efile.btf_maps_shndx >= 0 ||
obj->nr_extern > 0;
obj->efile.st_ops_shndx >= 0 ||
obj->nr_extern > 0;
}
static int bpf_object__init_btf(struct bpf_object *obj,
@ -2088,6 +2495,9 @@ static int bpf_object__elf_collect(struct bpf_object *obj)
} else if (strcmp(name, RODATA_SEC) == 0) {
obj->efile.rodata = data;
obj->efile.rodata_shndx = idx;
} else if (strcmp(name, STRUCT_OPS_SEC) == 0) {
obj->efile.st_ops_data = data;
obj->efile.st_ops_shndx = idx;
} else {
pr_debug("skip section(%d) %s\n", idx, name);
}
@ -2097,7 +2507,8 @@ static int bpf_object__elf_collect(struct bpf_object *obj)
int sec = sh.sh_info; /* points to other section */
/* Only do relo for section with exec instructions */
if (!section_have_execinstr(obj, sec)) {
if (!section_have_execinstr(obj, sec) &&
strcmp(name, ".rel" STRUCT_OPS_SEC)) {
pr_debug("skip relo %s(%d) for section(%d)\n",
name, idx, sec);
continue;
@ -2599,8 +3010,12 @@ static int bpf_map_find_btf_info(struct bpf_object *obj, struct bpf_map *map)
__u32 key_type_id = 0, value_type_id = 0;
int ret;
/* if it's BTF-defined map, we don't need to search for type IDs */
if (map->sec_idx == obj->efile.btf_maps_shndx)
/* if it's BTF-defined map, we don't need to search for type IDs.
* For struct_ops map, it does not need btf_key_type_id and
* btf_value_type_id.
*/
if (map->sec_idx == obj->efile.btf_maps_shndx ||
bpf_map__is_struct_ops(map))
return 0;
if (!bpf_map__is_internal(map)) {
@ -3025,6 +3440,9 @@ bpf_object__create_maps(struct bpf_object *obj)
if (bpf_map_type__is_map_in_map(def->type) &&
map->inner_map_fd >= 0)
create_attr.inner_map_fd = map->inner_map_fd;
if (bpf_map__is_struct_ops(map))
create_attr.btf_vmlinux_value_type_id =
map->btf_vmlinux_value_type_id;
if (obj->btf && !bpf_map_find_btf_info(obj, map)) {
create_attr.btf_fd = btf__fd(obj->btf);
@ -3899,7 +4317,7 @@ static struct btf *btf_load_raw(const char *path)
* Probe few well-known locations for vmlinux kernel image and try to load BTF
* data out of it to use for target BTF.
*/
static struct btf *bpf_core_find_kernel_btf(void)
static struct btf *bpf_find_kernel_btf(void)
{
struct {
const char *path_fmt;
@ -4180,7 +4598,7 @@ bpf_core_reloc_fields(struct bpf_object *obj, const char *targ_btf_path)
if (targ_btf_path)
targ_btf = btf__parse_elf(targ_btf_path, NULL);
else
targ_btf = bpf_core_find_kernel_btf();
targ_btf = bpf_find_kernel_btf();
if (IS_ERR(targ_btf)) {
pr_warn("failed to get target BTF: %ld\n", PTR_ERR(targ_btf));
return PTR_ERR(targ_btf);
@ -4379,6 +4797,10 @@ bpf_object__relocate(struct bpf_object *obj, const char *targ_btf_path)
return 0;
}
static int bpf_object__collect_struct_ops_map_reloc(struct bpf_object *obj,
GElf_Shdr *shdr,
Elf_Data *data);
static int bpf_object__collect_reloc(struct bpf_object *obj)
{
int i, err;
@ -4399,6 +4821,15 @@ static int bpf_object__collect_reloc(struct bpf_object *obj)
return -LIBBPF_ERRNO__INTERNAL;
}
if (idx == obj->efile.st_ops_shndx) {
err = bpf_object__collect_struct_ops_map_reloc(obj,
shdr,
data);
if (err)
return err;
continue;
}
prog = bpf_object__find_prog_by_idx(obj, idx);
if (!prog) {
pr_warn("relocation failed: no section(%d)\n", idx);
@ -4433,7 +4864,9 @@ load_program(struct bpf_program *prog, struct bpf_insn *insns, int insns_cnt,
load_attr.insns = insns;
load_attr.insns_cnt = insns_cnt;
load_attr.license = license;
if (prog->type == BPF_PROG_TYPE_TRACING) {
if (prog->type == BPF_PROG_TYPE_STRUCT_OPS) {
load_attr.attach_btf_id = prog->attach_btf_id;
} else if (prog->type == BPF_PROG_TYPE_TRACING) {
load_attr.attach_prog_fd = prog->attach_prog_fd;
load_attr.attach_btf_id = prog->attach_btf_id;
} else {
@ -4679,6 +5112,9 @@ __bpf_object__open(const char *path, const void *obj_buf, size_t obj_buf_sz,
enum bpf_prog_type prog_type;
enum bpf_attach_type attach_type;
if (prog->type != BPF_PROG_TYPE_UNSPEC)
continue;
err = libbpf_prog_type_by_name(prog->section_name, &prog_type,
&attach_type);
if (err == -ESRCH)
@ -4774,8 +5210,11 @@ int bpf_object__unload(struct bpf_object *obj)
if (!obj)
return -EINVAL;
for (i = 0; i < obj->nr_maps; i++)
for (i = 0; i < obj->nr_maps; i++) {
zclose(obj->maps[i].fd);
if (obj->maps[i].st_ops)
zfree(&obj->maps[i].st_ops->kern_vdata);
}
for (i = 0; i < obj->nr_programs; i++)
bpf_program__unload(&obj->programs[i]);
@ -4891,6 +5330,7 @@ int bpf_object__load_xattr(struct bpf_object_load_attr *attr)
err = err ? : bpf_object__resolve_externs(obj, obj->kconfig);
err = err ? : bpf_object__sanitize_and_load_btf(obj);
err = err ? : bpf_object__sanitize_maps(obj);
err = err ? : bpf_object__init_kern_struct_ops_maps(obj);
err = err ? : bpf_object__create_maps(obj);
err = err ? : bpf_object__relocate(obj, attr->target_btf_path);
err = err ? : bpf_object__load_progs(obj, attr->log_level);
@ -5478,6 +5918,13 @@ void bpf_object__close(struct bpf_object *obj)
map->mmaped = NULL;
}
if (map->st_ops) {
zfree(&map->st_ops->data);
zfree(&map->st_ops->progs);
zfree(&map->st_ops->kern_func_off);
zfree(&map->st_ops);
}
zfree(&map->name);
zfree(&map->pin_path);
}
@ -5746,6 +6193,7 @@ BPF_PROG_TYPE_FNS(raw_tracepoint, BPF_PROG_TYPE_RAW_TRACEPOINT);
BPF_PROG_TYPE_FNS(xdp, BPF_PROG_TYPE_XDP);
BPF_PROG_TYPE_FNS(perf_event, BPF_PROG_TYPE_PERF_EVENT);
BPF_PROG_TYPE_FNS(tracing, BPF_PROG_TYPE_TRACING);
BPF_PROG_TYPE_FNS(struct_ops, BPF_PROG_TYPE_STRUCT_OPS);
enum bpf_attach_type
bpf_program__get_expected_attach_type(struct bpf_program *prog)
@ -5899,6 +6347,7 @@ static const struct bpf_sec_def section_defs[] = {
BPF_CGROUP_GETSOCKOPT),
BPF_EAPROG_SEC("cgroup/setsockopt", BPF_PROG_TYPE_CGROUP_SOCKOPT,
BPF_CGROUP_SETSOCKOPT),
BPF_PROG_SEC("struct_ops", BPF_PROG_TYPE_STRUCT_OPS),
};
#undef BPF_PROG_SEC_IMPL
@ -5975,11 +6424,141 @@ int libbpf_prog_type_by_name(const char *name, enum bpf_prog_type *prog_type,
return -ESRCH;
}
static struct bpf_map *find_struct_ops_map_by_offset(struct bpf_object *obj,
size_t offset)
{
struct bpf_map *map;
size_t i;
for (i = 0; i < obj->nr_maps; i++) {
map = &obj->maps[i];
if (!bpf_map__is_struct_ops(map))
continue;
if (map->sec_offset <= offset &&
offset - map->sec_offset < map->def.value_size)
return map;
}
return NULL;
}
/* Collect the reloc from ELF and populate the st_ops->progs[] */
static int bpf_object__collect_struct_ops_map_reloc(struct bpf_object *obj,
GElf_Shdr *shdr,
Elf_Data *data)
{
const struct btf_member *member;
struct bpf_struct_ops *st_ops;
struct bpf_program *prog;
unsigned int shdr_idx;
const struct btf *btf;
struct bpf_map *map;
Elf_Data *symbols;
unsigned int moff;
const char *name;
u32 member_idx;
GElf_Sym sym;
GElf_Rel rel;
int i, nrels;
symbols = obj->efile.symbols;
btf = obj->btf;
nrels = shdr->sh_size / shdr->sh_entsize;
for (i = 0; i < nrels; i++) {
if (!gelf_getrel(data, i, &rel)) {
pr_warn("struct_ops reloc: failed to get %d reloc\n", i);
return -LIBBPF_ERRNO__FORMAT;
}
if (!gelf_getsym(symbols, GELF_R_SYM(rel.r_info), &sym)) {
pr_warn("struct_ops reloc: symbol %zx not found\n",
(size_t)GELF_R_SYM(rel.r_info));
return -LIBBPF_ERRNO__FORMAT;
}
name = elf_strptr(obj->efile.elf, obj->efile.strtabidx,
sym.st_name) ? : "<?>";
map = find_struct_ops_map_by_offset(obj, rel.r_offset);
if (!map) {
pr_warn("struct_ops reloc: cannot find map at rel.r_offset %zu\n",
(size_t)rel.r_offset);
return -EINVAL;
}
moff = rel.r_offset - map->sec_offset;
shdr_idx = sym.st_shndx;
st_ops = map->st_ops;
pr_debug("struct_ops reloc %s: for %lld value %lld shdr_idx %u rel.r_offset %zu map->sec_offset %zu name %d (\'%s\')\n",
map->name,
(long long)(rel.r_info >> 32),
(long long)sym.st_value,
shdr_idx, (size_t)rel.r_offset,
map->sec_offset, sym.st_name, name);
if (shdr_idx >= SHN_LORESERVE) {
pr_warn("struct_ops reloc %s: rel.r_offset %zu shdr_idx %u unsupported non-static function\n",
map->name, (size_t)rel.r_offset, shdr_idx);
return -LIBBPF_ERRNO__RELOC;
}
member = find_member_by_offset(st_ops->type, moff * 8);
if (!member) {
pr_warn("struct_ops reloc %s: cannot find member at moff %u\n",
map->name, moff);
return -EINVAL;
}
member_idx = member - btf_members(st_ops->type);
name = btf__name_by_offset(btf, member->name_off);
if (!resolve_func_ptr(btf, member->type, NULL)) {
pr_warn("struct_ops reloc %s: cannot relocate non func ptr %s\n",
map->name, name);
return -EINVAL;
}
prog = bpf_object__find_prog_by_idx(obj, shdr_idx);
if (!prog) {
pr_warn("struct_ops reloc %s: cannot find prog at shdr_idx %u to relocate func ptr %s\n",
map->name, shdr_idx, name);
return -EINVAL;
}
if (prog->type == BPF_PROG_TYPE_UNSPEC) {
const struct bpf_sec_def *sec_def;
sec_def = find_sec_def(prog->section_name);
if (sec_def &&
sec_def->prog_type != BPF_PROG_TYPE_STRUCT_OPS) {
/* for pr_warn */
prog->type = sec_def->prog_type;
goto invalid_prog;
}
prog->type = BPF_PROG_TYPE_STRUCT_OPS;
prog->attach_btf_id = st_ops->type_id;
prog->expected_attach_type = member_idx;
} else if (prog->type != BPF_PROG_TYPE_STRUCT_OPS ||
prog->attach_btf_id != st_ops->type_id ||
prog->expected_attach_type != member_idx) {
goto invalid_prog;
}
st_ops->progs[member_idx] = prog;
}
return 0;
invalid_prog:
pr_warn("struct_ops reloc %s: cannot use prog %s in sec %s with type %u attach_btf_id %u expected_attach_type %u for func ptr %s\n",
map->name, prog->name, prog->section_name, prog->type,
prog->attach_btf_id, prog->expected_attach_type, name);
return -EINVAL;
}
#define BTF_PREFIX "btf_trace_"
int libbpf_find_vmlinux_btf_id(const char *name,
enum bpf_attach_type attach_type)
{
struct btf *btf = bpf_core_find_kernel_btf();
struct btf *btf = bpf_find_kernel_btf();
char raw_tp_btf[128] = BTF_PREFIX;
char *dst = raw_tp_btf + sizeof(BTF_PREFIX) - 1;
const char *btf_name;
@ -6805,6 +7384,58 @@ struct bpf_link *bpf_program__attach(struct bpf_program *prog)
return sec_def->attach_fn(sec_def, prog);
}
static int bpf_link__detach_struct_ops(struct bpf_link *link)
{
struct bpf_link_fd *l = (void *)link;
__u32 zero = 0;
if (bpf_map_delete_elem(l->fd, &zero))
return -errno;
return 0;
}
struct bpf_link *bpf_map__attach_struct_ops(struct bpf_map *map)
{
struct bpf_struct_ops *st_ops;
struct bpf_link_fd *link;
__u32 i, zero = 0;
int err;
if (!bpf_map__is_struct_ops(map) || map->fd == -1)
return ERR_PTR(-EINVAL);
link = calloc(1, sizeof(*link));
if (!link)
return ERR_PTR(-EINVAL);
st_ops = map->st_ops;
for (i = 0; i < btf_vlen(st_ops->type); i++) {
struct bpf_program *prog = st_ops->progs[i];
void *kern_data;
int prog_fd;
if (!prog)
continue;
prog_fd = bpf_program__fd(prog);
kern_data = st_ops->kern_vdata + st_ops->kern_func_off[i];
*(unsigned long *)kern_data = prog_fd;
}
err = bpf_map_update_elem(map->fd, &zero, st_ops->kern_vdata, 0);
if (err) {
err = -errno;
free(link);
return ERR_PTR(err);
}
link->link.detach = bpf_link__detach_struct_ops;
link->fd = map->fd;
return (struct bpf_link *)link;
}
enum bpf_perf_event_ret
bpf_perf_event_read_simple(void *mmap_mem, size_t mmap_size, size_t page_size,
void **copy_mem, size_t *copy_size,

5
tools/lib/bpf/libbpf.h
View File

@ -239,6 +239,8 @@ bpf_program__attach_raw_tracepoint(struct bpf_program *prog,
LIBBPF_API struct bpf_link *
bpf_program__attach_trace(struct bpf_program *prog);
struct bpf_map;
LIBBPF_API struct bpf_link *bpf_map__attach_struct_ops(struct bpf_map *map);
struct bpf_insn;
/*
@ -315,6 +317,7 @@ LIBBPF_API int bpf_program__set_sched_act(struct bpf_program *prog);
LIBBPF_API int bpf_program__set_xdp(struct bpf_program *prog);
LIBBPF_API int bpf_program__set_perf_event(struct bpf_program *prog);
LIBBPF_API int bpf_program__set_tracing(struct bpf_program *prog);
LIBBPF_API int bpf_program__set_struct_ops(struct bpf_program *prog);
LIBBPF_API enum bpf_prog_type bpf_program__get_type(struct bpf_program *prog);
LIBBPF_API void bpf_program__set_type(struct bpf_program *prog,
@ -335,6 +338,7 @@ LIBBPF_API bool bpf_program__is_sched_act(const struct bpf_program *prog);
LIBBPF_API bool bpf_program__is_xdp(const struct bpf_program *prog);
LIBBPF_API bool bpf_program__is_perf_event(const struct bpf_program *prog);
LIBBPF_API bool bpf_program__is_tracing(const struct bpf_program *prog);
LIBBPF_API bool bpf_program__is_struct_ops(const struct bpf_program *prog);
/*
* No need for __attribute__((packed)), all members of 'bpf_map_def'
@ -354,7 +358,6 @@ struct bpf_map_def {
* The 'struct bpf_map' in include/linux/bpf.h is internal to the kernel,
* so no need to worry about a name clash.
*/
struct bpf_map;
LIBBPF_API struct bpf_map *
bpf_object__find_map_by_name(const struct bpf_object *obj, const char *name);

3
tools/lib/bpf/libbpf.map
View File

@ -213,6 +213,7 @@ LIBBPF_0.0.7 {
global:
btf_dump__emit_type_decl;
bpf_link__disconnect;
bpf_map__attach_struct_ops;
bpf_object__find_program_by_name;
bpf_object__attach_skeleton;
bpf_object__destroy_skeleton;
@ -223,5 +224,7 @@ LIBBPF_0.0.7 {
bpf_prog_attach_xattr;
bpf_program__attach;
bpf_program__name;
bpf_program__is_struct_ops;
bpf_program__set_struct_ops;
btf__align_of;
} LIBBPF_0.0.6;

2
tools/lib/bpf/libbpf_probes.c
View File

@ -103,6 +103,7 @@ probe_load(enum bpf_prog_type prog_type, const struct bpf_insn *insns,
case BPF_PROG_TYPE_CGROUP_SYSCTL:
case BPF_PROG_TYPE_CGROUP_SOCKOPT:
case BPF_PROG_TYPE_TRACING:
case BPF_PROG_TYPE_STRUCT_OPS:
default:
break;
}
@ -251,6 +252,7 @@ bool bpf_probe_map_type(enum bpf_map_type map_type, __u32 ifindex)
case BPF_MAP_TYPE_XSKMAP:
case BPF_MAP_TYPE_SOCKHASH:
case BPF_MAP_TYPE_REUSEPORT_SOCKARRAY:
case BPF_MAP_TYPE_STRUCT_OPS:
default:
break;
}