From: YiFei Zhu <zhuyifei@xxxxxxxxxx>
The patch adds a simple wrapper bpf_prog_add_map around the syscall.
And when using libbpf to load a program, it will probe the kernel for
the support of this syscall, and scan for the .metadata ELF section
and load it as an internal map like a .data section.
In the case that kernel supports the BPF_PROG_ADD_MAP syscall and
a .metadata section exists, the map will be explicitly attached to
the program via the syscall immediately after program is loaded.
-EEXIST is ignored for this syscall.
Signed-off-by: YiFei Zhu <zhuyifei@xxxxxxxxxx>
---
tools/lib/bpf/bpf.c | 11 +++++
tools/lib/bpf/bpf.h | 1 +
tools/lib/bpf/libbpf.c | 97 +++++++++++++++++++++++++++++++++++++++-
tools/lib/bpf/libbpf.map | 1 +
4 files changed, 109 insertions(+), 1 deletion(-)
diff --git a/tools/lib/bpf/bpf.c b/tools/lib/bpf/bpf.c
index eab14c97c15d..9b2173d4f92c 100644
--- a/tools/lib/bpf/bpf.c
+++ b/tools/lib/bpf/bpf.c
@@ -872,3 +872,14 @@ int bpf_enable_stats(enum bpf_stats_type type)
return sys_bpf(BPF_ENABLE_STATS, &attr, sizeof(attr));
}
+
+int bpf_prog_add_map(int prog_fd, int map_fd, int flags)
+{
+ union bpf_attr attr = {};
+
+ attr.prog_add_map.prog_fd = prog_fd;
+ attr.prog_add_map.map_fd = map_fd;
+ attr.prog_add_map.flags = flags;
+
+ return sys_bpf(BPF_PROG_ADD_MAP, &attr, sizeof(attr));
+}
diff --git a/tools/lib/bpf/bpf.h b/tools/lib/bpf/bpf.h
index 28855fd5b5f4..d76fee8f84e0 100644
--- a/tools/lib/bpf/bpf.h
+++ b/tools/lib/bpf/bpf.h
@@ -240,6 +240,7 @@ LIBBPF_API int bpf_task_fd_query(int pid, int fd, __u32 flags, char *buf,
enum bpf_stats_type; /* defined in up-to-date linux/bpf.h */
LIBBPF_API int bpf_enable_stats(enum bpf_stats_type type);
+LIBBPF_API int bpf_prog_add_map(int prog_fd, int map_fd, int flags);
#ifdef __cplusplus
} /* extern "C" */
#endif
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 7be04e45d29c..3ab1cb1f2af3 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -180,6 +180,8 @@ struct bpf_capabilities {
__u32 btf_func_global:1;
/* kernel support for expected_attach_type in BPF_PROG_LOAD */
__u32 exp_attach_type:1;
+ /* kernel support for BPF_PROG_ADD_MAP */
+ __u32 prog_add_map:1;
};
enum reloc_type {
@@ -288,6 +290,7 @@ struct bpf_struct_ops {
#define KCONFIG_SEC ".kconfig"
#define KSYMS_SEC ".ksyms"
#define STRUCT_OPS_SEC ".struct_ops"
+#define METADATA_SEC ".metadata"
enum libbpf_map_type {
LIBBPF_MAP_UNSPEC,
@@ -295,6 +298,7 @@ enum libbpf_map_type {
LIBBPF_MAP_BSS,
LIBBPF_MAP_RODATA,
LIBBPF_MAP_KCONFIG,
+ LIBBPF_MAP_METADATA,
};
static const char * const libbpf_type_to_btf_name[] = {
@@ -302,6 +306,7 @@ static const char * const libbpf_type_to_btf_name[] = {
[LIBBPF_MAP_BSS] = BSS_SEC,
[LIBBPF_MAP_RODATA] = RODATA_SEC,
[LIBBPF_MAP_KCONFIG] = KCONFIG_SEC,
+ [LIBBPF_MAP_METADATA] = METADATA_SEC,
};
struct bpf_map {
@@ -380,6 +385,8 @@ struct bpf_object {
size_t nr_maps;
size_t maps_cap;
+ struct bpf_map *metadata_map;
+
char *kconfig;
struct extern_desc *externs;
int nr_extern;
@@ -403,6 +410,7 @@ struct bpf_object {
Elf_Data *rodata;
Elf_Data *bss;
Elf_Data *st_ops_data;
+ Elf_Data *metadata;
size_t strtabidx;
struct {
GElf_Shdr shdr;
@@ -418,6 +426,7 @@ struct bpf_object {
int rodata_shndx;
int bss_shndx;
int st_ops_shndx;
+ int metadata_shndx;
} efile;
/*
* All loaded bpf_object is linked in a list, which is
@@ -1030,6 +1039,7 @@ static struct bpf_object *bpf_object__new(const char *path,
obj->efile.obj_buf_sz = obj_buf_sz;
obj->efile.maps_shndx = -1;
obj->efile.btf_maps_shndx = -1;
+ obj->efile.metadata_shndx = -1;
obj->efile.data_shndx = -1;
obj->efile.rodata_shndx = -1;
obj->efile.bss_shndx = -1;
@@ -1391,6 +1401,9 @@ bpf_object__init_internal_map(struct bpf_object *obj, enum libbpf_map_type type,
if (data)
memcpy(map->mmaped, data, data_sz);
+ if (type == LIBBPF_MAP_METADATA)
+ obj->metadata_map = map;
+
pr_debug("map %td is \"%s\"\n", map - obj->maps, map->name);
return 0;
}
@@ -1426,6 +1439,14 @@ static int bpf_object__init_global_data_maps(struct bpf_object *obj)
if (err)
return err;
}
+ if (obj->efile.metadata_shndx >= 0) {
+ err = bpf_object__init_internal_map(obj, LIBBPF_MAP_METADATA,
+ obj->efile.metadata_shndx,
+ obj->efile.metadata->d_buf,
+ obj->efile.metadata->d_size);
+ if (err)
+ return err;
+ }
return 0;
}
@@ -2665,6 +2686,9 @@ static int bpf_object__elf_collect(struct bpf_object *obj)
} else if (strcmp(name, STRUCT_OPS_SEC) == 0) {
obj->efile.st_ops_data = data;
obj->efile.st_ops_shndx = idx;
+ } else if (strcmp(name, METADATA_SEC) == 0) {
+ obj->efile.metadata = data;
+ obj->efile.metadata_shndx = idx;
} else {
pr_debug("skip section(%d) %s\n", idx, name);
}
@@ -3078,7 +3102,8 @@ static bool bpf_object__shndx_is_data(const struct bpf_object *obj,
{
return shndx == obj->efile.data_shndx ||
shndx == obj->efile.bss_shndx ||
- shndx == obj->efile.rodata_shndx;
+ shndx == obj->efile.rodata_shndx ||
+ shndx == obj->efile.metadata_shndx;
}
static bool bpf_object__shndx_is_maps(const struct bpf_object *obj,
@@ -3099,6 +3124,8 @@ bpf_object__section_to_libbpf_map_type(const struct bpf_object *obj, int shndx)
return LIBBPF_MAP_RODATA;
else if (shndx == obj->efile.symbols_shndx)
return LIBBPF_MAP_KCONFIG;
+ else if (shndx == obj->efile.metadata_shndx)
+ return LIBBPF_MAP_METADATA;
else
return LIBBPF_MAP_UNSPEC;
}
@@ -3633,6 +3660,59 @@ bpf_object__probe_exp_attach_type(struct bpf_object *obj)
return 0;
}
+static int
+bpf_object__probe_prog_add_map(struct bpf_object *obj)
+{
+ struct bpf_load_program_attr prog_attr;
+ struct bpf_create_map_attr map_attr;
+ char *cp, errmsg[STRERR_BUFSIZE];
+ struct bpf_insn insns[] = {
+ BPF_MOV64_IMM(BPF_REG_0, 0),
+ BPF_EXIT_INSN(),
+ };
+ int prog, map;
+
+ if (!obj->caps.global_data)
+ return 0;
+
+ memset(&map_attr, 0, sizeof(map_attr));
+ map_attr.map_type = BPF_MAP_TYPE_ARRAY;
+ map_attr.key_size = sizeof(int);
+ map_attr.value_size = 32;
+ map_attr.max_entries = 1;
+
+ map = bpf_create_map_xattr(&map_attr);
+ if (map < 0) {
+ cp = libbpf_strerror_r(errno, errmsg, sizeof(errmsg));
+ pr_warn("Error in %s():%s(%d). Couldn't create simple array map.\n",
+ __func__, cp, errno);
+ return -errno;
+ }
+
+ memset(&prog_attr, 0, sizeof(prog_attr));
+ prog_attr.prog_type = BPF_PROG_TYPE_SOCKET_FILTER;
+ prog_attr.insns = insns;
+ prog_attr.insns_cnt = ARRAY_SIZE(insns);
+ prog_attr.license = "GPL";
+
+ prog = bpf_load_program_xattr(&prog_attr, NULL, 0);
+ if (prog < 0) {
+ cp = libbpf_strerror_r(errno, errmsg, sizeof(errmsg));
+ pr_warn("Error in %s():%s(%d). Couldn't create simple program.\n",
+ __func__, cp, errno);
+
+ close(map);
+ return -errno;
+ }
+
+ if (!bpf_prog_add_map(prog, map, 0))
+ obj->caps.prog_add_map = 1;
+
+ close(map);
+ close(prog);
+ return 0;
+}
+
static int
bpf_object__probe_caps(struct bpf_object *obj)
{
@@ -3644,6 +3724,7 @@ bpf_object__probe_caps(struct bpf_object *obj)
bpf_object__probe_btf_datasec,
bpf_object__probe_array_mmap,
bpf_object__probe_exp_attach_type,
+ bpf_object__probe_prog_add_map,
};
int i, ret;
@@ -5404,6 +5485,20 @@ load_program(struct bpf_program *prog, struct bpf_insn *insns, int insns_cnt,
if (ret >= 0) {
if (log_buf && load_attr.log_level)
pr_debug("verifier log:\n%s", log_buf);
+
+ if (prog->obj->metadata_map && prog->obj->caps.prog_add_map) {
+ if (bpf_prog_add_map(ret, bpf_map__fd(prog->obj->metadata_map), 0) &&
+ errno != EEXIST) {
+ int fd = ret;
+
+ ret = -errno;
+ cp = libbpf_strerror_r(errno, errmsg, sizeof(errmsg));
+ pr_warn("add metadata map failed: %s\n", cp);
+ close(fd);
+ goto out;
+ }
+ }
+
*pfd = ret;
ret = 0;
goto out;
diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map
index 0c4722bfdd0a..86494a464c34 100644
--- a/tools/lib/bpf/libbpf.map
+++ b/tools/lib/bpf/libbpf.map
@@ -288,6 +288,7 @@ LIBBPF_0.1.0 {
bpf_map__set_value_size;
bpf_map__type;
bpf_map__value_size;
+ bpf_prog_add_map;
bpf_program__attach_xdp;
bpf_program__autoload;
bpf_program__is_sk_lookup;
--
2.28.0
