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NetBpfLoad: Add libbpf-style map definitions for libbpf support

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This updates the BPF map macros so programs can be loaded by both the
existing code and the libbpf.
The macros now generate ".maps" section in addition to the
".android_maps" section.

To prevent name collisions, the legacy map definitions are suffixed with
_def. This CL also adds the readMapNames method to get map names from
the ".android_maps" section, allowing the existing code path to continue
working.

Bug: 428792764
Flag: EXEMPT no-op
Test: TH
Change-Id: Ibe6f100b5684bc85d2cf9c100f2431740fa516ca
This commit is contained in:
Motomu Utsumi 2025-07-01 14:44:18 +09:00
commit e5dcaf78e3
2 changed files with 39 additions and 3 deletions
Download patch file Download diff file Expand all files Collapse all files

20
bpf/loader/NetBpfLoad.cpp
View file

@ -868,6 +868,22 @@ static bool isBtfSupported(enum bpf_map_type type) {
return type != BPF_MAP_TYPE_DEVMAP_HASH && type != BPF_MAP_TYPE_RINGBUF;
}
static int readMapNames(ifstream& elfFile, vector<string>& mapNames) {
int ret = getSectionSymNames(elfFile, ".android_maps", mapNames);
if (ret) return ret;
const string suffix = "_def";
for (string& name : mapNames) {
if (EndsWith(name, suffix)) {
name.erase(name.length() - suffix.length());
} else {
ALOGE("Failed to get map names, invalid symbol in .android_maps: %s", name.c_str());
return 1;
}
}
return 0;
}
static int createMaps(const char* elfPath, ifstream& elfFile, vector<unique_fd>& mapFds,
const char* prefix, const unsigned int bpfloader_ver) {
int ret;
@ -880,7 +896,7 @@ static int createMaps(const char* elfPath, ifstream& elfFile, vector<unique_fd>&
if (ret == -2) return 0; // no maps to read
if (ret) return ret;
ret = getSectionSymNames(elfFile, ".android_maps", mapNames);
ret = readMapNames(elfFile, mapNames);
if (ret) return ret;
struct btf *btf = NULL;
@ -1120,7 +1136,7 @@ static void applyRelo(void* insnsPtr, Elf64_Addr offset, int fd) {
static void applyMapRelo(ifstream& elfFile, vector<unique_fd> &mapFds, vector<codeSection>& cs) {
vector<string> mapNames;
int ret = getSectionSymNames(elfFile, ".android_maps", mapNames);
int ret = readMapNames(elfFile, mapNames);
if (ret) return;
for (int k = 0; k != (int)cs.size(); k++) {

22
bpf/progs/include/bpf_helpers.h
View file

@ -220,7 +220,7 @@ static int (*bpf_sk_storage_delete_unsafe) (const void* sk_storage,
#define DEFINE_BPF_MAP_BASE(the_map, TYPE, keysize, valuesize, num_entries, \
usr, grp, md, selinux, pindir, share, minkver, \
maxkver, minloader, maxloader, mapflags) \
const struct bpf_map_def SECTION(".android_maps") the_map = { \
const struct bpf_map_def SECTION(".android_maps") the_map##_def = { \
.type = BPF_MAP_TYPE_##TYPE, \
.key_size = (keysize), \
.value_size = (valuesize), \
@ -238,6 +238,23 @@ static int (*bpf_sk_storage_delete_unsafe) (const void* sk_storage,
.shared = (share).shared, \
};
#define __uint(name, val) int (*name)[val]
#define __type(name, val) typeof(val) *name
#define DEFINE_LIBBPF_MAP(the_map, TYPE, KeyType, ValueType, num_entries) \
struct { \
__uint(type, BPF_MAP_TYPE_##TYPE); \
__type(key, KeyType); \
__type(value, ValueType); \
__uint(max_entries, ABSOLUTE(num_entries)); \
} the_map SECTION(".maps");
#define DEFINE_LIBBPF_RINGBUF(the_map, num_entries) \
struct { \
__uint(type, BPF_MAP_TYPE_RINGBUF); \
__uint(max_entries, ABSOLUTE(num_entries)); \
} the_map SECTION(".maps");
// Type safe macro to declare a ring buffer and related output functions.
// Compatibility:
// * BPF ring buffers are only available kernels 5.8 and above. Any program
@ -250,6 +267,7 @@ static int (*bpf_sk_storage_delete_unsafe) (const void* sk_storage,
DEFINE_BPF_MAP_BASE(the_map, RINGBUF, 0, 0, size_bytes, usr, grp, md, \
selinux, pindir, share, KVER_5_10, KVER_INF, \
min_loader, max_loader, 0); \
DEFINE_LIBBPF_RINGBUF(the_map, size_bytes); \
\
_Static_assert((size_bytes) >= 4096, "min 4 kiB ringbuffer size"); \
_Static_assert((size_bytes) <= 0x10000000, "max 256 MiB ringbuffer size"); \
@ -284,6 +302,7 @@ static int (*bpf_sk_storage_delete_unsafe) (const void* sk_storage,
DEFINE_BPF_MAP_BASE(the_map, SK_STORAGE, sizeof(uint32_t), sizeof(ValueType), \
0, usr, grp, md, selinux, pindir, share, \
KVER_5_10, KVER_INF, min_loader, max_loader, mapFlags); \
DEFINE_LIBBPF_MAP(the_map, SK_STORAGE, uint32_t, ValueType, 0); \
BPF_ANNOTATE_KV_PAIR(the_map, uint32_t, ValueType); \
\
static inline __always_inline __unused ValueType* bpf_##the_map##_get( \
@ -324,6 +343,7 @@ static int (*bpf_sk_storage_delete_unsafe) (const void* sk_storage,
DEFINE_BPF_MAP_BASE(the_map, TYPE, sizeof(KeyType), sizeof(ValueType), \
num_entries, usr, grp, md, selinux, pindir, share, \
KVER_NONE, KVER_INF, min_loader, max_loader, mapFlags); \
DEFINE_LIBBPF_MAP(the_map, TYPE, KeyType, ValueType, num_entries); \
BPF_MAP_ASSERT_OK(BPF_MAP_TYPE_##TYPE, (num_entries), (md)); \
_Static_assert(sizeof(KeyType) < 1024, "aosp/2370288 requires < 1024 byte keys"); \
_Static_assert(sizeof(ValueType) < 65536, "aosp/2370288 requires < 65536 byte values"); \