joy/android_system_bpf
Watch
1
Fork
You've already forked android_system_bpf
 0
Code Issues Pull requests Projects Releases Wiki Activity

bpf - struct bpf_map_def - add min/max kernel version.

Browse source 
This is also bpfloader v0.2.
Some newer map types (for example DEVMAP) are unusable
on older kernel versions.

Bug: 190519702
Test: atest, TreeHugger
Signed-off-by: Maciej Żenczykowski <maze@google.com>
Change-Id: I085cc723ff1c19d8acc8972a391f894e16dd1875
This commit is contained in:
Maciej Żenczykowski 2021-07-05 15:20:34 -07:00
commit 36c53ba91e
3 changed files with 40 additions and 15 deletions
Download patch file Download diff file Expand all files Collapse all files

36
libbpf_android/Loader.cpp
View file

@ -28,10 +28,9 @@
#include <sys/utsname.h>
#include <unistd.h>
// This is BpfLoader 0.1, we need to define this prior to including bpf_map_def.h
// to get the 0.1 struct definitions
// This is BpfLoader v0.2
#define BPFLOADER_VERSION_MAJOR 0u
#define BPFLOADER_VERSION_MINOR 1u
#define BPFLOADER_VERSION_MINOR 2u
#define BPFLOADER_VERSION ((BPFLOADER_VERSION_MAJOR << 16) | BPFLOADER_VERSION_MINOR)
#include "../progs/include/bpf_map_def.h"
@ -494,6 +493,7 @@ static int createMaps(const char* elfPath, ifstream& elfFile, vector<unique_fd>&
memset(&m, 0, sizeof(m));
// Then we set non-zero defaults
m.bpfloader_max_ver = DEFAULT_BPFLOADER_MAX_VER; // v1.0
m.max_kver = 0xFFFFFFFFu; // matches KVER_INF from bpf_helpers.h
// Then we copy over the structure prefix from the ELF file.
memcpy(&m, dataPtr, trimmedSize);
// Move to next struct in the ELF file
@ -503,14 +503,9 @@ static int createMaps(const char* elfPath, ifstream& elfFile, vector<unique_fd>&
ret = getSectionSymNames(elfFile, "maps", mapNames);
if (ret) return ret;
for (int i = 0; i < (int)mapNames.size(); i++) {
unique_fd fd;
int saved_errno;
// Format of pin location is /sys/fs/bpf/<prefix>map_<filename>_<mapname>
string mapPinLoc =
string(BPF_FS_PATH) + prefix + "map_" + fname + "_" + string(mapNames[i]);
bool reuse = false;
unsigned kvers = kernelVersion();
for (int i = 0; i < (int)mapNames.size(); i++) {
if (BPFLOADER_VERSION < md[i].bpfloader_min_ver) {
ALOGI("skipping map %s which requires bpfloader min ver 0x%05x\n", mapNames[i].c_str(),
md[i].bpfloader_min_ver);
@ -525,6 +520,27 @@ static int createMaps(const char* elfPath, ifstream& elfFile, vector<unique_fd>&
continue;
}
if (kvers < md[i].min_kver) {
ALOGI("skipping map %s which requires kernel version 0x%x >= 0x%x\n",
mapNames[i].c_str(), kvers, md[i].min_kver);
mapFds.push_back(unique_fd());
continue;
}
if (kvers >= md[i].max_kver) {
ALOGI("skipping map %s which requires kernel version 0x%x < 0x%x\n",
mapNames[i].c_str(), kvers, md[i].max_kver);
mapFds.push_back(unique_fd());
continue;
}
// Format of pin location is /sys/fs/bpf/<prefix>map_<filename>_<mapname>
string mapPinLoc =
string(BPF_FS_PATH) + prefix + "map_" + fname + "_" + string(mapNames[i]);
bool reuse = false;
unique_fd fd;
int saved_errno;
if (access(mapPinLoc.c_str(), F_OK) == 0) {
fd.reset(bpf_obj_get(mapPinLoc.c_str()));
saved_errno = errno;

10
progs/include/bpf_helpers.h
View file

@ -59,6 +59,10 @@
* implemented in the kernel sources.
*/
#define KVER_NONE 0
#define KVER(a, b, c) (((a) << 24) + ((b) << 16) + (c))
#define KVER_INF 0xFFFFFFFFu
/* generic functions */
/*
@ -110,6 +114,8 @@ static int (*bpf_map_delete_elem_unsafe)(const struct bpf_map_def* map,
.mode = (md), \
.bpfloader_min_ver = DEFAULT_BPFLOADER_MIN_VER, \
.bpfloader_max_ver = DEFAULT_BPFLOADER_MAX_VER, \
.min_kver = KVER_NONE, \
.max_kver = KVER_INF, \
}; \
\
static inline __always_inline __unused TypeOfValue* bpf_##the_map##_lookup_elem( \
@ -147,10 +153,6 @@ static unsigned long long (*bpf_get_current_pid_tgid)(void) = (void*) BPF_FUNC_g
static unsigned long long (*bpf_get_current_uid_gid)(void) = (void*) BPF_FUNC_get_current_uid_gid;
static unsigned long long (*bpf_get_smp_processor_id)(void) = (void*) BPF_FUNC_get_smp_processor_id;
#define KVER_NONE 0
#define KVER(a, b, c) (((a) << 24) + ((b) << 16) + (c))
#define KVER_INF 0xFFFFFFFF
#define DEFINE_BPF_PROG_KVER_RANGE_OPT(SECTION_NAME, prog_uid, prog_gid, the_prog, min_kv, max_kv, \
opt) \
const struct bpf_prog_def SEC("progs") the_prog##_def = { \

9
progs/include/bpf_map_def.h
View file

@ -141,10 +141,15 @@ struct bpf_map_def {
// The following fields were added in version 0.1
unsigned int bpfloader_min_ver; // if missing, defaults to 0, ie. v0.0
unsigned int bpfloader_max_ver; // if missing, defaults to 0x10000, ie. v1.0
// The following fields were added in version 0.2
// kernelVersion() must be >= min_kver and < max_kver
unsigned int min_kver;
unsigned int max_kver;
};
// This needs to be updated whenever the above structure definition is expanded.
_Static_assert(sizeof(struct bpf_map_def) == 40, "sizeof struct bpf_map_def != 40");
_Static_assert(sizeof(struct bpf_map_def) == 48, "sizeof struct bpf_map_def != 48");
_Static_assert(__alignof__(struct bpf_map_def) == 4, "__alignof__ struct bpf_map_def != 4");
_Static_assert(_Alignof(struct bpf_map_def) == 4, "_Alignof struct bpf_map_def != 4");
@ -162,6 +167,8 @@ struct bpf_prog_def {
// The following fields were added in version 0.1
unsigned int bpfloader_min_ver; // if missing, defaults to 0, ie. v0.0
unsigned int bpfloader_max_ver; // if missing, defaults to 0x10000, ie. v1.0
// No new fields in version 0.2
};
// This needs to be updated whenever the above structure definition is expanded.