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vendorBpfLoader: remove mapMatchesExpectations() check

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This was primarily meant as a safety check for mainline,
it's not really needed in platform bpf loader.

Test: TreeHugger
Flag: EXEMPT cleanup
Signed-off-by: Maciej Żenczykowski <maze@google.com>
Change-Id: I615f54f10baa75f641129507ecce9159ff31a740
This commit is contained in:
Maciej Żenczykowski 2025-07-16 08:39:18 -07:00
commit d9201c1612
1 changed files with 0 additions and 53 deletions
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53
loader/Loader.cpp
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@ -431,54 +431,6 @@ static int getSymNameByIdx(ifstream& elfFile, int index, string& name) {
return getSymName(elfFile, symtab[index].st_name, name);
}
static bool mapMatchesExpectations(const unique_fd& fd, const string& mapName,
const struct bpf_map_def& mapDef) {
// Assuming fd is a valid Bpf Map file descriptor then
// all the following should always succeed on a 4.14+ kernel.
// If they somehow do fail, they'll return -1 (and set errno),
// which should then cause (among others) a key_size mismatch.
int fd_type = bpfGetFdMapType(fd);
int fd_key_size = bpfGetFdKeySize(fd);
int fd_value_size = bpfGetFdValueSize(fd);
int fd_max_entries = bpfGetFdMaxEntries(fd);
int fd_map_flags = bpfGetFdMapFlags(fd);
// DEVMAPs are readonly from the bpf program side's point of view, as such
// the kernel in kernel/bpf/devmap.c dev_map_init_map() will set the flag
int desired_map_flags = (int)mapDef.map_flags;
if (mapDef.type == BPF_MAP_TYPE_DEVMAP || mapDef.type == BPF_MAP_TYPE_DEVMAP_HASH)
desired_map_flags |= BPF_F_RDONLY_PROG;
// The .h file enforces that this is a power of two, and page size will
// also always be a power of two, so this logic is actually enough to
// force it to be a multiple of the page size, as required by the kernel.
unsigned int desired_max_entries = mapDef.max_entries;
if (mapDef.type == BPF_MAP_TYPE_RINGBUF) {
if (desired_max_entries < page_size) desired_max_entries = page_size;
}
// The following checks should *never* trigger, if one of them somehow does,
// it probably means a bpf .o file has been changed/replaced at runtime
// and bpfloader was manually rerun (normally it should only run *once*
// early during the boot process).
// Another possibility is that something is misconfigured in the code:
// most likely a shared map is declared twice differently.
// But such a change should never be checked into the source tree...
if ((fd_type == mapDef.type) &&
(fd_key_size == (int)mapDef.key_size) &&
(fd_value_size == (int)mapDef.value_size) &&
(fd_max_entries == (int)desired_max_entries) &&
(fd_map_flags == desired_map_flags)) {
return true;
}
ALOGE("bpf map name %s mismatch: desired/found: "
"type:%d/%d key:%u/%d value:%u/%d entries:%u/%d flags:%u/%d",
mapName.c_str(), mapDef.type, fd_type, mapDef.key_size, fd_key_size, mapDef.value_size,
fd_value_size, mapDef.max_entries, fd_max_entries, desired_map_flags, fd_map_flags);
return false;
}
static int createMaps(const char* elfPath, ifstream& elfFile, vector<unique_fd>& mapFds) {
int ret;
vector<char> mdData;
@ -558,11 +510,6 @@ static int createMaps(const char* elfPath, ifstream& elfFile, vector<unique_fd>&
if (!fd.ok()) return -saved_errno;
// When reusing a pinned map, we need to check the map type/sizes/etc match, but for
// safety (since reuse code path is rare) run these checks even if we just created it.
// We assume failure is due to pinned map mismatch, hence the 'NOT UNIQUE' return code.
if (!mapMatchesExpectations(fd, mapNames[i], md[i])) return -ENOTUNIQ;
if (!reuse) {
ret = bpfFdPin(fd, mapPinLoc.c_str());
if (ret) {