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bpfloader - remove dead code

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As with Android U we know the kernel is at least 4.14

Test: TreeHugger
Signed-off-by: Maciej Żenczykowski <maze@google.com>
Change-Id: I789d5e8c9b0fe9e2200f716034d1ec1151f258dc
This commit is contained in:
Maciej Żenczykowski 2022-10-25 09:20:55 +00:00
commit 90a866ed34
1 changed files with 2 additions and 21 deletions
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23
libbpf_android/Loader.cpp
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@ -30,9 +30,9 @@
#include <sys/wait.h>
#include <unistd.h>
// This is BpfLoader v0.28
// This is BpfLoader v0.29
#define BPFLOADER_VERSION_MAJOR 0u
#define BPFLOADER_VERSION_MINOR 28u
#define BPFLOADER_VERSION_MINOR 29u
#define BPFLOADER_VERSION ((BPFLOADER_VERSION_MAJOR << 16) | BPFLOADER_VERSION_MINOR)
#include "bpf/BpfUtils.h"
@ -648,15 +648,6 @@ static std::optional<unique_fd> getMapBtfInfo(const char* elfPath,
static bool mapMatchesExpectations(const unique_fd& fd, const string& mapName,
const struct bpf_map_def& mapDef, const enum bpf_map_type type) {
// bpfGetFd... family of functions require at minimum a 4.14 kernel,
// so on 4.9 kernels just pretend the map matches our expectations.
// This isn't really a problem as we only really support 4.14+ anyway...
// Additionally we'll get almost equivalent test coverage on newer devices/kernels.
// This is because the primary failure mode we're trying to detect here
// is either a source code misconfiguration (which is likely kernel independent)
// or a newly introduced kernel feature/bug (which is unlikely to get backported to 4.9).
if (!isAtLeastKernelVersion(4, 14, 0)) return true;
// 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),
@ -777,16 +768,6 @@ static int createMaps(const char* elfPath, ifstream& elfFile, vector<unique_fd>&
}
enum bpf_map_type type = md[i].type;
if (type == BPF_MAP_TYPE_DEVMAP && !isAtLeastKernelVersion(4, 14, 0)) {
// On Linux Kernels older than 4.14 this map type doesn't exist, but it can kind
// of be approximated: ARRAY has the same userspace api, though it is not usable
// by the same ebpf programs. However, that's okay because the bpf_redirect_map()
// helper doesn't exist on 4.9 anyway (so the bpf program would fail to load,
// and thus needs to be tagged as 4.14+ either way), so there's nothing useful you
// could do with a DEVMAP anyway (that isn't already provided by an ARRAY)...
// Hence using an ARRAY instead of a DEVMAP simply makes life easier for userspace.
type = BPF_MAP_TYPE_ARRAY;
}
if (type == BPF_MAP_TYPE_DEVMAP_HASH && !isAtLeastKernelVersion(5, 4, 0)) {
// On Linux Kernels older than 5.4 this map type doesn't exist, but it can kind
// of be approximated: HASH has the same userspace visible api.