x86 has 2 obvious ABIs:
32-bit registers/pointers/system calls (i386/i486/i586/i686)
64-bit registers/pointers/system calls (amd64 / x86_64)
but there also exists a third:
the memory optimizing hybrid 'x32' which uses 64-bit registers,
with 32-bit pointers, and 64-bit system calls (with minor tweaks).
(there is also technically an aarch64/arm64-ilp32 ABI mirroring x32)
Note: It would probably be trivial to add support if we wanted to.
Test: TreeHugger
Signed-off-by: Maciej Żenczykowski <maze@google.com>
Change-Id: I82138c5bafbc3bd37cad98eeb79441701d94c386
Consumer pos is only written to by userspace (except for
initialization), so reading from it does not require a memory barrier.
This change also moves producer pos to be acquired before anything else
and marks start_ptr as volatile, so it is only read once.
Test: atest BpfRingbufTest
Change-Id: I228578ef4b42c1732646f0ae928b9a0aa2445304
This change adds support for 32 bit kernels by capping mProducerPos to
4 bytes. mConsumerPos (which is written to by userspace) continues to
use 8 bytes. (This can be done because an entire page is allocated for
mConsumerPos to control access permissions). In a 32 bit kernel, that
means that the top order bits are just ignored. In addition, comparisons
in userspace only use the bottom 4 bytes to be bitness agnostic.
Test: atest BpfRingbufTest
Change-Id: I7fe6d9000a151512785f1aa2a53fa97d31967d19
Both consumer and producer position are wrapped in an std::atomic and
extended to uint64_t to enforce atomic access.
See resulting assembly instructions for aosp_cf_x86_phone-userdebug:
frameworks/libs/net/common/native/bpf_headers/include/bpf/BpfRingbuf.h:212
2d: 8b 41 18 mov 0x18(%ecx),%eax
external/libcxx/include/atomic:926 (discriminator 4)
30: f3 0f 7e 00 movq (%eax),%xmm0
This will not work on a 32 bit kernel (so we might want to explicitly
check for that in the test).
Test: atest BpfRingbufTest
Change-Id: I7fec435cbe49d392363d05f7e702d82ecacb9e91
I found this comment in aosp/2103424 helpful in figuring out the correct
selinux domain for a newly added map.
Test: documentation only change
Change-Id: I96c06ff33605c8ed3f2ae6e8810bbcdc8e66b51b
These were copied from
system/core/libsysutils/src/NetlinkEvent.cpp and the following changes
were applied:
- Mark isUserspace64bit as constexpr.
- Added __unused annotations
- Fixed a typo (s/meaningul/meaningful)
Test: TH
Change-Id: Ia0b8e6e02daca7e9b69f337a494d88eb1beffc22
(they're only of historical interest at this point)
Test: TreeHugger
Signed-off-by: Maciej Żenczykowski <maze@google.com>
Change-Id: I0e52efda62626091c3023c5fd3622ffcdcd00ee1
This is the default for BPFLOADER_MIN_VER if not otherwise specified.
This does not affect mainline code, see:
cs/p:aosp-master file:packages/modules/Connectivity/bpf_progs define.*BPFLOADER_MIN_VER
Test: TreeHugger
Signed-off-by: Maciej Żenczykowski <maze@google.com>
Change-Id: Ice5b14c3b580653f8889a5292abaa89cf8434da1
Since it just came up again, and I just verified this still works
Test: N/A
Signed-off-by: Maciej Żenczykowski <maze@google.com>
Change-Id: I292c94cf9af63488ed30a6ac367ac83c8912e97e
(and a few minor cleanups while at it)
Test: TreeHugger
Signed-off-by: Maciej Żenczykowski <maze@google.com>
Change-Id: I657c3314fb0ad2519dc4d1b0743e1be6a81a887a
This implements the bare minimum to read from BPF ring buffers in
userspace. The implementation uses two shared memory regions with
atomic-like access. Currently, the class only guarantees that the
element type has the same size (later can add btf support).
The alternative would be to use libbpf or bcc, but since this is a small
header-only library that seemed like it could end up being more
difficulty than it was worth.
Bug: 246985031
Test: atest libbpf_android_test
Change-Id: I7f08e76db9cb9672ef66c629bccb3db63d3c2229
This is similar to https://r.android.com/2374598 for maps.
Bug: 246985031
Test: build connectivity module
Change-Id: Id4c9f93b69e808d461b4554bf3fa591828635dd1
This updates the ringbuffer and program helpers to allow specifying
which platform builds they are ignored on. In order to use this, you
must specify a min loader version >= 0.32, so the helpers also add
options for setting this at the program/ringbuf level.
Bug: 246985031
Test: tethering build & install, full platform build & install
Change-Id: I6bf9f7945c3fbac8fd4e02b5805016ac275b7884
see kernel's
samples/bpf/bpf_helpers.h
or
tools/testing/selftests/bpf/bpf_legacy.h
Test: TreeHugger
Signed-off-by: Maciej Żenczykowski <maze@google.com>
Change-Id: Id331fb9abcd87df8bf87c5a86749acf0144ffbde
This is basically a no-op, but will make future compatibility checks easier.
The programs/maps already won't load on a bpfloader outside of
this range, as the entire .o will be skipped.
Test: TreeHugger
Signed-off-by: Maciej Żenczykowski <maze@google.com>
Change-Id: I0669c7ff9e04e24a8da68aa821c9ad705a8f5a93
(this should avoid kernel reading/writing from out of bounds)
Test: TreeHugger
Signed-off-by: Maciej Żenczykowski <maze@google.com>
Change-Id: I71fe71eee4e4e6a917477eef5fd2266439e803f3
This feature allows skipping a program or map based on the type of the
build. This allows things like userdebug-only programs.
Bug: 246985031
Test: added test program and watched it skipped on userdebug
Change-Id: I5cd9725ad8f133c98c86e6ba620a266313055157
There is only user left, let us simply move the macro
definition into the resolv_integration_test.cpp file.
Test: TreeHugger
Signed-off-by: Maciej Żenczykowski <maze@google.com>
Change-Id: I6eb66abaa7f6392ab43300e5087e4277491e44c9
This adds a BPF program with a ring buffer and an associated test that
ensures the program and ring buffer can be loaded by the bpf loader. In
the following changes, this foundation will be used to test the user
space ring buffer wrapper class.
Unlike BpfMap, userspace can't (easily) write to the ring buffer so the
most accurate way to test a userspace ring buffer implementation is to
write to it from a BPF program.
Note: the BPF program in this change is never actually attached to a
cgroup, it is only loaded. The program will be executed manually using
BPF_PROG_RUN which is "side-effect free" (it can have side effects on
BPF maps, but not on Kernel state, e.g. dropping packets).
Bug: 246985031
Test: atest libbpf_android_test
Change-Id: Ib9c591218188f5f358a755c8854bc6f87d26af12
_EXT suffix is used for the all-args versions of these, such as the one
here.
Bug: 246985031
Test: build and flash on 4.19 and 5.10
Change-Id: Ibd76cbdc38f4d1f9df4f440147e5f18d9a2ea026
BPF ring buffers are defined like maps, but cannot specify a key or
value size (attempting to do so is a verifier error). This change also
adds the type-safe methods for interacting with the map (output, reserve
and submit).
Bug: 246985031
Test: local run of Network Tracing w/ ring buffers
Change-Id: Ie8a47d987be6cb219fe7d73f2c61a56e3a3ab21a
