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author | Linus Torvalds <torvalds@linux-foundation.org> | 2019-11-25 20:02:57 -0800 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2019-11-25 20:02:57 -0800 |
commit | 386403a115f95997c2715691226e11a7b5cffcfd (patch) | |
tree | a685df70bd3d5b295683713818ddf0752c3d75b6 /Documentation/bpf/s390.rst | |
parent | 642356cb5f4a8c82b5ca5ebac288c327d10df236 (diff) | |
parent | 622dc5ad8052f4f0c6b7a12787696a5caa3c6a58 (diff) |
Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next
Pull networking updates from David Miller:
"Another merge window, another pull full of stuff:
1) Support alternative names for network devices, from Jiri Pirko.
2) Introduce per-netns netdev notifiers, also from Jiri Pirko.
3) Support MSG_PEEK in vsock/virtio, from Matias Ezequiel Vara
Larsen.
4) Allow compiling out the TLS TOE code, from Jakub Kicinski.
5) Add several new tracepoints to the kTLS code, also from Jakub.
6) Support set channels ethtool callback in ena driver, from Sameeh
Jubran.
7) New SCTP events SCTP_ADDR_ADDED, SCTP_ADDR_REMOVED,
SCTP_ADDR_MADE_PRIM, and SCTP_SEND_FAILED_EVENT. From Xin Long.
8) Add XDP support to mvneta driver, from Lorenzo Bianconi.
9) Lots of netfilter hw offload fixes, cleanups and enhancements,
from Pablo Neira Ayuso.
10) PTP support for aquantia chips, from Egor Pomozov.
11) Add UDP segmentation offload support to igb, ixgbe, and i40e. From
Josh Hunt.
12) Add smart nagle to tipc, from Jon Maloy.
13) Support L2 field rewrite by TC offloads in bnxt_en, from Venkat
Duvvuru.
14) Add a flow mask cache to OVS, from Tonghao Zhang.
15) Add XDP support to ice driver, from Maciej Fijalkowski.
16) Add AF_XDP support to ice driver, from Krzysztof Kazimierczak.
17) Support UDP GSO offload in atlantic driver, from Igor Russkikh.
18) Support it in stmmac driver too, from Jose Abreu.
19) Support TIPC encryption and auth, from Tuong Lien.
20) Introduce BPF trampolines, from Alexei Starovoitov.
21) Make page_pool API more numa friendly, from Saeed Mahameed.
22) Introduce route hints to ipv4 and ipv6, from Paolo Abeni.
23) Add UDP segmentation offload to cxgb4, Rahul Lakkireddy"
* git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next: (1857 commits)
libbpf: Fix usage of u32 in userspace code
mm: Implement no-MMU variant of vmalloc_user_node_flags
slip: Fix use-after-free Read in slip_open
net: dsa: sja1105: fix sja1105_parse_rgmii_delays()
macvlan: schedule bc_work even if error
enetc: add support Credit Based Shaper(CBS) for hardware offload
net: phy: add helpers phy_(un)lock_mdio_bus
mdio_bus: don't use managed reset-controller
ax88179_178a: add ethtool_op_get_ts_info()
mlxsw: spectrum_router: Fix use of uninitialized adjacency index
mlxsw: spectrum_router: After underlay moves, demote conflicting tunnels
bpf: Simplify __bpf_arch_text_poke poke type handling
bpf: Introduce BPF_TRACE_x helper for the tracing tests
bpf: Add bpf_jit_blinding_enabled for !CONFIG_BPF_JIT
bpf, testing: Add various tail call test cases
bpf, x86: Emit patchable direct jump as tail call
bpf: Constant map key tracking for prog array pokes
bpf: Add poke dependency tracking for prog array maps
bpf: Add initial poke descriptor table for jit images
bpf: Move owner type, jited info into array auxiliary data
...
Diffstat (limited to 'Documentation/bpf/s390.rst')
-rw-r--r-- | Documentation/bpf/s390.rst | 205 |
1 files changed, 205 insertions, 0 deletions
diff --git a/Documentation/bpf/s390.rst b/Documentation/bpf/s390.rst new file mode 100644 index 000000000000..21ecb309daea --- /dev/null +++ b/Documentation/bpf/s390.rst @@ -0,0 +1,205 @@ +=================== +Testing BPF on s390 +=================== + +1. Introduction +*************** + +IBM Z are mainframe computers, which are descendants of IBM System/360 from +year 1964. They are supported by the Linux kernel under the name "s390". This +document describes how to test BPF in an s390 QEMU guest. + +2. One-time setup +***************** + +The following is required to build and run the test suite: + + * s390 GCC + * s390 development headers and libraries + * Clang with BPF support + * QEMU with s390 support + * Disk image with s390 rootfs + +Debian supports installing compiler and libraries for s390 out of the box. +Users of other distros may use debootstrap in order to set up a Debian chroot:: + + sudo debootstrap \ + --variant=minbase \ + --include=sudo \ + testing \ + ./s390-toolchain + sudo mount --rbind /dev ./s390-toolchain/dev + sudo mount --rbind /proc ./s390-toolchain/proc + sudo mount --rbind /sys ./s390-toolchain/sys + sudo chroot ./s390-toolchain + +Once on Debian, the build prerequisites can be installed as follows:: + + sudo dpkg --add-architecture s390x + sudo apt-get update + sudo apt-get install \ + bc \ + bison \ + cmake \ + debootstrap \ + dwarves \ + flex \ + g++ \ + gcc \ + g++-s390x-linux-gnu \ + gcc-s390x-linux-gnu \ + gdb-multiarch \ + git \ + make \ + python3 \ + qemu-system-misc \ + qemu-utils \ + rsync \ + libcap-dev:s390x \ + libelf-dev:s390x \ + libncurses-dev + +Latest Clang targeting BPF can be installed as follows:: + + git clone https://github.com/llvm/llvm-project.git + ln -s ../../clang llvm-project/llvm/tools/ + mkdir llvm-project-build + cd llvm-project-build + cmake \ + -DLLVM_TARGETS_TO_BUILD=BPF \ + -DCMAKE_BUILD_TYPE=Release \ + -DCMAKE_INSTALL_PREFIX=/opt/clang-bpf \ + ../llvm-project/llvm + make + sudo make install + export PATH=/opt/clang-bpf/bin:$PATH + +The disk image can be prepared using a loopback mount and debootstrap:: + + qemu-img create -f raw ./s390.img 1G + sudo losetup -f ./s390.img + sudo mkfs.ext4 /dev/loopX + mkdir ./s390.rootfs + sudo mount /dev/loopX ./s390.rootfs + sudo debootstrap \ + --foreign \ + --arch=s390x \ + --variant=minbase \ + --include=" \ + iproute2, \ + iputils-ping, \ + isc-dhcp-client, \ + kmod, \ + libcap2, \ + libelf1, \ + netcat, \ + procps" \ + testing \ + ./s390.rootfs + sudo umount ./s390.rootfs + sudo losetup -d /dev/loopX + +3. Compilation +************** + +In addition to the usual Kconfig options required to run the BPF test suite, it +is also helpful to select:: + + CONFIG_NET_9P=y + CONFIG_9P_FS=y + CONFIG_NET_9P_VIRTIO=y + CONFIG_VIRTIO_PCI=y + +as that would enable a very easy way to share files with the s390 virtual +machine. + +Compiling kernel, modules and testsuite, as well as preparing gdb scripts to +simplify debugging, can be done using the following commands:: + + make ARCH=s390 CROSS_COMPILE=s390x-linux-gnu- menuconfig + make ARCH=s390 CROSS_COMPILE=s390x-linux-gnu- bzImage modules scripts_gdb + make ARCH=s390 CROSS_COMPILE=s390x-linux-gnu- \ + -C tools/testing/selftests \ + TARGETS=bpf \ + INSTALL_PATH=$PWD/tools/testing/selftests/kselftest_install \ + install + +4. Running the test suite +************************* + +The virtual machine can be started as follows:: + + qemu-system-s390x \ + -cpu max,zpci=on \ + -smp 2 \ + -m 4G \ + -kernel linux/arch/s390/boot/compressed/vmlinux \ + -drive file=./s390.img,if=virtio,format=raw \ + -nographic \ + -append 'root=/dev/vda rw console=ttyS1' \ + -virtfs local,path=./linux,security_model=none,mount_tag=linux \ + -object rng-random,filename=/dev/urandom,id=rng0 \ + -device virtio-rng-ccw,rng=rng0 \ + -netdev user,id=net0 \ + -device virtio-net-ccw,netdev=net0 + +When using this on a real IBM Z, ``-enable-kvm`` may be added for better +performance. When starting the virtual machine for the first time, disk image +setup must be finalized using the following command:: + + /debootstrap/debootstrap --second-stage + +Directory with the code built on the host as well as ``/proc`` and ``/sys`` +need to be mounted as follows:: + + mkdir -p /linux + mount -t 9p linux /linux + mount -t proc proc /proc + mount -t sysfs sys /sys + +After that, the test suite can be run using the following commands:: + + cd /linux/tools/testing/selftests/kselftest_install + ./run_kselftest.sh + +As usual, tests can be also run individually:: + + cd /linux/tools/testing/selftests/bpf + ./test_verifier + +5. Debugging +************ + +It is possible to debug the s390 kernel using QEMU GDB stub, which is activated +by passing ``-s`` to QEMU. + +It is preferable to turn KASLR off, so that gdb would know where to find the +kernel image in memory, by building the kernel with:: + + RANDOMIZE_BASE=n + +GDB can then be attached using the following command:: + + gdb-multiarch -ex 'target remote localhost:1234' ./vmlinux + +6. Network +********** + +In case one needs to use the network in the virtual machine in order to e.g. +install additional packages, it can be configured using:: + + dhclient eth0 + +7. Links +******** + +This document is a compilation of techniques, whose more comprehensive +descriptions can be found by following these links: + +- `Debootstrap <https://wiki.debian.org/EmDebian/CrossDebootstrap>`_ +- `Multiarch <https://wiki.debian.org/Multiarch/HOWTO>`_ +- `Building LLVM <https://llvm.org/docs/CMake.html>`_ +- `Cross-compiling the kernel <https://wiki.gentoo.org/wiki/Embedded_Handbook/General/Cross-compiling_the_kernel>`_ +- `QEMU s390x Guest Support <https://wiki.qemu.org/Documentation/Platforms/S390X>`_ +- `Plan 9 folder sharing over Virtio <https://wiki.qemu.org/Documentation/9psetup>`_ +- `Using GDB with QEMU <https://wiki.osdev.org/Kernel_Debugging#Use_GDB_with_QEMU>`_ |