Commit ae8a76fb authored by David S. Miller's avatar David S. Miller
Browse files

Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next 



Alexei Starovoitov says:

====================
pull-request: bpf-next 2019-11-02

The following pull-request contains BPF updates for your *net-next* tree.

We've added 30 non-merge commits during the last 7 day(s) which contain
a total of 41 files changed, 1864 insertions(+), 474 deletions(-).

The main changes are:

1) Fix long standing user vs kernel access issue by introducing
   bpf_probe_read_user() and bpf_probe_read_kernel() helpers, from Daniel.

2) Accelerated xskmap lookup, from Björn and Maciej.

3) Support for automatic map pinning in libbpf, from Toke.

4) Cleanup of BTF-enabled raw tracepoints, from Alexei.

5) Various fixes to libbpf and selftests.
====================

Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parents d31e9558 358fdb45

Documentation/bpf/index.rst

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Original line number Diff line number Diff line
@@ -47,6 +47,15 @@ Program types 
   prog_flow_dissector





Testing BPF

===========



.. toctree::

   :maxdepth: 1



   s390





.. Links:

.. _Documentation/networking/filter.txt: ../networking/filter.txt

.. _man-pages: https://www.kernel.org/doc/man-pages/

Documentation/bpf/s390.rst

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===================

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>`_

arch/x86/mm/Makefile

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@@ -13,7 +13,7 @@ CFLAGS_REMOVE_mem_encrypt_identity.o = -pg 
endif



obj-y	:=  init.o init_$(BITS).o fault.o ioremap.o extable.o pageattr.o mmap.o \

	    pat.o pgtable.o physaddr.o setup_nx.o tlb.o cpu_entry_area.o

	    pat.o pgtable.o physaddr.o setup_nx.o tlb.o cpu_entry_area.o maccess.o



# Make sure __phys_addr has no stackprotector

nostackp := $(call cc-option, -fno-stack-protector)

arch/x86/mm/maccess.c

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// SPDX-License-Identifier: GPL-2.0-only



#include <linux/uaccess.h>

#include <linux/kernel.h>



#ifdef CONFIG_X86_64

static __always_inline u64 canonical_address(u64 vaddr, u8 vaddr_bits)

{

	return ((s64)vaddr << (64 - vaddr_bits)) >> (64 - vaddr_bits);

}



static __always_inline bool invalid_probe_range(u64 vaddr)

{

	/*

	 * Range covering the highest possible canonical userspace address

	 * as well as non-canonical address range. For the canonical range

	 * we also need to include the userspace guard page.

	 */

	return vaddr < TASK_SIZE_MAX + PAGE_SIZE ||

	       canonical_address(vaddr, boot_cpu_data.x86_virt_bits) != vaddr;

}

#else

static __always_inline bool invalid_probe_range(u64 vaddr)

{

	return vaddr < TASK_SIZE_MAX;

}

#endif



long probe_kernel_read_strict(void *dst, const void *src, size_t size)

{

	if (unlikely(invalid_probe_range((unsigned long)src)))

		return -EFAULT;



	return __probe_kernel_read(dst, src, size);

}



long strncpy_from_unsafe_strict(char *dst, const void *unsafe_addr, long count)

{

	if (unlikely(invalid_probe_range((unsigned long)unsafe_addr)))

		return -EFAULT;



	return __strncpy_from_unsafe(dst, unsafe_addr, count);

}

include/linux/bpf.h

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Original line number Diff line number Diff line
@@ -373,6 +373,11 @@ enum bpf_cgroup_storage_type { 


#define MAX_BPF_CGROUP_STORAGE_TYPE __BPF_CGROUP_STORAGE_MAX



/* The longest tracepoint has 12 args.

 * See include/trace/bpf_probe.h

 */

#define MAX_BPF_FUNC_ARGS 12



struct bpf_prog_stats {

	u64 cnt;

	u64 nsecs;
@@ -1004,31 +1009,6 @@ static inline int sock_map_get_from_fd(const union bpf_attr *attr, 
}

#endif



#if defined(CONFIG_XDP_SOCKETS)

struct xdp_sock;

struct xdp_sock *__xsk_map_lookup_elem(struct bpf_map *map, u32 key);

int __xsk_map_redirect(struct bpf_map *map, struct xdp_buff *xdp,

		       struct xdp_sock *xs);

void __xsk_map_flush(struct bpf_map *map);

#else

struct xdp_sock;

static inline struct xdp_sock *__xsk_map_lookup_elem(struct bpf_map *map,

						     u32 key)

{

	return NULL;

}



static inline int __xsk_map_redirect(struct bpf_map *map, struct xdp_buff *xdp,

				     struct xdp_sock *xs)

{

	return -EOPNOTSUPP;

}



static inline void __xsk_map_flush(struct bpf_map *map)

{

}

#endif



#if defined(CONFIG_INET) && defined(CONFIG_BPF_SYSCALL)

void bpf_sk_reuseport_detach(struct sock *sk);

int bpf_fd_reuseport_array_lookup_elem(struct bpf_map *map, void *key,

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