** Tags added: patch

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https://bugs.launchpad.net/bugs/1988592

Title:
  [5.4.1089, arm64] eBPF opensnoop does not display PATH

Status in linux-azure package in Ubuntu:
  New

Bug description:
  Hi.

  FIrst, I hope you are fine and the same for your relatives.

  The actual kernel used on AKS arm64 (i.e. 5.4.1089) suffers from this problem:
  https://github.com/iovisor/bcc/issues/2253
  As a consequence, opensnoop does not display PATH:
  # Run the following from 
Canonical:UbuntuServer:18_04-daily-lts-arm64:18.04.202208290
  $ uname -a
  Linux francis-vm-arm64-ubuntu18vm 5.4.0-1089-azure #94~18.04.1-Ubuntu SMP Fri 
Aug 5 12:36:48 UTC 2022 aarch64 aarch64 aarch64 GNU/Linux
  $ lsb_release -rd
  Description:    Ubuntu 18.04.6 LTS
  Release:        18.04
  $ git clone --recurse-submodules https://github.com/iovisor/bcc
  Linux francis-vm-arm64-ubuntu18vm 5.4.0-1089-azure #94~18.04.1-Ubuntu SMP Fri 
Aug 5 12:36:48 UTC 2022 aarch64 aarch64 aarch64 GNU/Linux
  $ sudo sh -c 'apt update && apt install -qy clang-10 llvm-10 make gcc 
pkg-config libelf-dev libz-dev'
  ...
  $ cd bcc/libbpf-tools
  $ CLANG=clang-10 LLVM_STRIP=llvm-strip-10 make -j opensnoop
  ...
  BINARY opensnoop
  $ sudo ./opensnoop
  PID    COMM              FD ERR PATH
  1672   python3            3   0
  9746   opensnoop         20   0
  1672   python3            3   0
  1672   python3            3   0
  1672   python3           -1   2
  1672   python3            3   0
  1      systemd           18   0
  1672   python3            6   0
  1672   python3            3   0
  1672   python3            3   0
  1672   python3            3   0
  1672   python3            3   0
  1672   python3            3   0
  ^C
  As you can see, nothing is printed for the PATH while normal behavior prints 
the path of the opened file:
  $ uname -a
  Linux pwmachine 5.15.0-46-generic #49~20.04.1-Ubuntu SMP Thu Aug 4 19:15:44 
UTC 2022 x86_64 x86_64 x86_64 GNU/Linux
  $ sudo ./opensnoop
  PID    COMM              FD ERR PATH
  2704   systemd           23   0 virtual
  2704   systemd           22   0 misc
  2704   systemd           23   0 fuse
  2704   systemd           22   0 /sys/devices/virtual/misc/fuse/uevent
  2704   systemd           22   0 /run/udev/data/c10:229
  2704   systemd           22   0 /proc/2704/status
  2704   systemd           22   0 /proc/2704/status
  2704   systemd           22   0 /proc/2704/status
  ^C

  This bug was fixed in upstream patch:
  
https://github.com/torvalds/linux/commit/6ae08ae3dea2cfa03dd3665a3c8475c2d429ef47
  Sadly, this patch was not back ported, so it is not present in stable kernels.

  I backported the patches myself (see attachment) and was able to build the 
kernel package with the following command:
  sudo LANG=C $(dpkg-architecture -aarm64) CROSS_COMPILE=aarch64-linux-gnu- 
fakeroot debian/rules binary skipdbg=false
  Sadly, I was not able to successfully boot it on Azure, either by installing 
the package or using kexec.
  I suspect this is because my image is not signed.

  Best regards and thank you in advance.

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