[Bug 2041396] Autopkgtest regression report (gdb/12.1-0ubuntu1~22.04.1)

[Ubuntu SRU Bot]

All autopkgtests for the newly accepted gdb (12.1-0ubuntu1~22.04.1) for jammy have finished running.
The following regressions have been reported in tests triggered by the package:

linux-aws-5.19/5.19.0-1029.30~22.04.1 (arm64)
linux-aws-6.2/6.2.0-1015.15~22.04.1 (arm64)
linux-azure-5.19/5.19.0-1027.30~22.04.2 (arm64)
linux-azure-6.2/6.2.0-1016.16~22.04.1 (arm64)
linux-azure-6.5/6.5.0-1007.7~22.04.1 (arm64)
linux-gcp-5.19/5.19.0-1030.32~22.04.1 (arm64)
linux-gcp-6.2/6.2.0-1018.20~22.04.1 (arm64)
linux-gke/5.15.0-1046.51 (arm64)
linux-hwe-5.19/5.19.0-50.50 (arm64)
linux-hwe-6.2/6.2.0-39.40~22.04.1 (arm64)
linux-lowlatency/5.15.0-91.101 (arm64)
linux-lowlatency-hwe-5.19/5.19.0-1030.30 (arm64)
linux-lowlatency-hwe-6.2/6.2.0-1018.18~22.04.1 (arm64)
linux-nvidia-tegra/5.15.0-1019.19 (arm64)
linux-oracle-5.19/5.19.0-1027.30 (arm64)


Please visit the excuses page listed below and investigate the failures, proceeding afterwards as per the StableReleaseUpdates policy regarding autopkgtest regressions [1].

https://people.canonical.com/~ubuntu-archive/proposed-
migration/jammy/update_excuses.html#gdb

[1] https://wiki.ubuntu.com/StableReleaseUpdates#Autopkgtest_Regressions

Thank you!

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https://bugs.launchpad.net/bugs/2041396

Title:
  gdb 12.1 generates SIGILL on armhf

Status in gdb:
  Fix Released
Status in gdb package in Ubuntu:
  Fix Released
Status in gdb source package in Jammy:
  Fix Committed

Bug description:
  [ Impact ]

   * GDB 12.1 introduced a regression where it will break program execution when the program contains mixed ARM code and THUMB code.
   * Upstream stated they tested the changes on Ubuntu 20.04 and it went okay.

  [ Test Plan ]

  Considering the following C program:

  ```
  __attribute__((target("arm"), noinline))
  int thumb_func() {
    return 42;
  }

  __attribute__((target("thumb")))
  int main() { return thumb_func(); }
  ```

  If you build it using `gcc repro.c -ggdb3 -Og -o repro` and run the
  GDB using the following commands ...

  ```
  b 3
  r
  c
  ```

  (you can save the contents above to a file and run GDB using `gdb -x
  script ./repro`)

  ... you will notice GDB broke the program and threw SIGILL.
  If you run the program without GDB, the program exits normally.

  [ Where problems could occur ]

   * GDB is a complex software. As the patch suggests, it may break other use cases (like single-stepping) entirely.
   * Since this is an ARM-only patch, it's unlikely to affect other CPU architectures. However, it is possible that this fix may break ARM64 execution.

  [ Other Info ]
   
   * This bug has been fixed in GDB 13, but the fix was never backported to GDB 12. You can find the upstream bug in the remote bug watch.

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