[Bug 2041396] Re: gdb 12.1 generates SIGILL on armhf

[Zixing Liu]

> The where problems could occur section says "it is possible that this
fix may break ARM64 execution". How was it verified that this is not
broken?

I believe this could be verified by running the GDB tests inside the Rust testing suite.
Should I queue an autopkgtest against rustc for GDB in this case?

-- 
You received this bug notification because you are a member of Ubuntu
Foundations Bugs, which is subscribed to gdb in Ubuntu.
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:
  Incomplete

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.

To manage notifications about this bug go to:
https://bugs.launchpad.net/gdb/+bug/2041396/+subscriptions