broken signal handling in nios2 user-mode emulation

[Sandra Loosemore]

This bug is against the 3.0 release.

It appears that the signal handling parts of the nios2 user-mode emulation have never really been completed or tested. Some examples of failing tests from the GCC testsuite are gcc.dg/pr78185.c and gcc.dg/cleanup-10.c.

Some problems I've identified and tried to fix with the attached patch are:

- Code copied from the Linux kernel wasn't adjusted to differentiate between host and target data types and address spaces.

- The sigaltstack() system call returns EINVAL because fields are listed in the wrong order in struct target_sigaltstack.

With this patch, the system calls to set up the signal handler are returning successfully, but the handler isn't being invoked, so something is still wrong. I think I need another pair of eyes to look over this code.

[Thomas Huth (th-huth)]

The QEMU project is currently considering to move its bug tracking to another system. For this we need to know which bugs are still valid and which could be closed already. Thus we are setting older bugs to "Incomplete" now.
If you still think this bug report here is valid, then please switch the state back to "New" within the next 60 days, otherwise this report will be marked as "Expired". Or mark it as "Fix Released" if the problem has been solved with a newer version of QEMU already. Thank you and sorry for the inconvenience.

[Peter Maydell (pmaydell)]

A quick eyeball of the patch and the current QEMU tree indicates that at least some of the bugs it's trying to fix still exist (notably a lot of use of "long" in various target_* structures, which should not be using types with a width dependent on the host system.)

[Thomas Huth (th-huth)]

This is an automated cleanup. This bug report has been moved to QEMU's
new bug tracker on gitlab.com and thus gets marked as 'expired' now.
Please continue with the discussion here:

 https://gitlab.com/qemu-project/qemu/-/issues/261