Backport support for fs_base/gs_base and $_siginfo from GDB master.
Bring in two patchsets committed to GDB master along with a few other commits
those patchsets depend on.
- Add support for examining $_siginfo. When a thread has valid signal information, report the current information in a $_siginfo variable. For live processes the values are extracted via the PT_LWPINFO ptrace request. The values are also extracted from process core dumps that include NT_LWPINFO notes (currently only present in FreeBSD 12-current).
- Add support for the $fs_base and $gs_base registers on amd64. This only works for live processes via the PT_{GET,SET}{FS,GS}BASE ptrace requests. FreeBSD currently does not store these values in core dumps, so they are not available from core dumps.
Reviewed by: luca.pizzamiglio@gmail.com (maintainer)
Approved by: az, imp
Differential Revision: https://reviews.freebsd.org/D11813