um: fix shutdown __inittext access

Since first moving __init text into the right place in commit
8966ed0b2d48 ("um: move init text between __init_begin/end")
and then making all init sections inaccessible, shutdown and
reboot crash instead of working correctly, for the obvious
reason that the functions are __init but run on the way out.

Removing the __init markers would work in some way, but that
would bubble through a lot of functions.

Instead, mark the relevant functions __noreturn (including
longjmp() since that's now needed so start_idle_thread() can
be __noreturn), and split out the part of main() that's done
on the way out into a new os_exit() function that's called
directly.

Reported-by: Hajime Tazaki <thehajime@gmail.com>
Closes: https://lore.kernel.org/linux-um/m24ifc4v6m.wl-thehajime@gmail.com/
Fixes: a418ab8fddea ("um: mprotect() __init memory")
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Tested-by: Hajime Tazaki <thehajime@gmail.com>
Link: https://patch.msgid.link/20260928093934.ca7af44c59ca.I470ece16d176ea704aa6e5767b755055d106da35@changeid
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

0 files changed, 0 insertions, 0 deletions