On Wed, 30 Oct 2024 18:25:18 +0900, Hajime Tazaki wrote: > > > > > > - a crash on userspace programs crashes a UML kernel, not signaling > > > > > with SIGSEGV to the program.
after investigation with trying to save/restore FP registers, I found the register is not the reason that userspace programs cannot handle/recover with SIGSEGV. the cause is; I tried to call (!MMU version of) userspace() in segv() function if is_user == 1 (I configured the variable based on the address of $rip), but without returning hard_handler(), which is caller of segv(), SIGIO has been blocked even after switching the userspace process. Thus no console input is processed. With that issue, I didn't include the patch to mark is_user = 1, resulting kernel exit with panic(). I unblock signals (IO/WINCH/ALRM) after segv() && is_user==1, then the userspace can recover/handle the SEGV signal. I will try to implement this in a cleaner way. Thanks for your comment, -- Hajime
