Am 01.04.21 um 17:39 schrieb Linus Torvalds: > On Thu, Apr 1, 2021 at 7:58 AM Stefan Metzmacher <metze@xxxxxxxxx> wrote: >> >>> >>> Ok, the following makes gdb happy again: >>> >>> --- a/arch/x86/kernel/process.c >>> +++ b/arch/x86/kernel/process.c >>> @@ -163,6 +163,8 @@ int copy_thread(unsigned long clone_flags, unsigned long sp, unsigned long arg, >>> /* Kernel thread ? */ >>> if (unlikely(p->flags & (PF_KTHREAD | PF_IO_WORKER))) { >>> memset(childregs, 0, sizeof(struct pt_regs)); >>> + if (p->flags & PF_IO_WORKER) >>> + childregs->cs = current_pt_regs()->cs; >>> kthread_frame_init(frame, sp, arg); >>> return 0; >>> } >> >> Would it be possible to fix this remaining problem before 5.12 final? > > Please not that way. > > But doing something like > > childregs->cs = __USER_CS; > childregs->ss = __USER_DS; > childregs->ds = __USER_DS; > childregs->es = __USER_DS; > > might make sense (just do it unconditionally, rather than making it > special to PF_IO_WORKER). > > Does that make gdb happy too? I haven't tried it, but it seems gdb tries to use PTRACE_PEEKUSR against the last thread tid listed under /proc/<pid>/tasks/ in order to get the architecture for the userspace application, so my naive assumption would be that it wouldn't allow the detection of a 32-bit application using a 64-bit kernel. metze