On Tue, Mar 21, 2017 at 11:09 AM, Dmitry Safonov <dsafonov@xxxxxxxxxxxxx> wrote: > On 03/21/2017 08:45 PM, Andy Lutomirski wrote: >> >> On Tue, Mar 21, 2017 at 10:17 AM, Cyrill Gorcunov <gorcunov@xxxxxxxxx> >> wrote: >>> >>> On Tue, Mar 21, 2017 at 07:37:12PM +0300, Dmitry Safonov wrote: >>> ... >>>> >>>> diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c >>>> index d6b784a5520d..d3d4d9abcaf8 100644 >>>> --- a/arch/x86/kernel/process_64.c >>>> +++ b/arch/x86/kernel/process_64.c >>>> @@ -519,8 +519,14 @@ void set_personality_ia32(bool x32) >>>> if (current->mm) >>>> current->mm->context.ia32_compat = TIF_X32; >>>> current->personality &= ~READ_IMPLIES_EXEC; >>>> - /* in_compat_syscall() uses the presence of the x32 >>>> - syscall bit flag to determine compat status */ >>>> + /* >>>> + * in_compat_syscall() uses the presence of the x32 >>>> + * syscall bit flag to determine compat status. >>>> + * On the bitness of syscall relies x86 mmap() code, >>>> + * so set x32 syscall bit right here to make >>>> + * in_compat_syscall() work during exec(). >>>> + */ >>>> + task_pt_regs(current)->orig_ax |= __X32_SYSCALL_BIT; >>>> current->thread.status &= ~TS_COMPAT; >>> >>> >>> Hi! I must admit I didn't follow close the overall series (so can't >>> comment much here :) but I have a slightly unrelated question -- is >>> there a way to figure out if task is running in x32 mode say with >>> some ptrace or procfs sign? >> >> >> You should be able to figure out of a *syscall* is x32 by simply >> looking at bit 30 in the syscall number. (This is unlike i386, which >> is currently not reflected in ptrace.) > > > The process could be stopped with PTRACE_SEIZE and I think, it'll not > have x32 syscall bit at that moment. > > I guess the question comes from that we're releasing CRIU 3.0 with > 32-bit C/R and some other cool stuff, but we don't support x32 yet. > As we don't want release a thing that we aren't properly testing. > So for a while we should error on dumping x32 applications. I'm curious: shouldn't x32 CRIU just work? What goes wrong? --Andy -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>
