On Fri, Mar 25, 2016 at 8:58 AM, Dave Jones <da...@codemonkey.org.uk> wrote: > On Fri, Mar 25, 2016 at 08:51:39AM -0700, Andy Lutomirski wrote: > > On Fri, Mar 25, 2016 at 8:48 AM, Dave Jones <da...@codemonkey.org.uk> > wrote: > > > I had a trinity process get stuck last overnight. > > > The reason for it getting stuck is my bug (I think), but > > > there's an odd unrelated thing I noticed while debugging this.. > > > > > > $ strace -p 20966 > > > strace: Process 20966 attached > > > strace: [ Process PID=20966 runs in x32 mode. ] > > > > > > So I don't use that new-fangled x32 stuff. > > > I don't even have CONFIG_X86_X32 compiled in. > > > > > > Is this strace getting confused, or did we somehow screw > > > up the syscall entry code ? > > > > > > Dave > > > > > > > I think you're just seeing an oddity of how x32 works. Unlike > > "compat", x32-ness of the current syscall isn't a special magic state > > variable; it's just but 31 in the syscall nr. So trying to do an x32 > > syscall on a non-x32 syscall should still show bit 31 set to ptracers, > > and the strace probably decodes this as being in x32 mode. > > But this is an x86-64 binary, and it's the main process, not one of the > fuzzing > child processes. It shouldn't be even trying to do anything weird. > It creates a bunch of fd's, then enters a loop forking/reaping children. > (In this case it actually hung while creating the fd's) > > Trinity doesn't actually have any knowledge of x32 at all, mostly because > it's been irrelevant to me (and most other people). >
Hmm. Do you have the next couple lines of strace output by any chance? I'm wondering if this is a classic bug/misfeature/confusion in the way that orig_ax works. FWIW, the way that strace detects 32-bit mode is bogus, and I don't actually know how strace detects x32 mode. > Dave > > -- Andy Lutomirski AMA Capital Management, LLC
