On Tue, Jan 19, 2016 at 1:55 PM, Al Viro <viro@xxxxxxxxxxxxxxxxxx> wrote: > On Tue, Jan 19, 2016 at 01:47:24PM -0800, Andy Lutomirski wrote: >> Essentially all users of is_compat_task in the kernel are trying to >> determine whether they are executing in the context of a compat >> syscall. On at least x86_64 and sparc, these are not at all the >> same question. >> >> On x86_64 and sparc, therefore, is_compat_task doesn't return the >> overall compat state of the task; it returns true if the task is >> currently in a compat syscall. > > The hell it does. Andy, TIF_32BIT is *NOT* set on syscall entry; it is > set by execve(). And 64bit task (with that bit clear) can bloody well > issue 32bit syscalls. Really. It does on x86. It does not on sparc. But syscall_get_arch on sparc *also* doesn't appear to work right. davem, how can I check the current syscall bitness on sparc? It's not obvious to me that it's possible. Everyone should consider this patch withdrawn until I figure out what's going on with sparc. --Andy -- To unsubscribe from this list: send the line "unsubscribe linux-arch" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
